1. Automotive stamping parts - appearance defects

The appearance defects of punch machines mainly include cracks, neck shrinkage, pits, corrosion, wrinkling, burrs, pulls, indentations, scratches, overlaps, etc. Below are some common appearance defects of automotive stamping parts.

(1) Neck contraction and cracking

The direct cause of shrinkage necks and cracks is that the stress during the stretching process exceeds the material itself, resulting in the formation of shrinkage necks or cracks. Shrinkage necks and cracks usually occur in processes such as pulling, turning corners, and turning holes, which directly affect the lifespan and structural strength of steam connected components. Therefore, if severe neck shrinkage or cracks occur, the components will be disposed of as scrap, and manufacturing costs will significantly increase. In addition, if neck shrinkage or cracks occur, maintenance on the shutdown line usually takes a long time, which further increases costs while also reducing productivity.

(2) Fold and overlap

Wrinkling and overlap are caused by the significant difference between the thickness direction and the plane direction of the sheet, resulting in instability in the thickness direction. When the stress in the plane direction reaches a certain level, the thickness direction becomes unstable, leading to wrinkling. If the wrinkling phenomenon further intensifies, overlapping phenomenon will occur.

(3) Burr

It is generally inevitable to have varying degrees of burrs during the cutting process of automotive stamping parts, but by improving the stamping process and stamping conditions, burrs can be reduced. The occurrence not only makes the subsequent deformation process prone to cracking due to stress concentration, but also brings difficulties to the layering of subsequent process blanks. Big hairs are easily scratched by the handle, and welding is easy to drill open or poor. Therefore, the burrs that have already occurred are generally eliminated through rework such as documents, rolling, electrolysis, etc.

2. Functional and dimensional defects in automotive stamping parts

(1) The reason for the lack of holes, deformation of holes, and insufficient drilling of holes is due to stamping leakage or damage, which needs to be replaced. If the gap between the new stamping and repositioning punch is too large or too large, hole deformation will occur, and the punch gap must be readjusted before continuing production. When the mold stroke is insufficient or the position is not suitable, defects such as not punching holes usually occur. There are two main measures. One is to adjust the slider to the appropriate height during debugging, and the other is for the operator to strictly follow the operating program to operate the equipment.

(2) Size mismatch

In the manufacturing process of automotive stamping parts, there are often differences in the dimensions of parts and the dimensions required for design and development due to improper materials, mold equipment, processes, or employee operations. This type of error is acceptable within the range, and different companies have different criteria for determining size defects based on vehicle models and technological processes.

3. Defects in the return of automotive stamping parts

(1) Trim marks

When repairing and stamping individual parts, if the sandpaper is too thick or the grinding force is too strong, there may be grooves and scratches on the surface of the parts. After the punching machine is painted, the grooves and scratches on the surface will be illuminated. Expose the paint on the melon surface.

(2) The wooden board is thin

During the reprocessing process of the punch, due to long grinding time or high grinding force, it is often excessively polished, resulting in a plate thickness lower than the standard value. The thinning of the plate not only reduces the strength of the punch, but also affects its service life.