Smoking and supercritical foaming process of 3D printed parts

Abstract

The process for smoking and supercritical foaming of 3D printed parts comprises the steps of: smoking and polishing the completed 3D printed parts in solvent vapor to obtain smoked and polished parts; and supercritical foaming the smoked and polished parts in supercritical foaming gas to obtain foamed parts. The process can improve the folding resistance of 3D printed parts while effectively reducing the surface roughness.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a fumigation, polishing and supercritical foaming process for 3D printed parts. Background Technology

[0002] Supercritical foaming, as an advanced material foaming technology, typically uses a supercritical fluid (such as supercritical carbon dioxide) as a foaming agent, which is then thoroughly mixed with materials such as plastics. Supercritical fluids exhibit unique physical properties, possessing both the high diffusivity of gases and the good solubility of liquids. Under specific temperature and pressure conditions, supercritical fluids can rapidly form uniform microbubble nuclei within the material. Subsequently, by precisely controlling changes in pressure and temperature, these bubble nuclei are encouraged to gradually grow and stably exist within the material, ultimately forming the desired foamed structure.

[0003] However, during supercritical foaming, if the process parameters are not precisely controlled according to the characteristics of the product, the foamed 3D printed parts often fail to obtain uniform and fine pores, resulting in lower folding resistance than the parts before foaming. Therefore, it is necessary to select process parameters according to the characteristics of the product and precisely control these parameters to ensure that the foamed 3D printed parts obtain uniform and fine pores, which endow the 3D printed parts with excellent folding resistance.

[0004] For some 3D printed products, a low surface roughness is desirable for good visual effects. For 3D printed products that come into direct contact with the human body (such as protective gear), a lower surface roughness is even more desirable for superior skin-friendly properties. On the other hand, high flexural strength is also crucial. High flexural strength allows 3D printed products to withstand frequent pressure without breaking, meaning that even after repeated compression and bending during long-term use, the 3D printed product can maintain its integrity, thus achieving a longer lifespan.

[0005] While the folding resistance of 3D-printed parts produced through supercritical foaming is significantly improved by controlling process parameters, the surface roughness remains unchanged. This makes the final 3D-printed products unable to meet usage requirements, limiting their application range. Summary of the Invention

[0006] The purpose of this invention is to provide a fumigation and supercritical foaming process for 3D printed parts, which can effectively reduce the surface roughness of 3D printed parts while improving their folding resistance.

[0007] The fumigation, polishing, and supercritical foaming process for 3D printed parts provided by this invention includes the following steps: S10: The 3D-printed parts are fumigated and polished in solvent vapor to obtain the fumigated and polished parts; and S20: The fumigated and polished parts are subjected to supercritical foaming in a supercritical foaming gas to obtain foamed parts.

[0008] By performing fumigation and polishing treatment on 3D printed parts before the supercritical foaming process, the folding resistance of 3D printed parts can be improved while effectively reducing their surface roughness.

[0009] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, in S10, the fumigation pressure is -0.05 MPa to -0.105 MPa, and the fumigation time is 60 s to 400 s. In S20, the supercritical foaming temperature is 100℃ to 125℃, the supercritical foaming pressure is 17.8 MPa to 60 MPa, and the supercritical foaming time is 30 min to 60 min. By selecting appropriate parameters, 3D printed parts with satisfactory surface roughness and flexural strength can be obtained.

[0010] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, in S10, the fumigation pressure is -0.09 MPa to -0.105 MPa, and the fumigation time is 300 s to 340 s. In S20, the supercritical foaming temperature is 100℃ to 115℃, the supercritical foaming pressure is 23 MPa to 34 MPa, and the supercritical foaming time is 30 min to 50 min. By selecting appropriate parameters, 3D printed parts with satisfactory surface roughness and flexural strength can be obtained.

[0011] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, S10 specifically includes: S11: Place the 3D printed part into a fumigation and polishing chamber, inject solvent into the fumigation and polishing chamber to vaporize the solvent into solvent vapor, the pressure inside the fumigation and polishing chamber is negative, and the temperature inside the fumigation and polishing chamber is 1°C to 20°C higher than the boiling point of the solvent. S12: The parts are fumigated and polished in solvent vapor; and S13: Expel solvent vapor from the fumigation and blasting chamber and cool and recover it. At the same time, reduce the temperature inside the fumigation and blasting chamber to room temperature and evacuate the solvent vapor from the fumigation and blasting chamber.

[0012] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, the solvent is one or more of hexafluoroisopropanol, dimethylformamide, sulfuric acid, m-cresol, formic acid, trifluoroacetic acid, and benzyl alcohol.

[0013] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, S20 specifically includes: S21: Place the fumigated and polished parts into a foaming chamber, and sequentially introduce foaming gas and protective gas into the foaming chamber; S22: Supercritical foaming of parts after fumigation and polishing; and S23: Discharge the gas in the foaming chamber to bring the pressure in the foaming chamber to normal pressure, and obtain the foamed parts.

[0014] Using foaming gas and protective gas in the supercritical foaming process helps to obtain 3D printed parts with uniform and delicate pores and few defects.

[0015] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, the foaming gas is carbon dioxide with a pressure of 7.8 MPa to 30 MPa, the temperature inside the foaming chamber is 100°C to 125°C, the protective gas is nitrogen with a pressure of 10 MPa to 30 MPa, the time interval between introducing the foaming gas and the protective gas is 1 min to 10 min, and the supercritical foaming time is 30 min to 60 min. By selecting appropriate parameters, 3D printed parts with satisfactory surface roughness and flexural strength can be obtained.

[0016] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, the foaming gas is carbon dioxide with a pressure of 12 MPa to 30 MPa, the temperature inside the foaming chamber is 100°C to 115°C, the protective gas is nitrogen with a pressure of 10 MPa to 30 MPa, the time interval between introducing the foaming gas and the protective gas is 2 to 4 minutes, and the supercritical foaming time is 30 to 50 minutes. By selecting appropriate parameters, 3D printed parts with satisfactory surface roughness and flexural strength can be obtained.

[0017] In another illustrative embodiment of the fumigation and supercritical foaming process for 3D printed parts, in S23, the gas in the foaming chamber is discharged within 1 to 10 seconds.

[0018] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, in step S20: Before the fumigated and polished parts are supercritically foamed in a supercritical foaming gas to obtain the foamed parts, a fragrance agent is pre-injected into the foaming chamber for supercritical foaming. This helps to obtain 3D printed products with a long-lasting fragrance.

[0019] In another illustrative embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts, the parts are made of polyamide, PETG, polylactic acid, polypropylene, thermoplastic polyurethane, or thermoplastic polyamide. Attached Figure Description

[0020] The following figures are for illustrative purposes only and do not limit the scope of the invention.

[0021] Figure 1 A flowchart illustrating one implementation of the fumigation, polishing, and supercritical foaming process for 3D printed parts. Detailed Implementation

[0022] To provide a clearer understanding of the technical features, objectives, and effects of the invention, specific embodiments of the invention are now described with reference to the accompanying drawings, in which the same reference numerals denote the same parts.

[0023] In this document, “illustrative” means “serving as an example, illustration or description”, and any illustration or implementation described herein as “illustrative” should not be construed as a more preferred or advantageous technical solution.

[0024] Figure 1 A flowchart illustrating an embodiment of the fumigation, polishing, and supercritical foaming process for 3D printed parts. See also... Figure 1 The fumigation, polishing, and supercritical foaming processes for 3D printed parts specifically include S10 and S20.

[0025] S10: The 3D-printed part is fumigated and polished in solvent vapor to obtain the fumigated and polished part. The 3D-printed part is a polymer part. In the illustrative embodiment, the part is made of polyamide, PETG, polylactic acid, polypropylene, thermoplastic polyurethane, or thermoplastic polyamide. The solvent is a good solvent for the polymer used to make the 3D-printed part.

[0026] Chemical vapor polishing, also known as fumigation polishing, generally involves placing the 3D printed part in a sealed fumigation chamber, where solvent vapor is deposited on the surface of the part. Due to the inconsistency of the surface microstructure, the microscopic protrusions are preferentially dissolved, and the dissolution rate is greater than that of the concave areas. The resulting liquid, influenced by surface tension, tends to minimize its surface area, flowing from the protrusions to the concave areas, and solidifying to produce a uniform and smooth surface.

[0027] S20: The fumigated and polished parts are subjected to supercritical foaming in a supercritical foaming gas to obtain foamed parts.

[0028] By performing fumigation and polishing treatment on 3D printed parts before the supercritical foaming process, the folding resistance of 3D printed parts can be improved while effectively reducing their surface roughness.

[0029] The reason for performing fumigation and polishing before, rather than after, supercritical foaming is that after supercritical foaming, numerous micropores have formed inside the 3D printed part. Performing fumigation and polishing at this point would result in a large amount of polishing solvent remaining inside these micropores, which is difficult to remove quickly. When the 3D printed product is put into use, the residual polishing solvent in the micropores continues to be slowly released, seriously endangering the user's health.

[0030] In the illustrative embodiment, S10 specifically includes S11 to S13.

[0031] S11: The 3D-printed part is placed in a fumigation and polishing chamber. Solvent is injected into the chamber, causing it to vaporize into solvent vapor. The pressure inside the chamber (i.e., the fumigation and polishing pressure) is negative, and the temperature inside the chamber (i.e., the fumigation and polishing temperature) is 1°C to 20°C higher than the boiling point of the solvent. Generally, the solvent is a good solvent for the polymer used to make the 3D-printed part. In an illustrative embodiment, the solvent can be one or more of hexafluoroisopropanol, dimethylformamide, sulfuric acid, m-cresol, formic acid, trifluoroacetic acid, and benzyl alcohol. Preferably, hexafluoroisopropanol is chosen as the solvent for the fumigation and polishing process. Hexafluoroisopropanol has a boiling point of 59°C; therefore, in preferred embodiments, the fumigation and polishing temperatures are preferably 60°C, 70°C, and 75°C, respectively.

[0032] S12: The parts are fumigated and polished in solvent vapor. During the fumigation and polishing process, the pressure inside the fumigation and polishing chamber is preferably -0.05 MPa to -0.105 MPa, more preferably -0.09 MPa to -0.105 MPa. A negative value for the pressure inside the fumigation and polishing chamber indicates that it is lower than the external standard atmospheric pressure; for example, -0.05 MPa means that the pressure inside the fumigation and polishing chamber is 0.05 MPa lower than the external standard atmospheric pressure. The fumigation and polishing time is preferably 60 s to 400 s, more preferably 300 s to 340 s.

[0033] S13: Expel solvent vapor from the fumigation and blasting chamber and cool and recover it. At the same time, reduce the temperature inside the fumigation and blasting chamber to room temperature and evacuate the solvent vapor from the fumigation and blasting chamber.

[0034] During the fumigation and polishing process, operators need to select suitable solvents, temperatures, pressures, and fumigation and polishing times for 3D printed parts in order to obtain 3D printed parts with satisfactory surface roughness and folding resistance.

[0035] In the illustrative embodiment, S20 specifically includes S21 to S23.

[0036] S21: The 3D-printed part is placed in a foaming chamber, and foaming gas and protective gas are sequentially introduced into the chamber. In one illustrative embodiment, the foaming gas is carbon dioxide, with a pressure of 7.8 MPa to 30 MPa, and the temperature inside the foaming chamber is 100°C to 125°C. The protective gas is nitrogen, with a pressure of 10 MPa to 30 MPa. The time interval between introducing the foaming gas and the protective gas is 1 min to 10 min. In another illustrative embodiment, the foaming gas is carbon dioxide, with a pressure of 12 MPa to 30 MPa, and the temperature inside the foaming chamber is 100°C to 115°C. The protective gas is nitrogen, with a pressure of 10 MPa to 30 MPa. The time interval between introducing the foaming gas and the protective gas is 1 min to 10 min. The pressure of the foaming gas mentioned above refers to the pressure reached in the foaming chamber after the high-pressure foaming gas is introduced, and the pressure of the protective gas is also the same.

[0037] The purpose of introducing a protective gas is to dilute the concentration of the foaming gas that penetrates into the 3D printed part during the supercritical foaming process, slow down the supercritical foaming rate, and reduce defects such as cell collapse and rupture caused by excessively rapid cell expansion. This is beneficial for obtaining 3D printed parts with fine and uniform cell structure. In other illustrative embodiments, the foaming gas can also be other gases that easily reach a supercritical state, and the protective gas can also be other gases. Alternatively, depending on the actual application requirements, a suitable foaming gas can be selected and its pressure controlled without using a protective gas.

[0038] The time interval between introducing foaming gas and protective gas is affected by factors such as the material of the 3D printed part, the characteristics of the product, the required foaming ratio, and the internal space dimensions of the reactor.

[0039] In the three preferred embodiments, the foaming gas is carbon dioxide, the protective gas is nitrogen, the pressure of the foaming gas is preferably 10 MPa, 8 MPa and 12 MPa, respectively, the temperature inside the foaming chamber is preferably 120°C, 115°C and 125°C, respectively, the pressure of the protective gas is preferably 23 MPa, 15 MPa and 21.7 MPa, respectively, and the time interval between introducing the foaming gas and the protective gas is preferably 2 min, 4 min and 4 min, respectively.

[0040] S22: Perform supercritical foaming on the fumigated and polished parts for a time of 30 to 60 minutes, preferably 30 minutes.

[0041] S23: Expel the gas from the foaming chamber to bring the pressure inside the chamber to atmospheric pressure, thus obtaining the foamed part. In an illustrative embodiment, the gas in the processing chamber is expelled within 1 to 10 seconds; rapid gas expulsion facilitates obtaining a part with fine and uniform foam cells. In a preferred embodiment, the gas in the processing chamber is preferably expelled within 2 seconds.

[0042] During the supercritical foaming process, operators need to select suitable foaming gas, protective gas, and the respective pressure, temperature, and foaming time for both gases to obtain 3D printed parts that meet the requirements for surface roughness and folding resistance. Additionally, 3D printed parts that undergo both fumigation / polishing and supercritical foaming processes have lower density.

[0043] It is worth noting that in other illustrative embodiments, the fumigation and blasting chamber and the foaming chamber can also be the same chamber, that is, fumigation and blasting and supercritical foaming are carried out in one chamber, which can simplify the process, save floor space and improve process efficiency.

[0044] In other illustrative embodiments, a fragrance agent can be pre-injected into the foaming chamber before supercritical foaming. The fumigated and polished part is then subjected to supercritical foaming in the supercritical foaming gas to obtain the foamed part. The fragrance agent can be a well-known fragrance agent, such as peppermint oil. By adding the fragrance agent into the foaming chamber, the fragrance agent enters the pores of the 3D printed part along with the supercritical foaming gas. After the supercritical foaming process is completed, the fragrance agent remains inside the pores and is slowly released from the pores during subsequent use. This facilitates obtaining 3D printed products with a long-lasting fragrance.

[0045] The following examples and comparative examples further illustrate the fumigation, polishing, and supercritical foaming processes for 3D printed parts provided by the present invention. In the following examples and comparative examples, the 3D printed parts are midsoles with a lattice structure.

[0046] Example 1 S11: Place the 3D-printed part into a fumigation and polishing chamber. The part is made of thermoplastic polyamide elastomer (brand name: Precimid1170 RL). Inject hexafluoroisopropanol into the fumigation and polishing chamber to vaporize the hexafluoroisopropanol into steam. The pressure inside the fumigation and polishing chamber is -0.09MPa, and the temperature inside the fumigation and polishing chamber is 60℃.

[0047] S12: The parts are fumigated and polished in hexafluoroisopropanol vapor for 300 seconds.

[0048] S13: Expel hexafluoroisopropanol vapor from the fumigation and blasting chamber and cool it for recovery. At the same time, reduce the temperature inside the fumigation and blasting chamber to room temperature and evacuate the solvent vapor from the fumigation and blasting chamber.

[0049] S21: Place the fumigated and polished parts in a foaming chamber, and sequentially introduce carbon dioxide and nitrogen into the foaming chamber. The time interval between introducing the foaming gas and the protective gas is 2 minutes. The pressure of carbon dioxide in the foaming chamber is 12 MPa, the pressure of nitrogen in the foaming chamber is 21.7 MPa, and the temperature in the foaming chamber is 125℃.

[0050] S22: Perform supercritical foaming on the parts after fumigation and polishing. The supercritical foaming time is 30 minutes.

[0051] S23: Expel the gas in the foaming chamber within 2 seconds to bring the pressure in the foaming chamber to normal pressure, and obtain the foamed part.

[0052] Example 2 S11: Place the 3D-printed part into a fumigation and polishing chamber. The part is made of thermoplastic polyurethane elastomer (brand name: TPU88A). Inject hexafluoroisopropanol into the fumigation and polishing chamber to vaporize the hexafluoroisopropanol into steam. The pressure inside the fumigation and polishing chamber is -0.105MPa, and the temperature inside the fumigation and polishing chamber is 70℃.

[0053] S12: The parts are fumigated and polished in hexafluoroisopropanol vapor for 320 seconds.

[0054] S13: Expel hexafluoroisopropanol vapor from the fumigation and blasting chamber and cool it for recovery. At the same time, reduce the temperature inside the fumigation and blasting chamber to room temperature and evacuate the solvent vapor from the fumigation and blasting chamber.

[0055] S21: Place the fumigated and polished parts in a foaming chamber, and sequentially introduce carbon dioxide and nitrogen into the foaming chamber. The time interval between introducing the foaming gas and the protective gas is 4 minutes. The pressure of carbon dioxide in the foaming chamber is 8 MPa, the pressure of nitrogen in the foaming chamber is 15 MPa, and the temperature in the foaming chamber is 115℃.

[0056] S22: Perform supercritical foaming on the parts after fumigation and polishing. The supercritical foaming time is 30 minutes.

[0057] S23: Expel the gas in the foaming chamber within 2 seconds to bring the pressure in the foaming chamber to normal pressure, and obtain the foamed part.

[0058] Example 3 S11: Place the 3D-printed part into a fumigation and polishing chamber. The part is made of thermoplastic polyurethane elastomer (brand name: TPU95A). Inject hexafluoroisopropanol into the fumigation and polishing chamber to vaporize the hexafluoroisopropanol into steam. The pressure inside the fumigation and polishing chamber is -0.105MPa, and the temperature inside the fumigation and polishing chamber is 75℃.

[0059] S12: The parts are fumigated and polished in hexafluoroisopropanol vapor for 340 seconds.

[0060] S13: Expel hexafluoroisopropanol vapor from the fumigation and blasting chamber and cool it for recovery. At the same time, reduce the temperature inside the fumigation and blasting chamber to room temperature and evacuate the solvent vapor from the fumigation and blasting chamber.

[0061] S21: Place the fumigated and polished parts in a foaming chamber, and sequentially introduce carbon dioxide and nitrogen into the foaming chamber. The time interval between introducing the foaming gas and the protective gas is 4 minutes. The pressure of carbon dioxide in the foaming chamber is 10 MPa, the pressure of nitrogen in the foaming chamber is 13 MPa, and the temperature in the foaming chamber is 120℃.

[0062] S22: Perform supercritical foaming on the parts after fumigation and polishing. The supercritical foaming time is 30 minutes.

[0063] S23: Expel the gas in the foaming chamber within 2 seconds to bring the pressure in the foaming chamber to normal pressure, and obtain the foamed part.

[0064] Comparative Example 1 S11: Place the 3D-printed part into a fumigation and polishing chamber. The part is made of thermoplastic polyamide elastomer (brand name: Precimid1170 RL). Inject hexafluoroisopropanol into the fumigation and polishing chamber to vaporize the hexafluoroisopropanol into steam. The pressure inside the fumigation and polishing chamber is -0.09MPa, and the temperature inside the fumigation and polishing chamber is 60℃.

[0065] S12: The parts are fumigated and polished in hexafluoroisopropanol vapor for 300 seconds.

[0066] S13: Expel hexafluoroisopropanol vapor from the fumigation and polishing chamber and cool it for recovery. At the same time, reduce the temperature inside the fumigation and polishing chamber to room temperature, and evacuate the solvent vapor from the fumigation and polishing chamber to obtain the fumigated and polished parts.

[0067] Comparative Example 2 S21: Place the 3D printed part into a foaming chamber, and sequentially introduce carbon dioxide and nitrogen into the foaming chamber. The time interval between introducing the foaming gas and the protective gas is 2 minutes. The pressure of carbon dioxide in the foaming chamber is 8 MPa, the pressure of nitrogen in the foaming chamber is 15 MPa, and the temperature in the foaming chamber is 115℃.

[0068] S22: Supercritical foaming is performed on the parts after fumigation and polishing. The parts are made of thermoplastic polyamide elastomer (brand name: Precimid1170 RL). The supercritical foaming time is 30 minutes.

[0069] S23: Expel the gas in the foaming chamber within 2 seconds to bring the pressure in the foaming chamber to normal pressure, and obtain the foamed part.

[0070] The parts that underwent Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to surface roughness and flexural strength tests, and the test results are recorded in Table 1.

[0071] Table 1 Test results of surface roughness and flexural strength of 3D printed parts The original part 1 in the table above is from the same batch as the parts used in Example 1, Comparative Example 1, and Comparative Example 2, and they have the same surface roughness and flexural strength. Original part 2 is from the same batch as the parts used in Example 2, and they have the same surface roughness and flexural strength. Original part 3 is from the same batch as the parts used in Example 3, and they have the same surface roughness and flexural strength. Original parts 1, 2, and 3 did not undergo fumigation, polishing, and / or supercritical foaming; only their surface roughness and flexural strength were tested.

[0072] As shown in Table 1, for the group of original part 1 and parts that underwent Example 1, Comparative Example 1, and Comparative Example 2, original part 1 did not undergo fumigation and / or supercritical carbon dioxide foaming processes; the parts in Example 1 underwent both fumigation and supercritical carbon dioxide foaming processes; the parts in Comparative Example 1 underwent only fumigation and fumigation; and the parts in Comparative Example 2 underwent only supercritical foaming. Therefore, the 3D printed part that only underwent fumigation and fumigation (Comparative Example 1) showed a significant reduction in surface roughness, but no improvement in flexural strength. The 3D printed part that only underwent supercritical foaming (Comparative Example 2) showed a significant improvement in flexural strength, but its surface roughness improvement was very limited. The 3D printed part that underwent a combination of fumigation and fumigation and supercritical foaming (Example 1) showed a significantly reduced surface roughness and a significantly improved flexural strength compared to the original part 1. Its surface roughness was comparable to Comparative Example 1, but its flexural strength was significantly higher than that shown in Comparative Example 2.

[0073] Similarly, the test data from Examples 2 and 3 further demonstrate that the combined fumigation and polishing process with supercritical foaming can significantly reduce the surface roughness of 3D printed parts and substantially improve their folding resistance. This is because after fumigation and polishing, a denser surface layer is formed on the surface of the 3D printed part than the interior. After supercritical foaming, this surface layer maintains a denser structure than the interior, resulting in lower surface roughness and higher folding resistance.

[0074] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0075] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent implementation schemes or modifications made without departing from the spirit of the present invention, such as combinations, divisions or repetitions of features, should be included within the scope of protection of the present invention.

Claims

1. A fumigation, polishing, and supercritical foaming process for 3D printed parts, characterized in that, Including the following steps: S10: The 3D printed parts are fumigated and polished in solvent vapor to obtain the fumigated and polished parts; The fumigation and polishing process involves depositing solvent vapor onto the surface of the 3D printed part, where microscopic protrusions are preferentially dissolved, and the dissolution rate is greater than that of recessed areas; and S20: The fumigated and polished parts are supercritically foamed in a supercritical foaming gas to obtain foamed parts. The parts are made of polyamide, PETG, polylactic acid, polypropylene, or thermoplastic polyurethane.

2. The fumigation, polishing, and supercritical foaming process as described in claim 1, characterized in that, In S10, the fumigation and polishing pressure is -0.05MPa to -0.105MPa, and the fumigation and polishing time is 60s to 400s. In S20, the supercritical foaming temperature is 100℃ to 125℃, the supercritical foaming pressure is 17.8MPa to 60MPa, and the supercritical foaming time is 30min to 60min.

3. The fumigation, polishing, and supercritical foaming process as described in claim 2, characterized in that, In S10, the fumigation and polishing pressure is -0.09MPa to -0.105MPa, and the fumigation and polishing time is 300s to 340s. In S20, the supercritical foaming temperature is 100℃ to 115℃, the supercritical foaming pressure is 23MPa to 34MPa, and the supercritical foaming time is 30min to 50min.

4. The fumigation, polishing, and supercritical foaming process as described in claim 1, characterized in that, S10 specifically includes: S11: Place the 3D printed part into a fumigation and polishing chamber, inject solvent into the fumigation and polishing chamber to vaporize the solvent into solvent vapor, the pressure inside the fumigation and polishing chamber is negative, and the temperature inside the fumigation and polishing chamber is 1°C to 20°C higher than the boiling point of the solvent. S12: The parts are fumigated and polished in solvent vapor; and S13: Vacuum is drawn to remove solvent vapor from the fumigation and blasting chamber and cool it for recovery, while the temperature inside the fumigation and blasting chamber is reduced to room temperature.

5. The fumigation, polishing, and supercritical foaming process as described in claim 4, characterized in that, The solvent is one or more of hexafluoroisopropanol, dimethylformamide, sulfuric acid, m-cresol, formic acid, trifluoroacetic acid, and benzyl alcohol.

6. The fumigation, polishing, and supercritical foaming process as described in claim 1, characterized in that, S20 specifically includes: S21: Place the fumigated and polished parts into a foaming chamber, and sequentially introduce foaming gas and protective gas into the foaming chamber; S22: Supercritical foaming of parts after fumigation and polishing; and S23: Discharge the gas in the foaming chamber to bring the pressure in the foaming chamber to normal pressure, and obtain the foamed part.

7. The fumigation, polishing, and supercritical foaming process as described in claim 6, characterized in that, The foaming gas is carbon dioxide, the pressure of the foaming gas is 7.8 MPa to 30 MPa, the temperature inside the foaming chamber is 100°C to 125°C, the protective gas is nitrogen, the pressure of the protective gas is 10 MPa to 30 MPa, the time interval between introducing the foaming gas and the protective gas is 1 min to 10 min, and the supercritical foaming time is 30 min to 60 min.

8. The fumigation, polishing, and supercritical foaming process as described in claim 6, characterized in that, The foaming gas is carbon dioxide, the pressure of the foaming gas is 12 MPa to 30 MPa, the temperature inside the foaming chamber is 100°C to 115°C, the protective gas is nitrogen, the pressure of the protective gas is 10 MPa to 30 MPa, the time interval between introducing the foaming gas and the protective gas is 2 min to 4 min, and the supercritical foaming time is 30 min to 50 min.

9. The fumigation, polishing, and supercritical foaming process as described in claim 6, characterized in that, In S23, the gas inside the foaming chamber is discharged within 1 to 10 seconds.

10. The fumigation, polishing, and supercritical foaming process as described in claim 1, characterized in that, In step S20: Before the fumigated and polished parts are supercritically foamed in supercritical foaming gas to obtain foamed parts, a fragrance is injected into the foaming chamber where the supercritical foaming is performed.

11. The fumigation, polishing, and supercritical foaming process as described in claim 1, characterized in that, The part is made of thermoplastic polyamide.

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