Mirror polishing method for stainless steel
By using a synergistic approach of plant-based abrasives and chemical polishing paste, the environmental pollution and consistency issues of traditional stainless steel polishing are solved, achieving a low-cost and efficient mirror polishing effect suitable for large flat and irregularly shaped stainless steel workpieces.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JOMOO KITCHEN & BATHROOM
- Filing Date
- 2026-03-12
- Publication Date
- 2026-04-21
AI Technical Summary
Traditional stainless steel polishing methods suffer from environmental pollution, high costs, heavy reliance on manpower, and poor product consistency, especially when dealing with large flat surfaces and irregularly shaped parts.
Using renewable and biodegradable plant abrasives, combined with polishing paste containing oxidants and complexing agents, the synergistic effect of coarse and fine polishing achieves a combination of mechanical and chemical polishing. It prioritizes the removal of microscopic protrusions to achieve mirror-level surface quality, and adapts to workpieces of different shapes by controlling the polishing path and frequency.
It achieves low-cost, environmentally friendly mirror polishing, reduces reliance on manual labor, improves product consistency and production efficiency, and is suitable for large flat and irregularly shaped stainless steel workpieces, achieving a mirror-level surface roughness of less than 0.05μm.
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Abstract
Description
Technical Field
[0001] This application relates to the field of polishing technology, and in particular to a method for mirror polishing stainless steel. Background Technology
[0002] Stainless steel products have extremely high requirements for surface finish and mirror effect. Currently, the mirror effect of stainless steel products mainly relies on traditional mechanical polishing and abrasive fluid polishing.
[0003] Traditional mechanical polishing widely uses abrasives such as synthetic diamond, silicon carbide, and corundum. However, these abrasives have high hardness and good chemical stability, generating large amounts of non-biodegradable industrial sludge and dust during production and use. The sludge contains a large amount of heavy metals and non-biodegradable inorganic particles, and is classified as hazardous solid waste, which is environmentally unfriendly and difficult and costly to handle. Furthermore, when using these traditional abrasives to polish stainless steel products, the hard abrasives remove material through cutting, leaving deep scratches on the polished surface, which are easily embedded. Even if the Ra (Ra value) appears low after rough polishing, groove defects will appear after subsequent cleaning processes (acid pickling). At the same time, traditional mechanical polishing suffers from poor geometric accessibility when dealing with complex and highly precision stainless steel irregularly shaped parts, making it difficult to achieve uniform polishing. For many high-requirement irregularly shaped parts, the final fine polishing stage still heavily relies on manual operation by skilled workers. The skill level, proficiency, and physical condition of workers directly determine the consistency and stability of polishing quality. Defects such as "over-polishing," "collapsed edges," "orange peel," surface scratches, and excessive waviness can easily occur due to unstable human operation. This leads to poor product consistency, large fluctuations in product yield, low production efficiency, high labor costs, and difficulty in achieving large-scale, standardized mass production.
[0004] Abrasive Flow Machining (AFM) is a polishing process that involves repeatedly extruding a semi-solid viscoelastic medium containing abrasive particles over the surface of a workpiece. This technology is well-suited for complex internal cavities and intersecting holes, but it has inherent limitations: the fluid medium cannot form effective flow channels in open planes, requiring specialized fixtures to guide the flow; it is not suitable for large flat or large-sized workpieces; and the viscoelastic carrier and specialized abrasives are expensive, resulting in high costs and long production cycles. Summary of the Invention
[0005] Based on this, this application provides a method for mirror polishing stainless steel, the technical solution of which is as follows: A method for mirror polishing stainless steel includes the following steps: The stainless steel product to be polished is coarsely polished using a coarse polishing medium, wherein the coarse polishing medium includes a first plant abrasive and a polishing paste, and the polishing paste includes an oxidant and a complexing agent; The stainless steel product to be polished after coarse polishing is finely polished using a fine polishing medium, wherein the fine polishing medium includes a second plant-based abrasive.
[0006] Compared with traditional solutions, this application has the following advantages: This application uses renewable and biodegradable plant-based abrasives instead of the rigid abrasives used in traditional mechanical polishing throughout the entire process, solving the pollution problem of traditional abrasives at the source. Simultaneously, during rough polishing, a polishing paste containing oxidants and complexing agents is added, effectively synergizing the mechanical grinding and chemical polishing actions. This prioritizes the removal of softened microscopic protrusions, resulting in a smoother surface and a shallower damage layer after rough polishing. Fine polishing then follows this foundation, achieving microscopic leveling rather than simply refining scratches without relying on manual labor by skilled workers. This improves the surface quality of the polished surface, resulting in good consistency and stability of polishing quality, saving labor costs and enabling large-scale, standardized mass production. This application can precisely process the surface roughness Ra of stainless steel to a mirror-like level below 0.05μm. Furthermore, by using the aforementioned polishing media and following a polishing path from coarse to fine polishing, this method exhibits good polishing uniformity for both flat and irregularly shaped stainless steel products. Specifically, for flat stainless steel products, the polished surface exhibits fewer groove defects, minimizing their impact on appearance. Unlike abrasive fluid polishing, the polishing media can flow freely to cover the entire surface, enabling the processing of large flat surfaces and large-sized workpieces without the need for specialized fixtures. Additionally, the polishing media is cost-effective. For irregularly shaped stainless steel products, this method offers good geometric accessibility. Detailed Implementation
[0007] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.
[0008] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.
[0009] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings: In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.
[0010] In this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.
[0011] In this application, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they can be selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.
[0012] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.
[0013] In this application, numerical intervals (i.e. numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the above-mentioned numerical intervals are considered continuous, and include the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical range, as well as every value between the two numerical endpoints.
[0014] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.
[0015] This application provides a method for mirror polishing stainless steel. In one embodiment, the method for mirror polishing stainless steel includes the following steps: The stainless steel product to be polished is coarsely polished using a coarse polishing medium, wherein the coarse polishing medium includes a first plant abrasive and a polishing paste, and the polishing paste includes an oxidant and a complexing agent; The stainless steel product to be polished after coarse polishing is finely polished using a fine polishing medium, wherein the fine polishing medium includes a second plant-based abrasive.
[0016] This application uses renewable and biodegradable plant-based abrasives instead of the rigid abrasives used in traditional mechanical polishing throughout the entire process, solving the pollution problem of traditional abrasives at the source. Simultaneously, during rough polishing, a polishing paste containing oxidants and complexing agents is added, effectively synergizing the mechanical grinding and chemical polishing actions. This prioritizes the removal of softened microscopic protrusions, resulting in a smoother surface and a shallower damage layer after rough polishing. Fine polishing then follows this foundation, achieving microscopic leveling rather than simply refining scratches without relying on manual labor by skilled workers. This improves the surface quality of the polished surface, resulting in good consistency and stability of polishing quality, saving labor costs and enabling large-scale, standardized mass production. This application can precisely process the surface roughness Ra of stainless steel to a mirror-like level below 0.05μm. Furthermore, by using the aforementioned polishing media and following a polishing path from coarse to fine polishing, this method exhibits good polishing uniformity for both flat and irregularly shaped stainless steel products. Specifically, for flat stainless steel products, the polished surface exhibits fewer groove defects, minimizing their impact on appearance. Unlike abrasive fluid polishing, the polishing media can flow freely to cover the entire surface, enabling the processing of large flat surfaces and large-sized workpieces without the need for specialized fixtures. Additionally, the polishing media is cost-effective. For irregularly shaped stainless steel products, this method offers good geometric accessibility.
[0017] Optionally, before rough polishing the stainless steel product to be polished, the following step is also included: degreasing the stainless steel product to be polished.
[0018] Optionally, the first plant-based abrasive has a Mohs hardness of 2.5 to 4.0, a breakage resistance of ≥85% during coarse polishing, and high toughness. Optionally, the first plant-based abrasive includes walnut shell particles. The mesh size of the first plant-based abrasive is 10 to 20 mesh.
[0019] Optionally, the second plant-based abrasive has a Mohs hardness of 3.5 to 4.5, a breakage resistance of 50% to 70% during fine polishing, and medium to low toughness. Optionally, the second plant-based abrasive includes olive shell particles. The mesh size of the second plant-based abrasive is 36 to 50 mesh.
[0020] The formula for calculating the breakage resistance rate is: (initial abrasive mass - broken abrasive mass) / initial abrasive mass × 100%.
[0021] Walnut shells have good toughness and strong cutting force, while olive shells have high hardness and good finishing effect. Walnut shells are used as the main abrasive for coarse polishing, while olive shells are used as the main abrasive for fine polishing. Combining the polishing path from coarse to fine can achieve both polishing efficiency and polishing quality.
[0022] If plant-based abrasives are used alone for polishing, they can achieve basic processing such as deburring, oxide scale removal, and chamfering, or a matte finish. However, the material removal rate is low, and the polishing ability is limited. This is insufficient to precisely process the surface roughness Ra of stainless steel to a mirror level of 0.05μm or less. This embodiment combines physical grinding with coarse and fine polishing paths using plant-based abrasives with chemical polishing, which can effectively process the surface roughness Ra of stainless steel to a mirror level of 0.05μm or less, achieving a scratch-free and orange peel-free mirror effect.
[0023] Optionally, the oxidant is selected from at least one of hydrogen peroxide, ammonium persulfate, and sodium percarbonate, and accounts for 5 to 15% of the mass of the polishing paste. For example, 5%, 10%, and 15%.
[0024] Optionally, the complexing agent is selected from at least one of citric acid, tartaric acid, oxalic acid, and gluconic acid, and accounts for 3 to 10% of the polishing paste by mass. For example, 3%, 5%, and 10%.
[0025] When using conventional hard abrasives for rough polishing, the hard abrasives remove material through cutting, leaving deep scratches on the polished surface. These scratches are easily embedded in the polished surface, and even if the Ra (Ra value) appears low after rough polishing, groove defects will appear after subsequent cleaning processes (acid washing). In this embodiment, a first plant-based abrasive and polishing paste are used for rough polishing. With the synergistic effect of the chemical polishing paste, the softened microscopic protrusions are preferentially removed, resulting in a smoother surface and a shallower damage layer after rough polishing.
[0026] Optionally, the polishing paste further includes a pH adjuster and water. The pH adjuster is selected from at least one of ammonia, triethanolamine, and a boric acid-borax buffer system, and the pH value of the polishing paste is between 3.5 and 5.5. In some embodiments, the pH adjuster accounts for 1% to 5% of the mass of the polishing paste, with the remainder being water.
[0027] Optionally, the coarse polishing medium further includes at least one of polishing oil and a dispersant. The polishing oil is selected from at least one of synthetic ester oils and sulfurized fatty acid esters. The dispersant is selected from at least one of sodium pyrophosphate, sodium hexametaphosphate, and sodium polyacrylate.
[0028] Optionally, the fine polishing medium further includes at least one of polishing oil and a surfactant. The polishing oil is selected from at least one of synthetic ester oils and sulfurized fatty acid esters. The surfactant is selected from at least one of alkyl polysaccharide glycosides, fatty alcohol polyoxyethylene ethers, and the Tween series. In this case, the second plant-based abrasive acts as a mechanical carrier, working in conjunction with the lubrication and removal of chemical residues by the polishing oil to achieve microscopic leveling rather than simple scratch refinement. Therefore, it is possible to achieve the surface quality that only ultrafine abrasives (micron-sized diamond paste) can achieve with seemingly coarser abrasives (e.g., 36 mesh).
[0029] Optionally, the surface to be polished of the stainless steel product is a flat or irregularly shaped surface, the roughness Ra of the surface to be polished is 0.2~0.8μm, and the surface roughness Ra of the polished stainless steel obtained after fine polishing is ≤0.05μm.
[0030] The surface of the stainless steel product to be polished can be a flat surface or an irregularly shaped surface.
[0031] For stainless steel products with a flat surface, the above-mentioned use of a first plant-based abrasive and polishing paste for rough polishing, followed by a second plant-based abrasive for fine polishing, results in fewer grooves and defects on the polished surface, minimizing the impact on appearance. Furthermore, unlike abrasive fluid polishing where uniform polishing is difficult to control, the polishing medium of this application can flow freely to cover the entire flat surface, enabling the processing of large flat surfaces and large-sized workpieces without the use of specialized fixtures. Simultaneously, the polishing medium is low in cost.
[0032] When the surface to be polished on a stainless steel product is irregularly shaped, such as a stainless steel faucet, a stainless steel pendant, or a stainless steel showerhead, the product may be an irregularly shaped part. These products have complex geometries (such as deep holes, narrow grooves, internal threads, and complex curved surfaces), with intricate structures and extremely high precision requirements. Traditional fixed polishing tools (such as polishing wheels and abrasive belts), due to their rigidity and shape limitations, cannot effectively reach and evenly process all areas of these complex surfaces, resulting in uneven polishing. Protruding parts are over-polished ("over-polished"), while grooves, corners, and other areas are under-polished. This not only fails to achieve an overall mirror finish but also easily damages the original geometric precision of the workpiece, causing problems such as "collapsed edges" or excessively large rounded corners. Furthermore, the brushed surface is prone to yellowing, leading to low user acceptance. For many high-requirement irregularly shaped parts, the final fine polishing stage still heavily relies on manual operation by skilled workers. The skill level, proficiency, and physical condition of workers directly determine the consistency and stability of polishing quality. Defects such as "over-polishing," "collapsed edges," "orange peel," surface scratches, and excessive waviness due to unstable human operation are highly likely to occur. This results in poor product consistency, large fluctuations in product yield, low production efficiency, high labor costs, and difficulty in achieving large-scale, standardized mass production. Compared to the methods mentioned above, this application offers better geometric accessibility, does not rely on manual operation by skilled workers, provides better consistency and stability of polishing quality, helps save labor costs, and enables large-scale, standardized mass production.
[0033] In this embodiment, based on the type of surface to be polished (flat / irregularly shaped), and in addition to coarse polishing with the first plant-based abrasive and polishing paste and fine polishing with the second plant-based abrasive, the frequencies of coarse and fine polishing are controlled. Furthermore, the frequencies are adjusted according to the mass of the stainless steel with an irregular shape. Specifically: for heavy, irregularly shaped stainless steel parts, a higher coarse polishing frequency is used to ensure polishing force and avoid media deposition. For flat surfaces and light-weight, irregularly shaped stainless steel parts, appropriate frequencies of coarse and fine polishing are used to prevent workpiece collision damage and ensure uniform flow. Optionally, the coarse polishing frequency is higher than the fine polishing frequency. The coarse and fine polishing frequencies can be adaptively adjusted according to the mass and the complexity of the geometric shape of the stainless steel to be polished. Optionally, if the surface to be polished is flat, the coarse polishing frequency is 28~32Hz, and the fine polishing frequency is 23~27Hz. Optionally, if the surface to be polished is irregularly shaped, and the mass of the stainless steel product to be polished is ≥1Kg, the coarse polishing frequency is 38~42Hz, and the fine polishing frequency is 33~37Hz. Optionally, the surface to be polished is an irregularly shaped surface, the weight of the stainless steel product to be polished is <1Kg, the frequency of coarse polishing is 43~47Hz, and the frequency of fine polishing is 33~37Hz. Through precise control, the stainless steel to be polished can be uniformly polished to achieve a mirror finish, while ensuring the practicality and stability of the process, reducing reliance on manual operation, ensuring product consistency and yield, and realizing large-scale, standardized production.
[0034] Understandably, rough polishing and fine polishing can be performed in a polishing device, which can be a high-speed eddy current polisher or a centrifugal tumbler. The rough polishing frequency and fine polishing frequency mentioned above refer to the power frequency of the motor that drives the turntable (roller frame) of the polishing device, and the unit is also Hertz (Hz). This frequency directly determines the rotational speed of the turntable.
[0035] Optionally, the temperature for coarse polishing is 40-50℃, and the temperature for fine polishing is 50-60℃. The coarse polishing time is 100-140 minutes, and the fine polishing time is 50-70 minutes. This standardized parameter system reduces reliance on skilled workers, significantly improving yield and production efficiency. Furthermore, the relatively short coarse and fine polishing times further contribute to increased production efficiency.
[0036] Traditional mechanical polishing uses rigid abrasives, generating significant dust and waste throughout the process, polluting both the working and natural environments. This contradicts clean production and sustainable development strategies implemented by companies and increases their environmental compliance costs. In contrast, this method uses renewable and biodegradable plant-based abrasives instead of rigid abrasives. Specifically, during coarse polishing, a first plant-based abrasive with a Mohs hardness of 2.5–4.0 and a breakage resistance of ≥85% is used in combination with chemical polishing paste to preferentially remove softened microscopic protrusions, resulting in a smoother surface and shallower damage layer after coarse polishing. During fine polishing, a second plant-based abrasive with a Mohs hardness of 3.5–4.5 and a breakage resistance of 50%–70% is used to achieve microscopic smoothing rather than simply refining scratches. This allows the surface quality achieved with seemingly coarser abrasives (e.g., 36 mesh) to be comparable to that of ultrafine abrasives (micron-level diamond paste). This not only achieves mirror-like finishes of 0.05 μm and below but also addresses the pollution problems associated with traditional abrasives at their source, meeting green manufacturing requirements. In addition, chemical electroplating can also achieve a mirror finish, but it is expensive and causes environmental pollution. Compared to chemical electroplating, this embodiment uses plant-based abrasives in combination with chemical polishing paste for synergistic polishing, which not only achieves a mirror finish of 0.05μm and below, but also helps to reduce costs and environmental pollution compared to electroplating.
[0037] In summary, traditional polishing processes often require multiple steps and long operating times, accompanied by high abrasive consumption, waste disposal, and labor costs, resulting in high overall production costs and long processing cycles. This makes them uncompetitive when facing the rapid response demands and cost control requirements of the high-end market. This implementation method uses low-cost, biodegradable plant-based abrasives, combined with a coarse-to-fine polishing path and synergistic chemical polishing. This approach can reduce costs while ensuring polishing effectiveness, giving it a strong competitive edge in the market.
[0038] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.
[0039] Example 1 (Small irregularly shaped parts) This embodiment provides a mirror polishing method for stainless steel (small irregular-shaped parts), the steps of which are as follows: The stainless steel workpiece to be polished is a 304 stainless steel faucet semi-spherical cap accessory, with a single piece weighing approximately 0.1 kg and an initial surface roughness Ra of approximately 0.3 μm.
[0040] S1. Pretreatment: Clean and degrease the stainless steel irregular parts to be polished.
[0041] S2. Coarse Grinding and Polishing: Mix 10-mesh walnut shell particles, water-based polishing paste, and synthetic ester polishing oil in a weight ratio of 96:2:2, stir evenly, and prepare a coarse grinding and polishing medium. The water-based polishing paste comprises, by mass percentage: oxidant (hydrogen peroxide): 10%, complexing agent (citric acid): 5%, pH adjuster (triethanolamine): 2%, and deionized water: 83%. Add the degreased stainless steel shaped parts to be polished and the coarse grinding and polishing medium to a high-speed vortex polishing machine in a weight ratio of 1:20. Set the equipment frequency to 45Hz, temperature to 45℃, and time to 120 minutes, alternating between forward and reverse rotation.
[0042] S3. Fine Grinding and Polishing: Mix 36-mesh olive shell particles with synthetic ester polishing oil at a weight ratio of 98:2, stir evenly to prepare a fine grinding and polishing medium. Discharge the coarse grinding and polishing medium from the equipment, rinse the working tank and workpiece surface with clean water, and then, according to the weight ratio of the coarse-polished stainless steel irregularly shaped part to be polished and the fine grinding and polishing medium, feed the prepared fine grinding and polishing medium into a high-speed vortex polishing machine. Set the equipment frequency to 35Hz, temperature to 55℃, and time to 60 minutes.
[0043] S4. Post-processing: After polishing, separate the workpiece from the polishing medium, clean it with deionized water using ultrasound for 5 minutes, and dry it with hot air.
[0044] Measurements showed that all surfaces of the polished stainless steel shaped parts achieved a mirror finish, with a surface roughness Ra value of 0.031μm, uniform gloss, and no defects.
[0045] Example 2 (Large Irregularly Shaped Parts) The workpiece to be polished is a stainless steel faucet valve body (machined from bar stock), weighing approximately 1.5 kg. It has a complex structure and an initial surface roughness Ra of approximately 0.4 μm.
[0046] S1. Pretreatment: Clean and degrease the stainless steel irregular parts to be polished.
[0047] S2. Coarse Grinding and Polishing: Mix 20-mesh walnut shell particles, water-based polishing paste, and synthetic ester polishing oil at a weight ratio of 95:3:2, stir evenly, and prepare a coarse grinding and polishing medium. The water-based polishing paste comprises, by weight percentage: oxidant (hydrogen peroxide): 8%, complexing agent (citric acid): 6%, pH adjuster (triethanolamine): 2%, and deionized water: 84%. Add the degreased stainless steel shaped parts to be polished and the coarse grinding and polishing medium to a centrifugal tumbling machine at a weight ratio of 1:40. Set the machine frequency to 40Hz, temperature to 48℃, and time to 120 minutes, alternating between forward and reverse rotation.
[0048] S3. Fine Grinding and Polishing: Mix 40-mesh olive shell particles with synthetic ester polishing oil at a weight ratio of 97:3, stir evenly to prepare fine grinding and polishing media. Drain the coarse grinding and polishing media from the equipment, rinse the working tank and workpiece surface with clean water, and then add the fine grinding and polishing media to the coarse-polished stainless steel irregular-shaped parts to be polished at a weight ratio of 1:40 into a centrifugal tumbling machine. Set the equipment frequency to 38Hz, temperature to 58℃, and time to 60 minutes.
[0049] S4. Post-processing: After polishing, separate the workpiece from the polishing medium, clean it with deionized water using ultrasound for 5 minutes, and dry it with hot air.
[0050] Measurements showed that all surfaces of the polished stainless steel irregular parts achieved a mirror finish, with a surface roughness Ra value of 0.029μm, uniform gloss, and no defects.
[0051] Example 3 (Planar Workpiece) This embodiment provides a mirror polishing method for stainless steel (flat workpiece), the steps of which are as follows: Workpiece to be polished: 304 stainless steel plate, with dimensions of 200mm×200mm×5mm, and an initial surface roughness Ra of approximately 0.35μm.
[0052] S1. Pretreatment: Place the stainless steel plate to be polished in the degreasing cleaning solution, ultrasonically clean for 8 minutes to remove surface oil, then rinse with deionized water and dry with hot air for later use.
[0053] S2. Coarse Grinding and Polishing: Mix 15-mesh walnut shell particles, water-based polishing paste, and synthetic ester polishing oil at a weight ratio of 96:2:2, stir evenly, and prepare a coarse grinding and polishing medium. The water-based polishing paste comprises, by weight percentage: oxidant (hydrogen peroxide): 9%, complexing agent (citric acid): 5%, pH adjuster (triethanolamine): 2%, and deionized water: 84%. Add the degreased stainless steel plate to be polished and the coarse grinding and polishing medium to a high-speed vortex polishing machine at a weight ratio of 1:25. For polishing flat workpieces, the medium ratio needs to be appropriately increased to ensure uniform coverage of the workpiece surface. Start the equipment and set the following process parameters: equipment frequency: 30Hz, process temperature: 45℃, polishing time: 150 minutes (the coarse grinding time for flat workpieces should be slightly longer to ensure a smoothing effect), operating mode: alternating forward and reverse rotation, with forward rotation accounting for 70% of the total time and reverse rotation accounting for 30%. For flat workpieces, increasing the forward rotation ratio helps the medium to flow directionally on the plane, improving cutting efficiency.
[0054] S3. Fine Grinding and Polishing: Mix 36-mesh olive shell particles with synthetic ester polishing oil at a weight ratio of 98:2, stir evenly, and prepare a fine grinding and polishing medium. Discard the coarse grinding and polishing medium from the equipment, rinse the working tank and workpiece surface with clean water, and then add the fine grinding and polishing medium to the stainless steel plate to be polished at a weight ratio of 1:25. Start the equipment and set the following process parameters: Equipment frequency: 25Hz, Process temperature: 55℃, Polishing time: 90 minutes (the fine grinding time for flat workpieces should be slightly longer to ensure mirror surface uniformity), Operating mode: Alternating forward and reverse rotation, with forward rotation accounting for 60% of the total time and reverse rotation accounting for 40%. Appropriately increasing the reverse rotation ratio during the fine grinding stage helps eliminate directional grinding marks.
[0055] S4. Post-processing: After polishing, separate the workpiece from the polishing medium, clean it with deionized water using ultrasound for 5 minutes, and dry it with hot air.
[0056] Measurements showed that the polished stainless steel plate had a smooth, mirror-like surface, free of any scratches, orange peel-like defects, and a surface roughness Ra value of 0.025μm.
[0057] Comparative Example 1 This comparative example provides a mirror polishing method for stainless steel (small irregular-shaped parts), the steps of which are as follows: The stainless steel workpiece to be polished is the same as in Example 1.
[0058] S1 is the same as in Example 1.
[0059] S2, Mechanical Polishing 36-mesh brown fused alumina abrasive and synthetic ester polishing oil were mixed at a weight ratio of 98:2 and stirred evenly to form a polishing medium. Brown fused alumina is a traditional hard abrasive with a Mohs hardness of approximately 9 and contains no chemical polishing components.
[0060] The degreased stainless steel shaped parts to be polished were fed into a high-speed vortex polishing machine at a weight ratio of 1:20 with the aforementioned polishing medium. The machine frequency was set to 45 Hz, the process temperature to 45℃, and the polishing time to 6 hours (twice the total polishing time of Example 1), with alternating forward and reverse rotation.
[0061] S3. Post-processing: After polishing, separate the workpiece from the polishing medium, clean it with deionized water using ultrasound for 5 minutes, and dry it with hot air.
[0062] Visual inspection revealed obvious fine scratches on the workpiece surface, especially denser in areas with greater curvature; visible wear was observed at the edges, with the original sharp edges polished into small rounded corners, a phenomenon known as "edge collapse." Measurements showed a surface roughness Ra value of 0.15 μm, far below the requirements for a mirror finish.
[0063] As can be seen, in Examples 1 and 2, based on physical grinding using plant abrasives for coarse and fine polishing paths, combined with chemical polishing, the precision polishing process system with the above-mentioned chemical-mechanical synergy can effectively process the surface roughness Ra of stainless steel to a mirror level of less than 0.05μm, achieving a mirror effect without scratches or orange peel.
[0064] In contrast, Comparative Example 1 uses traditional rigid abrasives for polishing, which not only takes a long time but also incurs high abrasive consumption, waste disposal, and labor costs. More importantly, it still fails to achieve the mirror finish of stainless steel with Ra≤0.05μm after polishing.
[0065] Comparative Example 2 (Abrasive Fluid Polishing) This comparative example provides a mirror polishing method for stainless steel (flat workpiece), the steps of which are as follows: Workpiece to be polished: 304 stainless steel plate, the same as in Example 3, with dimensions of 200mm×200mm×5mm and an initial surface roughness Ra of approximately 0.35μm.
[0066] S1. Pretreatment: Same as in Example 3, the stainless steel plate to be polished is degreased and cleaned.
[0067] S2. Fixture Design and Installation: To attempt abrasive fluid polishing of the flat plate, a special fixture was designed to fix the plate inside the fixture cavity, with only a narrow flow channel of about 5mm reserved above the plate surface to force the medium to flow over the plate surface. The fixture took 2 days to manufacture, and the material cost was approximately 2000 yuan.
[0068] S3. Polishing media preparation: Commercially available abrasive fluid polishing media is used, in which the abrasive is silicon carbide (36 mesh), the carrier is a high molecular viscoelastic polymer, and the abrasive content is about 60%.
[0069] S4. Polishing operation: Place the fixture with the workpiece installed on the abrasive fluid polishing equipment and set the following parameters: extrusion pressure: 10MPa; medium flow rate: 50L / min; number of cycles: 200 times (corresponding to polishing time of about 4 hours).
[0070] S5. Post-processing: Surface quality: Visually, the surface polishing of the plate is extremely uneven. There are obvious polishing marks in the medium inlet area, indicating some improvement in surface roughness; however, areas far from the inlet are almost unpolished, retaining their original surface condition. Due to the high medium flow rate, the edges of the plate are over-polished, resulting in rounded corners.
[0071] Surface roughness: Roughness was measured in different areas of the plate: Medium inlet area: Ra is 0.18 μm; Plate center area: Ra is 0.31 μm (basically unchanged); Plate edge area: Ra is 0.15 μm (but the edges are worn); Overall average: Ra is about 0.25 μm, far from meeting the requirements for a mirror finish.
[0072] Process evaluation: Low efficiency: It takes 4 hours and only improves local areas; Poor uniformity: It is impossible to achieve uniform polishing over a large area; High cost: The special fixture is expensive to manufacture and the medium is expensive.
[0073] It is clear that abrasive fluid polishing is indeed not suitable for large flat workpieces.
[0074] Table 1 summarizes the key parameters and polishing effects of the above embodiments and comparative examples.
[0075] Table 1
[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0077] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A method for mirror polishing stainless steel, characterized in that, Includes the following steps: The stainless steel product to be polished is coarsely polished using a coarse polishing medium, wherein the coarse polishing medium includes a first plant abrasive and a polishing paste, and the polishing paste includes an oxidant and a complexing agent; The stainless steel product to be polished after coarse polishing is finely polished using a fine polishing medium, wherein the fine polishing medium includes a second plant-based abrasive.
2. The method for mirror polishing stainless steel according to claim 1, characterized in that, The first and second plant abrasives satisfy at least one of the following conditions: (1) The first plant abrasive has a Mohs hardness of 2.5~4.0 and a breakage resistance of ≥85% during the coarse polishing process; (2) The second plant abrasive has a Mohs hardness of 3.5 to 4.5 and a breakage resistance of 50% to 70% during the fine polishing process.
3. The method for mirror polishing stainless steel according to claim 2, characterized in that, The first and second plant abrasives satisfy at least one of the following conditions: (1) The first plant abrasive includes walnut shell particles; (2) The second plant abrasive includes olive shell particles.
4. The method for mirror polishing stainless steel according to claim 3, characterized in that, The first and second plant abrasives satisfy at least one of the following conditions: (1) The mesh size of the first plant abrasive is 10 mesh to 20 mesh; (2) The mesh size of the second plant abrasive is 36-50 mesh.
5. The method for mirror polishing stainless steel according to claim 1, characterized in that, The polishing compound satisfies at least one of the following conditions: (1) The oxidant is selected from at least one of hydrogen peroxide, ammonium persulfate and sodium percarbonate, and accounts for 5-15% of the mass of the polishing paste; (2) The complexing agent is selected from at least one of citric acid, tartaric acid, oxalic acid and gluconic acid, and accounts for 3 to 10% of the mass of the polishing paste; (3) The polishing paste further includes a pH adjuster, which is selected from at least one of ammonia, triethanolamine and boric acid-borax buffer system, and the pH value of the polishing paste is between 3.5 and 5.
5.
6. The method for mirror polishing stainless steel according to any one of claims 1 to 5, characterized in that, The coarse polishing media and the fine polishing media satisfy at least one of the following conditions: (1) The coarse grinding polishing medium further includes at least one of polishing oil and dispersant; (2) The fine grinding polishing medium also includes at least one of polishing oil and surfactant.
7. The method for mirror polishing stainless steel according to any one of claims 1 to 5, characterized in that, The surface of the stainless steel product to be polished is a flat or irregularly shaped surface, and the roughness Ra of the surface to be polished is 0.2~0.8μm. After fine polishing, the surface roughness Ra of the polished stainless steel surface is ≤0.05μm.
8. The method for mirror polishing stainless steel according to claim 7, characterized in that, Includes at least one of the following features: (1) The surface to be polished is a plane, the frequency of coarse polishing is 28~32Hz, and the frequency of fine polishing is 23~27Hz; (2) The surface to be polished is an irregularly shaped surface, the mass of the stainless steel product to be polished is ≥1Kg, the frequency of coarse polishing is 38~42Hz, and the frequency of fine polishing is 33~37Hz; (3) The surface to be polished is an irregularly shaped surface, the mass of the stainless steel product to be polished is <1Kg, the frequency of coarse polishing is 43~47Hz, and the frequency of fine polishing is 33~37Hz.
9. The method for mirror polishing stainless steel according to any one of claims 1 to 5 and 8, characterized in that, The coarse and fine polishing satisfy at least one of the following conditions: (1) The temperature for rough polishing is 40~50℃; (2) The temperature for fine polishing is 50~60℃; (3) The coarse polishing time is 100 min to 140 min; (4) The fine polishing time is 50 min to 70 min.
10. The method for mirror polishing stainless steel according to any one of claims 1 to 5 and 7, characterized in that, Before rough polishing the stainless steel product to be polished, the following steps are also included: The stainless steel product to be polished is degreased.