DFM - Design for Manufacturability - Sheet Metal
General
1. Reduce total number of parts in weldments or assemblies without making part too heavy.
2. Standardize components to reduce costs and make more consistent.
3. Use common parts across product lines (same materials, hardware, feature, tooling).
4. Make parts multifunctional.
5. Design parts for easy fabrication. Think of material weight and ergonomics.
6. Avoid tight tolerances.
7. Avoid/minimize secondary operations where able.
8. Standardize everything possible; tooling, materials, features, processes, plating/painting, packaging.
9. Use tab and slot (self fixturing) wherever possible.
10. Allow access for tooling; tapping, hardware, forming, riveting, welding, masking.
11. Keep in mind that run qty will change DFM guidelines. Automation generally has a a longer set-up time but much faster processing methods.
12. Seek out machine operator input on potential design improvements. Be able to measure and analyze.
13. Pre-protype meetings will almost always find potential issues/design improvements.
Punching
1. Holes should be at least one material thickness in diameter or from the part edge.
2. Can there be burrs? Indicate if so and what side they should be on.
3. Design holes and reliefs around standard tool sizes. Minimize new tool loading.
4. Standardize hole sizes and tooling cutouts common where able to reduce tooling changes
5. Consider reducing odd shapes to minimize material waste from sheet nesting.
6. Design parts from same material thickness to reduce material change over setup and increase nesting flexibility.
7. Make parts common to different assemblies where applicable. Standardize.
8. Allow for clearance between embosses and extrusions.
Laser Cutting
1. Holes should be at least one material thickness in diameter or from the part edge.
2. Consider reducing odd shapes to minimize material waste from sheet nesting.
3. Design parts from same material thickness to reduce material change over setup and increase nesting flexibility.
4. Include small radii on corners to reduce corner burnouts
5. Make parts common to different assemblies where applicable. Standardize.
Tapping
1. Keep tapped holes standardized to eliminate error and reduce setup.
2. Callout if light tapped burr acceptable or not
3. Use tapped holes where clearance for pem hardware is minimal.
4. Parts that are plated should have allowance for pitch diameters change by calling for preplating tap.
5. Thread forming tap over thread cutting tap.
6. Thru hole tapping over blind hole tapping
Pem Hardware
1. Ensure there is adequate clearance for installation after forming.
2. Keep hardware standard to eliminate risk of error and help in reducing setup cost.
3. Use PEMs instead of threaded inserts.
Graining
1. Indicate where burrs are and are not acceptable.
2. If graining is required say if it is for cosmetics or deburr only. EX: “Grain to deburr burr side only”
3. Parts under 6″ long must be fixtured in order to grain.
Forming
1. Make parts symmetrical to eliminate the risk of forming errors and help in reducing set-up cost.
2. Allow for bend reliefs where required for bending.
3. Make flanges the same height where possible.
4. Flanges lengths should be 6x material thickness at minimum.
5. Keep bends at 90 deg where possible to avoid added set-up costs.
6. Allow for 1 to 2 degrees of angle tolerance.
7. Make flanges wide enough so that parts can be located against backstop easily at correct location.
8. Use common bend radii across all bends of part(s).
9. Keep holes away from bend lines to eliminate distortion.
10. Consider tooling clearance when design bends close to each other.
11. Avoid large sheet metal parts with small formed flanges.
13. Avoid parts so large that (2) operators are required.
14. Avoid deep channels or boxes.
Welding
1. Use slot and tab features in subparts where possible for self-fixturing.
2. Give easy access and allow clearance welding tip.
3. Call for welding only where needed.
4. Call for grinding only where needed.
5. Design weldment for easy robotic fixturing and access if parts will be ran in large volumes.
6. Weld in area’s that are thinner, requiring less heat.
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