Injection Molding Materials Guide | Plastic Resin & Mold Steel Selection Reference | JBRplas

Mon, 01 Jan 0001 00:00:00 +0000

Part 1: Plastic Material Selection

Selecting the right plastic resin is the single most consequential material decision in any injection molding project. The resin determines part performance, tooling requirements, cycle time, and unit cost — and changing materials mid-program is expensive. This reference covers the resins JBRplas processes daily, organized to support engineering decisions.

Decision Framework

Work through these questions before opening a data sheet:

Mechanical — What loads, impacts, fatigue cycles, and creep conditions does the part face?
Thermal — Continuous and peak service temperature?
Chemical — Exposure to solvents, cleaners, fuels, body fluids, UV?
Regulatory — UL 94, FDA, USP Class VI, RoHS, REACH, EN71?
Cosmetic — Class A surface, optical clarity, colour accuracy, texture?
Production — Annual volume, target cycle time, tolerance requirements?
Cost — What is the resin cost envelope for the part?

Engineering Resins — Properties at a Glance

Resin	Density (g/cm³)	Tensile (MPa)	Flex Mod (GPa)	HDT (°C)	Impact (J/m)	Shrinkage (%)	Relative Cost
ABS	1.03–1.06	40–50	2.0–2.8	85–100	150–250	0.4–0.7	$$
PC	1.20	55–65	2.3–2.4	125–135	600–900	0.5–0.7	$$$
PC/ABS	1.12–1.16	50–60	2.3–2.8	105–120	350–550	0.5–0.7	$$$
PA6	1.13	70–80	2.5–3.0	65 (dry)	50–150	0.8–1.5	$$
PA66	1.14	75–90	2.8–3.3	90 (dry)	40–100	0.8–1.5	$$$
PA66-GF30	1.37	140–170	7.0–9.0	250	80–120	0.2–0.5	$$$
POM (Acetal)	1.41	60–70	2.5–3.0	110	50–100	1.8–2.2	$$$
PBT-GF30	1.53	100–120	5.0–7.0	200–210	50–80	0.2–0.5	$$$
PPO/PPE	1.06–1.10	50–65	2.3–2.5	120–140	150–250	0.5–0.7	$$$$
PMMA (Acrylic)	1.19	65–75	3.0–3.5	85–100	15–25	0.3–0.6	$$$
PEEK	1.30–1.50	90–170	3.5–11.0	250–315	40–80	1.0–1.4	$$$$$
TPE / TPU	0.90–1.25	5–40	0.01–0.50	60–120	No break	1.0–2.5	$$–$$$$

Commodity Resins

Resin	Density (g/cm³)	Tensile (MPa)	Flex Mod (GPa)	HDT (°C)	Shrinkage (%)	Relative Cost
PP (homopolymer)	0.90	25–40	1.0–1.7	100–115	1.0–2.5	$
PP (copolymer)	0.90	20–30	0.8–1.4	90–105	1.0–2.5	$
PP-GF20	1.04	60–80	3.5–4.5	140–155	0.3–0.7	$$
HDPE	0.95	20–30	0.8–1.4	65–80	1.5–3.0	$
LDPE	0.92	10–15	0.2–0.5	40–50	1.5–3.5	$
GPPS	1.04	40–50	3.0–3.5	70–85	0.4–0.7	$
HIPS	1.04	20–35	1.8–2.5	75–90	0.4–0.7	$
SAN	1.08	65–75	3.5–3.9	85–95	0.3–0.6	$$
PVC (rigid)	1.40	40–50	2.5–3.5	65–75	0.2–0.5	$
PVC (flexible)	1.25–1.35	10–20	—	50–65	1.0–3.5	$

Specialty Grade Quick Reference

Requirement	Available Grades
Flame retardant (UL 94 V-0)	ABS FR, PC FR, PC/ABS FR, PA66 FR, PP FR, PBT FR
Flame retardant (UL 94 V-1/V-2)	ABS V-1, PP V-2, PA6 V-2
Glass-filled (stiffness + dimensional stability)	PA6-GF15/30/50, PA66-GF15/30/50, PP-GF20/30, PBT-GF15/30, POM-GF20, PEEK-GF30
UV-stabilized (outdoor)	PP UV, ABS UV, PC UV, PA66 UV
Food-contact (FDA / EU 10/2011)	PP, PE, PC, ABS (food-grade), POM
Medical-grade (USP Class VI)	PP, PE, PC, ABS, PEEK, TPE
Biocompatible (ISO 10993)	PC (medical), PEEK, medical-grade TPE/TPU
Conductive / ESD-safe	Carbon-filled ABS, carbon-filled PC, carbon-fibre reinforced PA
Wear-resistant	POM, PA+PTFE, PEEK, PA66+MoS2
High-gloss / optical	PMMA, PC (optical grade), SAN, GPPS
Soft-touch / elastomeric	TPE (Shore 30A–70A), TPU (Shore 60A–90A), TPV

Material Recommendations by Industry

Industry	Primary Resins	Key Requirements
Automotive interior	PC/ABS, ABS, PA66-GF30, POM	Heat resistance, UV stability, low VOC, PPAP documentation
Automotive under-bonnet	PA66-GF30, PA6-GF15, PP-GF20, PBT-GF30	High-temp resistance, chemical resistance, validated Cpk
Medical device	PC (medical), ABS (medical), PP (medical), PEEK	USP Class VI, ISO 10993, ISO 13485 traceability, clean room molding
Health care consumer	ABS, PC, PP, TPE	Skin-contact rated, IP-rated, cosmetic Class A, colour consistency
Smart home / IoT	ABS FR, PC FR, PC/ABS FR	UL 94 V-0, cosmetic Class A, RoHS/REACH, ΔE < 1.5 colour
Consumer electronics	ABS, PC, PC/ABS	Impact resistance, cosmetic finish, snap-fit durability, thin-wall capability
Financial devices	PC/ABS FR, ABS FR (carbon-filled), PA66 FR	ESD-safe, tamper-evident, EMV slot precision, UL 94 V-0
Branded toys	ABS, PP, HDPE, HIPS, TPE	EN71, ASTM F963, CPSIA, phthalate-free, colour accuracy ΔE < 1.5
Industrial equipment	PA66-GF30, POM, PC, ABS	High stiffness, wear resistance, chemical resistance, long service life

Part 2: Mold Steel Selection

The mold steel determines tool life, part quality, cycle time, and maintenance cost. Selecting the right steel requires balancing the resin being molded, the production volume, and the cosmetic and dimensional requirements of the part.

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