A method for sintering and cutting zirconia material and fabricating dental crowns.

Abstract

This application relates to the field of zirconia material processing technology, specifically providing a method for sintering and cutting zirconia materials and fabricating dental crowns. The preparation method includes mixing zirconia powder with a binder, molding it into a blank, the blank having a density reaching a predetermined density standard (less than the fully dense density), sintering the blank at a high temperature and holding it at that temperature, cooling it to room temperature after holding to obtain a sintered body with a fully dense density, cutting the sintered body using carbide or diamond tools, and then sandblasting and ultrasonically cleaning the cut sintered body to remove surface burrs and cutting residues. By sintering the zirconia material before cutting, material utilization is improved, processing accuracy is enhanced, production cycle is shortened, and equipment costs are reduced.

Description

Technical Field

[0001] This invention relates to the field of zirconia material processing technology, and in particular to a method for preparing zirconia material by sintering and cutting and for fabricating dental crowns. Background Technology

[0002] In existing zirconia manufacturing methods, a "cutting before sintering" process is adopted. The specific steps are as follows: first, a pre-sintered zirconia block (commonly known as "green blank") is selected, then it is processed into a blank that is close to the final shape by CNC cutting equipment, and finally the blank is placed in a high-temperature furnace for sintering and densification.

[0003] However, this method has several drawbacks, as shown below: First, it generates a large amount of powdery waste during the green blank cutting process, and this waste is difficult to recycle and reuse, resulting in a serious waste of zirconium oxide material and low material utilization. Second, the green blank has low strength, and defects such as chipping and cracking are easily generated when cutting it, leading to deviations in the dimensional accuracy of the final product and limiting the processing accuracy of the product. Third, when using green blanks for processing, multiple processes such as green blank preparation, cutting, degreasing, and sintering are required, resulting in a long production cycle and low production efficiency. Fourth, when cutting the green blank, special high-speed cutting equipment is required, and the equipment investment cost is higher than that of ordinary metal cutting equipment.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a method for sintering and cutting zirconia material and for fabricating dental crowns. By sintering the zirconia material first and then cutting it, the material utilization rate is improved, the processing accuracy is enhanced, the production cycle is shortened, and the equipment cost is reduced.

[0006] The technical solution adopted by this application to solve the technical problem is as follows: a sintering and cutting preparation method for zirconium oxide material, the preparation method comprising: Zirconia powder is mixed with a binder and molded into a blank. The density of the blank reaches a predetermined density standard, which is less than the density of a fully dense blank. The green blank is heated and sintered and held at that temperature. After holding, it is cooled to room temperature to obtain a sintered body with a fully dense density. The sintered body is machined using carbide or diamond tools; The sintered body after cutting is subjected to sandblasting and ultrasonic cleaning to remove surface burrs and cutting residues.

[0007] Furthermore, the purity of the zirconium oxide powder is greater than or equal to 99.5%, and the particle size of the zirconium oxide powder is 0.5-2 μm.

[0008] Furthermore, the adhesive is polyvinyl alcohol, and the amount of adhesive added is 3-5 wt%. The forming pressure is 50-100 MPa, so as to control the density of the green blank to be 55-65% of the theoretical density.

[0009] Furthermore, the heating rate is 5-10℃ / min to raise the sintering temperature to 1450-1600℃ and hold it for 2-4 hours.

[0010] Furthermore, when heated, the binder is decomposed into a gaseous substance and discharged through the pores inside the green blank to form the sintered body with a density ≥6.0 g / cm³ and a flexural strength ≥900 MPa.

[0011] Furthermore, the cemented carbide cutting tool is coated with tungsten carbide-cobalt, and the hardness of the cemented carbide cutting tool is ≥90HRA.

[0012] Furthermore, when cutting the sintered body, the cutting tool rotates at a speed of 8000-15000 rpm, the feed rate is 50-200 mm / min, the cutting depth is 0.1-0.5 mm, and the cutting tool is cooled by oil mist lubrication.

[0013] Furthermore, when performing sandblasting, 80-120 mesh alumina sand should be used; When performing ultrasonic cleaning, the frequency is 40kHz and the cleaning time is 10-15 minutes to remove surface burrs and cutting residues from the product. After ultrasonic cleaning, polishing is performed to control the surface roughness to ≤0.2μm.

[0014] A method for fabricating a dental crown includes a sintering and cutting preparation method for zirconium oxide material, the method comprising: When the zirconia material is in an uncrystallized green state, the area where the crown will be placed is preliminarily machined using high-precision cutting equipment; The pre-cut zirconia green blanks in the designated area are sintered according to standard process parameters. After sintering, the inner and outer surfaces of the crown are finely finished.

[0015] Furthermore, after sintering, the inner and outer surfaces of the crown are subjected to coarse grinding, fine grinding and polishing in sequence to optimize the occlusal surface morphology, axial surface protrusion and marginal fit.

[0016] Beneficial effects: This application provides a method for sintering and cutting zirconia materials and for fabricating dental crowns. By first preparing a blank and then sintering it to form a sintered body, the high strength properties of sintered zirconia are utilized to precisely machine the sintered body, thereby better manufacturing products of different shapes. At the same time, the cutting tools and cutting parameters can be improved, which can extend the tool life and improve the quality of the formed products. Ultimately, while reducing costs, it can also improve the quality and efficiency of product production. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of a sintering and cutting preparation method for a zirconium oxide material according to an embodiment of this application; Figure 2 This is a flowchart illustrating a method for fabricating a dental crown according to an embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer and more explicit, the following detailed description of this application is provided with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0019] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] This embodiment provides a method for preparing zirconia material by sintering and cutting, and for fabricating dental crowns. By sintering the zirconia material before cutting, material utilization is improved, processing accuracy is enhanced, production cycle is shortened, and equipment costs are reduced. Specifically, the method for preparing zirconia material by sintering and cutting is as follows: Figure 1 As shown, the method includes the following steps: Zirconia powder is mixed with a binder and molded into a blank. The density of the blank reaches a predetermined density standard, which is less than the density of a fully dense blank. The green blank is heated and sintered and held at that temperature. After holding, it is cooled to room temperature to obtain a sintered body with a fully dense density. The sintered body is machined using carbide or diamond tools; The sintered body after cutting is subjected to sandblasting and ultrasonic cleaning to remove surface burrs and cutting residues.

[0022] Therefore, after the zirconium oxide material is first made into a blank, the blank is sintered to form a sintered body. Then the sintered body is cut, and after the cutting is completed, surface treatments such as sandblasting or ultrasonic cleaning are performed to form the product.

[0023] To ensure the formation of a preform from zirconia powder, this application requires controlling the purity of the zirconia powder to be greater than or equal to 99.5%, and the particle size to be 0.5-2µm. Simultaneously, the zirconia powder of this specification needs to be bonded together to form the preform. Therefore, a binder is required; specifically, polyvinyl alcohol is used as the binder, and to ensure complete bonding of the zirconia powder while controlling the amount of binder, the amount added is 3-5wt%. After adding the binder, the mixture of zirconia and binder needs to be molded. In this application, the mixture is subjected to dry pressing or injection molding. During the molding process, to achieve better molding results, the molding pressure is 50-100MPa. By controlling the molding pressure within this range, the density of the preform is controlled to be 55-65% of the theoretical density. When the density of the preform is within this range, it ensures that the zirconia powder and 3-5 wt% polyvinyl alcohol binder are mixed evenly, allowing for smooth molding without the risk of a loose and easily broken preform due to excessively low density. It also eliminates the need for excessively high molding pressure and allows for sufficient sintering shrinkage space. If the preform density is below 55%, it will result in excessive porosity, making it prone to cracking and deformation after sintering, failing to achieve a flexural strength of ≥900 MPa. If the preform density is above 65%, the powder particles inside will be too densely packed, making it difficult for gases generated inside the preform to escape during sintering, resulting in insufficient density and internal defects in the sintered body. Generally, controlling the preform density within the range of 55-65% is sufficient; however, for optimal sintering results, the optimal preform density is 60%.

[0024] In this application, the green blank is sintered in a sintering furnace. During sintering, the temperature is gradually increased until a specified temperature is reached, and then maintained to complete the sintering process. Specifically, the heating rate is controlled at 5-10°C / min to ensure a slow temperature rise within the furnace, preventing damage to the green blank caused by rapid temperature increases and ensuring successful sintering. Furthermore, the temperature is not allowed to rise indefinitely during sintering; instead, it is maintained at a certain value to better sinter the green blank. Therefore, the temperature in the sintering furnace is raised to 1450-1600°C and held for 2-4 hours to fully sinter the green blank, transforming the loose zirconium oxide powder particles into a dense crystalline structure, thus forming a sintered body. Furthermore, the binder, which acts as a binder, is decomposed into gaseous substances, including water vapor and carbon dioxide, when heated in the sintering furnace. These gaseous substances are discharged outside the furnace through the pores inside the green blank, preventing the sintered body from being contaminated with other substances that could affect the product's use and improving product quality. After sintering, a sintered body with a density ≥6.0 g / cm³ and a flexural strength ≥900 MPa is formed, facilitating subsequent processing to create products that meet requirements. In other embodiments, sintering can also be performed in other devices.

[0025] After the green blank is sintered to form a sintered body, the hardness of the sintered body is increased compared to that of the green blank. Conventional zirconia cutting tools cannot cut the sintered body, so tools with higher hardness are required. Therefore, in this application, the cemented carbide tool used for cutting has a tungsten carbide-cobalt coating, and the hardness of the cemented carbide tool is ≥90HRA, in order to cut the sintered body with increased hardness. Because the thermal stability of the tool material limits the cutting of the sintered body, if the speed of the cemented carbide tool is too high, the tungsten carbide-cobalt coating will peel off or oxidize due to heat, greatly reducing the tool life. Diamond tools undergo oxidation at high temperatures, and the oxidation reaction will further generate heat. Therefore, in order to reduce the heat generated by cutting, the speed of the tool needs to be slowed down. Thus, in this application, the speed of the tool is 8000-15000 rpm, the feed rate is 50-200 mm / min, and the depth of cut is 0.1-0.5 mm. Furthermore, even if heat generation can be reduced by decreasing the rotation speed, the generated heat will inevitably lead to a temperature rise. This temperature rise will still cause the tungsten carbide-cobalt coating to peel off or oxidize due to heat, affecting the tool's lifespan. Therefore, cooling is still necessary during cutting. In this application, oil mist lubrication is used to cool the tool, preventing excessively high tool temperatures that could cause the tungsten carbide-cobalt coating to peel off.

[0026] In addition, the waste generated from cutting can be crushed, ball-milled, and then re-made into blanks, thereby increasing the material utilization rate from 60% to over 90%. Specifically, a two-stage crushing process of coarse crushing and fine crushing is adopted.

[0027] During coarse crushing, a jaw crusher is used to crush lumpy waste into coarse particles of 1-3mm. The crushing process is carried out in a closed system to prevent dust loss and impurity contamination. To improve the coarse crushing effect, the discharge particle size of the jaw crusher is directly determined by the width of the discharge port. The discharge port of the equipment is fixed at 1-3mm, and wedge block adjustment or hydraulic adjustment is preferred. The adjustment accuracy is ±1~2mm to suit small laboratory or mass production models. Avoid shim adjustment (accuracy ±5mm, which cannot meet the precise control of 1-3mm), which causes large particles larger than 3mm to be returned for re-crushing. At the same time, the single crushing time is controlled to 10-30 seconds. The material can be discharged after crushing is completed, sampled and sieved, and the machine is stopped when it meets the standard. Before coarse crushing, ensure that the waste is completely dry and free of impurities. At the same time, the jaw plate and liner are made of zirconia ceramic to prevent iron contamination of the recycled material.

[0028] During fine crushing, coarse particles are transferred to a double-roll crusher for further crushing into fine particles of 0.1-0.5mm, preparing for subsequent ball milling. To control the particle size to 0.1-0.5mm, a high-precision double-roll crusher is required, adjusting the gap between the two rollers to 0.1-0.5mm, preferably using hydraulic / wedge adjustment (accuracy ±0.05mm). The roller surface is coated with zirconia or corundum ceramic to prevent iron contamination. Zirconia is a hard and brittle material; particle size is not determined by time, but by passing sieving. Samples are taken and sieved; the machine is stopped once the standard is met.

[0029] Once the initial crushing is complete, fine grinding begins. The zirconia particles are further pulverized using a ball mill. When the zirconia particles are pulverized to 0.5-2 μm powder, they are passed through a 200-mesh (75 μm) standard sieve to remove large, unground particles and agglomerates. The material passing through the sieve is the qualified recycled zirconia powder. Fine grinding uses zirconia grinding balls at 200-300 rpm, with intermittent forward and reverse rotation (5 minutes of reversal after every 30 minutes of rotation) to forcibly break up agglomerates and ensure uniform particle size. Samples are taken every 4 hours to measure the D50 using a laser particle size analyzer. The milling stops when the particle size reaches 0.5-2 μm. After ball milling, the powder is passed through a 200-mesh (75 μm) sieve to remove large, unground particles. Particle size is not determined by time, but by passing the sieve test. The chemical composition of the recycled zirconia powder is identical to that of the original powder. It can be mixed and then dry-pressed with binders such as polyvinyl alcohol to form a green body for subsequent sintering and cutting processes. In addition, large, unground particles and agglomerates need to go through the above process again for recycling.

[0030] After the sintering of the green blank to form a sintered body and subsequent cutting, surface treatment is required. This involves sandblasting and ultrasonic cleaning of the cut product to remove surface burrs and cutting material, preventing injury to users during use. For better surface treatment, 80-120 mesh alumina sand is used for sandblasting. During cleaning, the ultrasonic frequency is 40kHz, and the cleaning time is 10-15 minutes. Furthermore, if surface imperfections remain after ultrasonic cleaning, polishing can be performed to control the surface roughness to ≤0.2µm, further improving product quality. By employing the above-mentioned sintering and cutting preparation method for zirconia materials, the production cycle can be shortened from 24-48 hours to 12-18 hours, and the dimensional accuracy of the product can be improved from ±0.1mm to ±0.02mm. Moreover, the sintering and cutting preparation method in this application only requires ordinary CNC equipment, resulting in low equipment investment costs, while existing production methods require dedicated high-speed equipment, leading to high investment costs.

[0031] Therefore, the preparation method described in this application is lower in cost and more effective, representing a significant improvement over existing technologies. Specific embodiments are shown below: Example 1, Preparation of zirconia denture base: 1. Mix 3 mol% yttrium oxide stabilized zirconium oxide powder with 4 wt% polyvinyl alcohol, and dry press it into a round blank with a diameter of 50 mm and a thickness of 15 mm at a molding pressure of 80 MPa; 2. Place the green blank into a box furnace, heat it to 1500℃ at 8℃ / min, hold it for 3 hours, and after cooling, obtain a sintered body with a density of 99.2%; 3. Use a diamond end mill (φ6mm) on a CNC milling machine with the following parameters: speed 12000rpm, feed rate 100mm / min, depth of cut 0.2mm, to machine the tooth groove shape; 4. Sandblast (100-mesh alumina) for 10 minutes, followed by ultrasonic cleaning and polishing to obtain a denture base with a surface roughness Ra0.1μm and a dimensional error of ±0.015mm.

[0032] Example 2, Fabrication of zirconia structural ceramic parts: 1. Zirconia powder (with 1 wt% cerium dioxide added) was injection molded into a complex structure preform with a density of 60% of the theoretical density; 2. Sintering process: 1550℃×2.5 hours, heating rate 10℃ / min, to obtain a sintered body with a flexural strength of 1100MPa; 3. Machining with carbide cutting tools, feed rate 150 mm / min, depth of cut 0.3 mm, to produce structural parts with holes and grooves; 4. After surface treatment, the form and position tolerances of the parts reach IT5 level, which meets the requirements of precision mechanical assembly.

[0033] This application also includes a method for fabricating a dental crown, comprising a sintering and cutting preparation method for zirconium oxide material, such as... Figure 2 As shown, the manufacturing method includes: When the zirconia material is in an uncrystallized green state, the area where the crown will be placed is preliminarily machined using high-precision cutting equipment; The pre-cut zirconia green blanks in the designated area are sintered according to standard process parameters. After sintering, the inner and outer surfaces of the crown are finely finished.

[0034] Specifically, preliminary processing of the crown placement area avoids deformation of the placement area caused by direct cutting after sintering, thus improving the yield of crown fabrication. By controlling the cutting depth and path, a 0.3-0.5mm sintering shrinkage allowance is reserved to effectively prevent placement difficulties or edge chipping caused by dimensional changes after sintering, avoiding shrinkage of the zirconia crown after sintering that could prevent placement failure. During sintering, the heating rate and holding time must also be strictly controlled. Specifically, the heating rate should be maintained at 5-10℃ / min, and the holding time should be set according to the material thickness, maintaining 2-4 hours to reduce the generation of internal stress during sintering.

[0035] After sintering, the crown needs to be finished. Specifically, the inner and outer surfaces of the crown are subjected to rough grinding, fine grinding, and polishing in sequence to optimize the occlusal surface morphology, axial surface projection, and marginal fit. This is achieved by controlling the machining template and adjusting parameters such as the grit size of the cutting tool, tool speed, and feed rate. The sequential processing of rough grinding, fine grinding, and polishing is a fundamental principle of machining. Rough grinding uses a coarse-grit grinding head with sharp abrasive grains and a large cutting depth, removing most of the excess material in a short time, significantly shortening processing time. If a fine grinding head is used directly to remove a large amount of excess material, the fine abrasive grains are too small, resulting in weak cutting ability, reduced processing efficiency, and rapid wear of the fine grinding head, increasing tool costs. Furthermore, rough grinding can only guarantee a basic contour accuracy (±0.05mm), failing to meet the clinically required ±0.02mm accuracy. Fine grinding, based on the uniform allowance left by rough grinding, uses a fine-grit grinding head for micro-cutting to precisely correct shape errors and dimensional deviations. If coarse grinding is skipped and fine grinding is performed directly, large surface defects cannot be effectively removed. As a result, a large number of scratches will remain on the surface, affecting the wear resistance and biocompatibility of the crown, which means that bacteria are more likely to grow on the crown surface.

[0036] Therefore, rough grinding uses a 200-grit diamond grinding head at a spindle speed of 20,000 rpm, a feed rate of 100 mm / min, and a depth of cut of 0.05 mm, employing a reciprocating cutting path to avoid localized stress concentration. After rough grinding, a 600-grit diamond grinding head is switched to complete fine grinding at a spindle speed of 24,000 rpm, a feed rate of 50 mm / min, and a depth of cut of 0.02 mm. Polishing is performed using 1000-3000 grit ultrafine diamond polishing paste in conjunction with a rubber polishing wheel and a felt wheel, using a low-speed, light-pressure method, with the polishing speed controlled at 5000-10000 rpm. Before polishing, 1000-grit polishing paste is used to remove scratches from the fine grinding, followed by mirror polishing with 2000-3000 grit polishing paste until the surface exhibits a uniform luster. This improves the wear resistance, biocompatibility, and aesthetics of the crown. Furthermore, during the finishing process, water cooling or air cooling is used to avoid thermal damage that could lead to a decline in material properties, ultimately controlling the gap at the crown margin to within 50μm, meeting the clinical placement requirements.

[0037] Therefore, by pre-cutting the placement area during the blanking stage, the impact of sintering shrinkage on critical mating parts can be avoided in advance, reducing the difficulty of adjustments during clinical fitting and improving placement accuracy. Furthermore, zirconia material that crystallizes without sintering has good cutting toughness, reducing the risk of edge chipping. Compared to traditional fully sintered post-cutting processes, the edge breakage rate can be reduced by more than 40%. Moreover, by focusing only on critical placement areas during the blanking stage and postponing complex finishing processes, the step-by-step processing mode reduces repeated cutting, shortening the overall processing cycle by 15%-20% and optimizing processing efficiency.

[0038] In practical applications, existing methods and the crown fabrication method in this application can be flexibly selected according to clinical needs. For example, for simple crown restorations (such as single crowns or crowns in non-functional areas), existing methods can be used for direct fabrication; for complex cases (such as multi-unit bridges or crowns with limited occlusal space), the crown fabrication method in this application is preferred, ensuring the accuracy and stability of the restoration through pre-cutting the placement area. Existing methods and the crown fabrication method in this application maintain consistency in basic processes such as material selection and sintering parameters, facilitating unified management of the production process.

[0039] Therefore, when preparing zirconia products using the sintering and cutting preparation method of zirconia material in this application, zirconia powder is first mixed with a binder and the mixture is shaped to form a blank. The blank is then sintered in a sintering furnace. The temperature inside the sintering furnace is first raised to a certain value, and then held at that temperature for a period of time to continue sintering the blank. Finally, it is naturally cooled to room temperature to form a sintered body. The sintered body is then machined, and the surface of the machined product is treated to meet product requirements and prevent the product from causing harm to the user. When fabricating dental crowns based on the sintering and cutting preparation method of zirconia material in this application, the crown placement area is pre-processed before sintering. When sintering the blank, the heating rate and holding time must also be controlled. After sintering, the inner and outer surfaces of the crown are then finished by rough grinding, fine grinding, and polishing to meet clinical placement requirements.

[0040] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing zirconia material by sintering and cutting, characterized in that, The preparation method includes: Zirconia powder is mixed with a binder and molded into a blank. The density of the blank reaches a predetermined density standard, which is less than the density of a fully dense blank. The green blank is heated and sintered and held at that temperature. After holding, it is cooled to room temperature to obtain a sintered body with a fully dense density. The sintered body is machined using carbide or diamond tools; The sintered body after cutting is subjected to sandblasting and ultrasonic cleaning to remove surface burrs and cutting residues.

2. The sintering and machining preparation method of zirconia material according to claim 1, characterized in that, The zirconium oxide powder has a purity of ≥99.5% and a particle size of 0.5-2μm.

3. The sintering and cutting preparation method of zirconia material according to claim 2, characterized in that, The adhesive is polyvinyl alcohol, and the amount of adhesive added is 3-5 wt%. The forming pressure is 50-100 MPa, so as to control the density of the green blank to be 55-65% of the theoretical density.

4. The sintering and cutting preparation method of zirconia material according to claim 3, characterized in that, The heating rate is 5-10℃ / min to raise the sintering temperature to 1450-1600℃ and hold it for 2-4 hours.

5. The sintering and machining preparation method of zirconia material according to claim 4, characterized in that, When heated, the binder is decomposed into a gaseous substance and discharged through the pores inside the green blank to form the sintered body with a density ≥6.0 g / cm³ and a flexural strength ≥900 MPa.

6. The sintering and cutting preparation method of zirconium oxide material according to claim 5, characterized in that, The cemented carbide cutting tool is coated with tungsten carbide-cobalt, and the hardness of the cemented carbide cutting tool is ≥90HRA.

7. The sintering and cutting preparation method of zirconia material according to claim 6, characterized in that, When cutting the sintered body, the cutting tool rotates at 8000-15000 rpm, feeds at 50-200 mm / min, and cuts to a depth of 0.1-0.5 mm. The cutting tool is cooled by oil mist lubrication.

8. The sintering and cutting preparation method of zirconia material according to claim 7, characterized in that, When performing sandblasting, use 80-120 mesh alumina sand; When performing ultrasonic cleaning, the frequency is 40kHz and the cleaning time is 10-15 minutes to remove surface burrs and cutting residues from the product. After ultrasonic cleaning, polishing is performed to control the surface roughness to ≤0.2μm.

9. A method for fabricating a dental crown, comprising a sintering and cutting preparation method of the zirconia material according to any one of claims 1 to 8, characterized in that, The manufacturing method includes: When the zirconia material is in an uncrystallized green state, the area where the crown will be placed is preliminarily machined using high-precision cutting equipment; The pre-cut zirconia green blanks in the designated area are sintered according to standard process parameters. After sintering, the inner and outer surfaces of the crown are finely finished.

10. The method for fabricating a dental crown according to claim 9, characterized in that, After sintering, the inner and outer surfaces of the crown are subjected to coarse grinding, fine grinding and polishing in sequence to optimize the occlusal surface morphology, axial surface protrusion and marginal fit.

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