Testing apparatus and method for testing susceptor arrangements under simulated heating conditions - Patents.com

Abstract

The present invention relates to a testing apparatus and method for testing a susceptor arrangement under simulated heating conditions of a heated susceptor arrangement disposed in an aerosol generating device during a user experience. The testing apparatus comprises a holder module comprising a holder for receiving the susceptor arrangement to be tested, a control module comprising an induction heating arrangement and a measurement device comprising a control circuit, the induction heating arrangement being configured to generate an alternating magnetic field for inductively heating the susceptor arrangement. The measurement device is configured to determine a value associated with a physical property of the susceptor arrangement from measurements related to a load applied to the control circuit in response to the susceptor arrangement being in operative communication with the induction heating arrangement, the control circuit being configured to power the induction heating arrangement during one test cycle or several subsequent test cycles of the susceptor arrangement, and configured to determine whether the determined value associated with the physical property of the susceptor arrangement corresponds to a predetermined susceptor value.

Description

[Technical field]

[0001] The present invention relates to a testing apparatus and method for testing a susceptor arrangement under simulated heating conditions of a heated susceptor arrangement disposed within an aerosol generating device during a user experience. [Background technology]

[0002] Articles comprising an aerosol-forming substrate and a heating element in the form of a susceptor for heating the substrate and generating an aerosol are generally known from the prior art. The material parameters of the susceptor need to be within very specific ranges for optimized performance of the susceptor and according to the aerosol generation. However, especially in multi-layer susceptor arrangements, the physical material parameters of the susceptor may be too complex to link to the required or necessary susceptor performance. Thus, for example, the individual material parameters provided by the susceptor supplier are often not sufficient to characterize the heating performance of the multi-layer susceptor arrangement.

[0003] There is therefore a need for a testing apparatus and method that allows testing of susceptor arrangements, particularly multi-layer susceptor arrangements, under simulated and realistic conditions. Summary of the Invention

[0004] According to the present invention, a testing apparatus is provided for testing a susceptor arrangement under simulated heating conditions of a heated susceptor arrangement disposed in an aerosol generating device during a user experience. The testing apparatus comprises a holder module comprising a holder for receiving the susceptor arrangement to be tested, and a control module comprising an induction heating arrangement and a measurement device comprising a control circuit. The induction heating arrangement is configured to generate an alternating magnetic field for inductively heating the susceptor arrangement. The measurement device is configured to determine a value associated with a physical property of the susceptor arrangement from measurements related to a load applied to the control circuit in response to the susceptor arrangement being in operative communication with the induction heating arrangement. The control circuit is configured to power the induction heating arrangement during one test cycle of the susceptor arrangement or during several subsequent test cycles, and is configured to determine whether the determined value associated with the physical property of the susceptor arrangement corresponds to a predetermined susceptor value, preferably a predetermined susceptor value for a predetermined susceptor arrangement at a predetermined user experience.

[0005] It has been found that when testing a susceptor arrangement under simulated heating conditions and comparing the test results with the desired heating characteristics of the susceptor arrangement during user experience, it is not necessary to know the detailed material properties of the susceptor arrangement. The desired heating characteristics correspond to a predetermined susceptor value of the susceptor arrangement disposed in the aerosol-forming substrate when heated in an induction heating device and according to user experience. The predetermined susceptor value is preferably in particular a predetermined electrical conductance value, more particularly a change in electrical conductance value or rate of change of electrical conductance.

[0006] Typically, the measurement device is configured to determine a value associated with a physical property of the susceptor arrangement from measurements of the current and voltage drawn by the induction heating device. The susceptor arrangement represents a load to a control circuit, and the measurements are responsive to the susceptor arrangement in operative communication with the induction heating arrangement. During a test cycle, particularly during heating of the susceptor arrangement, the load applied to the control circuit changes in response to changes in the physical properties of the susceptor arrangement at different temperatures and times, and a physical value of the susceptor arrangement, particularly an apparent electrical resistance or apparent electrical conductance value, may be determined from the current and voltage drawn by the induction heating device.

[0007] Preferably, the control module is configured to output acceptance of the tested susceptor assembly if the predetermined susceptor value is reached, or to output rejection of the tested susceptor assembly if the predetermined susceptor value is not reached.

[0008] Preferably, the predetermined values ​​related to the physical properties of the susceptor arrangement include maximum and minimum electrical conductance values ​​for each test cycle at predetermined times during the test cycle, preferably during the heating period of the test cycle.

[0009] The acceptance or rejection of the tested susceptor assembly may be determined by different test results. For example, in some embodiments, the control module may be configured to compare the determined value associated with the physical characteristic of the susceptor arrangement per each test cycle with a predefined susceptor value. In some other embodiments, the control module is configured to average the determined value associated with the physical characteristic of the susceptor arrangement over two, several, or all performed test cycles and compare the averaged susceptor value with a predefined susceptor value. Running several tests, performing at least two, and preferably three to five tests, and averaging the test results may reduce the number of susceptor arrangements that are deemed defective because a single test result exceeds a predefined threshold of the predefined susceptor value.

[0010] The set of predetermined thresholds within the set of determined values ​​associated with the physical properties of the susceptor arrangement, or the set of predetermined thresholds for acceptable deviations from the set of predetermined susceptor values, may be defined depending on the required or desired accuracy of the heating properties of the susceptor arrangement.

[0011] The predetermined threshold is preferably between 5 percent and 30 percent of the predetermined value. The predetermined threshold is preferably less than 10 percent of the predetermined value. Thus, the tested and measured susceptor arrangement values ​​may deviate from the predetermined value by between 5 percent and 30 percent, or up to ±10 percent.

[0012] Preferably, the value associated with the physical property of the susceptor arrangement is a permeability, an apparent electrical resistance or an apparent electrical conductance value and the predetermined susceptor value is a predetermined permeability, an electrical resistance or an electrical conductance value, most preferably, the value associated with the physical property of the susceptor arrangement is an apparent electrical conductance value and the predetermined susceptor value is a predetermined electrical conductance value.

[0013] The measurement device may comprise a current measurement device for determining a DC current drawn by the induction heating arrangement from a DC power supply of the apparatus, and a voltage measurement device for determining a DC voltage supplied to the induction heating arrangement by the DC power supply, The measurement device is configured to determine an electrical conductance value of the induction heating arrangement from a ratio of the determined DC current and the determined DC voltage.

[0014] The test apparatus preferably simulates the actual use of the aerosol-generating article in an actual electronic heating apparatus as close as possible. A specific induction heating apparatus for an aerosol-forming substrate comprising a susceptor, in particular a solid aerosol-forming substrate comprising a susceptor, is described in WO2015 / 177255. The description of the setup, operation and principle of operation of this document and its electronic aerosol generating apparatus is incorporated herein by reference. The control unit of the test apparatus preferably comprises a power supply, power supply electronics and a cavity for receiving an article to be tested, which is the same or substantially the same as the apparatus described in WO2015 / 177255, in order to carry out heating of the susceptor arrangement in the test apparatus in a condition close to the heating of the susceptor arrangement that is part of the article used in the actual induction heating apparatus.

[0015] Thus, the control module preferably comprises a power supply circuit configured to operate at high frequency, the power supply circuit comprising a DC / AC inverter connected to a DC power source, the DC / AC inverter comprising a class E power amplifier including a transistor switch and an LC load network configured to operate with a low ohmic load.

[0016] The DC power source may generally comprise any suitable DC power source, including in particular a mains connected power supply unit, one or more disposable batteries, rechargeable batteries, or any other suitable DC power source capable of providing the required DC power voltage and the required DC power amperage. In one embodiment, the DC power source has a DC power voltage in the range of about 2.5 volts to about 4.5 volts and a DC power amperage in the range of about 2.5 to about 5 amps (corresponding to a DC power supply range of about 6.25 watts to about 22.5 watts). The power supply circuit is configured to operate at a high frequency. For purposes of this application, the term "high frequency" is understood to mean a frequency in the range of about 1 megahertz (MHz) to about megahertz (MHz) (including the range of 1 MHz to 30 MHz), specifically about 1 megahertz (MHz) to about 10 MHz (including the range of 1 MHz to 10 MHz), and even more specifically about 5 megahertz (MHz) to about 7 megahertz (MHz) (including the range of 5 MHz to 7 MHz).

[0017] The power supply circuit includes a DC / AC inverter connected to a DC power source. The DC / AC inverter includes a class-E power amplifier, which includes a transistor switch, a transistor switch driver, and an LC load network. Class-E power amplifiers are generally known and are described in detail, for example, in the article "Class-E RF Power Amplifiers" by Nathan O. Sokal, published in the bimonthly magazine QEX, January / February 2001, pages 9-20, American Radio Relay League (ARRL), Newington, Connecticut, USA. Class-E power amplifiers are advantageous for operating at high frequencies while at the same time having a simple circuit structure with a minimum number of components (e.g., only one transistor switch is required, which is advantageous compared to class-D power amplifiers with two transistor switches that must be controlled at high frequencies in a way that ensures that one of the two transistors is off when the other one is on). Furthermore, class-E power amplifiers are known to have minimal power losses in the switching transistors during switching transitions.

[0018] The class E power amplifier is preferably a single-ended, primary class E power amplifier having only a single transistor switch.

[0019] The transistor switches of the class E power amplifier can be any type of transistor and may be embodied as bipolar junction transistors (BJTs), although more preferably the transistor switches are embodied as field effect transistors (FETs), such as metal oxide semiconductor field effect transistors (MOSFETs) or metal semiconductor field effect transistors (MESFETs).

[0020] The LC load network of the class E power amplifier of the induction heating device according to the invention is configured to operate a low ohmic load, the term "low ohmic load" being understood to mean an ohmic load less than about 2 ohms.

[0021] Preferably, in the test apparatus, the LC load network includes a shunt capacitor and a series connection of the capacitor and an inductor having an ohmic resistance. This ohmic resistance of the inductor is typically a few tenths of an ohm. In operation, the ohmic resistance of the susceptor is added to the ohmic resistance of the inductor and should be higher than the ohmic resistance of the inductor because the power provided should be converted to heat as extensively as possible within the susceptor to increase the efficiency of the power amplifier and to allow as much heat transfer as possible from the susceptor to the remainder of the aerosol-forming substrate to effectively generate an aerosol. When testing the susceptor arrangement itself, the induction heating arrangement is configured to generate an alternating magnetic field within a portion of the holder to inductively heat the susceptor arrangement within the holder when the holder is disposed within the range of the induction heating arrangement.

[0022] The control module also includes a receiving slot for receiving at least a portion of the holder, the slot being arranged such that when a portion of the holder is accommodated within the receiving slot, the inductor of the LC load network is inductively coupled to a susceptor arrangement within the holder during testing.

[0023] In some embodiments, the holder comprises a cavity for receiving and housing the susceptor arrangement therein. The cavity has a shape and size for housing the susceptor arrangement. The cavity preferably has a shape of a slit for receiving and housing an elongated flat susceptor arrangement, for example a strip-like susceptor arrangement.

[0024] At least one clip may be disposed in the cavity to fix the susceptor arrangement therein. The holder preferably comprises two clips disposed oppositely in the cavity to fix the susceptor arrangement at both ends of the susceptor arrangement. The clip is a very simple and effective fixing means. The clip allows the susceptor arrangement to be held in place, for example during testing, in particular during heating and cooling of the susceptor arrangement. The clip also has the advantage that the susceptor arrangement can be held without further physical contact of the susceptor arrangement with the holder, for example the cavity wall. This is not only preferred to improve the test efficiency in terms of time and power supply, but also maximizes the heat transfer to the susceptor and minimizes heat dissipation. Furthermore, minimal physical contact between the susceptor arrangement and the parts of the holder may prevent burning or smoldering of the holder housing. For manufacturing reasons, the holder housing is made of plastic material, while the temperature of the susceptor arrangement during testing may reach, for example, 400 degrees Celsius.

[0025] To further reduce the risk of excessive heating of the holder housing, the walls defining the cavity may be coated with a high temperature resistant coating, preferably a ceramic coating. Such high temperature resistant coatings typically have a thermal conductivity of less than 1 W / mK (Watts per meter times Kelvin), preferably less than 0.05 W / mK.

[0026] To simulate the thermal load of an aerosol-forming substrate, particularly a tobacco substrate, into which the susceptor arrangement is typically inserted when used in an electronic heating device, the cavity may contain a heat-resistant fibrous material having a thermal conductivity higher than that of air. The cavity may contain a heat-resistant felt material having a thermal conductivity higher than that of air, such as, for example, a heat-resistant Kevlar® felt. Such a heat-resistant fibrous material influences the temperature distribution across the surface of the susceptor arrangement.

[0027] In some embodiments, the testing device is adapted to test an article comprising a susceptor arrangement. In these embodiments, the holder comprises a holding means for holding a rod-shaped article comprising a susceptor arrangement. Such holding means is adapted to hold, preferably clamp, the rod-shaped article. Such holding means may be, for example, one or more pins, a clamp in the form of a half shell, a cavity in which the article is pressed and disposed, or the like.

[0028] The test apparatus may further comprise a cooling device for cooling the susceptor arrangement, preferably at least between heating cycles. The cooling device may preferably be capable of maintaining the test apparatus at a predetermined temperature. The cooling device may prevent overheating of the holder or the susceptor arrangement. In order to repeat a test or to perform a next test, the test apparatus must be cooled. By actively cooling the test apparatus, and in particular the control unit, multiple tests may be performed without or with little interruption until the next test is performed.

[0029] The testing apparatus may comprise a support, the holder module and the control module being mounted on the support, the holder module and the control module being preferably movable relative to one another on the support such that at least a portion of the holder in the holder module is receivable in and releasable from a respective receiving slot in the control module, whereby a susceptor arrangement held in the holder may be disposed in a receiving slot in the control module to be tested.

[0030] The holder module is preferably linearly movable along a guide relative to and away from the control module, the control module being preferably fixedly arranged on a support and the holder module is preferably movably arranged on the support relative to the control module and movable away from the control module.

[0031] Advantageously, the test device is calibrated before testing the susceptor arrangement. To perform such a calibration test, the test device may comprise a calibration susceptor for performing a test cycle for determining the calibration factor of the test device. To perform such a calibration test cycle, the calibration susceptor has a fixed susceptor value, for example a fixed permeability value, a fixed electrical resistance value or a fixed electrical conductance value, throughout the test cycle. Thereby, the result Y of a test run with the calibration susceptor can then be corrected by a known physical characteristic, such as a known permeability value, a known electrical resistance value or a known electrical conductance value X of the calibration susceptor, with the error corresponding to YX. The calibration susceptor preferably has a fixed electrical conductance value.

[0032] According to the present invention, there is also provided a method for testing a susceptor arrangement in a testing apparatus under simulated heating conditions of a heated susceptor arrangement in an aerosol generating device during a user experience, the method comprising providing a susceptor arrangement including at least a first susceptor material and a second susceptor material, a) placing the susceptor arrangement in operative communication with an induction heating arrangement and inductively heating the susceptor arrangement with the induction heating arrangement; b) determining a value associated with a physical characteristic of the susceptor arrangement from measurements related to a load applied to the control circuit, the measurements being responsive to the susceptor arrangement being in operative communication with the induction heating arrangement during a test cycle; repeating steps a) and b), thereby determining values ​​associated with the physical property of the susceptor arrangement for subsequent test cycles; and comparing the determined value associated with the physical property of the tested susceptor arrangement with a predetermined susceptor value, preferably with a predetermined susceptor arrangement at a predetermined user experience, and if the difference between the determined susceptor value and the predetermined susceptor value exceeds a predetermined threshold value; and accepting or rejecting the tested susceptor arrangement.

[0033] The method preferably includes measuring the current and voltage drawn by the control circuit during a text cycle and determining a value associated with a physical property of the susceptor arrangement from the measured current and voltage.

[0034] In some embodiments, accepting or rejecting the tested susceptor arrangement indicates accepting or rejecting the entire susceptor arrangement batch from which the tested susceptor arrangement was taken. Thereby, testing of one or more susceptor arrangements cut from the same bobbin, for example comprising a continuous band of susceptors, indicates the quality of the entire batch. If the tested susceptor arrangement or susceptor arrangements fail the test, the entire batch is rejected. This is advantageous because no articles are produced with defective susceptor material. This may save time and material costs and may reduce waste.

[0035] The method and test apparatus offer a reliable and rapid way to check the quality of a batch of susceptor material without the need to investigate the exact material properties of the susceptor arrangement, which can be very complicated.

[0036] In some embodiments, the method includes comparing the determined value associated with the physical property of the susceptor arrangement for each test cycle to a predetermined susceptor value, hi some other embodiments, the method includes averaging the determined value associated with the physical property of the susceptor arrangement over at least two, and thus over several or all, of the test cycles, and comparing the averaged susceptor value to a predetermined susceptor value.

[0037] In a preferred embodiment, the method includes comparing determined values ​​associated with the physical characteristic of the susceptor arrangement for subsequent test cycles and determining that the susceptor arrangement is defective if a difference between the determined values ​​for the subsequent test cycles exceeds a predetermined threshold. This includes refusing to

[0038] Preferably, the determined value associated with the physical property of the susceptor arrangement corresponds to a determined apparent electrical conductance value, and the given susceptor value corresponds to a given electrical conductance value.

[0039] Typically, a test cycle includes a heating period and a cooling period.

[0040] The method may include actively cooling the susceptor arrangement between the heating periods. Cooling may be provided via a cooling medium to the control module or directly to the susceptor arrangement.

[0041] As the susceptor assembly heats up, its apparent resistance increases. This increase in resistance can be observed and detected, for example, by monitoring the DC current drawn from the DC power supply. At a constant voltage, the DC current decreases as the temperature of the susceptor arrangement increases. The high frequency alternating magnetic field provided by the inductor induces eddy currents in close proximity to the surface of the susceptor arrangement, an effect known as the skin effect. The resistance of the susceptor arrangement depends in part on the electrical resistivity of the first and second susceptor materials, and in part on the depth of the skin layers of the respective materials available for the induced eddy currents. When the second susceptor material reaches its Curie temperature, it loses its magnetism. This increases the skin layer available for eddy currents in the second susceptor material, which decreases the apparent resistance of the susceptor. As a result, there is a temporary increase in the detected DC current when the second susceptor material reaches its Curie temperature. This can be seen as a valley (local minimum) in the measured or determined resistance curve. The current continues to increase until it reaches a maximum skin depth at which point the second susceptor material reaches its Curie temperature.

[0042] By remotely detecting the change in resistance of the susceptor assembly, the moment when the susceptor assembly reaches the second Curie temperature can be determined, which point can be seen as a hill (local maximum) in the measured or determined resistance curve.

[0043] At this point in the practical apparatus, electronic circuitry within the practical apparatus would operate to vary the power supplied, thereby reducing or stopping the heating of the susceptor assembly. The temperature of the susceptor assembly would then drop below the Curie temperature of the second susceptor material. The power supply could be increased or resumed again either after a period of time or after it has been detected that the second susceptor material has cooled below its Curie temperature. By using such a feedback loop, the temperature of the susceptor assembly could be maintained at approximately the second Curie temperature.

[0044] This behavior in the physical properties of the susceptor assembly, especially the electrical resistance or electrical conductance, is very specific to a particular susceptor assembly having a particular combination of susceptor materials. Comparison of the test results with these optimized heating properties of the susceptor assembly provides reliable information about acceptable or defective susceptor arrangements. Thus, reliable information is obtained by the test device if the tested susceptor arrangement meets the test parameters. This allows it to be determined that either the susceptor arrangement or the entire batch of which the susceptor arrangement was a part as a sample is suitable for use as a heating element in an aerosol-generating article, or a series of articles including susceptor arrangements from that batch meets the quality requirements.

[0045] In some embodiments of the method, the predetermined value associated with the physical property of the susceptor arrangement comprises a maximum and minimum electrical conductance value per test cycle at a predetermined time during the test cycle, particularly during the heating period of the test cycle.

[0046] These maximum and minimum values ​​of electrical conductance are specific to the susceptor arrangement as they correlate to the process by which the susceptor material in the susceptor arrangement reaches its Curie temperature and loses its magnetism (a temporary increase in detected current, a decrease in resistance or an increase in conductance, a resistance minimum or conductance maximum), as well as the time at which the Curie temperature of the susceptor material is reached (at which point the susceptor material loses its natural magnetism and undergoes a phase change from a ferromagnetic or ferrimagnetic state to a paramagnetic state, i.e., a resistance maximum or conductance minimum).

[0047] The method preferably includes measuring a DC current drawn by the induction heating arrangement from a DC power supply, measuring a DC voltage supplied to the induction heating arrangement by the DC power supply, and determining an electrical conductance value of the induction heating arrangement from a ratio of the determined DC current and the determined DC voltage.

[0048] In a preferred embodiment, the method may include operating a power supply circuit of a test apparatus at a high frequency, the power supply circuit comprising a DC / AC inverter connected to a DC power source, the DC / AC inverter including a class E power amplifier including a transistor switch and an LC load network configured to operate with a low ohmic load.

[0049] The LC load network may include a shunt capacitor and a series connection of the capacitor and an inductor having an ohmic resistance. The method may include receiving the susceptor arrangement in a receiving slot of a control module including the inductive heating arrangement such that the inductor of the LC load network is inductively coupled to the susceptor arrangement during testing.

[0050] Preferably the susceptor arrangement is an elongated susceptor arrangement, preferably in the form of a strip. Most preferably the susceptor arrangement is an elongated, multi-layer susceptor arrangement.

[0051] The elongated susceptor arrangement may have a thickness in the range of 0.03 mm to 0.15 mm, more preferably 0.05 mm to 0.09 mm. The elongated susceptor arrangement may have a width in the range of 2 mm to 6 mm, specifically 4 mm to 5 mm. Similarly, the elongated susceptor arrangement may have a length in the range of 8 mm to 19 mm, specifically 10 mm to 14 mm, preferably 10 mm to 12 mm.

[0052] Alternatively, the susceptor arrangement may be a susceptor rod, or a susceptor pin, or a multi-layer susceptor sleeve, or a susceptor cup, or a cylindrical susceptor arrangement.

[0053] The first susceptor material is preferably selected for maximum heating efficiency. Inductive heating of the magnetic susceptor material located within the varying magnetic field occurs through a combination of resistive heating due to eddy currents induced within the susceptor and heat generated by magnetic hysteresis losses. The first susceptor material of the susceptor arrangement and the second susceptor material of the susceptor arrangement are in intimate physical contact with each other, and the second susceptor material preferably includes a Curie temperature of less than 500 degrees Celsius.

[0054] The first susceptor material preferably does not have a Curie temperature or has a Curie temperature greater than 500 degrees Celsius.

[0055] The first susceptor material is preferably used primarily to heat the susceptor when the susceptor is placed in a fluctuating electromagnetic field. Any suitable material may be used. For example, the first susceptor material may be aluminum or an iron-based material such as stainless steel. The first susceptor material preferably comprises or consists of a metal, such as ferritic iron, or stainless steel, specifically grade 410, grade 420, or grade 430 stainless steel.

[0056] The second susceptor material is preferably used primarily to indicate when the susceptor has reached a particular temperature, which is the Curie temperature of the second susceptor material. The Curie temperature of the second susceptor material can be used to regulate the temperature of the entire susceptor assembly during operation. Therefore, the Curie temperature of the second susceptor material should be below the ignition point of the aerosol-forming substrate. Close proximity of the first and second susceptor materials can be advantageous in providing precise temperature control.

[0057] The first susceptor material is preferably a magnetic material having a Curie temperature above 500 degrees Celsius. From the standpoint of heating efficiency, it is desirable for the Curie temperature of the first susceptor to exceed any maximum temperature to which the susceptor assembly can be heated. The Curie temperature of the second susceptor material may be selected to be preferably lower than 400 degrees Celsius, preferably lower than 380 degrees Celsius, or lower than 360 degrees Celsius. The second susceptor material is preferably a magnetic material selected to have a Curie temperature that is substantially the same as the desired maximum heating temperature. The Curie temperature of the second susceptor material may be, for example, within the range of 200 degrees Celsius to 400 degrees Celsius, or 250 degrees Celsius to 360 degrees Celsius.

[0058] Thus, when heated, the first and second susceptor materials have the same temperature. The first susceptor material may be optimized for heating the aerosol-forming substrate when the susceptor arrangement is housed in the article and may have a first Curie temperature higher than a predetermined maximum heating temperature. When the susceptor reaches the second Curie temperature, the magnetic properties of the second susceptor material change. At the second Curie temperature, the second susceptor material reversibly changes from a ferromagnetic phase to a paramagnetic phase. During induction heating, this phase change of the second susceptor material may be detected without physical contact with the second susceptor material. Detection of the phase change may allow control over the heating of the aerosol-forming substrate in practical use of the susceptor arrangement. For example, induction heating may be automatically stopped when a phase change associated with the second Curie temperature is detected. In this way, overheating of the aerosol-forming substrate can be avoided even if the first susceptor material, which is mainly responsible for heating the aerosol-forming substrate, does not have a Curie temperature, i.e. a first Curie temperature higher than the desired maximum heating temperature. After the induction heating is stopped, the susceptor is cooled until it reaches a temperature lower than the second Curie temperature. At this point, the second susceptor material regains its ferromagnetic properties. This phase change can be detected without contacting the second susceptor material, so that induction heating can be reactivated. In this way, the induction heating of the susceptor arrangement, and therefore of the aerosol-forming substrate surrounded by the susceptor assembly, can be controlled by repeatedly activating and deactivating the induction heating device. This temperature control is achieved by contactless means. In the test device, such temperature or power limitations are generally not used as constraints for testing, since there is no risk of adverse effects due to overheating of the substrate.

[0059] The intimate contact between the first susceptor material and the second susceptor material may be by any suitable means. For example, the second susceptor material may be plated, deposited, coated, clad, or welded onto the first susceptor material. Preferred methods include electroplating, galvanizing, and cladding. The second susceptor material is preferably present as a dense layer. A dense layer has a higher magnetic permeability than a porous layer, making it easier to detect minute changes in the Curie temperature. If the first susceptor material is optimized for heating the substrate, it may be preferred that the amount of the second susceptor material is not greater than is required to provide a detectable second Curie point.

[0060] Suitable materials for the second susceptor material may include nickel and certain nickel alloys.

[0061] It has been found that the specific material selection of the second susceptor material can reduce undesirable effects in the susceptor arrangements that arise during their manufacture due to the effect of limited free movement between the various susceptor materials, especially between the various layers, on magnetic shrinkage that is difficult to control during mass production of such susceptor arrangements. In particular, these undesirable effects may vary across different locations of the precursor laminate material from which the susceptor arrangements are ultimately made. As a result, the magnetic properties may vary between different susceptor arrangements, even when made with the same precursor material.

[0062] Therefore, the second susceptor material preferably comprises or consists of a Ni-Fe alloy comprising 75 weight percent to 85 weight percent Ni and 10 weight percent to 25 weight percent Fe. More specifically, the Ni-Fe alloy may comprise 79 weight percent to 82 weight percent Ni and 13 weight percent to 15 weight percent Fe. It has been found that Ni-Fe alloys comprising Ni and Fe within the above ranges exhibit only weak or no magnetostriction. As a result, the second susceptor material of the second layer undergoes no change or at least only a decrease in its magnetic properties after its processing and throughout the temperature range of its operation. This consequently allows mass production of multi-layer susceptor arrangements having a second magnetic layer with no or only negligible variation in its magnetic properties after its processing and during subsequent operation.

[0063] As used herein, the term "weight percent" or "weight percent" also refers to the mass fraction of an element in the alloy, which is the ratio of the mass of the respective element to the total mass of a sample of the alloy.

[0064] In addition to the main constituents, the balance of the Ni-Fe alloy may include one or more of the following elements: Co, Cr, Cu, Mn, Mo, Nb, Si, Ti and V.

[0065] As used herein, the symbol Ni represents the chemical element nickel, the symbol Fe represents the chemical element iron, the symbol Co represents the chemical element cobalt, the symbol Cr represents the chemical element chromium, the symbol Cu represents the chemical element copper, the symbol Mn represents the chemical element manganese, the symbol Mo represents the chemical element molybdenum, the symbol Nb represents the chemical element niobium, the symbol Si represents the chemical element silicon, the symbol Ti represents the chemical element titanium, and the symbol V represents the chemical element vanadium.

[0066] The first susceptor material may be a first susceptor layer and may have a first layer thickness in the range of 20 micrometers to 60 micrometers, specifically 30 micrometers to 50 micrometers, preferably 40 micrometers.

[0067] The second susceptor material may be a second susceptor layer and may have a second layer thickness in the range of 4 micrometers to 20 micrometers, specifically 8 micrometers to 16 micrometers, preferably 10 micrometers to 15 micrometers.

[0068] The second material may be intimately connected to the first material. As used herein, the term "intimately connected" refers to a mechanical connection between two susceptor material layers, in particular susceptor layers, in a susceptor arrangement, such that mechanical forces may be transmitted between the two materials, in particular in a direction parallel to the layer structure. The connection may be a layered, two-dimensional, area connection, or a full-area connection, i.e. a connection on both sides of the respective opposing surfaces of the two layers. The connection may be a direct connection. In particular, the two materials that are intimately connected to each other may be in direct contact with each other. Alternatively, the connection may be an indirect connection. In particular, the two materials may be indirectly connected via at least one intermediate material. The second layer is disposed on the first layer and is intimately connected to the first layer, in particular preferably directly connected to the first layer.

[0069] The susceptor arrangement may further include a third susceptor material. The third susceptor material may be intimately connected to the second susceptor material. In this context, the term "intimately connected" is used in the same manner as defined above with respect to the first and second materials.

[0070] Preferably, the third susceptor material is a protective layer configured to do at least one of: prevent the aerosol-forming substrate from sticking to the surface of the susceptor arrangement; prevent material diffusion (e.g., metal migration) from the susceptor material into the aerosol-forming substrate; prevent or reduce thermal bending due to differences in thermal expansion between the materials of the susceptor arrangement; or protect other materials (specifically, the second material) from any corrosive effects.

[0071] The latter is particularly important when the susceptor arrangement is embedded in the aerosol-forming substrate of the aerosol-generating article, i.e., when the susceptor arrangement is in direct physical contact with the aerosol-forming substrate. For this reason, the third susceptor material preferably comprises or consists of a corrosion-resistant material. Advantageously, the corrosion-resistant material improves the aging properties of those portions of the outer surface of the second susceptor material that are not corrosion-resistant that are covered by the third susceptor material and therefore are not directly exposed to the environment.

[0072] The term "third layer" as used herein refers to a layer different from and in addition to the first and second layers. Specifically, any possible oxide layer on the surface of the first or second layer resulting from oxidation of the first or second susceptor material should not be considered a third layer (specifically, a third layer including or consisting of a corrosion-resistant material).

[0073] The third susceptor material or third layer may comprise or consist of the same material as the first susceptor material of the first layer. Due to this, the multi-layer susceptor arrangement comprises at least two layers having the same thermal expansion coefficient, which results in reduced deformation of the susceptor arrangement throughout the operating temperature range. This is particularly true when the susceptor arrangement comprises only the first, second and third layers and when the second layer is sandwiched symmetrically between the first and third layers.

[0074] As a result, the third susceptor material may comprise a metal, such as ferritic iron, or a stainless steel, such as a ferritic stainless steel, in particular a 400 series stainless steel (such as grade 410 stainless steel, or grade 420 stainless steel, or grade 430 stainless steel, or a similar grade stainless steel). Alternatively, the third susceptor material may comprise or be a suitable non-magnetic material, in particular a paramagnetic conductive material (such as aluminum (Al)). Similarly, the third material may comprise or be a non-conductive ferrimagnetic material, such as a non-conductive ferrimagnetic ceramic.

[0075] It is also possible that the third material comprises or consists of austenitic stainless steel. Advantageously, austenitic stainless steel, due to its paramagnetic properties and high electrical resistance, slightly shields the second layer from the magnetic field applied to the first and second susceptor materials. By way of example, the third layer may comprise or consist of X5CrNi18-10 (designation according to EN (European Standards), material number 1.4301, also known as V2A steel) or X2CrNiMo17-12-2 (designation according to EN (European Standards), material number 1.4571 or 1.4404, also known as V4A steel). In particular, the third layer may comprise or consist of one of 301 stainless steel, 304 stainless steel, 304L stainless steel, 316 stainless steel, or 316L stainless steel (designation according to SAE steel grades [Society of Automotive Engineers]).

[0076] If present, the third material may be a third susceptor layer having a layer thickness in the range of 2 micrometers to 6 micrometers, in particular 3 micrometers to 5 micrometers, preferably 3 micrometers to 4 micrometers.

[0077] The layer thickness of the third layer may be in the range of 0.05 to 1.5 times, particularly 0.1 to 1.25 times, or 0.95 to 1.05 times, particularly 1 times, the layer thickness of the first layer.

[0078] In the case of a symmetrical or nearly symmetrical layer configuration, the first layer as well as the third layer may have a thickness in the range of 2 micrometers to 20 micrometers, specifically 3 micrometers to 10 micrometers, preferably 3 micrometers to 6 micrometers.

[0079] The second layer may then have a thickness in the range of 5 micrometers to 50 micrometers, specifically 10 micrometers to 40 micrometers, preferably 20 micrometers to 40 micrometers.

[0080] In general, the susceptor arrangements described herein may be used to achieve different geometric configurations of the susceptor arrangement.

[0081] The method may further include fixing the susceptor arrangement for testing within a cavity of the holder. The method preferably includes clamping the susceptor arrangement within the cavity, preferably such that the susceptor arrangement does not contact the cavity walls except for clips used for clamping. This may prevent or reduce heat loss by radiation to surrounding material.

[0082] To further reduce heat conduction or dissipation, the susceptor arrangement may be insulated by providing a high temperature resistant material surrounding the susceptor assembly, which is preferably used to cover the cavity walls in which the susceptor arrangement is housed during testing.

[0083] Additionally or alternatively, it may be advantageous to wrap the susceptor arrangement in a heat-resistant fibrous material, thereby simulating the actual environment of the susceptor arrangement in an aerosol-forming substrate, such as a tobacco material containing an aerosol-forming substrate. The heat-resistant fibrous material may be as described above with respect to the test apparatus.

[0084] The method may further include calibrating a test apparatus using a calibration susceptor having a fixed susceptor value throughout the test cycle and performing the test cycle therein, and determining a calibration factor of the test apparatus by comparing the calibration susceptor value of the calibration susceptor measured by the test apparatus with the fixed susceptor value of the calibration susceptor.

[0085] Preferably, the fixed susceptor value is a fixed electrical conductance value and the calibrated susceptor value is a calibrated electrical conductance value.

[0086] In such a calibration cycle, a calibration susceptor simulates a load, which may be done, for example, by a calibration susceptor comprising a bobbin operatively connected to the induction heating arrangement, preferably the bobbin being operatively connected to an induction coil of the induction heating arrangement.

[0087] Advantages and features of the invention described with respect to the test apparatus or with respect to the test method are also applicable vice versa.

[0088] In some embodiments of the present invention, the testing device and method for testing are adapted to enhance the speed for testing rod-shaped articles with susceptor arrangements. In these embodiments, it is preferable that a continuous, in particular continuous, test of rod-shaped articles with susceptor arrangements is available. The control module, in particular the induction heating arrangement in the control module, is constructed in an open manner so that the article to be tested can be inserted into the control module for testing and can pass through the control module after testing. For example, the control module may be equipped with a receiving slot extending through the control module or with a through hole for the article to pass through the through hole. Thereby, the article can be inserted into and removed from the control module with a linear movement and in the same direction. This may increase the speed of providing new articles to be tested to the control module. It also makes it possible to automate or semi-automate the provision of articles to the control module by simply pushing the tested article out of the control module. For example, this may be done by a subsequent article to be tested being inserted into the receiving slot, thereby pushing the tested article out of the receiving slot and out of the control module. Thus, in a preferred embodiment of the test device, the control module includes a receiving slot that defines a passageway through the control module.

[0089] The holder module may also comprise a passage for receiving the rod-shaped article therein, whereby the article may be provided to the holder module from one side of the holder module, and the holder module may supply the article to the control module from the other side of the holder module, whereby the provision of the rod-shaped article to be tested, the supply of the article to the control module, and the removal of the tested article from the control module may be performed in the same linear direction. For the supply of the article from the holder module to the control module, the passages of the receiving slots of the holder module and the control module are preferably linearly alignable.

[0090] In a preferred embodiment, the control module is arranged such that the receiving slots in the control module are vertically arranged such that the articles to be tested can be received and passed vertically through the control module, and therefore the articles are presented from above and guided into and through the testing apparatus primarily by gravity.

[0091] In the test device, two control modules may be arranged in series. The induction heating arrangements, especially the coils, are arranged at a distance from each other so that not only single-length articles but also double-length articles can be tested. The positioning of the article for testing, and also maintaining the position of the article during measurement, are preferably kept within small limits. Thus, the variable positioning of articles with different lengths in one control unit and one coil can be improved by providing two coils.

[0092] Depending on the orientation of the single-length article, and thus the location of the susceptor arrangement within the article, the single-length article may be tested in the first or second of the two control modules. For double-length articles, each of the two susceptor arrangements within the article is tested by one of the measurement devices in the two control modules. These embodiments are particularly advantageous for testing articles having different lengths and vertically fed into and through the testing device by gravity.

[0093] Several control modules may be arranged parallel to one another. One holder module may be assigned to several control modules. Alternatively, one holder module can be assigned to each of several control modules. Combinations are possible, for example in that a holder module provides only some of several control modules.

[0094] Thus, the testing method may include inserting a rod-shaped article comprising a susceptor arrangement into a receiving slot in the control module, testing the susceptor arrangement in the rod-shaped article, and then removing the tested rod-shaped article at a site on the opposite side of the control module by passing the rod-shaped article through the receiving slot. The method may include feeding the rod-shaped article comprising the susceptor assembly into and through the holder module from one side of the holder module.

[0095] The method preferably includes guiding a rod-shaped article vertically through a receiving slot in the control module.

[0096] The method preferably includes pushing the tested article out of the receiving slot of the control module by inserting a further rod-shaped article to be tested into the receiving slot of the control module.

[0097] The method may include providing two control modules arranged in series, testing a single-length article in either one of the two control modules, and testing a double-length article in both of the two control modules.

[0098] The method may include the step of performing parallel testing of several rod-like articles including susceptor arrangements in several control modules arranged in parallel.

[0099] The present invention is defined in the claims. However, below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein. EXAMPLES

[0100] Example 1: 1. A test apparatus for testing a susceptor arrangement under simulated heating conditions of a heated susceptor arrangement disposed within an aerosol generating device during a user experience, the test apparatus comprising: a holder module comprising a holder for receiving a susceptor arrangement to be tested; a control module comprising an induction heating arrangement and a measurement device comprising a control circuit, the induction heating arrangement being configured to generate an alternating magnetic field for inductively heating the susceptor arrangement; A testing apparatus, comprising: a measuring device configured to determine a value associated with a physical characteristic of the susceptor arrangement from a measurement value related to a load applied to a control circuit in response to a susceptor arrangement in operative communication with the induction heating arrangement; the control circuit configured to power the induction heating arrangement during one test cycle or a number of subsequent test cycles of the susceptor arrangement; and configured to determine whether the determined value associated with the physical characteristic of the susceptor arrangement corresponds to a predetermined susceptor value. Example 2: The testing apparatus of example 1, wherein the measurement device is configured to determine a value associated with a physical property of the susceptor arrangement from measurements of the current and voltage drawn by the induction heating device. Example 3: A testing apparatus as described in any one of Examples 1 to 2, wherein the control module is configured to output acceptance of the tested susceptor assembly if a predetermined physical characteristic value is reached, or to output rejection of the tested susceptor assembly if the predetermined physical characteristic value is not reached. Example 4: The testing apparatus of any one of claims 1 to 3, wherein the control module is configured to compare a determined value associated with the physical property of the susceptor arrangement for each test cycle with a predetermined physical property value. Example 5: A testing apparatus as described in any one of Examples 1 to 3, wherein the control module is configured to average determined values ​​associated with the physical property of the susceptor arrangement over two, several, or all performed test cycles, and compare the averaged physical property value with a predetermined physical property value. Example 6: 6. The testing apparatus of any one of Examples 1-5, wherein the value associated with the physical property of the susceptor arrangement is an apparent electrical conductance value, and the predetermined physical property value is the predetermined electrical conductance value. Example 7: A testing apparatus as described in any one of Examples 1 to 6, wherein the measuring device comprises a current measuring device for determining a DC current drawn by the induction heating arrangement from a DC power supply of the apparatus, and a voltage measuring device for determining a DC voltage supplied to the induction heating arrangement by the DC power supply, and the measuring device is configured to determine an apparent electrical conductance value of the induction heating arrangement from a ratio of the determined DC current and the determined DC voltage. Example 8: 8. The test apparatus of any one of claims 1 to 7, wherein the control module comprises a power supply circuit configured to operate at high frequency, the power supply circuit comprising a DC / AC inverter connected to a DC power source, the DC / AC inverter comprising a class E power amplifier including a transistor switch and an LC load network configured to operate with a low ohmic load. Example 9: The test apparatus of Example 8, wherein the LC load network comprises a series connection of a shunt capacitor, a capacitor, and an inductor having an ohmic resistance, and the control module comprises a receiving slot for receiving at least a portion of the holder, the slot being arranged such that when a portion of the holder is accommodated within the receiving slot, the inductor of the LC load network is inductively coupled to the susceptor arrangement during testing. Example 10: The testing apparatus of any one of Examples 1-9, wherein the holder comprises a cavity for receiving and housing the susceptor arrangement within the cavity. Example 11: The test apparatus of Example 10, wherein the cavity has a shape of a slit for receiving and accommodating an elongated flat susceptor arrangement. Example 12: 12. The testing apparatus of any one of Examples 10-11, wherein at least one clip is disposed within the cavity for securing the susceptor arrangement within the cavity. Example 13: The test apparatus of Example 12, wherein the holder includes two clips disposed opposite each other within the cavity for securing the susceptor arrangement at either end of the susceptor arrangement. Example 14: 14. The test device of any one of Examples 10-13, wherein the walls defining the cavity are coated with a high temperature resistant coating, preferably a ceramic coating. Example 15: 15. The test apparatus of any one of Examples 10-14, wherein the cavity comprises a heat resistant fiber material having a thermal conductivity higher than that of air, preferably a heat resistant felt material having a thermal conductivity higher than that of air, such as, for example, a heat resistant Kevlar® felt. Example 16: 10. The testing apparatus according to any one of the first to ninth embodiments, wherein the holder comprises a holding means for holding a rod-shaped article comprising a susceptor arrangement. Example 17: The testing apparatus of any one of Examples 1-16, further comprising a cooling device for cooling the susceptor arrangement between heating cycles. Example 18: A testing apparatus as described in any one of Examples 1 to 17, further comprising a support, the holder module and the control module being attached to the support, and the holder module and the control module being movable relative to each other on the support, such that at least a portion of the holders in the holder module can be accommodated in and released from their respective receiving slots in the control module. Example 19: 20. The testing apparatus of example 18, wherein the holder module is linearly movable along the guide relative to and away from the control module. Example 20: 20. The testing device according to any one of Examples 18 to 19, wherein the control module is fixedly disposed on a support. Example 21: The test apparatus of any one of Examples 1 to 20, further comprising a calibration susceptor for performing a test cycle to determine a calibration factor of the test apparatus, the calibration susceptor having a fixed physical characteristic, e.g., a fixed electrical conductance value, throughout the test cycle. Example 22: 1. A method for testing a susceptor arrangement in a test apparatus under simulated heating conditions of a heated susceptor arrangement in an aerosol generating device during a user experience, the method comprising: Providing a susceptor arrangement including at least a first susceptor material and a second susceptor material, a) placing the susceptor arrangement in operative communication with an induction heating arrangement and inductively heating the susceptor arrangement with the induction heating arrangement; b) determining a value associated with a physical characteristic of the susceptor arrangement from measurements related to a load applied to the control circuit, the measurements being responsive to the susceptor arrangement being in operative communication with the induction heating arrangement during a test cycle; repeating steps a) and b), thereby determining values ​​associated with the physical property of the susceptor arrangement for subsequent test cycles; and comparing the determined value associated with the physical property of the tested susceptor arrangement with a predetermined physical property value of a given susceptor arrangement at a given user experience; and accepting or rejecting the tested susceptor arrangement if a difference between the determined physical property value and the predetermined physical property value exceeds a predetermined threshold. Example 23: 23. The method of example 22, further comprising measuring the current and voltage drawn by the control circuit during the text cycle and determining a value associated with a physical property of the susceptor arrangement from the measured current and voltage. Example 24: The method of any one of embodiments 22-23, wherein accepting or rejecting the tested susceptor arrangement indicates accepting or rejecting the entire batch of susceptor arrangements of which the tested susceptor arrangement is a part. Example 25: The method according to any one of examples 22-24, wherein the determined value associated with the physical property of the susceptor arrangement for each test cycle is compared to a predetermined value associated with the physical property value. Example 26: The method according to any one of claims 22-24, further comprising averaging the determined values ​​associated with the physical property of the susceptor arrangement over several or all of the test cycles, and comparing the averaged physical property value to a predetermined physical property value. Example 27: comparing the determined values ​​associated with the physical characteristic of the susceptor arrangement for subsequent test cycles, and determining that the susceptor arrangement is defective if a difference between the physical characteristic values ​​for the subsequent test cycles exceeds a predetermined threshold value; The method according to any one of Examples 22 to 26, wherein the method rejects the Example 28: 28. The method of any one of Examples 22-27, wherein the determined value associated with the physical property of the susceptor arrangement corresponds to a determined electrical conductance value, and the predetermined physical property value corresponds to the predetermined electrical conductance value. Example 29: The method of any one of embodiments 22 to 28, wherein the test cycle includes a heating period and a cooling period. Example 30: The method of example 29, wherein the susceptor arrangement is actively cooled between heating periods. Example 31: The method of any one of Examples 22-30, wherein the predetermined value associated with the physical property of the susceptor arrangement comprises a maximum and a minimum value of electrical conductance per test cycle at a predetermined time during the test cycle, preferably during the heating period of the test cycle. Example 32: 32. The method of any one of claims 22 to 31, comprising measuring a DC current drawn from the DC power supply by the induction heating arrangement, measuring a DC voltage supplied to the induction heating arrangement by the DC power supply, and determining an electrical conductance value of the induction heating arrangement from a ratio of the determined DC current and the determined DC voltage. Example 33: The method of any one of Examples 22-32, further comprising operating a power supply circuit of the test apparatus at a high frequency, the power supply circuit comprising a DC / AC inverter connected to a DC power source, the DC / AC inverter comprising a class E power amplifier including a transistor switch and an LC load network configured to operate with a low ohmic load. Example 34: The method described in Example 33, wherein the LC load network comprises a shunt capacitor and a series connection of the capacitor and an inductor having an ohmic resistance, and the susceptor arrangement is received in a receiving slot of a control module comprising an inductive heating arrangement so that the inductor of the LC load network is inductively coupled to the susceptor arrangement during testing. Example 35: The method of any one of embodiments 22 to 34, wherein the susceptor arrangement is an elongated susceptor arrangement in the form of a strip. Example 36: The method of any one of embodiments 22-35, wherein the first susceptor material of the susceptor arrangement and the second susceptor material of the susceptor arrangement are in intimate physical contact with each other, and the second susceptor material comprises a Curie temperature less than 500 degrees Celsius. Example 37: The method of any one of embodiments 22-36, wherein the first susceptor material does not have a Curie temperature or has a Curie temperature greater than 500 degrees Celsius. Example 38: The method of any one of Examples 22-37, wherein the first susceptor material comprises or consists of a metal, such as ferritic iron, or stainless steel, particularly grade 410, grade 420, or grade 430 stainless steel. Example 39: The method of any one of embodiments 22-38, wherein the second susceptor material comprises or consists of a Ni-Fe alloy containing 75 weight percent to 85 weight percent and 10 weight percent to 25 weight percent Fe. Example 40: Ni-Fe alloys contain the following elements: 40. The method of example 39, further comprising one or more of Co, Cr, Cu, Mn, Mo, Nb, Si, Ti, and V. Example 41: The method of any one of Examples 38-40, wherein the Ni-Fe alloy comprises 79 weight percent to 82 weight percent Ni and 13 weight percent to 15 weight percent Fe. Example 42: The method of any one of Examples 22 to 41, wherein the first susceptor material is a first layer having a layer thickness in the range of 20 micrometers to 60 micrometers. Example 43: The method of any one of Examples 22 to 42, wherein the second susceptor material is a second layer having a layer thickness in the range of 4 micrometers to 20 micrometers. Example 44: The method of any one of embodiments 22-43, wherein the susceptor arrangement comprises a third layer of susceptor material intimately coupled to the second susceptor material. Example 45: The method of example 44, wherein the third susceptor material is at least partially identical to the first susceptor material. Example 46: 46. ​​The method of any one of embodiments 44-45, wherein the third susceptor material comprises or consists of an austenitic stainless steel, specifically one of 301 stainless steel, 304 stainless steel, 316 stainless steel, or 316L stainless steel. Example 47: 47. The method according to any one of 44 to 46, wherein the third susceptor material is a third layer having a layer thickness in the range of 2 micrometers to 6 micrometers. Example 48: The method of any one of Examples 22-47, further comprising securing the susceptor arrangement within a cavity of a test holder. Example 49: The method of example 48, further comprising clamping the susceptor arrangement within the cavity, the susceptor arrangement not contacting the cavity walls except for clips used for clamping. Example 50: The method of any one of embodiments 22-49, further comprising insulating the susceptor arrangement by providing a high temperature resistant material surrounding the susceptor arrangement. Example 51: The method according to any one of Examples 22 to 50, wherein the susceptor arrangement is surrounded by a heat-resistant fibrous material, thereby simulating the actual environment of the susceptor arrangement in the aerosol-forming substrate, e.g. a tobacco material containing the aerosol-forming substrate. Example 52: The method of any one of Examples 22 to 51, further comprising: calibrating a test apparatus, wherein the test cycle is performed using a calibrated susceptor having a fixed physical property value throughout the test cycle; and determining a calibration factor of the test apparatus by comparing the calibrated physical property value of the calibrated susceptor measured by the test apparatus with the fixed physical property value of the calibrated susceptor. Example 53: 53. The method of example 52, wherein the fixed physical property value is a fixed electrical conductance value and the calibrated physical property value is a calibrated electrical conductance value. Example 54: 54. The method of any one of Examples 52-53, wherein the calibration susceptor simulates a load and includes a bobbin operatively connected to the induction heating arrangement. Example 55: 56. The method of example 55, wherein the bobbin is operatively connected to an induction coil of an induction heating arrangement. Example 56: The testing device of any one of Examples 1-8, wherein the control module includes a receiving slot that forms a passageway through the control module. Example 57: 57. The testing device of example embodiment 56, wherein the receiving slot is a through hole through the control module. Example 58: 58. The testing device of any one of Examples 56-57, wherein the holder module comprises a passage for receiving a rod-shaped article within the passage. Example 59: 59. The testing device of Example 58, wherein the passage of the holder module and the receiving slot of the control module are linearly alignable. Example 60: A testing apparatus as described in any one of Examples 56 to 59, wherein the control module is arranged such that the receiving slot in the control module is vertically arranged, such that the article to be tested can be received and passed vertically through the control module. Example 61: 61. The testing device according to any one of Examples 56 to 60, wherein two control modules are arranged in series. Example 62: 62. The testing device according to any one of Examples 56 to 61, wherein several control modules are arranged in parallel with each other. Example 63: 63. The test device of embodiment 62, wherein one holder module is assigned to several control modules. Example 64: 63. The testing apparatus of example 62, wherein the holder module is assigned to each of several control modules. Example 65: A method according to any one of Examples 22 to 47, comprising inserting a rod-shaped article including a susceptor arrangement into a receiving slot in a control module, testing the susceptor arrangement in the rod-shaped article, and then removing the tested rod-shaped article at a site on the opposite side of the control module by passing the rod-shaped article through the receiving slot. Example 66: 66. The method of example 65, wherein the rod-shaped article comprising the susceptor assembly is fed into and through the holder module from one side of the holder module. Example 67: 67. The method of any one of claims 65-66, wherein the rod-shaped article is guided vertically through a receiving slot in the control module. Example 68: A method according to any one of claims 65 to 67, whereby the tested article is pushed out of the receiving slot of the control module by inserting a further rod-shaped article to be tested into the receiving slot of the control module. Example 69: A method according to any one of claims 65 to 68, providing two control modules arranged in series, testing a single-length article in one of the two control modules, and testing a double-length article in both of the two control modules. Example 70: The method according to any one of embodiments 65 to 69, carrying out parallel testing of several rod-shaped articles comprising susceptor arrangements in several control modules arranged in parallel.

[0101] The embodiments will now be further described with reference to the following figures: [Brief description of the drawings]

[0102] [Figure 1] FIG. 1 illustrates the test setup. [Diagram 2] FIG. 2 illustrates diagrammatically a holder for an elongated flat susceptor arrangement. [Diagram 3]FIG. 3 shows an internal view of the control module. [Figure 4] FIG. 4 shows a schematic of the excitation coil arrangement within the control module. [Diagram 5] FIG. 5 is a graph showing the conductance curves of one embodiment of a susceptor arrangement during a test cycle. [Figure 6] FIG. 6 shows the conductance values ​​determined during a series of text cycles. [Figure 7] FIG. 7 illustrates a test fixture having a calibration susceptor. [Figure 8] FIG. 8 illustrates the open coil configuration prior to article insertion. [Figure 9] FIG. 9 illustrates the open coil configuration after item insertion. [Figure 10] FIG. 10 shows a coil arrangement with electrical contacts aligned with the coil passages. [Figure 11] FIG. 11 shows a coil arrangement with bent electrical contacts for electrical contact. [Figure 12] FIG. 12 shows a test fixture with a vertical passage. [Figure 13] FIG. 13 shows a modular setup of two test devices, each with two control modules arranged in series. [Figure 14] FIG. 14 is an internal view of a test fixture with two control modules arranged in series. [Figure 15] FIG. 15 shows an apparatus set-up with integrated test fixtures used during article manufacturing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0103] FIG. 1 illustrates the test fixture 1 in an open position and thus ready to be equipped with a susceptor arrangement to be tested.

[0104] The test device 1 comprises a holder module 10 and a control module 13 arranged on a support 15 .

[0105] The control module 13 is fixedly disposed on a support 15. The holder module 10 is movably disposed on the support 15. The holder module 10 includes a user handle 12, by which the holder module 10 may be moved linearly relative to the control module 13 along two rails 16 disposed in parallel along the support 15.

[0106] The holder module 10 comprises a holder 11 for holding a susceptor arrangement (not shown). The holder 11 may be an integral part of the holder module 10. The holder 11 is centrally arranged on the front side of the holder module 10 facing the control module 13.

[0107] Advantageously, after the susceptor arrangement is inserted into the holder 11, the holder module 10 is slid relative to the control module 13 and the holder 11 is inserted into the control module 13 through an opening 20 arranged in the side of the control module 13 facing the holder module 10.

[0108] The control module 13 internally comprises an excitation device and a measurement device (not shown) for carrying out one or preferably several subsequent test cycles, and thus heating and cooling cycles, of the susceptor arrangement. When the holder module 10 is moved into the control module 13, the holder 11 is inserted, and with it the susceptor arrangement in the holder, in the internal excitation device of the control module 13 to carry out the test.

[0109] The excitation device includes an excitation coil that penetrates the susceptor arrangement during testing and generates a changing magnetic field that induces eddy currents for heating. The measurement device is configured to measure induced loads on the system, including voltages and currents absorbed upstream of the excitation device.

[0110] The test apparatus shown in Figure 1 further comprises a cooling unit 17 for cooling the control module 13. By means of the cooling unit 17 the test apparatus 1, in particular the control unit 13, can preferably be maintained at a predetermined temperature, for example below 100 degrees Celsius.

[0111] This is advantageous because it allows for the testing of consecutive samples, avoiding overheating and allowing multiple tests to be performed with little or no interruption.Without active cooling, more time is required as the instrument must wait to cool before running the next test.

[0112] Data from the tests is sent via a serial streaming cable 14 provided in the control unit 13 to a processor (not shown) where data and test analysis may be performed.

[0113] 2 shows in more detail the holder 11. The holder 11 is provided with a cavity in the form of a longitudinal slit 3 for the insertion of an elongated susceptor arrangement (not shown) to be tested.

[0114] A clip 31 is disposed at each of the opposing longitudinal ends of the cavity 3. The clips 31 hold the susceptor arrangement in place within the cavity 3 during testing.

[0115] Direct physical contact between the susceptor arrangement and the holder 11 is minimized. With the cavity 3 in the form of slits and clips 31 for holding the susceptor arrangement, the susceptor arrangement is substantially suspended in air with little physical contact with the holder (except for the clips 31).

[0116] The cavity walls are provided along the longitudinal side walls of the cavity 3 with a thermal insulating coating 32, for example a thermal insulating ceramic coating. With such a coating 32, the risk of burning of the holder 11 can be reduced or avoided, especially if the holder body is made of plastic.

[0117] The holder 11 is provided with an insertion means 35, here in the form of a flat circumferential side of an otherwise rod-shaped holder. The insertion means 35 is arranged at the end of the holder 11 opposite the cavity 3. The flat insertion means 35 allows the insertion of the holder 11 into the holder module 10 only in one fixed rotational position. Furthermore, the insertion means 35 ensures that the holder 11 is fixed in its rotational position when arranged in the holder module 10 and is therefore stable during testing. The insertion means may make it possible to supply the holder 11 with a susceptor arrangement before the holder 11 is placed in the holder module 10.

[0118] In other embodiments, the test device 1 may also be used with consumables. Hence, the test device 1 may be used directly to test aerosol-generating articles with susceptor arrangements, such as, for example, induction-heated tobacco rods with strip-like multi-layer susceptor arrangements. In these embodiments, the consumables to be tested are mainly replaced by the holder 11. Thus, the holder module 10 may be configured with a tubular slot for directly receiving and housing the article. Alternatively, the holder may comprise holder means configured to receive such heat sticks.

[0119] Figure 3 shows an internal view of the control module 13. The control housing 23 comprises an opening 20 and a cylindrical slot 21 for receiving the holder 11 with the susceptor arrangement. The control module 13 further comprises a PCB (Printed Circuit Board) 22. The PCB 22 comprises all components that are typically included in a commercially available device such as power supply, excitation devices, measurement devices, etc. However, the test device 1 preferably does not include any envelope constraints as the corresponding real device, e.g. power limitations, temperature limitations, etc. Thus, the testing of the susceptor arrangement can be performed under very stable conditions with accordingly accurate test results.

[0120] When the holder 11 is inserted into the slot 21 of the control module 13, the configuration is such that the susceptor arrangement reaches a nominal position within the control module 13. To perform the test, the test device 1 starts generating a number of calibration pulses with the aim of measuring characteristic points of a calibration curve of the susceptor arrangement, preferably in terms of the conductance values ​​of the susceptor arrangement.

[0121] 4 is a schematic diagram of the control module 13 and a slot 21 in the control module 13. A part of a holder with a susceptor arrangement is accommodated in the slot 21 in order to check the quality of the susceptor arrangement.

[0122] Located within the control module 13 is an excitation coil 129 which longitudinally surrounds the slot 21 and forms part of an LRC measurement circuit indicated at block 130 .

[0123] The test fixture 1 operates in a manner similar to the coil module used in a commercial device, and is intended to simulate such a real device as closely as possible, such that the susceptor arrangement heats in a manner similar to the real device, and thus heats the aerosol-forming substrate of the article for aerosol formation.

[0124] A calibration curve for conductance values ​​(in millimens) over time (in milliseconds) is shown in Figure 5. A typical output for a single susceptor test provided by a test device 1 according to the invention is shown in Figure 5. The calibration curve is shown along the listening period H and the cooling period C of the test cycle.

[0125] The heating pulse is such that the susceptor conductance value reaches a valley 50 with a conductance value GV1 after a time tV1, and after further heating at a time tH1 reaches a hill 51 having a conductance value GH1.

[0126] In the measurement device of the control module 12, the hill value 51 and the valley value 50 are detected and measured 50, resulting in ΔS (the difference in conductance between the hill 51 and the valley 50, and the associated times tV1 and tH1 to reach the valley and hill points, resulting in Δt (the time to reach the hill from the valley). The susceptor is then cooled as shown by the dashed line.

[0127] During the test, the susceptor reaches hill 51, and thus the shape of the hill can also be detected and measured. This is illustrated in the graph by the curve from points 51 to 81 (corresponding to conductance values ​​GH1 to GE1).

[0128] In the test apparatus there is no risk of overheating the heat stick or tobacco plug; in real conditions the susceptor arrangement is accommodated for heating the consumable.

[0129] If it is found that a valid calibration curve has been produced in the tests, this means that the susceptor arrangement is correctly manufactured, has satisfactory material quality, and provides satisfactory performance upon heating.

[0130] The conductance curve of FIG. 5, and the corresponding valleys and hills in conductance, essentially show the relationship between the DC current drawn from the power supply in the test fixture over time as the temperature of the susceptor arrangement increases.

[0131] The DC current drawn from the power supply is measured at the input of the DC / AC converter. The voltage of the power supply can be assumed to be approximately constant. When the susceptor arrangement is inductively heated, the apparent resistance of the susceptor increases. This increase in resistance is observed as a decrease in the DC current drawn from the power supply, which at constant voltage decreases as the temperature of the susceptor arrangement increases. The high frequency alternating magnetic field provided by the excitation device of the control module 13 induces eddy currents in the vicinity of the susceptor surface (skin effect). The resistance of the susceptor arrangement depends partly on the electrical resistivity of the first susceptor material, partly on the resistivity of the second susceptor material, and partly on the depth of the skin layer of the respective materials available for the induced eddy currents, the resistivity being temperature dependent. When the second susceptor material reaches its Curie temperature, it loses its magnetism. This increases the skin layer available for eddy currents in the second susceptor material, which reduces the apparent resistance of the susceptor arrangement. This results in a momentary increase in the detected DC current as the skin depth of the second susceptor material begins to increase and the resistance begins to drop. The current continues to increase until it reaches a maximum skin depth that coincides with the point at which the second susceptor material loses its natural magnetic properties. This point is called the Curie temperature and is seen in FIG. 5 as a hill (local maximum) 51. At this point, the second susceptor material has undergone a phase change from a ferromagnetic or ferrimagnetic state to a paramagnetic state. At this point, the susceptor arrangement is at a known temperature (the Curie temperature, which is a unique material specific temperature). If the control unit continues to generate the alternating magnetic field after the Curie temperature is reached (i.e., power to the DC / AC converter is not interrupted), the eddy currents generated within the susceptor arrangement will flow against the resistance of the susceptor arrangement, which will continue to Joule heat the susceptor arrangement, which will cause the resistance to increase again and the current to begin to drop again as long as the control unit 13 continues to supply power to the susceptor arrangement.

[0132] Thus, the apparent resistance of the susceptor arrangement (and the corresponding current IDC drawn from the power supply) may vary with the temperature of the susceptor arrangement in a strictly monotonic relationship over a particular temperature range of the susceptor arrangement. The strictly monotonic relationship allows for an unambiguous determination of the temperature of the susceptor arrangement from a determination of the apparent resistance or apparent conductance (1 / R). This is because each determined value of apparent resistance represents only one value of temperature, and there is no ambiguity in the relationship. The monotonic relationship between the temperature and apparent resistance of the susceptor arrangement allows the temperature of the susceptor arrangement to be determined and controlled, and thus the temperature of the aerosol-forming substrate to be determined and controlled, where the susceptor arrangement is intended to be disposed for heating the substrate.

[0133] The apparent resistance of the susceptor arrangement can be detected remotely by monitoring at least the DC current drawn from the DC power supply.

[0134] At a minimum, the DC current drawn from the power supply is monitored by the control module 13. Preferably, both the DC current drawn from the power supply and the DC power supply voltage are monitored. The control module 13 adjusts the supply of power provided to the induction heating device based on a conductance or resistance value, where conductance is defined as the ratio of the DC current to the DC power supply voltage and resistance is defined as the ratio of the DC power supply voltage to the DC current.

[0135] The measurement device of the control module 13 may comprise a current sensor for measuring the DC current. The measurement may optionally include a voltage sensor for measuring the DC power supply voltage. The current sensor and the voltage sensor are located on the input side of the DC / AC converter. The DC current and optionally the DC power supply voltage are provided by a feedback channel to the controller, which controls the further supply of AC power to the exciter.

[0136] The calibration of the susceptor arrangement is preferably repeated multiple times so that the variation in ΔS over time can be recorded as an additional output. Figure 6 illustrates a typical output of a susceptor test provided by a test apparatus 1, such as that shown in Figure 1, in which a series of three test cycles 91, 92, 93 are performed.

[0137] The first heating pulse is such that the susceptor reaches a valley 50 at a conductance value GV1 after a time tV1, and then reaches a hill 51 at a conductance value GH1 after a time tH1. The susceptor is then cooled (dashed line) until a second heating pulse is provided, such that the susceptor reaches a valley 60 at a conductance value GV2 after a time tV2, and then reaches a hill 61 at a conductance value GH2 after a time tH2. The susceptor is then cooled again until a third heating pulse is provided, such that the susceptor reaches a valley 70 at a conductance value GV3 after a time tV3, and then reaches a hill 71 at a conductance value GH3 after a time tH3. This can be continued for as many calibrations as desired.

[0138] Also, in three test cycles 91, 92, 93, the susceptor reaches and exceeds hills 51, 61, 71. This is illustrated on the graph by the curves from points 51-81 (corresponding to conductance values ​​GH1-GE1), points 61-82 (corresponding to conductance values ​​GH2-GE2), and points 71-83 (corresponding to conductance values ​​GH3-GE3).

[0139] The device may monitor subsequent values ​​of ΔS, as well as their evolution and average values.

[0140] The measurement device results may be in terms of, for example, the number of calibrations and the associated average ΔS obtained with the ΔS value at each calibration pulse.

[0141] Depending on such analysis, a decision may be taken to accept or reject the sample. The testing is preferably performed on a susceptor arrangement that is a "sample". This means that the sample represents the entire batch of material, generally in the form of a susceptor bobbin. If the sample tests positive, then the entire batch is accepted. If the sample tests unsuccessfully, then the entire batch is rejected. This simplifies testing of the entire batch, since it is known that within a batch, there is generally very little variation in the physical properties of the batch materials.

[0142] Figure 7 shows the test fixture 1 used with a calibration susceptor 7, indicated by block 95 in Figure 7. The calibration susceptor 7 is not an actual susceptor, but rather comprises a bobbin (not shown) which acts as a transformer unit when inserted into the slot 21 of the control module 13. This is made possible by having two windings, an inner winding which is one of the bobbins of the calibration susceptor 7 and an outer winding which is the excitation coil 11 of the control module 13. The calibration susceptor block 95 comprises an electrical arrangement inside which simulates a load.

[0143] As a result, when the bobbin of the calibration susceptor 7 is used to perform a test, the configuration is such that the conductance of the calibration susceptor 7 is fixed and does not change throughout the test.

[0144] Using this test, the test device 1 may advantageously be calibrated prior to the actual test.

[0145] The conductance of the calibration susceptor 7 is a known value X, so that the result Y given by the test fixture 1 can be adjusted based on this known value (with an error YX).

[0146] For example, the calibration susceptor 7 is configured to have a conductance value equal to 880 mS. If the output of the test device is 881 mS, this means that the conductance value returned by the device 1 at the end of the test must be subtracted by 1 mS to compensate.

[0147] The calibration susceptor 7 acts as an offset for the test fixture 1 and is used to calibrate the test fixture 1 prior to running a test to test the susceptor arrangement.

[0148] In Fig. 8 and Fig. 9 an open coil arrangement 129 is shown. In Fig. 8 an article 4 to be tested is about to be inserted into the coil arrangement 129 from the left side of Fig. 8. As seen in Fig. 9 the article is moved further into and partially through the coil arrangement to the right side of Fig. 9. The article 4 is moved into the cylindrical passage 21 in the coil arrangement 129 to a measurement position. After testing the article 4 moves in the same linear motion out of the coil arrangement 129. Subsequent articles to be tested can be used to push the previous article forward. This requires little product handling for subsequent or successive testing of the article 4. The coil arrangement 129 for the present test device may have an inductivity, for example, in the range of 120 nanohenries to 135 nanohenries, preferably 125 nanohenries to 130 nanohenries.

[0149] 10 and 11 show a coil arrangement 129 with electrical contacts 128 to provide power to the coil arrangement. In FIG. 10, the contacts 128 are arranged parallel to the passage 21 in the coil arrangement 129 so as not to impede the insertion or passage of an item 4 into the coil arrangement. This contact arrangement also simplifies the removal and insertion of the coil arrangement 129 into a control module. In FIG. 9, the electrical contacts 128 are bent radially outward 90 degrees to establish electrical contact within the control module. The bent contacts allow for mounting, e.g., soldering, of the coil arrangement 129 perpendicular to a PCB board for vertical set-up of the coils and vertical passage of an item through the coil arrangement 129.

[0150] FIG. 12 shows the test fixture 1 with a vertical passageway 21 that extends through the coil arrangement 129 of the control module 13 and through the control module. The control module 13 otherwise has a similar setup to the control module described with respect to FIG. 3, including a PCB (printed circuit board) 22 having the components necessary to measure the physical properties of the susceptor arrangement within the article. The control module 13 is mounted on a support 15. The support 15 includes an opening 150 that aligns with the passageway 21 through the control module 13. The article to be tested may pass through the passageway 21 and exit the control module 13 by gravity alone.

[0151] 13 shows a modular setup of two test fixtures 1 mounted in parallel. The arrows indicate the vertical insertion direction of the articles in each of the test fixtures 1. Still further test fixtures 1 may be arranged in parallel to increase the number of articles tested per hour.

[0152] Each of the two test devices 1 is provided with two control modules 13 arranged in series. Each of the control modules 13 comprises an open coil, the passages in which are arranged perpendicularly and in alignment with each other. Thus, an article to be tested can pass through both control modules of the same test device 1.

[0153] A test fixture having two serially arranged control modules 13 is shown diagrammatically in Figure 14. In the internal view of the test fixture 1 in Figure 14, a serial arrangement of two coil arrangements 129 can be seen. One coil arrangement is located at the top of the test fixture and the second coil arrangement 129 is located at the bottom of the test fixture.

[0154] To prevent the article from falling further through the equipment, two stops 25, 26 are provided. An upper stop 25 is provided approximately halfway down the length of the test device and a lower stop 26 is provided at the end of the device, more precisely at the exit end of the second coil arrangement 129.

[0155] The testing apparatus is adapted to measure short articles, for example single-length articles with a susceptor arrangement, which may be located at either end of the article. If an article is inserted into the testing apparatus with its susceptor arrangement at its top end (in a given orientation relative to the vertical processing direction of the article), the top stopper 25 is actuated and the article is positioned in the top control unit and measured using the top control unit 13. If an article is inserted into the testing apparatus with its susceptor arrangement at its bottom end, the bottom stopper 26 is actuated and the article is positioned in the bottom control unit and measured using the bottom control unit 13. This ensures that the susceptor arrangement in the article to be tested is always accurately positioned in the coil arrangement 129.

[0156] The testing apparatus is also adapted to measure long articles, e.g. double-length articles, and accordingly comprises two susceptor arrangements. The two susceptor arrangements are arranged at each end of the double-length article. When the double-length article is inserted into the testing apparatus, the lower stopper 26 is activated so that the two susceptor arrangements of the double-length article can be measured by the two coil arrangements. After the measurement has been performed, the respective stoppers 25, 26 are withdrawn. The tested article may fall downwards from the testing apparatus to make room for the next article to be tested.

[0157] Alternatively, or in addition to the stopper, other forms of holding the dropped article within the test apparatus may be used. Such a holder may, for example, be a clamp in the form of half shells that can be opened and closed, clamping the article between the shells.

[0158] FIG. 15 shows a setup of a test apparatus 1 adapted to test a dropped article 4 passing through the test apparatus 1. This setup may for example be integrated into an article manufacturing process. For example, some of the manufactured articles may be bypassed and essentially tested in-line to check whether they meet the required quality specifications. It is also possible to pass all manufactured articles through the test apparatus but occasionally select an article to be tested and have it tested. All other articles are not tested and simply fall under the setup shown.

[0159] A reservoir 40 in the form of a hopper contains a plurality of articles, e.g., elongated sticks, carrying one or two susceptor arrangements to be tested. The hopper can preferably contain several hundred sticks, e.g., 200-300 sticks.

[0160] From the hopper, the articles 4 fall downwards and are positioned along a vertical line, for example in a slide assembly arranged below the reservoir 40. The articles 4 then reach the test device 1. In the set-up, the falling articles are guided into a passage 21 in the test device. After passing the excitation coil or excitation coils in the test device 1, the tested articles leave the passage in the coil, pass through an indicator and selection portion 43 and then into a container 44 that collects the articles.

[0161] The indicator and selection portion 43 may include a sensor and, for example, an indicator light to indicate the result of the tested article, for example acceptance of the tested article.

[0162] The indicator lights may indicate the status of the test equipment or whether the tested article is acceptable or defective, for example, by changing the color of the light. For example, one color may indicate that the equipment is ready to measure, that a measurement is in progress, that the measured article is within the product tolerance, or that the article is outside the product tolerance.

[0163] The test conditions are preferably kept constant throughout the measurement cycle, e.g., over a certain number of tested articles, or over a certain test time, e.g., 24 hours. For example, the test conditions include about 20-24 degrees Celsius and about 40-60 percent relative humidity. An acceptable deviation from the desired electrical resistance is, for example, ±40 milliohms for a susceptor element electrical resistance of 300-450 milliohms. The deviation is preferably determined relative to an average value, e.g., over five measurements.

[0164] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like should be understood in all instances as being modified by the term "about." Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A±5%. Within this context, the number A may be considered to include values ​​that are within the general standard error for the measurement of the property that the number A modifies. The number A may, in some instances used in the appended claims, deviate by the percentages recited above, without materially affecting the basic and novel properties of the claimed invention. Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. 1. A test apparatus for testing a susceptor arrangement under simulated heating conditions of a heated susceptor arrangement disposed within an aerosol generating device during a user experience, the test apparatus comprising: a holder module comprising a holder for receiving a susceptor arrangement to be tested; a control module comprising an induction heating arrangement and a measurement device comprising a control circuit, the induction heating arrangement configured to generate an alternating magnetic field for inductively heating the susceptor arrangement; a measuring device configured to determine a value associated with a physical property of the susceptor arrangement from measurements related to a load applied to the control circuit in response to a susceptor arrangement in operative communication with the induction heating arrangement, the control circuit configured to power the induction heating arrangement during one test cycle or several subsequent test cycles of the susceptor arrangement, and a testing apparatus configured to determine whether the determined value associated with the physical property of the susceptor arrangement corresponds to a predetermined susceptor value.

2. 10. The testing apparatus of claim 1, wherein the control module is configured to output acceptance of the tested susceptor assembly if a predetermined susceptor value is reached or to output rejection of the tested susceptor assembly if the predetermined susceptor value is not reached.

3. 3. The testing apparatus of claim 1, wherein the value associated with the physical property of the susceptor arrangement is an apparent electrical conductance value, and the predetermined susceptor value is a predetermined electrical conductance value.

4. 10. The testing device of claim 1, wherein the holder comprises a cavity for receiving and housing a susceptor arrangement within the cavity.

5. 5. The testing device of claim 4, wherein at least one clip is disposed within the cavity for securing a susceptor arrangement within the cavity.

6. 10. The testing apparatus of claim 1, further comprising a cooling device for cooling the susceptor arrangement between heating cycles.

7. 2. The testing apparatus of claim 1, further comprising a support, wherein the holder module and the control module are attached to the support, and the holder module and the control module are movable relative to each other on the support such that at least a portion of the holder in the holder module can be accommodated in and removed from respective receiving slots in the control module.

8. 2. The test apparatus of claim 1, further comprising a calibration susceptor for performing a test cycle to determine a calibration factor of the test apparatus, the calibration susceptor having a fixed susceptor value, e.g., a fixed electrical conductance value, throughout the test cycle.

9. 1. A method for testing a susceptor arrangement in a test apparatus under simulated heating conditions of a heated susceptor arrangement in an aerosol generating device during a user experience, the method comprising: providing a susceptor arrangement including at least a first susceptor material and a second susceptor material; a) placing the susceptor arrangement in operable communication with an induction heating arrangement and inductively heating the susceptor arrangement with the induction heating arrangement; b) determining a value associated with a physical property of the susceptor arrangement from measurements related to a load applied to a control circuit, the measurements being responsive to the susceptor arrangement being in operative communication with the induction heating arrangement during a test cycle; repeating steps a) and b), thereby determining values ​​associated with the physical properties of the susceptor arrangement for subsequent test cycles; comparing the determined value associated with the physical property of the tested susceptor arrangement with a predetermined susceptor value; and accepting or rejecting the tested susceptor arrangement if the difference between the determined susceptor value and a predetermined susceptor value exceeds a predetermined threshold.

10. 10. The method of claim 9, further comprising averaging the determined values ​​associated with the physical properties of the susceptor arrangement over several or all test cycles, and comparing the averaged susceptor values ​​to the predetermined susceptor values.

11. 11. The method of claim 9, wherein the predetermined values ​​associated with the physical properties of the susceptor arrangement comprise maximum and minimum values ​​of electrical conductance per test cycle at predetermined times during a test cycle, preferably during a heating period of the test cycle.

12. 11. The method of claim 9, wherein the first susceptor material of the susceptor arrangement and the second susceptor material of the susceptor arrangement are in intimate physical contact with each other, and the second susceptor material comprises a Curie temperature of less than 500 degrees Celsius.

13. The method of any one of claims 9 to 10, wherein the first susceptor material does not have a Curie temperature or has a Curie temperature above 500 degrees Celsius.

14. 11. The method of claim 9, wherein the second susceptor material comprises or consists of a Ni—Fe alloy comprising 75 weight percent to 85 weight percent and 10 weight percent to 25 weight percent Fe.

15. The method of any one of claims 9 to 10, wherein the susceptor arrangement comprises a third susceptor material intimately coupled to the second susceptor material.

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