A smooth surface is a key characteristic of stainless steel products and crucial for maintaining their proper function. Therefore, the polishing process for stainless steel products is extremely important. Based on the manufacturing process, the polishing process for stainless steel products can be divided into two steps: grinding and polishing.
Grinding
The primary goal of polishing stainless steel welds is to remove weld spots and achieve a surface roughness of R10µm, preparing for polishing.
Grinding generally includes:
Three steps: rough grinding, semi-finishing grinding, and finishing grinding
Three surfaces: two sides and one edge
Nine polishing machines
Twenty-seven adjustment mechanisms
Detailed instructions are as follows:
Visually inspect the workpieces that have been transferred to the polishing process from the previous step to check for weld leaks, weld penetration, uneven weld depth, excessive deviation from the joint, localized depressions, misaligned joints, deep scratches, dents, severe deformation, and other defects that cannot be corrected in this step. If any of these defects are present, return to the previous step for repair. If none are present, proceed to the current polishing step.
Rough grinding: Use a 600# abrasive belt to grind the workpiece back and forth on three sides. This step aims to remove weld spots and dents from the previous step, achieve a preliminary rounded corner, and leave virtually no major scratches or dents on both horizontal and vertical surfaces. After this step, the workpiece surface roughness should reach R0.8mm. During polishing, pay attention to the angle of the belt sander and control the pressure on the workpiece. Generally, a straight line with the polished surface is appropriate.
Semi-finishing grinding: Use an 800# abrasive belt to grind the workpiece on three sides using the same back-and-forth grinding method as above. This primarily corrects any seams left by the previous step and further refines any marks left by the rough grinding. Marks left by the previous step should be repeatedly ground until the workpiece surface is scratch-free and generally bright. The surface roughness should reach R0.4mm. (Be careful not to create new scratches or dents during this step, as these defects cannot be repaired in subsequent steps.)
Fine grinding: Use a 1000# abrasive belt primarily to correct fine lines introduced in the previous step. The grinding method is the same as above. The goal of this step is to virtually eliminate the seam between the ground and unground parts of the workpiece, further polishing the workpiece surface. The finished workpiece should be nearly mirror-finished, with a surface roughness of R0.1mm.
Regarding belt replacement: Generally, a 600# belt can polish 6-8 1500mm long workpieces, an 800# belt can polish 4-6 workpieces, and a 1000# belt can polish 1-2 workpieces. The specific situation depends greatly on the weld conditions, polishing pressure, and grinding method. Also, ensure that the belt rotates smoothly on the sponge wheel when changing the belt to achieve uniform grinding.
Polishing
The main purpose of polishing is to polish the previously polished stainless steel to a mirror finish. This process generally includes:
Two steps: Waxing and polishing
Two motors, two wool wheels, large blue wax, and cloth
The specific steps are as follows:
Visually inspect the welded parts entering this process from the previous step to confirm any defects that have not been polished to 1000#, incomplete polishing of all welds, signs of rough polishing, severe damage to the protective film, excessive grinding, excessively large corner radius, severe grinding at both ends, uneven polishing, or uneven depths. These defects, which cannot be corrected during the polishing stage, require re-polishing or repair. (This process cannot repair dents, gouges, or large scratches caused by polishing. However, it can repair very fine lines, such as those caused by 1000# polishing. However, this process is laborious.)
Mirror Finish
Use a high-speed motor to drive a wool wheel (available commercially) and apply a large amount of wax to a mirror finish, similar to the previous polishing method. This process primarily aims to mirror-finish the workpiece after the previous polishing steps, rather than further grinding. Be careful not to rub the polishing wax onto the workpiece's surface coating during this step, and be careful not to damage it.
Polishing
This process is the final step in mirror polishing. Use a clean cotton wheel to rub the workpiece's surface after the mirror finish to clean and polish it after all the previous steps. The goal of this process is to eliminate any visible weld marks on the workpiece's surface and to polish the waxed and polished workpiece to a brightness of 8k, achieving a mirror-like reflectivity of 8k. The polished and unpolished areas are virtually indistinguishable, achieving a completely mirror finish.
