What are the sheet metal parts defects in manufacturing?

Sheet metal parts are the parts that are produced by stamping operation by sheet metals. During stamping operation, there are many sheet metal parts defects such as burrs, dents, scratches, wrinkles, fractures, cracks & wrong dimensions etc. So below are the operation-wise defects, their causes & remedies.

These are the defects that increase internal rejections. An increase in internal rejection increases the cost of poor quality. So root cause and action below will help in rejection analysis during red bin analysis.

Sheet metal defects and remedies:

Punching, Blanking and trimming operations:

Defect: Burr on blank or punching parts

Causes	Remedies
Cutting edge blunt	Do grinding of punch & die face
More clearance between the die & punch	Maintain adequate clearance
The punch position shifted as per die	Maintain uniform clearance between die & punch
The top of the tool shifted from its bottom	Replace guide post or pillar bush
Die part shifted	Set the die part in the socket & use the dowel pin

Draw operation:

Defect: Wrinkle

Causes	Remedies
The wrong lubricant used	Change the lubricant
Blank holding pressure low	Increase the blank-holding pressure

Defect: Fractured Rim & bottom in the draw

Cause	Remedy
Blank holding pressure too high	Reduce the pressure

Punching Operation:

Defect: Dent on cutting edge

Cause	Remedy
More play of posts in bushings	Replace bushings
Cutting element shifted	Maintain uniform clearance in die & punch
Press slide not parallel with the bed surface	Repair the press
Tool shoes not parallel ( Spacer below tool)	Grind the shoes

Blanking operation:

Defects: Press jerks when blanking:

Cause	Remedy
Cutting force too large No taper on die cutting-edge	Grind die face & make taper on die cutting edge

Defect: Stripper fails to remove stocks:

Cause	Remedy
Spring too weak	Replace spring

Bending & Forming operation:

Defect: Wrong dimension:

Cause	Remedy
Locator worn out	Repair or replace the locator
Locator shifted	Rectify the locator position
The Workpiece shifted as the operation starts	Make provision for blank holding
Spring back	Change the tool working part to allow the spring back

Sheet metal defects and remedies pdf: