CN115229190A - MIM metal injection molding process - Google Patents
MIM metal injection molding process Download PDFInfo
- Publication number
- CN115229190A CN115229190A CN202210911825.3A CN202210911825A CN115229190A CN 115229190 A CN115229190 A CN 115229190A CN 202210911825 A CN202210911825 A CN 202210911825A CN 115229190 A CN115229190 A CN 115229190A
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- Prior art keywords
- injection molding
- temperature
- feed
- sintering
- metal injection
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
- B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/103—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing an organic binding agent comprising a mixture of, or obtained by reaction of, two or more components other than a solvent or a lubricating agent
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1003—Use of special medium during sintering, e.g. sintering aid
- B22F3/1007—Atmosphere
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
- B22F3/1021—Removal of binder or filler
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Powder Metallurgy (AREA)
Abstract
The invention provides a MIM metal injection molding process, and belongs to the technical field of metal injection molding processes. The invention obtains the injection molding part with stable quality and higher precision by the preparation of metal powder, kneading granulation, injection molding, catalytic degreasing and sintering treatment. The process method is simple and easy to implement, the adhesion between the metal powder is improved after the metal powder and the adhesive are kneaded, and the blank after catalytic degreasing does not bubble or crack and has higher quality. And the degreased blank is respectively subjected to vacuum sintering and partial pressure sintering, so that the density and the precision of the product are improved, grinding equipment is not additionally used, and the production efficiency is high.
Description
Technical Field
The invention relates to the technical field of metal injection molding processes, in particular to an MIM metal injection molding process.
Background
The metal powder injection molding technology integrates the crossing products of a plurality of subjects such as plastic molding, powder metallurgy technology, metal material technology and the like, and utilizes a mold to perform injection molding, and manufactures structural parts with high density, high precision, high strength and complex structure through degreasing, sintering and other processes.
However, with the continuous development of metal injection molding technology, the quality requirement of a molded product is higher and higher, the general process of the existing metal injection molding technology is complex, the product needs to be subjected to a plurality of post-treatment processing steps to ensure the quality and precision of the product, and if the operation is improper, the product can bubble, crack and the like. Therefore, how to obtain a metal injection molding process which has a simple process and can improve the product quality and precision is a technical problem to be solved at present.
Disclosure of Invention
The invention aims to provide an MIM metal injection molding process to solve the technical problem that the product obtained by the existing metal injection molding process is low in quality and precision.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a MIM metal injection molding process, which comprises the following steps:
1) Kneading metal powder and a binder and then granulating to obtain a feed;
2) Injection molding the feed to obtain a raw blank;
3) Heating the green blank under the protective atmosphere, and then introducing nitric acid gas for catalytic degreasing;
4) And sequentially carrying out vacuum sintering, partial pressure sintering and forced cooling treatment on the green part subjected to catalytic degreasing treatment to obtain the formed part.
Further, in the step 1), the mass ratio of the metal powder to the binder is 91-94: 6 to 9.
Further, the adhesive is prepared from the following components in a mass ratio of 60-75: 5 to 10:2 to 5: 1-3 of polyformaldehyde, polyethylene, microcrystalline wax and an antioxidant; the antioxidant comprises one or more of ascorbyl palmitate, butyl hydroxy anisole, 2,6 di-tert-butyl-4-cresol and n-octadecanol ester.
Further, in the step 1), the kneading temperature is 150-170 ℃, and the kneading time is 1-2 h;
the granulation temperature is 120-150 ℃, and the grain size of the feeding material is 10-100 mm.
Further, in the step 2), the injection molding is as follows: heating the feed to 180-200 ℃ to obtain a fluid feed, and performing injection molding on the fluid feed to obtain a blank.
Further, in the step 3), the protective atmosphere contains nitrogen and/or argon, the temperature of the heating treatment is 160-180 ℃, and the time of the heating treatment is 0.5-1.5 h.
Further, in the step 3), the flow rate of the nitric acid gas is 0.2-0.5 mL/min, the temperature of the catalytic degreasing treatment is 100-120 ℃, and the time of the catalytic degreasing treatment is 30-40 min.
Further, in the step 4), the temperature of vacuum sintering is 1000-1100 ℃, the time of vacuum sintering is 20-50 min, and the vacuum degree of vacuum sintering is 3-5 Pa.
Further, in the step 4), partial pressure sintering is as follows: argon with the flow rate of 10-20L/min is introduced after vacuum sintering, the mixture is heated to 1200-1300 ℃ and sintered for 2-3 h under 20-25 kPa.
Further, in the step 4), the forced cooling treatment includes: after partial pressure sintering, argon with the flow of 10-20L/min is continuously introduced, and the temperature is reduced to the room temperature at the speed of 20-30 ℃/min.
The invention has the beneficial effects that:
the process method is simple and easy to implement, the adhesion between the metal powder is improved after the metal powder and the adhesive are kneaded, the blank after catalytic degreasing does not bubble or crack, and the quality and the qualification rate are higher. And the degreased blank is respectively subjected to vacuum sintering and partial pressure sintering, so that the density and the precision of the product are improved, grinding equipment is not additionally used, and the production efficiency is high.
Detailed Description
The invention provides a MIM metal injection molding process, which comprises the following steps:
1) Kneading metal powder and a binder, and then granulating to obtain a feed;
2) Injection molding the feed to obtain a raw blank;
3) Heating the green blank under the protective atmosphere, and then introducing nitric acid gas for catalytic degreasing;
4) And sequentially carrying out vacuum sintering, partial pressure sintering and forced cooling treatment on the green part subjected to catalytic degreasing treatment to obtain the formed part.
In the invention, in the step 1), the mass ratio of the metal powder to the binder is 91-94: 6 to 9, preferably 92 to 93:7 to 8, more preferably 92:8.
in the invention, the adhesive is prepared from the following components in a mass ratio of 60-75: 5 to 10:2 to 5: 1-3, preferably 62-72: 6 to 8:3 to 4:1 to 2, more preferably 65 to 70:7:3:2.
in the invention, the antioxidant comprises one or more of ascorbyl palmitate, butyl hydroxy anisole, 2,6 di-tert-butyl-4-cresol and n-octadecyl carbonate, and is preferably ascorbyl palmitate and/or butyl hydroxy anisole.
In the invention, in the step 1), the kneading temperature is 150-170 ℃, and the kneading time is 1-2 h; preferably, the kneading temperature is 155-165 ℃, and the kneading time is 1.5-2 h; further preferably, the kneading temperature is 160 ℃ and the kneading time is 1.5 hours.
In the present invention, the temperature for granulation in the step 1) is 120 to 150 ℃, preferably 130 to 140 ℃, and more preferably 135 ℃.
In the present invention, the feed material in step 1) has a particle size of 10 to 100mm, preferably 20 to 80mm.
In the present invention, in the step 2), the injection molding is: heating the feed to 180-200 ℃ to obtain a fluid feed, and performing injection molding on the fluid feed to obtain a blank piece, preferably heating the feed to 190 ℃.
In the present invention, in the step 3), the protective atmosphere contains nitrogen and/or argon, preferably argon.
In the invention, in the step 3), the temperature of the heating treatment is 160-180 ℃, and the time of the heating treatment is 0.5-1.5 h; preferably, the temperature of the heating treatment is 165-175 ℃, and the time of the heating treatment is 1.0h; more preferably, the temperature of the heat treatment is 170 ℃ and the time of the heat treatment is 1.0 hour.
In the present invention, the flow rate of the nitric acid gas in the step 3) is 0.2 to 0.5mL/min, preferably 0.3 to 0.4mL/min.
In the invention, in the step 3), the temperature of the catalytic degreasing treatment is 100-120 ℃, and the time of the catalytic degreasing treatment is 30-40 min; preferably, the temperature of the catalytic degreasing treatment is 110 ℃, and the time of the catalytic degreasing treatment is 35min.
In the invention, in the step 4), the temperature of vacuum sintering is 1000-1100 ℃, the time of vacuum sintering is 20-50 min, and the vacuum degree of vacuum sintering is 3-5 Pa; preferably, the temperature of the vacuum sintering is 1050 ℃, the time of the vacuum sintering is 30-40 min, and the vacuum degree of the vacuum sintering is 4Pa.
In the present invention, in the step 4), the partial pressure sintering is: argon with the flow rate of 10-20L/min is introduced after vacuum sintering, the mixture is heated to 1200-1300 ℃ and sintered for 2-3 h under 20-25 kPa; preferably, argon gas with the flow rate of 15L/min is introduced after vacuum sintering, the mixture is heated to 1250 ℃, and sintering is carried out for 2 hours under 22-24 kPa.
In the present invention, in the step 4), the forced cooling treatment includes: after partial pressure sintering, continuously introducing argon with the flow of 10-20L/min, and cooling to room temperature at the speed of 20-30 ℃/min; preferably, argon gas with a flow rate of 15L/min is continuously introduced after the partial pressure sintering, and the temperature is reduced to the room temperature at a speed of 25 ℃/min.
In the invention, the molded part after the forced cooling treatment is polished to remove surface impurities.
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
A process for MIM metal injection molding comprising the steps of:
1) Mixing metal powder and a binder, adding the mixture into an internal mixer, kneading the mixture for 2 hours at the temperature of 150 ℃, and then feeding the mixture into a granulator to granulate at the temperature of 120 ℃ to obtain feed with the particle size of 50 mm; the adhesive is prepared from the following components in percentage by mass of 75:8:2:2, preparing polyformaldehyde, polyethylene, microcrystalline wax and ascorbyl palmitate;
2) Heating the feed to 200 ℃ to obtain a fluid feed, injecting the fluid feed into a mold through an injection molding machine, and cooling and molding to obtain a blank;
3) Placing the green blank piece in a catalytic degreasing furnace, introducing argon, heating to 170 ℃, treating for 1h, introducing nitric acid gas with the flow of 0.5mL/min, cooling to 120 ℃, performing catalytic degreasing treatment for 30min, stopping introducing the nitric acid gas, keeping the temperature, continuously introducing argon, and purging for 20min;
4) Placing the green part subjected to catalytic degreasing treatment in a vacuum sintering furnace, and sintering for 50min at 1100 ℃ in an environment of 5Pa; then argon with the flow rate of 20L/min is introduced, the temperature is raised to 1300 ℃, the pressure is 20kPa, and sintering is carried out for 2 hours; and (3) continuously introducing argon with the flow rate of 20L/min, cooling to room temperature at the speed of 30 ℃/min to obtain a formed part, and polishing the formed part to remove surface impurities.
Example 2
A process for MIM metal injection molding comprising the steps of:
1) Mixing metal powder and a binder, adding the mixture into an internal mixer, kneading the mixture for 1.5 hours at 170 ℃, and then feeding the mixture into a granulator to granulate at 150 ℃ to obtain feed with the particle size of 80 mm; the adhesive is prepared from the following components in percentage by mass of 60:10:5:2, polyethylene, microcrystalline wax and 2, 6-di-tert-butyl-4-cresol;
2) Heating the feed to 190 ℃ to obtain a fluid feed, injecting the fluid feed into a mold through an injection molding machine, and cooling and molding to obtain a blank;
3) Placing the green blank in a catalytic degreasing furnace, introducing argon, heating to 160 ℃, treating for 1.5h, then introducing nitric acid gas with the flow of 0.4mL/min, cooling to 120 ℃, performing catalytic degreasing treatment for 40min, stopping introducing the nitric acid gas, keeping the temperature, continuously introducing argon, and purging for 20min;
4) Placing the green part subjected to catalytic degreasing treatment in a vacuum sintering furnace, and sintering for 40min at 1100 ℃ in a 4Pa environment; then argon with the flow rate of 15L/min is introduced, the temperature is raised to 1300 ℃, the pressure is 20kPa, and sintering is carried out for 2 hours; and continuously introducing argon with the flow rate of 15L/min, cooling to room temperature at the speed of 25 ℃/min to obtain a formed part, and polishing the formed part to remove surface impurities.
Example 3
A process for MIM metal injection molding comprising the steps of:
1) Mixing metal powder and a binder, adding the mixture into an internal mixer, kneading the mixture for 2 hours at 160 ℃, and then feeding the mixture into a granulator to granulate at 150 ℃ to obtain a feed with the particle size of 30 mm; the adhesive is prepared from the following components in percentage by mass 66:8:5:3, polyformaldehyde, polyethylene, microcrystalline wax and n-octadecanol carbonate;
2) Heating the feed to 180 ℃ to obtain a fluid feed, injecting the fluid feed into a mold through an injection molding machine, and cooling and molding to obtain a blank;
3) Placing the green blank piece in a catalytic degreasing furnace, introducing argon, heating to 170 ℃, treating for 1.5h, introducing nitric acid gas with the flow of 0.3mL/min, cooling to 100 ℃, performing catalytic degreasing treatment for 40min, stopping introducing the nitric acid gas, keeping the temperature, continuously introducing argon, and purging for 20min;
4) Placing the green part subjected to catalytic degreasing treatment in a vacuum sintering furnace, and sintering for 40min at 1000 ℃ in a 3Pa environment; then argon with the flow rate of 10L/min is introduced, the temperature is raised to 1200 ℃, the pressure is 25kPa, and sintering is carried out for 2 hours; and continuously introducing argon with the flow rate of 10L/min, cooling to room temperature at the speed of 20 ℃/min to obtain a formed part, and polishing the formed part to remove surface impurities.
Comparative example 1
The difference from example 1 is that partial pressure sintering was not performed, and only strong cooling treatment was performed after vacuum sintering.
The molded articles obtained in examples 1 to 3 and comparative example 1 above were subjected to a performance test, and the results are shown in the following table 1:
table 1 results of property tests of molded articles of examples 1 to 3 and comparative example 1
| Item | Example 1 | Example 2 | Example 3 | Comparative example 1 |
| Presence or absence of blistering and cracking | Is free of | Is free of | Is free of | Slight surface cracking |
| Product precision/mm | 0.001 | 0.001 | 0.001 | 0.01 |
| Percent pass/%) | 99 | 99 | 100 | 85 |
From the above embodiments, the present invention provides a process of MIM metal injection molding. The performance tests of the formed parts obtained in the above examples 1 to 3 and comparative example 1 show that the strength and impact resistance of the formed part in the example of the invention meet the application standards of the formed part, no cracks, bulges and the like are generated on the surface of the formed part, the formed part has high precision and stable quality, and the qualified rate of the finished product is more than 99%.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A process for MIM metal injection molding comprising the steps of:
1) Kneading metal powder and a binder, and then granulating to obtain a feed;
2) Injection molding the feed to obtain a raw blank;
3) Heating the green blank under the protective atmosphere, and then introducing nitric acid gas for catalytic degreasing;
4) And sequentially carrying out vacuum sintering, partial pressure sintering and forced cooling treatment on the green part subjected to catalytic degreasing treatment to obtain the formed part.
2. The MIM metal injection molding process according to claim 1 wherein in step 1), the mass ratio of metal powder to binder is from 91 to 94:6 to 9.
3. The MIM metal injection molding process according to claims 1 or 2, wherein the binder is prepared from a mixture of, by mass, 60 to 75:5 to 10:2 to 5: 1-3 of polyformaldehyde, polyethylene, microcrystalline wax and an antioxidant; the antioxidant comprises one or more of ascorbyl palmitate, butyl hydroxy anisole, 2,6 di-tert-butyl-4-cresol and n-octadecanol ester.
4. The process for injection molding of MIM metal according to claim 3, wherein in step 1), the kneading temperature is 150 to 170 ℃ and the kneading time is 1 to 2 hours;
the granulation temperature is 120-150 ℃, and the grain size of the feed is 10-100 mm.
5. The MIM metal injection molding process according to claim 1, 2 or 4, wherein in step 2), the injection molding is: heating the feed to 180-200 ℃ to obtain a fluid feed, and performing injection molding on the fluid feed to obtain a blank.
6. The process of claim 5, wherein in step 3), the protective atmosphere comprises nitrogen and/or argon, the temperature of the heat treatment is 160-180 ℃, and the time of the heat treatment is 0.5-1.5 h.
7. The process of claim 6, wherein the flow rate of the nitric acid gas in the step 3) is 0.2-0.5 mL/min, the temperature of the catalytic degreasing treatment is 100-120 ℃, and the time of the catalytic degreasing treatment is 30-40 min.
8. The process of claim 6 or 7, wherein in step 4), the temperature of vacuum sintering is 1000-1100 ℃, the time of vacuum sintering is 20-50 min, and the degree of vacuum sintering is 3-5 Pa.
9. The MIM metal injection molding process according to claim 8 wherein in step 4), partial pressure sintering is: argon with the flow rate of 10-20L/min is introduced after vacuum sintering, the mixture is heated to 1200-1300 ℃ and sintered for 2-3 h under 20-25 kPa.
10. The MIM metal injection molding process according to claim 9 wherein in step 4), the forced cooling process is: after partial pressure sintering, argon with the flow of 10-20L/min is continuously introduced, and the temperature is reduced to the room temperature at the speed of 20-30 ℃/min.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210911825.3A CN115229190A (en) | 2022-07-29 | 2022-07-29 | MIM metal injection molding process |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210911825.3A CN115229190A (en) | 2022-07-29 | 2022-07-29 | MIM metal injection molding process |
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| CN115229190A true CN115229190A (en) | 2022-10-25 |
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| CN202210911825.3A Withdrawn CN115229190A (en) | 2022-07-29 | 2022-07-29 | MIM metal injection molding process |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117226094A (en) * | 2023-10-28 | 2023-12-15 | 广东凯洋新材料有限公司 | Metal injection molding process |
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2022
- 2022-07-29 CN CN202210911825.3A patent/CN115229190A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117226094A (en) * | 2023-10-28 | 2023-12-15 | 广东凯洋新材料有限公司 | Metal injection molding process |
| CN117226094B (en) * | 2023-10-28 | 2024-03-26 | 广东凯洋新材料有限公司 | Metal injection molding process |
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Application publication date: 20221025 |
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