What is the finish standard for sheet metal processing
surface finish scale is an indicator in the surface treatment process, which is used to indicate the finish of the surface of the workpiece and is one of the important indicators of surface treatment quality. In sheet metal processing, finish greatly affects the quality and appearance of sheet metal products.
Finish standard in sheet metal processing
In sheet metal processing, the following indicators are commonly used to indicate finish:
1. Stretch streaks
Under light, the finish of the product surface is characterized by the stretch streaks that appear on the surface of the product. The surface with clear and uniform stripes has a higher finish; on the contrary, the surface with blurred and uneven stripes has a lower finish.
2. Scratch marks
The surface is inspected with a scratch detector. The lighter the marks, the higher the finish.
3. Surface metallography
The surface of the sample is observed through an electron microscope to determine the surface defects of the sample. In sheet metal processing, there should be no burrs or protrusions on the surface of the product, and there should be no cracks or holes in the metallographic diagram, so as to ensure the surface finish.
Of course, there are more detailed and professional numerical values corresponding to the above three visual cleanliness standards. The finish grade of sheet metal processing surface is usually evaluated based on surface roughness parameters. Commonly used parameters include Ra (arithmetic mean roughness), Rz (ten-point height), Rq (root mean square roughness), Rt (total height), Rp (peak height) and Rv (valley depth). These parameters are used to describe the tiny irregularities on the surface of metal materials. The higher the finish, the smoother the surface.
surface finish scale:
Ra 0.012: surface finish grade 14
Ra 0.025: surface finish grade 13
Ra 0.050: surface finish grade 12
Ra 0.1: surface finish grade 11
Ra 0.2: surface finish grade 10
Ra 0.4: surface finish grade 9
Ra 0.8: surface finish grade 8
Ra 1.6: surface finish grade 7
Ra 3.2: surface finish grade 6
Ra 6.3: surface finish grade 5
Ra 12.5: surface finish grade 4
Ra 25: surface finish grade 3
Ra 50: surface finish grade 2
Ra 100: Surface finish level 1
Factors affecting the surface finish of sheet metal processing and improvement methods
1. Accuracy and maintenance of processing equipment:
High-precision processing equipment is the basis, and regular calibration and maintenance of equipment are essential. For example, laser cutting machines require accurate optical path systems, and shearing machines require sharp blades and reasonable blade gaps.
2. Selection and control of processing technology:
Selecting appropriate processing technologies, such as laser cutting, grinding and polishing, can significantly improve surface finish. Laser cutting can provide a smoother cutting surface than flame cutting, while polishing can achieve a mirror effect by using polishing wheels and polishing paste.
3. Quality control of raw materials:
Select plates of qualified quality to avoid problems such as uneven surfaces, stratification or impurities. Cold-rolled plates usually have higher surface accuracy and finish.
At this point, we basically know the specific levels of surface finish, from Ra0.012 to Ra100. The smaller the value, the higher the surface finish level. Of course, the finish in sheet metal processing is an important criterion for judging product quality. During the processing, various indicators need to be strictly controlled to ensure the quality and appearance of the processed parts.
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