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Injection Molding Specifications and Guidelines

Wall thickness, draft angles, ribs, gates, shrinkage, SRI finishes, and cost optimization.

2°–3°

Rec. Draft

2-3mm

Nominal Wall

±0.030"

Standard Tol

10 Days

T1 Samples

Configuration panel: Process set to Injection Molding with an 'Apply configuration' button on a teal background and a 3D orange injection mold in the background.

Wall Thickness & Uniformity ▾

Material	Range
ABS	1.2–3.5mm
Polycarbonate	1.0–4.0mm
Polypropylene	0.8–3.8mm
Nylon	0.8–3.0mm
PEEK	0.5–3.0mm

Maintain uniform ±10%. Thick = sink marks.
Transitions 3:1 ratio max. Core out thick areas.

Draft Angles ▾

Material	Draft
Rigid (ABS, PC)	0.5°–2°
Semi-rigid (PP, PE)	0.5°–1.5°
Flexible (TPE)	Can be 0°
Textured	0.5 - 1.5

Ribs, Bosses & Gussets ▾

Rib: 50–65% wall, height:thick 3:1 max
Boss OD: 2× internal Ø. Wall 60% nominal.
Gussets: 50–65% wall. Radius at intersections.
Fillet at rib base ≥0.25× wall

Gates & Runners ▾

Edge: Common, visible mark. Tunnel: Auto-degate.
Pin Point: Small mark, hot runner. Fan: Wide, low shear.
Tab: Gate on tab. Hot Tip: Minimal vestige.
Place at thickest section. Avoid cosmetic surfaces.

Shrinkage by Material ▾

Material	Shrinkage
ABS	0.4–0.7%
PC	0.5–0.7%
PP	1.0–2.5%
Nylon	1.0–1.5%
Nylon GF	0.2–1.0%
Acetal	1.5–3.5%
PEEK	1.2–1.5%

SPI Surface Finish Standards ▾

Grade	Description	Ra
A-1 to A-3	Mirror polish	0.012–0.05μm
B-1 to B-3	Semi-gloss	0.05–0.1μm
C-1 to C-3	Matte	0.35–0.7μm
D-1 to D-3	Textured	0.8–3.2μm

Cost Optimization ▾

Simplify: fewer features = simpler mold
Use adequate draft. Avoid undercuts.
AL molds for proto (<10K shots)
Family molds for related assemblies

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T1 samples in 10 days with DFM support.

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