Injection Molding Materials Guide: Properties, Selection Criteria, and Processing Data

Injection molding material selection is the process of matching a polymer’s mechanical, thermal, chemical, and processing properties to a specific part geometry, production volume, and regulatory requirement. The stakes are quantifiable: PA66 GF30 delivers 185 MPa tensile strength at 23 °C per ISO 527, while unfilled PP reaches 35 MPa under the same test condition, a 5.3x difference that wall thickness changes alone cannot compensate. Material choice also determines mold steel grade, gate geometry, cycle time, and per-part cost before tooling is cut. A datasheet value such as “MFR 12 g/10 min” is incomplete without its test temperature and load per ISO 1133-1:2022. A UL 94 V-0 rating at 1.6 mm does not guarantee the same classification at 0.8 mm under the Seventh Edition (2023, revised January 2024). This guide covers mechanical and thermal properties, processing parameters for twelve common injection molding resins, flammability classifications per UL 94, and a five-filter decision framework. Every data point includes its test standard and condition, so you can transfer values directly onto a specification sheet.

1. Why Material Selection Locks In 80% of Your Unit Cost

Material choice fixes the largest share of injection molded part cost before tooling begins. Resin price, mold steel grade, cycle time, scrap rate, and secondary operations all trace back to the polymer on your specification sheet. Changing resin after tool steel is cut forces gate resizing, runner rework, and new shrinkage compensation, adding $2,000 to $15,000 per cavity depending on mold complexity.

1.1 The Real Cost of Choosing Wrong

Selecting ABS for a bracket exposed to continuous 110 °C fails within weeks. ABS heat deflection temperature sits at 98 °C (1.8 MPa, ISO 75), so the part softens under load and warps. Replacing ABS with PA66 GF30 (HDT 250 °C at 1.8 MPa) after tool steel is hardened means re-cutting the gate from 1.2 mm to 0.8 mm to match the narrower processing window, re-shimming the cavity for 0.4% higher mold shrinkage, and re-validating the first article. Lead time cost: four to six weeks. Financial cost on a single-cavity tool: $5,000 to $8,000 in rework alone, before scrap from the failed ABS run.

Engineering note: Shrinkage mismatch between the original and replacement resin is the root cause of most mid-program tool rework. PP shrinks 1.0 to 2.5%, PC shrinks 0.5 to 0.7%. Swapping one for the other in the same cavity without dimensional compensation produces out-of-spec parts on every shot.

1.2 What a Correct Material Decision Prevents

A material locked in before mold design starts eliminates three failure modes that account for over 60% of first-run rejects at EPOC CRAFTER’s molding facility: sink marks from resin-wall thickness mismatch, warpage from uneven crystallization in semi-crystalline polymers, and short shots from insufficient melt flow at the selected gate diameter. Each of these traces directly to a property on the datasheet: recommended wall thickness range, mold shrinkage percentage, and melt flow rate at the specified temperature and load.

The five-filter framework in the next section gives you a repeatable sequence for matching part requirements to resin properties, so the decision is locked before your rapid injection molding program quotes tooling.

2. The Five-Filter Material Decision Framework

The Five-Filter framework sequences material selection into five pass/fail stages, each eliminating resins that cannot meet one non-negotiable requirement. Running filters in this fixed order prevents the most common selection error: choosing a resin for its mechanical strength and discovering at T0 trial that it fails a flammability or regulatory gate.

2.1 Filter 1: Mechanical Performance

Tensile strength, flexural modulus, and impact resistance define whether a resin survives the load case. Start with the dominant stress mode on your part.

A structural clip loaded in cantilever bending needs flexural modulus above 2,000 MPa. Unfilled PP (flexural modulus 1,300 MPa per ISO 178) fails this filter. PA66 GF30 (flexural modulus 9,500 MPa) passes with margin. For impact-loaded housings, notched Izod values matter more than tensile strength: PC delivers 650 J/m at 23 °C per ISO 180, while general-purpose PS breaks at 21 J/m under the same test, a 30x gap that no wall thickness increase closes without adding sink risk.

Engineering note: Datasheet values are measured on injection molded ISO 527 test bars, not on your part geometry. Weld lines reduce local tensile strength by 10 to 40% depending on resin and gate location. Request weld-line tensile data from your resin supplier before finalizing selection for multi-gated parts.

2.2 Filter 2: Thermal Limits

Heat deflection temperature under load sets the upper boundary for continuous service. HDT at 1.8 MPa (ISO 75) is the standard comparison point across injection molding polymers.

ABS (HDT 98 °C at 1.8 MPa) works for consumer electronics enclosures that stay below 70 °C. Automotive under-hood brackets require PA66 GF30 (HDT 250 °C) or PPS GF40 (HDT 260 °C). Selecting a resin with HDT less than 20 °C above your maximum service temperature leaves no safety margin for solar loading, adjacent heat sources, or process variation during assembly.

Short-term temperature excursions follow a separate metric. Vicat softening point (ISO 306) runs 5 to 15 °C above HDT for amorphous polymers and converges with crystalline melting point for semi-crystalline resins. A resin that passes the HDT filter can still fail under a 30-second reflow soldering exposure if the Vicat value is too low.

2.3 Filter 3: Chemical and Environmental Exposure

Chemical resistance eliminates resins that degrade under the fluids, UV radiation, or moisture levels present in the use environment.

PC stress-cracks on contact with isopropyl alcohol concentrations above 50%. ABS yellows and embrittles after 2,000 hours of unprotected UV exposure per ASTM G154 Cycle 1. PA6 absorbs 2.5 to 3.0% moisture by weight at equilibrium (ISO 62), causing a 15 to 20% drop in tensile strength and a 0.2 to 0.4% dimensional change. POM resists most organic solvents, fuels, and lubricants but degrades in strong acids below pH 4. Each of these boundary conditions is a hard filter: if the part contacts the incompatible agent, the resin is eliminated no matter how well it scores on Filters 1 and 2.

2.4 Filter 4: Processing Compatibility

Melt flow rate, mold shrinkage, and drying requirements determine whether a resin runs reliably in your tool at the target cycle time.

MFR comparison across plastic injection molding materials requires identical test conditions. A “12 g/10 min” MFR for ABS tested at 220 °C/10.0 kg and a “12 g/10 min” MFR for PP tested at 230 °C/2.16 kg represent entirely different flow behaviors per ISO 1133-1:2022. Annex A of that standard lists 15 test temperatures and 7 load levels; comparing two resins tested at different combinations produces invalid conclusions about fill behavior.

Mold shrinkage separates amorphous and semi-crystalline families. Amorphous resins (ABS 0.4 to 0.7%, PC 0.5 to 0.7%) shrink less and more uniformly. Semi-crystalline resins (PP 1.0 to 2.5%, PA66 1.2 to 1.8%) shrink more and exhibit directional variation, especially in glass-filled grades where flow-direction shrinkage differs from cross-flow shrinkage by 0.3 to 0.8%.

According to Dewey Wu, General Manager and senior mechanical engineer at EPOC CRAFTER: “We reject roughly 1 in 5 first-submission material requests because the customer’s chosen resin has a shrinkage range wider than the part’s critical tolerance band. A part holding ±0.10 mm on a 50 mm dimension cannot use an unfilled PP with 1.0 to 2.5% shrinkage spread without compensation features in the tool design.”

2.5 Filter 5: Regulatory and Flammability Compliance

UL 94, FDA 21 CFR, and ISO 10993 are pass/fail gates, not sliding scales.

UL 94 V-0 at 1.6 mm means afterflame time per specimen stays below 10 seconds and total afterflame for five specimens stays below 50 seconds, with no flaming drips igniting cotton, per UL 94 Seventh Edition (2023, revised January 2024). V-0 at 1.6 mm does not automatically extend to V-0 at 0.8 mm. Minimum and maximum thicknesses covering the claimed range must be tested separately (UL 94 §8.3.2). For food-contact applications, FDA 21 CFR 177.1500 covers PA resins; FDA 21 CFR 177.1580 covers PC. Each regulation specifies extraction testing conditions the resin grade must pass, not just the base polymer family.

Engineering note: UL 94 classification is a preliminary indication of flammability acceptability (§1.1). The standard states that results shall not be assumed to correlate with end-use performance (§1.4). Color, density, and molding-induced anisotropy can all shift the classification at a given thickness (§4.3). Specify the exact resin grade, color, and minimum wall thickness when requesting a UL rating from your supplier.

Five-Filter Summary

Filter	Core Question	Key Metric(s)	Fail Consequence
1. Mechanical	Does the resin survive the load case?	Tensile strength (ISO 527), flexural modulus (ISO 178), notched Izod (ISO 180)	Part deforms, cracks, or fractures in service
2. Thermal	Does the resin hold shape at service temperature?	HDT at 1.8 MPa (ISO 75), Vicat (ISO 306)	Part softens, warps, or loses dimensional tolerance under heat
3. Chemical/Environmental	Does the resin resist fluids, UV, and moisture in the use environment?	Chemical compatibility data, UV hours (ASTM G154), moisture absorption % (ISO 62)	Stress cracking, embrittlement, swelling, or discoloration
4. Processing	Does the resin fill the mold and hold tolerance at target cycle time?	MFR at stated conditions (ISO 1133-1), mold shrinkage %, drying temp/time	Short shots, warpage, dimensional scatter, extended cycle time
5. Regulatory	Does the resin grade pass all required certifications?	UL 94 at min thickness, FDA CFR, ISO 10993, REACH, RoHS	Product cannot ship; compliance failure discovered at or after T0 trial

3. Injection Molding Materials Compared: Properties and Processing Data

Twelve resins cover over 90% of injection molded part applications across consumer, industrial, automotive, and medical sectors. The comparison table below presents the properties you need on a specification sheet to run each resin through the Five-Filter framework. All mechanical values are at 23 °C dry-as-molded (DAM) unless noted. HDT is at 1.8 MPa per ISO 75. MFR conditions follow the resin manufacturer’s stated temperature/load pair, not a single universal test condition. This is the most complete injection molding plastics comparison you will find with processing data included alongside mechanical properties.

Properties Comparison Table (12 Resins)

Resin	Tensile MPa (ISO 527)	HDT °C 1.8 MPa (ISO 75)	MFR g/10 min (Condition)	Shrinkage %	UL 94 (grade, thickness)	Wall mm
PP Homopolymer	33 to 38	56 to 65	10 to 25 (230 °C/2.16 kg)	1.0 to 2.5	HB at 1.6 mm	0.8 to 3.8
HDPE	26 to 33	50 to 80	5 to 30 (190 °C/2.16 kg)	1.5 to 3.0	HB at 1.6 mm	0.8 to 3.0
HIPS	23 to 35	80 to 95	3 to 12 (200 °C/5.0 kg)	0.4 to 0.7	HB at 1.6 mm	1.0 to 3.5
ABS	40 to 50	95 to 100	5 to 25 (220 °C/10.0 kg)	0.4 to 0.7	HB; V-0 grades avail.	1.1 to 3.5
PA6	70 to 85	60 to 70	15 to 60 (235 °C/2.16 kg)	0.8 to 1.5	V-2 at 0.8 mm (FR)	0.8 to 3.0
PA66	80 to 85	75 to 90	10 to 80 (275 °C/5.0 kg)	1.0 to 1.8	V-2 at 0.8 mm (FR)	0.8 to 3.0
PA66 GF30	175 to 195	245 to 255	10 to 30 (275 °C/5.0 kg)	0.3 to 0.8	V-0 at 0.8 mm (FR)	0.8 to 3.2
PC	60 to 66	130 to 140	10 to 25 (300 °C/1.2 kg)	0.5 to 0.7	V-0 at 1.5 mm (FR)	1.0 to 3.8
POM	60 to 70	105 to 115	9 to 27 (190 °C/2.16 kg)	1.8 to 2.5	HB at 0.8 mm	0.8 to 3.0
PBT	50 to 55	55 to 65	10 to 35 (250 °C/2.16 kg)	1.5 to 2.0	HB; V-0 at 0.75 mm	0.8 to 3.0
PEEK	97 to 100	155 to 160	3 to 10 (400 °C/5.0 kg)	1.0 to 1.5	V-0 at 1.5 mm	1.0 to 3.2
PPS GF40	135 to 185	260 to 270	30 to 70 (316 °C/5.0 kg)	0.2 to 0.5	V-0 at 0.4 mm	0.5 to 3.2

Sources: published datasheets from SABIC, DuPont, BASF, Celanese, Victrex, and Solvay. Ranges reflect multiple commercial grades within each family. Verify specific grade values with your resin supplier’s current datasheet.

3.1 Commodity Resins: PP, HDPE, HIPS, ABS

PP costs $1.20 to $2.00/kg and fills fast, but its 1.0 to 2.5% shrinkage range makes tight-tolerance molding difficult without compensation features. PP’s fatigue resistance supports living hinges that flex over one million cycles without cracking. HDPE adds toughness (notched Izod up to 200 J/m) and chemical resistance to household cleaners, but its low flexural modulus (800 to 1,400 MPa) eliminates it from structural applications.

ABS sits at the commodity/engineering boundary. With 0.4 to 0.7% shrinkage, ABS holds tighter dimensions than PP and accepts textures, painting, and plating. ABS fails Filter 3 for outdoor applications: UV exposure above 2,000 hours per ASTM G154 causes surface chalking and a 30 to 40% drop in impact strength. ASA replaces ABS when UV resistance is a hard requirement, at roughly 1.3x the resin cost.

3.2 Engineering Resins: PA, PC, POM, PBT

PA66 GF30 carries the highest strength-to-cost ratio in the engineering tier. Its 185 MPa tensile strength and 250 °C HDT handle structural brackets, connectors, and under-hood automotive clips. The tradeoff is moisture sensitivity: PA66 absorbs 2.5% water by weight at equilibrium, causing a 15% tensile strength drop and 0.2 to 0.4% dimensional growth. Drying PA66 at 80 °C for 4 to 6 hours before molding is mandatory, not optional; skipping this step produces silver streaks (splay) on every part.

PC delivers the highest impact resistance in this tier (650 to 850 J/m notched Izod) with optical clarity above 88% light transmission. PC stress-cracks on contact with aromatic solvents and isopropyl alcohol above 50% concentration. For parts cleaned with IPA during assembly, switch to PC/ABS blends or PMMA.

POM provides low friction (dynamic coefficient 0.20 to 0.35 on steel), self-lubricating performance for gears, bearings, and conveyor components. POM cannot achieve any UL 94 V rating and burns with a formaldehyde-releasing decomposition, ruling it out for electronics housings requiring flammability compliance.

3.3 High-Performance Resins: PEEK, PPS

PEEK and PPS GF40 pass Filters 1 through 5 for aerospace, semiconductor, and medical implant applications that no commodity or engineering resin survives. PEEK resin costs $80 to $120/kg and requires mold temperatures of 170 to 200 °C, which means hardened tool steel (H13) and oil-heated mold temperature controllers. PPS GF40 offers similar HDT (260 °C) at roughly one-third the resin cost of PEEK, making it the preferred alternative when chemical resistance requirements allow it. PPS resists nearly all solvents below 200 °C but lacks PEEK’s fatigue life and FDA biocompatibility history for implantable devices.

For most hardware startups and consumer electronics programs, the materials and properties resource covers the commodity and engineering tiers where 95% of part programs land. High-performance resins enter the conversation when continuous service temperature exceeds 150 °C or when regulatory requirements (ISO 10993 for implants, FDA 21 CFR for food contact) narrow the field. Among all types of plastic for injection molding, fewer than 5% of programs require this tier.

4. Processing Parameters That Belong on Your Spec Sheet

Resin selection without processing parameters produces tooling quotes based on assumptions. Melt temperature, mold temperature, drying requirements, and injection pressure ranges belong on your material specification before the mold designer starts gate sizing.

Processing Parameters Table (12 Resins)

Resin	Melt Temp °C	Mold Temp °C	Drying °C / h	Pressure MPa	Cycle Indicator
PP	200 to 280	20 to 60	Not required	70 to 120	Short: fast crystallization
HDPE	200 to 280	10 to 60	Not required	70 to 105	Short: low viscosity
HIPS	180 to 260	20 to 60	70 to 80 / 2	70 to 120	Short: amorphous, fast fill
ABS	210 to 270	40 to 80	80 / 2 to 4	80 to 150	Medium: moderate viscosity
PA6	230 to 280	60 to 90	80 / 4 to 6	80 to 150	Medium: moisture-sensitive
PA66	260 to 300	60 to 100	80 / 4 to 6	80 to 150	Medium: higher melt temp
PA66 GF30	270 to 300	80 to 120	80 / 4 to 6	100 to 150	Medium to long: glass wear
PC	270 to 320	80 to 120	120 / 3 to 4	80 to 150	Medium: high mold temp
POM	190 to 230	60 to 100	Not required (sealed)	80 to 140	Short to medium
PBT	240 to 270	40 to 80	120 / 3 to 4	80 to 130	Medium: semi-crystalline
PEEK	360 to 400	170 to 200	150 / 3 to 4	100 to 170	Long: slow cooling
PPS GF40	300 to 340	130 to 170	150 / 3 to 4	80 to 130	Medium to long

Sources: SABIC, DuPont, BASF, Celanese, Victrex, and Solvay published processing guides. Ranges reflect general-purpose grades; verify against the specific grade datasheet for your program.

4.1 Why MFR Alone Does Not Predict Moldability

Melt flow rate measures low-shear extrusion through a standardized die at a fixed temperature and load. Injection molding operates at shear rates 100x to 1,000x higher than the MFR test. Two resins showing identical MFR values at their respective test conditions can behave entirely differently during cavity fill at injection speeds of 100 to 500 mm/s.

ISO 1133-1:2022 Annex A lists 15 test temperatures from 100 °C to 300 °C and 7 loads from 0.325 kg to 21.60 kg. A single MFR number without its temperature/load pair cannot be compared across polymer families. Within a single polymer family, lower MFR values correlate with higher molecular weight, which improves impact resistance, fatigue life, and barrier properties at the cost of harder cavity fill and longer pack times.

Interlaboratory precision data from ISO 1133-1:2022 shows ±5% within-lab repeatability and ±10% between-lab reproducibility for MFR. A “12 vs 14 g/10 min” difference between two supplier datasheets for the same grade may fall within measurement uncertainty instead of representing a real material difference.

Engineering note: For filled resins, MVR (melt volume rate, cm³/10 min) gives a more accurate comparison than MFR because it removes density variation caused by different filler loadings. ISO 1133-1 Procedure B measures displacement directly to calculate MVR, avoiding the mass-measurement bias that fillers introduce.

4.2 Drying: The Cheapest Quality Gate You Can Enforce

PA6, PA66, PC, and PBT are hygroscopic. Molding undried PA66 at 0.20% residual moisture produces visible splay (silver streaks) on part surfaces and reduces tensile strength by up to 20%. The target moisture content before molding is below 0.05% for nylons and below 0.02% for PC.

Drying costs less than $0.01/kg of resin in energy and adds 2 to 6 hours of lead time before a production run. Skipping this step to save time produces cosmetic rejects on the first 50 to 200 shots until the barrel purges wet material, wasting $200 to $500 in scrap on a typical run. Your rapid prototyping partner should confirm drying protocol as part of the T0 trial checklist. EPOC CRAFTER published a detailed walkthrough of pre-molding material preparation in our injection molding process insights.

5. How to Match Material to Application

The Five-Filter framework narrows the field. This section maps filtered resins to six application categories where EPOC CRAFTER’s low-volume production programs most frequently require material decisions.

Application Decision Table

Application	Primary Filter	Top Candidates	Avoid	Why
Structural brackets, clips	Filter 1: modulus > 5,000 MPa	PA66 GF30, PPS GF40	Unfilled PP	Deflects under sustained load; creep at room temp
Electronics enclosures	Filter 2: HDT > 85 °C + Filter 5: UL 94 V-0	PC (FR), ABS (FR)	POM	Cannot achieve V-0; formaldehyde during combustion
Living hinges, snap fits	Filter 1: fatigue > 1M cycles	PP Homopolymer	PA66, PBT	Crack at hinge radii below 0.3 mm
Gears, bearings	Filter 3: lubricant resistance + low friction	POM, PA66	PC	Stress-cracks on lubricant contact
Medical device housings	Filter 5: ISO 10993 + FDA 21 CFR	Medical PC, PEEK	GP ABS	No biocompatibility cert; colorant migration
Food-contact containers	Filter 5: FDA 21 CFR 177.1520/1580	FDA PP, FDA PC	POM, PBT	Extraction test failures under FDA conditions

Parts that span multiple categories stack the corresponding filters. A food-contact structural hinge requires PP that passes both the fatigue filter and the FDA extraction test at the target wall thickness. Your DFM design guidelines review should confirm that the chosen resin’s recommended wall range accommodates both the hinge geometry and the structural load path.

Detailed design rules for wall thickness, draft angles, ribs, and boss geometry by material appear in the injection molding design guide, the first supporting article in this content cluster.

Defect prevention strategies tied to material behavior, including sink marks from crystallization in PA66 and warpage from glass-fiber orientation in PPS GF40, are covered in the injection molding defects and DFM fixes guide.

Process parameters, mold tooling options (aluminum vs P20 vs H13 steel), and T0/T1 trial workflows are detailed in the plastic injection molding process overview.

6. Frequently Asked Questions

6.1 What is the strongest plastic for injection molding?

PA66 GF30 delivers the highest tensile strength (185 MPa at 23 °C DAM, ISO 527) among resins that process on standard injection molding equipment. PEEK reaches 100 MPa unfilled but requires melt temperatures of 360 to 400 °C and mold temperatures of 170 to 200 °C, which rules out aluminum tooling. PPS GF40 reaches 185 MPa with HDT of 260 °C at roughly one-third the resin cost of PEEK. The answer depends on your load mode: for impact resistance instead of tensile load, PC (650 to 850 J/m notched Izod) outperforms all glass-filled resins. Define your load case before ranking strength.

6.2 What is the cheapest plastic for injection molding?

PP Homopolymer at $1.20 to $2.00/kg is the lowest-cost injection molding resin by material price. HDPE runs $1.30 to $2.20/kg. Resin price alone does not determine part cost. PP’s 1.0 to 2.5% shrinkage range forces wider dimensional tolerances or compensation features in the mold, adding $1,500 to $4,000 in tooling complexity on tight-tolerance parts. ABS at $1.80 to $2.80/kg shrinks 0.4 to 0.7%, holds tighter dimensions, and avoids that tooling surcharge. Calculate total part cost, not resin cost per kilogram.

6.3 How do I choose between ABS and polycarbonate?

ABS costs less ($1.80 to $2.80/kg vs PC at $2.50 to $4.00/kg), molds at lower temperatures (210 to 270 °C vs 270 to 320 °C), and produces shorter cycle times. PC wins on impact resistance (650 J/m vs 250 J/m notched Izod), optical clarity (88% light transmission), and heat resistance (HDT 135 °C vs 98 °C). PC fails Filter 3 when parts contact aromatic solvents or IPA above 50%. ABS fails Filter 2 when continuous service temperature exceeds 90 °C. For opaque enclosures below 90 °C with no chemical exposure, ABS is the lower-cost, lower-risk choice.

6.4 What does UL 94 V-0 mean for injection molded parts?

UL 94 V-0 means each of five test specimens extinguishes afterflame within 10 seconds of removing the 50 W test flame, with total afterflame for all five specimens below 50 seconds, and no flaming drips igniting the cotton indicator below the specimen. This classification is thickness-dependent: V-0 achieved at 1.6 mm does not extend to thinner sections without separate testing per UL 94 §8.3.2 (Seventh Edition, 2023). Color, density, and molding anisotropy can shift the result at a given thickness (§4.3). Specify the exact resin grade, color, and minimum wall thickness when requesting a UL rating.

6.5 Do injection molding materials need drying before processing?

PA6, PA66, PC, PBT, PEEK, and PPS require drying. PP, HDPE, HIPS, and POM do not under normal storage conditions. Undried PA66 at 0.20% residual moisture produces splay (silver streaks) on part surfaces and reduces tensile strength by up to 20%. PC requires drying to below 0.02% moisture at 120 °C for 3 to 4 hours. Skipping drying wastes the first 50 to 200 shots in scrap before the barrel purges wet material. Confirm drying protocol, target moisture percentage, and verification method (moisture analyzer, not oven weight-loss) with your molder before the first production run.

6.6 What shrinkage values should I expect for injection molded parts?

Amorphous resins (ABS 0.4 to 0.7%, PC 0.5 to 0.7%, HIPS 0.4 to 0.7%) shrink less and more uniformly than semi-crystalline resins (PP 1.0 to 2.5%, PA66 1.0 to 1.8%, POM 1.8 to 2.5%). Glass-filled grades reduce shrinkage and narrow the range: PA66 GF30 shrinks 0.3 to 0.8% vs unfilled PA66 at 1.0 to 1.8%. Glass fibers also introduce anisotropic shrinkage where flow-direction shrinkage differs from cross-flow by 0.3 to 0.8%. Mold dimensions must compensate for the specific grade’s published shrinkage, not the polymer family average. Request the resin supplier’s mold shrinkage data at the wall thickness closest to your part geometry.

6.7 Can injection molded parts withstand high temperatures?

PA66 GF30 (HDT 250 °C at 1.8 MPa), PPS GF40 (HDT 260 °C), and PEEK (HDT 155 °C unfilled, 315 °C GF30) handle continuous service above 150 °C. Commodity resins fail at lower thresholds: PP softens at 65 °C, ABS at 98 °C, HIPS at 90 °C, all measured at 1.8 MPa per ISO 75. HDT measures deflection under sustained load, not short-term peak exposure. For brief thermal spikes (soldering reflow, autoclave sterilization), check Vicat softening temperature (ISO 306) separately. A resin that passes HDT for your service temperature can still deform during a 260 °C reflow cycle if the Vicat value is too low.

Related Resources

Related Capability: Rapid Injection Molding. Production-grade injection molded parts from aluminum or steel tooling, bridging prototype validation to volume production.

Related Article: Injection Molding Design Rules by Material. Wall thickness, draft angles, rib proportions, and boss geometry rules broken out by resin family.

Related Material Guide: Materials and Properties. Searchable property data for CNC machining, sheet metal, and injection molding material grades.

Related Standards Reference: Tolerances and Standards. ISO 2768, ASME Y14.5, and process-specific tolerance tables for quoting and inspection.

Related Capability: End-to-End Manufacturing. Single-source programs from DFM review through T0 trial to production delivery.

Upload your part drawing and material requirements at EPOC CRAFTER’s rapid injection molding page for a tooling quote that includes resin recommendation, gate sizing, and shrinkage compensation review.

Download the Five-Filter Material Decision Checklist, a one-page PDF you can fill in before requesting quotes, covering all five filters with pass/fail fields for your specific part requirements.