Device and method for dynamically testing spreadability of powder with multiple granularity sections
Through dynamic testing devices and methods, the problem that traditional powder metallurgy performance indicators cannot reflect powder spreading performance is solved, and accurate detection and optimization of powders in different particle size segments is achieved, and the quality and performance of additive manufacturing parts are improved.
Patent Information
- Application Number
- CN202411136025.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-19
- Publication Date
- 2024-12-13
Smart Images
Figure CN119124924A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a device and method for dynamically testing the spreading performance of powders in multiple particle sizes. Background Art
[0002] Additive manufacturing (AM) processes, such as laser powder bed fusion (LPBF) technology, are characterized by the construction of uniformly spread powder layers by laser scanning, which can provide a high degree of design freedom. In recent years, the fields of aerospace, automobiles, etc. have put forward higher requirements for the accuracy of additively manufactured parts, which has also promoted the development of higher-precision additive manufacturing technology. Improving the accuracy of additively manufactured parts requires three aspects: reducing the diameter of the laser spot, reducing the thickness of the spreading layer, and using ultrafine powders with finer particle sizes. However, due to the characteristics of small mass and high cohesion, ultrafine powders are very easy to agglomerate, resulting in problems such as empty spots and uneven powder thickness during the spreading process of small layer thickness, and easily causing melting defects during the laser forming process, which makes the surface quality and overall performance of the back-end parts worse.
[0003] At present, the determination of whether the powder can meet the printing requirements in the additive manufacturing industry still relies on the standard characterization methods of traditional powder metallurgy, such as characterizing fluidity, bulk density and other properties. It is generally believed that powders with fluidity or smaller flow rate values (tested by Hall flowmeter) can better meet the printing requirements. The industry generally stipulates that the particle size of powders that meet the printing requirements is within the range of 15-53μm. However, in actual production, operators found that some powders without fluidity can also be printed. In view of the emerging micron-level laser powder bed fusion (μ-LPBF) technology in recent years, the powder particle size range is even more limited to 0-25μm. According to experimental tests, ultrafine powders in the particle size range of 0-25μm cannot be tested for fluidity using traditional Hall flowmeters, and agglomerated powders are difficult to flow down the funnel mouth, that is, they do not have fluidity. It can be seen that traditional performance indicators such as fluidity cannot objectively reflect the spreading performance of powders, but there is still a lack of standardized testing devices and methods for the actual spreading performance of powders, which cannot fully meet the testing needs of raw materials required for higher-precision additive manufacturing processes.
[0004] In summary, the actual spreading characteristics of powders in the additive manufacturing process directly affect the quality of additively manufactured parts. Therefore, in addition to direct observation, it is crucial to develop a device and method that can judge the spreading properties of powders in various particle size ranges, which is of great significance for promoting the development of the high-precision additive manufacturing industry. This patent provides a solution that can dynamically test the spreading properties of powders in multiple particle size ranges. Summary of the invention
[0005] The main purpose of the present invention is to provide a device and method for dynamically testing the spreading performance of powders in multiple particle size segments. By setting steps S1-S7 and a spreading module and a testing module, the problem that traditional performance indicators such as fluidity cannot objectively reflect the spreading performance of powders is solved. However, there is still a lack of standardized testing devices and methods for the actual spreading performance of powders, which cannot fully meet the detection requirements of raw materials required for higher-precision additive manufacturing processes.
[0006] To achieve the above object, the present invention provides the following technical solutions: A device and method for dynamically testing the spreading performance of powders in multiple particle sizes, comprising a testing platform, and also comprising: A powder storage bin, which is arranged on the top of the test platform; A spreading module, wherein the spreading module is arranged on the top of the test platform; The spreading module includes a guide rail arranged relatively on the top of the test platform and a scraper arranged on the side of the guide rail; A test module, wherein the test module is arranged on a side of the powder storage bin; The test module includes a wedge-shaped groove arranged on the top surface of the test platform, a circular groove arranged on the side of the wedge-shaped groove, and a square groove arranged on the side of the circular groove; A light mirror is arranged on the top of the wedge-shaped groove; A lifting platform is arranged at the bottom of the circular groove and the square groove.
[0007] Preferably, a motor is provided on the side of the guide rail; A vibration pump is installed on the side of the scraper.
[0008] Preferably, the depth of the wedge-shaped groove varies in a gradient, and a scale line of 0-100 μm is provided at the bottom of the wedge-shaped groove, and the depth is zero at the 0 μm mark line, that is, the end is on the same level as the top surface of the test platform.
[0009] Preferably, the bottom of the scraper is in close contact with the top of the test platform, and the height of the scraper is adjustable.
[0010] Preferably, the test module is used to test the spreadability of powder in different particle size segments, including spreading coverage and spreading density.
[0011] The method for using the device for dynamically testing the spreading performance of multi-size powders comprises the following steps: S1, preparation stage, ensure that the test platform is clean and free of impurities, and load the powder material to be tested into the powder storage bin; S2, powder spreading, start the powder storage bin platform, push the powder upward to make it higher than the test platform surface, then start the scraper in the spreading module, drive the scraper to reciprocate on the guide rail through the motor, and push the powder forward to spread; S3, powder spreading performance test, the powder is pushed to the test module, the test module integrates wedge-shaped grooves, circular grooves and square grooves, and adjusts the height of the lifting platform to simulate different layer thicknesses in the actual printing process; S4, observation and evaluation, using an optical microscope to observe the powder spreading state in the wedge-shaped groove, and using an image method and an optical microscope projection area method to evaluate the spreading coverage, respectively, using image processing software to analyze the area ratio of the powder covered area to the uncovered area, and using the feedback value of the weighing sensor integrated on the platform below the circular groove (42) and square groove (43) functional modules to calculate the powder spreading density; S5. Data recording and analysis: record the spreading coverage and spreading density of different particle size segments, analyze the data, determine the spreading performance of the powder, optimize the powder material or adjust the spreading process parameters; S6. Adjustment and optimization: according to the test results, adjust the vibration frequency of the scraper, the powder spreading speed or the particle size distribution of the powder material to improve the spreading performance; S7. Repeat the test and repeat the above steps to test different powder materials or different process parameters to obtain the best spreading performance.
[0012] Preferably, in step S4, the spreading coverage is calculated using an image method, and the area ratio of the powder covered area to the uncovered area is analyzed by image processing software, comprising the following steps: S41, performing overall imaging of the powder spread within the range of 0-100 μm in the wedge-shaped groove, adjusting the contrast between the powder covered area and the uncovered area in the wedge-shaped groove, and converting it into a threshold map of two colors; S42. The red area in the threshold image represents the powder-covered area, and the gray area represents the uncovered area. The proportion of the powder-covered area to the overall area is calculated using image processing software; S43. When the ratio is greater than 50%, the powder is considered to have good spreadability; when the ratio is less than 50%, the powder is considered to have poor spreadability.
[0013] Preferably, the calculation of the spreading density using the optical microscope projection area method in step S4 comprises the following steps: S401. Apply the powder at a uniform speed within 10 seconds, place the fineness meter under a light microscope, and take a strip of about 3 mm at the required spreading layer thickness scale as the observation range; S402, using image processing software to calculate the ratio of the projected area of the powder in each field of view to the area of the entire field of view; S403. When the ratio value is greater than 20%, it is considered to have good spreadability; when the ratio value is less than 10%, it is considered to have poor spreadability; and when the ratio value is between 10% and 20%, it is considered to have average spreadability.
[0014] Preferably, the calculation of the spreading density using the circular groove (42) and square groove (43) functional modules in step S4 comprises the following steps: S4001, lowering the lifting platform (44) below the circular groove (42) and the square groove (43) to form a groove with a fixed depth of h, and calculating the volumes of the circular groove (42) and the square groove (43), which are respectively counted as v1 and v2; S4002, applying powder at a uniform speed to fill the circular groove (42) and the square groove (43), and reading the weight of the weighing platform below the groove, which are respectively calculated as m1 and m2; S4003. Use the volume calculation formula to calculate the spread density values ρ1 and ρ2 measured in each groove, and compare the loose density ρ of the powder. 松装 And the tap density value ρ 振实 , evaluate the spreading properties of powders; S4004, when ρ1, ρ2 values are greater than ρ 振实 , it is considered to have excellent spreading properties; when the values of ρ1 and ρ2 are between ρ 振实 and ρ 松装 When the values of ρ1 and ρ2 are less than ρ 松装 , which is considered to have poor spreadability.
[0015] Compared with the prior art, the present invention has the following beneficial effects: It solves the needs of powder spreading test at various particle size ends, such as 0-25um, 15-53um, 63-100um. The application technology of powders in different particle size segments is different. For example, fine powders of 0-25um are very easy to agglomerate and difficult to characterize using flowability test methods. The frequency and spreading speed of the scraper can be adjusted dynamically to verify the influence of these process parameters on the spreading state of the powder bed and the later forming performance. Combined with the current experimental results, it is consistent with the expected results: as the vibration frequency of the scraper increases, the powder spreading property becomes better, but when the vibration frequency is too high, the powder begins to agitate and the effect becomes worse; The spreading density of the powder bed during printing can be accurately measured, which truly reflects the powder accumulation state during printing and is of great help in material estimation. It can be used to study the effects of scraper speed and vibration frequency on powder spreading density and the performance of later formed parts (such as density, roughness, etc.). BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is a plan view of the present invention; Figure 2 This is a schematic diagram of the powder spreading coverage test process of the present invention; Figure 3This is a schematic diagram of the powder spreading density test process of the present invention; Figure 4 This is a schematic diagram of the comparison of the spreading density of the powder of the present invention; Figure 5-6 It is a threshold map of the powder covered area and uncovered area of the present invention; Figure 7-10 This is a diagram of the spreading state of the powder observed under a 5X field of view of a light microscope according to the present invention.
[0017] In the figure: Test platform; Powder storage silo; Spreading module; 31. guide rail; 32. scraper; Test module; 41. wedge-shaped groove; 42. circular groove; 43. square groove; 44. lifting platform; 45. optical mirror. DETAILED DESCRIPTION
[0018] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.
[0019] Example 1: Figure 1-5 As shown, the device and method for dynamically testing the spreading performance of powders in multiple particle sizes include a testing platform 1, and also include: Powder storage bin 2, the powder storage bin 2 is arranged on the top of the test platform 1; Spreading module 3, the spreading module 3 is arranged on the top of the testing platform 1; The spreading module 3 includes a guide rail 31 arranged relatively on the top of the test platform 1 and a scraper 32 arranged on the side of the guide rail 31; A test module 4, which is arranged on the side of the powder storage bin 2; The test module 4 includes a wedge-shaped groove 41 disposed on the top surface of the test platform 1, a circular groove 42 disposed on the side of the wedge-shaped groove 41, and a square groove 43 disposed on the side of the circular groove 42; A light mirror 45 is provided at the top of the wedge-shaped groove 41; A lifting platform 44 is disposed at the bottom of the circular groove 42 and the square groove 43 .
[0020] Preferably, a motor is provided on the side of the guide rail 31; A vibration pump is installed on the side of the scraper 32; The scraper 32 is fixed on both sides and can be driven by gear meshing or pulley to ensure that the scraper 32 reciprocates at a constant speed and direction. The motor on the guide rail device can dynamically adjust the powder spreading speed of the scraper 32, which can help us study the influence of the powder spreading speed on the powder spreading state. Generally speaking, the faster the powder spreading speed, the worse the spreading effect.
[0021] The depth of the wedge-shaped groove 41 varies gradually, and a scale line of 0-100 μm is set at the bottom of the wedge-shaped groove 41 . The depth is zero at the 0 μm mark, that is, the end is on the same level as the top surface of the test platform 1 .
[0022] The bottom of the scraper 32 is in close contact with the top of the test platform 1, and the height of the scraper 32 is adjustable. The height of the scraper 32 can be adjusted using a device in the prior art, such as a lifting cylinder to achieve the height adjustment of the scraper 32.
[0023] Among them, the test module 4 is used to test the spreadability of powder in different particle size segments, including spread coverage and spread density. The spread coverage and spread density test process is shown in Figure 2 as well as Figure 3 ; According to common sense, the larger the area covered by the powder in the groove, that is, the higher the spreading coverage, the better the spreading property; the higher the spreading density, the more powder falls into the groove within the same volume. Figure 4 It illustrates the comparison of powder spreading density, Figure III shows the ideal state.
[0024] The method for using the device for dynamically testing the spreading performance of multi-size powders comprises the following steps: S1, preparation stage, ensure that the test platform 1 is clean and free of impurities, and load the powder material to be tested into the powder storage bin 2; S2, powder spreading, start the powder storage bin platform, push the powder upward to make it higher than the test platform surface, then start the scraper 32 in the spreading module 3, drive the scraper to reciprocate on the guide rail 31 through the motor, and push the powder forward to spread; S3, powder spreading performance test, the powder is pushed to the test module 4, the test module 4 integrates the wedge-shaped groove 41, the circular groove 42 and the square groove 43, and adjusts the height of the lifting platform 44 to simulate different layer thicknesses in the actual printing process; S4, observation and evaluation, using an optical microscope 45 to observe the powder spreading state in the wedge-shaped groove 41, and the spreading coverage rate can be evaluated by using an image method and an optical microscope projection area method respectively, and the area ratio of the powder covered area to the uncovered area is analyzed by image processing software, and the powder spreading density is calculated by the numerical feedback of the weighing sensor integrated in the platform below the circular groove (42) and the square groove (43) functional module; S5. Data recording and analysis: record the spreading coverage and spreading density of different particle size segments, analyze the data, determine the spreading performance of the powder, optimize the powder material or adjust the spreading process parameters; S6. Adjustment and optimization: according to the test results, adjust the vibration frequency of the scraper, the powder spreading speed or the particle size distribution of the powder material to improve the spreading performance; S7. Repeat the test and repeat the above steps to test different powder materials or different process parameters to obtain the best spreading performance.
[0025] Wherein, in step S4, the spreading coverage is calculated by using an image method, and the area ratio of the powder covered area to the uncovered area is analyzed by image processing software, including the following steps: S41, performing overall imaging of the powder spread within the range of 0-100 μm in the wedge-shaped groove 41, adjusting the contrast between the powder covered area and the uncovered area in the wedge-shaped groove 41, and converting it into a threshold map of two colors; S42. The red area in the threshold image represents the powder-covered area, and the gray area represents the uncovered area. Image processing software (image threshold method / binarization) is used to calculate the proportion of the powder-covered area to the overall area. S43. When the ratio is greater than 50%, the powder is considered to have good spreadability; when the ratio is less than 50%, the powder is considered to have poor spreadability. Figure 5 As shown in (1), the red area accounts for 66.491% of the yellow box. Figure 5 As shown in (2), the red area accounts for 75.176% of the yellow box, which means that the spreadability is good; Figure 6 As shown in (1), the red area accounts for 42.958% of the yellow box. Figure 6 As shown in (2), the red area accounts for 1.891% of the yellow box, which means that the spreading property is poor.
[0026] Wherein, the calculation of the spreading coverage rate by using the optical microscope projection area method in step S4 comprises the following steps: S401. Apply the powder at a uniform speed within 10 seconds, place the fineness meter under a light microscope (5X field of view), and take a strip of about 3 mm at the required spreading layer thickness scale as the observation range; S402, using image processing software to calculate the ratio of the projected area (red area) of the powder in each field of view to the area of the entire field of view; S403. When the ratio value is greater than 20%, it is considered to have good spreadability; when the ratio value is less than 10%, it is considered to have poor spreadability; and when the ratio value is between 10% and 20%, it is considered to have average spreadability.
[0027] Preferably, the calculation of the spreading density using the circular groove (42) and square groove (43) functional modules in step S4 comprises the following steps: S4001, lower the lifting platform (44) below the circular groove (42) and the square groove (43) to form a groove with a fixed depth of h, and calculate the volume of the circular groove (42) and the square groove (43) (measure the side length and diameter), which are recorded as v1 and v2 respectively; S4002, applying powder at a uniform speed to fill the circular groove (42) and the square groove (43), and reading the weight of the weighing platform below the groove, which are respectively calculated as m1 and m2; S4003. Use the volume calculation formula (ρ=m / v) to calculate the spread density values ρ1 and ρ2 measured in each groove, and compare the loose density ρ of the powder 松装 And the tap density value ρ 振实 (This value is obtained according to the standards "GB / T 1479.1-2011 Determination of bulk density of metal powders Part 1: Funnel method" and "GB / T 5162-2021 Determination of tap density of metal powders"), to evaluate the spreading performance of the powder; S4004, when ρ1, ρ2 values are greater than ρ 振实 , it is considered to have excellent spreading properties (this condition generally does not occur); when the values of ρ1 and ρ2 are between ρ 振实 and ρ 松装 When the values of ρ1 and ρ2 are less than ρ 松装 , which is considered to have poor spreadability.
[0028] Taking the commonly used 15-53μm GH4169 powder as an example, the powder layer thickness in the actual printing process is 30μm. A fineness meter with a specification of 0-100μm was selected for spreading test. A strip of about 3mm was taken at the 30μm scale of the fineness meter as the observation range. The spreading state of the powder in the strip was observed under the 5X field of view of the optical microscope. The powder showed different spreading characteristics, as shown in Figure 7-10 As shown, within the selected viewing area, the red area of powders 1 and 2 accounts for more than 20% of the total area, which is considered to be powders with good spreadability; the red area of powders 3 and 4 accounts for less than 10% of the total area, which is considered to be powders with poor spreadability.
[0029] A weighing sensor is integrated under the forming platform to weigh the powder falling into the groove in real time. The volume of the groove can be calculated based on the groove depth and bottom area. The calculation of the powder spreading density value ρ can be carried out according to the following formula:
[0030] The spreading characteristics of the powder can be determined by the value of the spreading density: theoretically, if the volume of the groove of the fineness gauge is constant, the better the powder spreading property is, the greater the weight of the powder remaining in the groove after the scraper is applied, and the higher the corresponding powder spreading density value is. On the contrary, the worse the powder spreading property is, the smaller the weight of the powder remaining in the groove after the scraper is applied, and the lower the corresponding powder spreading density value is. Example
[0031] Prior to this, we made a simple device with a fixed height to test and evaluate the spreading density of three powders with a particle size of 0-25um, and conducted on-machine tests to study the influence of scraper vibration on powder packing density. The spreading density test device is to print a thin-walled circular ring structure with a height of 5mm, a diameter of 90mm, and a thickness of 1mm on the existing Φ100mm printing substrate. The volume of the groove surrounded by the ring and the substrate is fixed. The test substrate is connected to the forming platform so that the upper surface of the ring, the lower surface of the scraper, and the platform surface are kept at the same level. The powder in the silo is scraped into the groove of the test substrate by the scraper, and the scraping is repeated until the powder in the groove is completely filled. Take out the test substrate, weigh the powder deposited in the groove, and then test its spreading density. In order to ensure the smooth test of the spreading density, we modify the powder before the test to ensure that it has good spreading characteristics. The experiment used a recoating speed of 50 mm / s (scraper movement speed) and the vibrator air source strength was maintained at 4 bar. The spreading density of the following three powders was measured. The test results are shown in the following table: Powder spreading density test results
[0032] The test results show that the spreading density of the three powders is between the loose density and the tapped density, which means that the powder has good spreading properties. Combined with the actual LPBF printing process, it is found that the three powders all show good spreading effects and can fully meet the raw material requirements of printing.
Claims
1. A device for dynamically testing the spreading performance of powders of multiple particle sizes, comprising a testing platform (1), characterized in that: Also includes: A powder storage bin (2), wherein the powder storage bin (2) is arranged on the top of the test platform (1); A spreading module (3), wherein the spreading module (3) is arranged on the top of the test platform (1); The spreading module (3) comprises a guide rail (31) arranged relative to the top of the test platform (1), and a scraper (32) arranged on the side of the guide rail (31); A test module (4), the test module (4) being arranged on a side of the powder storage bin (2); The test module (4) comprises a wedge-shaped groove (41) arranged on the top surface of the test platform (1), a circular groove (42) arranged on the side of the wedge-shaped groove (41), and a square groove (43) arranged on the side of the circular groove (42); A light mirror (45) is provided on the top of the wedge-shaped groove (41); A lifting platform (44) is provided at the bottom of the circular groove (42) and the square groove (43).
2. The device for dynamically testing the spreading performance of multi-size powders according to claim 1, characterized in that: A motor is provided on the side of the guide rail (31); A vibration pump is installed on the side of the scraper (32).
3. The device for dynamically testing the spreading performance of multi-size powders according to claim 2, characterized in that: The depth of the wedge-shaped groove (41) changes in a gradient, and a scale line of 0-100 μm is provided at the bottom of the wedge-shaped groove (41). The depth is zero at the 0 μm scale line, i.e. the end is on the same horizontal plane as the top surface of the test platform (1).
4. The device for dynamically testing the spreading performance of multi-size powders according to claim 3, characterized in that: The bottom of the scraper (32) is in close contact with the top of the test platform (1), and the height of the scraper (32) is adjustable.
5. The device for dynamically testing the spreading performance of multi-size powders according to claim 4, characterized in that: The test module (4) is used to test the spreadability of powder in different particle size segments, including spread coverage and spread density.
6. A method for using a device for dynamically testing the spreading performance of powders in multiple particle sizes, characterized in that: The following steps are involved: S1, preparation stage, ensuring that the test platform (1) is clean and free of impurities, and loading the powder material to be tested into the powder storage bin (2); S2, powder spreading, starting the powder storage bin platform, pushing the powder upwards so that it is higher than the test platform surface, and then starting the scraper (32) in the spreading module (3), driving the scraper to reciprocate on the guide rail (31) through the motor, pushing the powder forward to spread; S3, powder spreading performance test, the powder is pushed to the test module (4), the test module (4) integrates a wedge-shaped groove (41), a circular groove (42) and a square groove (43), and adjusts the height of the lifting platform (44) to simulate different layer thicknesses in a real printing process; S4, observation and evaluation, using an optical microscope (45) to observe the powder spreading state in the wedge-shaped groove (41), and using an image method and an optical microscope projection area method to evaluate the spreading coverage, respectively, using image processing software to analyze the area ratio of the powder covered area to the uncovered area, and using the feedback value of the weighing sensor integrated on the platform below the circular groove (42) and square groove (43) functional modules to calculate the powder spreading density; S5. Data recording and analysis: record the spreading coverage and spreading density of different particle size segments, analyze the data, determine the spreading performance of the powder, optimize the powder material or adjust the spreading process parameters; S6. Adjustment and optimization: according to the test results, adjust the vibration frequency of the scraper, the powder spreading speed or the particle size distribution of the powder material to improve the spreading performance; S7. Repeat the test and repeat the above steps to test different powder materials or different process parameters to obtain the best spreading performance.
7. The method for using the device for dynamically testing the spreading performance of multi-size powders according to claim 6, characterized in that: In step S4, the spreading coverage rate is calculated by using an image method, and the area ratio of the powder covered area to the uncovered area is analyzed by image processing software, which includes the following steps: S41, performing overall imaging of the powder spread within the range of 0-100 μm in the wedge-shaped groove (41), adjusting the contrast between the powder covered area and the uncovered area in the wedge-shaped groove (41), and converting the image into a threshold map of two colors; S42. The red area in the threshold image represents the powder-covered area, and the gray area represents the uncovered area. The proportion of the powder-covered area to the overall area is calculated using image processing software; S43. When the ratio is greater than 50%, the powder is considered to have good spreadability; when the ratio is less than 50%, the powder is considered to have poor spreadability.
8. The method for using the device for dynamically testing the spreading performance of multi-size powders according to claim 7, characterized in that: The calculation of the spreading density using the light microscope projection area method in step S4 comprises the following steps: S401. Apply the powder at a uniform speed within 10 seconds, place the fineness meter under a light microscope, and take a strip of about 3 mm at the required spreading layer thickness scale as the observation range; S402, using image processing software to calculate the ratio of the projected area of the powder in each field of view to the area of the entire field of view; S403. When the ratio value is greater than 20%, it is considered to have good spreadability; when the ratio value is less than 10%, it is considered to have poor spreadability; and when the ratio value is between 10% and 20%, it is considered to have average spreadability.
9. The method for using the device for dynamically testing the spreading performance of multi-size powders according to claim 6, characterized in that: The calculation of the spreading density using the circular groove (42) and square groove (43) functional modules in step S4 comprises the following steps: S4001, lowering the lifting platform (44) below the circular groove (42) and the square groove (43) to form a groove with a fixed depth of h, and calculating the volumes of the circular groove (42) and the square groove (43), which are respectively counted as v1 and v2; S4002, applying powder at a uniform speed to fill the circular groove (42) and the square groove (43), and reading the weight of the weighing platform below the groove, which are respectively calculated as m1 and m2; S4003. Use the volume calculation formula to calculate the spread density values ρ1 and ρ2 measured in each groove, and compare the loose density ρ of the powder. 松装 and tap density ρ 振实 , evaluate the spreading properties of powders; S4004, when ρ1, ρ2 values are greater than ρ 振实 , it is considered to have excellent spreading properties; when the values of ρ1 and ρ2 are between ρ 振实 and ρ 松装 When the values of ρ1 and ρ2 are less than ρ 松装 , which is considered to have poor spreadability.