1. Grinding
The main objective of grinding stainless steel weldments is to eliminate welding marks and obtain a surface roughness of R10um on the workpiece in preparation for bright dipping.
Related reading: Surface Roughness: The Comprehensive Guide
The grinding step typically covers:
- Three steps: coarse grinding, intermediate grinding and fine grinding;
- Roughing of three surfaces: two faces and one edge;
- The use of nine polishing machines;
- The involvement of 27 control agencies.
Details are as follows:
1. Visual inspection
A visual inspection must be carried out on the parts before transferring them to the final stage of the polishing process. This inspection will evaluate any defects that cannot be corrected in this process, such as missing welds, weld penetration, inconsistent depth of weld points, welding too far from the joint, local depression, uneven butt joint, deep scratches, bruises, severe deformation , etc.
If any of these defects are present, the parts must be returned to the previous process for repair.
If there are no such defects, the parts can then proceed to the polishing process.
2. Rough grinding,
Use a #600 abrasive belt to sand the workpiece, moving it back and forth on three sides.
The objective of this process is to remove the welding marks left on the part by the welding process and eliminate any bruises that may have occurred in previous processes, in order to achieve the initial formation of the fillet at the weld joint.
Horizontal and vertical surfaces must be practically free of major scratches and bruises.
After this process, the surface roughness of the part should be R0.8mm.
Take care to maintain the correct tilt angle of the abrasive belt machine and control the pressure applied by the machine to the workpiece during the polishing process.
As a general rule, it is advisable to form a straight line with the surface to be worked on.
3. Semi-fine grinding
Use a #800 abrasive belt to sand three sides of the workpiece, moving it back and forth. This process is mainly used to correct joints from previous processes and further refine marks produced during grinding.
Repeatedly sand the marks left by previous processes until the surface of the workpiece is scratch-free and appears shiny.
The surface roughness of the part after this process must reach R0.4mm.
It is important to note that new scratches and bruises are not allowed during this process, as they cannot be corrected in subsequent processes.
4. Fine grinding
The #1000 abrasive belt is primarily used to correct any fine lines from previous processes. The grinding method is the same as described previously.
The purpose of this process is to eliminate any seams between the ground part of the part and the non-ground part, to further increase the shine of the part's surface and achieve an almost mirror-like effect. The surface roughness of the part after this process must reach R0.1mm.
5. Instructions for replacing the abrasive belt:
As a general guide, a #600 abrasive belt can sand 6 to 8 workpieces 1500 mm long, a #800 abrasive belt can sand 4 to 6 pieces, and a #1000 abrasive belt can sand 1 to 2 pieces.
The exact number of parts that can be ground may vary depending on factors such as the welding points of the parts, the pressure used for polishing and the method of polishing.
It is important to note that when replacing the abrasive belt, it must be ensured that the belt rotates smoothly on the sponge wheel to achieve uniform grinding of the workpiece.
Description of three-sided grinding:
The two sides of the weld separated by the welding edge, both horizontal and vertical, need to be polished.
In total, three sides of the weld require polishing.
A diagram of the polishing process is shown in the attached figure.
The polishing method is similar to the waxing method, but instead of using wax, a cloth wheel is used in the polishing process.
Polishing is the final step in the polishing process.
It is important to ensure that the mirror surface is not damaged after polishing, as this will render all previous efforts ineffective.
The. The polishing process involves connecting a fabric wheel to a high-speed motor, which rotates the wheel at high speed. The wheel is then used to clean the surface of the workpiece, removing dirt and residual wax. This results in a polished surface.
In actual polishing, it is often done in conjunction with the use of grinding powder. Grinding powder helps to remove oily substance such as blue wax from the workpiece. Its main objective is to facilitate the removal of the blue wax that has adhered to the surface.
If the polishing process is not carried out using abrasive powder, it can be difficult to remove the blue wax from the surface and can also be easily transferred to other areas, affecting the overall appearance.
B. To obtain the mirror shine necessary for the piece, it is essential to keep the fabric wheel used in the polishing process clean.
In practical production, it may be necessary to replace the fabric wheel depending on the specific circumstances.
