Guides / Process
Common Metal Stamping Defects and What Causes Them
October 11, 2026
Most stamped part defects trace back to one of a small number of causes, and knowing which one you are looking at tells you whether the fix belongs on the print, in the die, or in the material specification. This is what the common ones look like and what usually causes them.
Burr beyond the callout
Burr is the small ridge of material left on the edge where a punch shears through it. Some burr is unavoidable on every blanked or pierced edge, which is why prints should state a maximum height and which face it is allowed on.
Usual causes: a dull or worn punch, excessive clearance between punch and die, or a burr callout that was never specified so the shop had nothing to aim for.
What to check: ask what burr height the die was designed to hold, and confirm your print states a number, not just “deburr as needed.”
Wrinkling on formed or drawn features
Wrinkles show up on the flange or wall of a formed or drawn part where material has nowhere to go and buckles instead of stretching smoothly.
Usual causes: insufficient blank holder pressure, a draw ratio too aggressive for the material, or a material temper that is too soft to hold its shape under the forming load.
What to check: if wrinkling appears during a deep draw program, ask whether it is a die pressure adjustment or a material temper change that fixes it. Both are legitimate fixes, but the die adjustment is usually the first thing to try since it costs nothing.
Splitting or cracking at bends and draws
A split is the material tearing rather than forming, usually right at the tightest radius of a bend or the corner of a draw.
Usual causes: a bend radius specified tighter than the material and thickness can support, grain direction running the wrong way relative to the bend line, or a material temper harder than the forming operation needs.
What to check: confirm your bend radius callouts against standard minimums for your material and thickness before tooling starts, not after a splitting part shows up in try out. This is one of the print issues covered in metal stamping tolerances, since a tolerance that is achievable on paper can still be a forming problem in practice.
Warp or twist after forming
A part that measures flat in the die but twists or bows after it is removed from the press has released residual stress unevenly.
Usual causes: asymmetric part geometry, uneven material thickness across the blank, or springback that was not accounted for in die design.
What to check: ask whether the shop plans a restrike or coining station to correct known springback, especially on parts with features on only one side. A part that is symmetric in its features usually warps less than one that is not, which is worth knowing at the design stage if you have flexibility on the print.
Dimensional drift over a production run
A part that measured in spec at first article and then drifts out of tolerance over weeks or months of running is a die wear problem, not a one time defect.
Usual causes: normal wear on punches and guide components, loosening of die set components over many cycles, or a die that was never rated for the hit count it is now running.
What to check: this is exactly what a stated die life in hits and a maintenance schedule are for. See what stamping tooling costs and who owns the die for what should be in writing about maintenance before you approve tooling.
Surface marks, scratches and galling
Visible marks on the part surface, sometimes with material transfer or galling where the die contacts the part.
Usual causes: insufficient lubrication, a worn die surface, or a coating on the tool steel that has broken down.
What to check: if your part has an appearance requirement, say so on the print explicitly, since a shop quoting a non-cosmetic part may not budget for the lubrication control or die finish that a visible part needs.
Is it the print, the die or the material
A quick way to sort a defect once you see it:
| Symptom | Most likely source |
|---|---|
| Same defect on every part from day one | Die design or print tolerance |
| Defect appears gradually over a production run | Die wear |
| Defect appears with a new coil or lot | Material |
| Defect appears only on certain features | Print geometry, radius or forming direction |
Where we fit
We match your RFQ with stamping shops based on the die type, tolerance and material your part actually needs, so defects tied to a poor process fit get caught before tooling starts, not after. Send your print through our RFQ form and we reply within 24 business hours. For what to specify up front to avoid these issues, start with the RFQ checklist.
Frequently asked questions
Is a burr on a stamped part always a defect?
No. Every blanked or pierced edge has some burr, and prints should state a maximum height and which side it can be on. A burr within that callout is normal, not a defect. A burr exceeding the callout, or on the wrong side of the part, is what counts as a rejection.
Why did my part pass first article inspection but start failing weeks into production?
This is usually die wear rather than a design problem. Punches dull, springs weaken and guide components loosen with hits, which shows up first as burr growth or dimensional drift before it becomes visible scrap. It is why die maintenance schedules exist, and why asking about them before you order matters.
Can a defect be fixed by changing the material instead of the die?
Sometimes. Splitting and wrinkling are often more about material grade, temper and grain direction than pure die design. A shop that suggests a material change instead of only reworking the die may be pointing at the real cause rather than treating the symptom.
Need a quote for this part?
Send the print. We match you with up to 3 stamping shops and reply within 24 business hours.
Send my RFQ