Sheet Metal Design for Manufacturability (DFM) Checklist
Most sheet metal problems are cheaper to fix on the drawing than on the shop floor. This checklist walks through the points that cause rework, quote changes and delayed deliveries so you can review a part before release.
0 of 31 items complete
8 critical items still open - these are the highest-risk gaps.
Material and drawing basics
Cutting features
Bending
Hardware and assembly
Quality and cost
Mark each item as you review the drawing. Resolve every critical item before releasing to quote or production. The distance rules are common shop guidelines, so confirm limits with your own fabrication process.
Track DFM findings by revision
Optional: a short chat on linking review findings to part revisions in your ERP.
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How to use the checklist
Open the drawing and model side by side, then check each group in order: material and drawing basics, cutting features, bending, hardware and assembly, and quality and cost. Items marked critical usually stop a part from being made or quoted correctly. Anything unchecked should become a question to the designer, with the answer recorded against the part revision in your PLM or ERP.
- Review at quote time and again at first article.
- Record resolved items against the revision.
- Use the export to attach the review to the job.
Rules of thumb behind the checklist
Hole diameter of at least one times material thickness avoids punch breakage and poor edge quality. A hole edge two times thickness from the part edge, and a hole placed at least two to three times thickness plus the bend radius from a bend line, avoid distortion. Reliefs allow the material to deform without tearing at the corner of a bend. These are guidelines shops use, and your equipment and tooling may allow more or less.
Tolerances in formed parts
Sheet metal accumulates tolerance across every bend, including thickness variation, springback, angle and flat pattern accuracy. Dimensions that cross two or more bends cannot be held as tightly as a dimension on a single flat feature. Call out critical dimensions on the formed part, define the datum scheme, and avoid tolerances tighter than the process delivers unless a secondary operation is planned and priced.
Common mistakes
Frequent issues are bend lines running through holes, flanges shorter than the die allows, missing relief at bend ends, radii that do not match any available tooling, and gauge numbers without a material. Hardware placed too close to a bend or an edge also fails often because the clinch needs undeformed material.
Frequently Asked Questions
Why must hole diameter be at least the material thickness?
Smaller holes load the punch beyond its strength, causing breakage, burrs and poor hole quality. Laser cutting handles smaller holes but heat and dross can reduce quality, so the guideline is still a useful default.
What is a bend relief?
A small notch or cut at the end of a bend line where the bend meets a flat edge. It prevents tearing and bulging at the corner and lets the flange form cleanly.
When should DFM review happen?
At quoting, before releasing a new revision to the shop, and when the first article is inspected. Catching a flange problem at quote time costs a phone call, while catching it at the brake costs a scrapped part.
Do these distances apply to every shop?
They are common starting guidelines. Actual limits depend on tooling, equipment, material and tolerance. Ask your fabricator for their own design guide and align your checklist to it.
If your drawing review notes never make it into the item or routing record, we can help connect them to your ERP.
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