Common Defects in Deep Drawing and How to Prevent Them
Deep drawing defects usually have a clear cause: insufficient clearance, wrong blank size, poor lubrication, material properties or tool wear. Recognizing the defect is the first step; correcting the process is the second.
This article covers the most common defects and the practical countermeasures.
Common defects and causes
| Defect | Typical cause | Countermeasure |
|---|---|---|
| Wrinkling | Insufficient blank holder force, too much clearance | Increase blank holder force, adjust clearance |
| Tearing / cracking | Draw ratio too high, sharp radius, poor lubrication | Reduce draw ratio, increase radius, improve lubrication |
| Earing | Material anisotropy | Adjust blank shape, select material with lower anisotropy |
| Springback | Elastic recovery after forming | Over-form, adjust die, stress-relief |
| Orange peel | Large grain size, excessive deformation | Use finer grain material, reduce strain |
| Galling | Friction, poor lubrication, tool surface | Improve lubrication, polish tool, use coating |
| Thinning | Excessive stretch, tight clearance | Adjust blank, clearance and draw sequence |
Wrinkling
Wrinkling occurs when the flange is not held firmly enough. Increasing blank holder force and reducing clearance are common fixes. In some cases, a draw bead is added to control material flow.
Tearing and cracking
Tearing usually means the material is being stretched beyond its limit. Reduce the draw ratio, increase the punch or die radius, improve lubrication, or add an annealing step between draws.
Springback
Deep drawn parts can spring back after the punch is removed, especially at the bottom and flange. Over-forming and die compensation are common approaches. For critical dimensions, a sizing or restrike operation may be needed.
Galling
Galling is surface damage caused by friction between the tool and the workpiece. Better lubrication, polished tool surfaces and coatings can reduce it. Stainless steel is more prone to galling than mild steel.
FAQ
Can wrinkles be removed after drawing?
Sometimes by restriking or sizing, but prevention is usually cheaper. Fix the blank holder force and clearance first.
Why does stainless crack more than mild steel?
Stainless work-hardens quickly and has lower ductility in the worked condition. It often needs a larger radius, lower draw ratio or intermediate annealing.
How is wall thickness checked?
With a micrometer, ultrasonic thickness gauge or by sectioning a sample. The method depends on the part size and access.
Related: deep drawing services and quality control.
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