DFM & Design for Manufacturability Guide

Wall Thickness

Keep wall thickness as uniform as possible — typically 0.5 mm to 5 mm for most silicone parts. Avoid abrupt changes and thick sections, which cause sink marks, uneven curing and longer cycle times.

Draft Angles

Add a draft angle of 1° to 3° on vertical faces to make demolding easier and reduce tearing. Higher draft is recommended for deep cavities and textured surfaces.

Undercuts & Parting Lines

Minimize undercuts where possible — they require side actions or hand demolding that add tooling cost. Plan the parting line early so it lands in a low-visibility area.

Tolerances

Silicone is flexible, so use generous tolerances where you can. Standard linear tolerance is typically ±0.1 mm to ±0.3 mm depending on part size, with tighter results achievable on LSR injection. Mold cavities are machined to ±0.01 mm so the tool itself never limits your precision.

These four layers are easy to confuse — the number changes meaning depending on whether it describes the mold, the instrument, the general part or a specific critical feature. We always state which layer a figure refers to. See testing & measuring equipment for instrument accuracy and mold making for cavity tolerance.

Fillets & Radii

Add fillets to sharp internal corners to reduce stress concentration and tearing. Avoid sharp edges that can catch during demolding or in use.

Shrinkage & Overmolding

Account for material shrinkage (typically 2%–4%) in the mold design. For overmolded or multi-material parts, keep bonding surfaces clean and specify the substrate material clearly.