The 15-point design checklist our engineers use to review every thermoforming project. Draft angles, radii, draw ratios, wall thickness, undercuts — everything you need to design parts that form correctly the first time.
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Checklist Preview
Here's a preview of the 5 key categories covered. The full PDF includes detailed specifications, visual diagrams, and Formpack-specific guidelines.
Minimum 3° draft on all vertical walls (5° preferred)
Increase to 5–7° for textured surfaces
Female (cavity) molds require less draft than male (plug) molds
Deep draws (>150mm) may need 7°+ draft
Minimum inside radius = 1× material thickness
Preferred inside radius = 2× material thickness
No sharp corners — they cause thinning and stress concentration
Transition radii between surfaces ≥ 3mm
Maximum draw ratio (depth:width) = 1:1 for simple shapes
Deeper draws require plug assist or pressure forming
Uniform depth preferred — avoid extreme depth variations
Consider splitting deep parts into two bonded halves
Starting sheet thickness: 1.5–8mm typical
Expect 30–50% thinning in deep-draw areas
Design critical areas at thickest point of draw
Specify minimum wall thickness on drawings
Avoid undercuts where possible — they require side-pulls or split molds
Snap-fit features can be CNC-trimmed post-forming
Mounting bosses: bond or rivet post-forming (not formed-in)
Holes and slots: CNC-routed after forming for precision
Complete Contents
Draft angles for all vertical surfaces
Inside and outside radii specifications
Draw ratio analysis (depth vs. width)
Wall thickness distribution map
Undercut identification and solutions
Material selection guide (ABS, PC, Kydex, PETG, HDPE, PP)
Tolerance expectations by feature type
Surface finish and texture specifications
Trimming and secondary operations planning
Assembly and fastening considerations
Tooling type recommendation (aluminum vs. composite)
Cost optimization checklist
Common mistakes and how to avoid them
Drawing annotation standards for thermoforming
Formpack-specific capabilities and limits
Related Resources
Use the DFM checklist to optimize your design, then send us your drawings. We'll provide a free DFM review and quote — typically within 48 hours.