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How to solve the problem that the punching size of automobile metal stamping parts does not meet the requirements?

In the production process of metal stamping parts, there will be situations where the size of the punching hole is too large or too small, and the size of the punch is quite different. In addition to the components such as accuracy and blanking gap, the following aspects should be considered.

  • 1. During the production of metal stamping parts, it is caused by the burrs of the punching parts during punching. It is necessary to study the punching edge, and pay attention to check whether the punching gap is reasonable. It is caused by the instability of the stamping parts during bending, mainly for U-shaped and V-shaped bending, guiding the stamping parts before bending, guiding during the bending process, and pressing the material during the bending process to prevent the stamping parts. Slippage during bending is the key to solving the problem.
  • 2. During the production of metal stamping parts, the tensile stress of the material increases, and the tendency of the stamping parts to turn over and twist increases. When the material is turned over, the size of the punching hole will become smaller. The strong pressure on the material causes plastic deformation of the material, which will lead to a larger punching size. When the strong pressure is reduced, the size of the punching hole will become smaller.
  • 3. In the production of metal stamping parts, if the end is trimmed with a slope or arc, because the punching force is relieved, the punching parts are prone to turning over and smearing, so the size of the punching hole will become larger. While the end of the punch is flat, the size of the punching hole will be relatively small.

Inspection method of automobile stamping parts

1. Touch inspection

Wipe the surface of the outer cover clean with a clean gauze. The inspector needs to wear touch gloves and touch the surface of the stamping part along the longitudinal direction of the stamping part. This inspection method depends on the experience of the inspector. If necessary, the detected suspicious area can be polished with a whetstone and verified, but this method can be regarded as an effective rapid inspection method.

2. Oiling inspection

Wipe the surface of the outer cover clean with a clean gauze. Then use a clean brush to apply oil evenly to the entire outer surface of the stamping in the same direction. Put the oiled stamping parts under strong light for inspection. It is recommended to erect the stamping parts on the body position. With this method, tiny pits, slumps, and ripples on stamping parts can be easily found.

3. Grinding of flexible gauze

Wipe the surface of the outer cover clean with a clean gauze. Use a flexible sand mesh to close to the surface of the stamping part and grind it to the entire surface in the longitudinal direction, and any pitting and indentation will be easily found.

4. Whetstone grinding

  • (1) First wipe the surface of the outer cover with a clean gauze, and then use a whetstone (20×20×100mm or larger) for polishing, and use a relatively small whetstone for places with arcs and hard-to-reach places (Example: 8×100mm semi-circular whetstone)
  • (2) The choice of whetstone particle size depends on the surface condition (such as roughness, galvanizing, etc.). Fine-grained Whetstone is recommended. The direction of whetstone grinding is basically carried out in the longitudinal direction, and it fits well with the surface of the stamping parts, and some special places can also supplement the horizontal grinding.

5. Visual inspection

Visual inspection is mainly used to find abnormal appearance and macroscopic defects of stamping parts

6. Inspection tool

Put the stamping parts into the inspection tool, and test the Nanpi stamping parts according to the operation requirements of the inspection tool manual.

Automotive Sheet Metal Fabrication

Pintejin Sheet Metal shop offers a cost-effective solution for a wide range of industries with our custom metal stamping and custom sheet metal fabrication capabilities. Our stampnig operations include a variety of sheet-metal forming manufacturing processes, such as punching, blanking, embossing, bending, flanging, and coining. Our professional, experienced and well-trained engineers can execute the complex metal stamping operations with precision and accuracy.

No matter what your metal fabrication needs are, Pintejin can offer the right solution: from single sheet metal part or sub-assembly of stamped metal parts to turnkey solutions for mechanical and electrical assemblies. We have the technology, equipment and the experience to fabricate customised metal products from aluminium sheet metal fabrication, steel, zinc plated steel, stainless steel sheet metal fabrication, brass and copper. Designs that require CNC machining of surfaces or components can be accommodated. We can supply polished, galvanized, zinc coated or powder coated finishes for any sheet metal work or stamped metal components. Coupled with our accurate and reliable metal fabricating equipment, we guarantee precision and repeatability in custom sheet metal work. You’ll be taking advantage of the best sheet metal fabrication china can produce.


With Pintejin automated and highly streamlined sheet metal fabrication service, you can expect a sheet metal fabrication quote within 12 hours and lead times as quickly as three days.Our rapid prototyping offering also includes a solid and reliable manufacturing capability (led by our expert team with 15+ years of experience) and technical and quality assurance, including SGS and RoHS material certifications, in-process quality reports, and First Article Inspection.



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