The polishing process of brass CNC machining parts has gradually become mainstream in the brassindustry, because this process can solve the problem of dull brassmaterials to a certain extent. So what is its use method and the entire process?
1. Chemical Polishing for Copper:
Chemical polishing is an eco-friendly method used on the surface of brass CNC machined parts. It typically involves the use of a mixture of acids, such as hydrochloric acid and sulfuric acid, to achieve the desired level of brightness.
The workflow for chemical polishing of brassis as follows:
(1) Ensure that the polishing process is performed without water, as water can affect the quality of the polishing. Use the polishing solution at room temperature in a well-ventilated area.
(2) Immerse the brass CNC machined part in the brasspolishing solution for approximately 2-3 minutes, then remove the part and rinse it thoroughly with clean water to remove any residues.
(3) After polishing and cleaning the brasspart, it can proceed to the next process, such as coating or passivation. To prevent re-discoloration of the brasspart, it should be air-dried and passivated.
(4) During the polishing process, if the copper’s shine does not meet the requirements, a small amount of long-lasting additive should be added to the polishing solution. The addition should be about 1%-2% of the original polishing solution, and additives should be added gradually in small quantities. If the polishing solution turns dark green and does not meet the requirements even after adding the additive, it’s advisable to replace the polishing solution with a new one.
Precautions for chemical polishing of copper:
(1) Tri-acid is corrosive. Pay attention to protective measures when operating. Do not let the polishing fluid come into contact with human skin. Handle it with care to prevent splashing.
(2) The working tank of the polishing fluid is preferably made of plastic. Do not use utensils made of metal, ceramics, etc.
(3) Please store the product in a cool and ventilated place.
(4) The workpiece must be turned over during polishing. At the same time, multiple workpieces cannot be turned over at one time. There must be a certain gap between the workpieces.
2. Mechanical Polishing for Copper:
Mechanical polishing involves using mechanical means to remove impurities and oxidation layers from the surface of brass CNC machined parts, resulting in a smooth and shiny surface. Common tools include oil stones, polishing wheels, and sandpaper, with manual operation as the primary method. For special parts or curved surfaces, auxiliary tools such as rotary tables may be used. For high-quality surface finishes, ultra-precision grinding and polishing can be employed.
The workflow for mechanical polishing of brassincludes:
Cleaning: Immerse the brass CNC machined part in deionized water or a cleaning agent to remove dust and oil contamination from the surface. Soft brushes or ultrasonic cleaning can be used to enhance cleaning.
Removal of Oxidation Layer: Use chemical agents (acidic solutions) or mechanical means (sandpaper or grinding wheels) to remove the oxidation layer from the brasssurface. Begin with coarser abrasives to remove thicker layers, gradually switching to finer abrasives for a smoother finish.
Grinding: Employ grinding machines or hand tools with fine abrasives (e.g., sandpaper or grinding discs) to further refine the surface, making it smoother.
Polishing: Use polishing machines or hand tools with polishing compounds (such as aluminum oxide or iron oxide) to achieve a high-gloss finish. Polishing compounds fill in tiny grooves and scratches on the brasssurface, enhancing its smoothness and shine.
Cleaning: Thoroughly clean the polished brasspart with deionized water or a cleaning agent to remove any residual polishing compounds or chemical residues.
Protection: Apply an appropriate protective coating or wax to the brasssurface after polishing to maintain the finish and prevent further oxidation or contamination.
Please note that the specific process of brassphysical polishing and the tools or chemicals used may vary depending on different application scenarios and requirements. Before performing physical polishing, be sure to understand and comply with relevant safety operating procedures, and select appropriate polishing methods and materials.
When performing brassphysical polishing, there are several things to pay attention to:
Safe Handling: Use appropriate personal protective equipment such as goggles, gloves, and protective clothing to prevent injury and chemical splash to the skin or eyes. At the same time, make sure to operate in a well-ventilated environment to avoid inhaling harmful gases.
Clean the surface: Before you begin polishing, make sure the brasssurface is clean and free of dust. Clean first to remove grease, dirt and other impurities, you can use deionized water or detergent to ensure a better polish.
Proper Polishing Tools and Materials: Choose tools and materials suitable for brasspolishing. Grinding and polishing paper or grinding wheels should be of appropriate grit size and material. Polishes should also be selected with the appropriate particle size and composition as needed.
Control the polishing time and intensity: Control the time and intensity when polishing to avoid excessive polishing that may cause surface wear or grooves. During the polishing process, apply force evenly and operate in a gentle manner.
Avoid Overheating: During the polishing process, avoid overheating or excessive frictional heat, as overheating may cause the brassto discolor or soften. Temperature can be controlled using coolant or appropriate cooling time.
Cleaning Residues: After polishing, be sure to clean your brassitems thoroughly to remove residual polish and chemicals created during the polishing process. The chemicals left behind may corrode or oxidize the copper.
Protective layer: To prolong the polishing effect and protect the brasssurface from further oxidation or contamination, an appropriate protective agent or wax can be applied.
Always follow relevant safe operating procedures and adapt your polishing process and material selection to your specific situation and requirements. If necessary, it is recommended to consult a professional CNC machining manufacturer for consultation or help.
The reason why brass CNC machined parts turn black after polishing: The high temperature generated by friction during polishing causes brassto react with oxygen to form black brassoxide.
Brass polishing method:
1. Mechanical polishing is a polishing method that relies on cutting and plastic deformation of the material surface to remove the polished convex parts to obtain a smooth surface. Generally, oilstone strips, wool wheels, sandpaper, etc. are used, and manual operations are mainly used. Special parts such as the surface of a rotary body are used. , auxiliary tools such as turntables can be used, and ultra-precision grinding and polishing methods can be used if the surface quality is high. Super-precision polishing is a kind of abrasive tool that is pressed against the surface of the workpiece to be processed in a polishing fluid containing abrasives and performs high-speed rotation. This technology can achieve a surface roughness of Ra0.008μm, which is the highest among various polishing methods. This method is often used for optical lens molds. Mechanical polishing has the advantages of high efficiency, low cost, and high precision.
2. Chemical polishing is to allow the microscopic convex parts of the surface of the material to be dissolved preferentially in the chemical medium than the concave parts, thereby obtaining a smooth surface. The main advantage of this method is that it does not require complex equipment, can polish workpieces with complex shapes, and can polish many workpieces at the same time, so it is highly efficient. The problem with chemical polishing is the preparation of polishing fluid. The surface roughness obtained by chemical polishing is generally several 10 μm.
3. The basic principle of electrolytic polishing is the same as that of chemical polishing, which is to selectively dissolve the tiny protrusions on the surface of the material to make the surface smooth. Compared with chemical polishing, the influence of cathode reaction can be eliminated and the effect is better.
4. Bonded abrasive polishing: Bonded abrasive polishing uses tools such as abrasive-coated file plates and grinding cylinders to polish brassparts. Bonded abrasive polishing can not only carry out surface polishing, but also can carry out small area and deep polishing.
It should be noted that during the polishing process of brass CNC machined parts, safe operating specifications should be followed to ensure operation in a safe environment and conditions.
It’s essential to follow safety guidelines, wear the appropriate personal protective equipment (PPE), and work in well-ventilated areas during the polishing process. Additionally, the choice of polishing method and materials should align with the specific requirements and desired finish of the brass CNC machined part. Experimentation with different compounds and techniques may be necessary to achieve the optimal polished finish.