Melt temperature, mold temperature, mold shrinkage and barrel residence time for 34 thermoplastic families, taken from manufacturer processing guides and technical data sheets. Sources are listed at the bottom. Companion to our resin drying chart.
How to read this chart
These are family-level typical values from manufacturer processing guides. They are a starting point for a process and a sanity check on a data sheet — not a substitute for the sheet on the grade you are actually running. Where suppliers disagree materially, both figures appear.
Processing parameters by resin
Scroll the table sideways to see all columns →
| Resin | Melt temp | Mold temp | Shrinkage, unfilled % | Shrinkage, filled % | Max residence | Notes |
|---|---|---|---|---|---|---|
| Nylon 6 (PA6) | 482–536°F / 250–280°C | 104–212°F / 40–100°C | 0.90 ∥ / 0.90 ⊥ constrained part 0.4 | — | 10 min | Mold temp is the biggest disagreement on this chart — BASF 40–60°C, Lanxess 80–100°C. |
| Nylon 6, 30% glass | 518–554°F / 270–290°C | 176–248°F / 80–120°C | — | 0.30 ∥ / 0.75 ⊥ | 10 min | 2.5× anisotropic. |
| Nylon 66 (PA66) | 527–580°F / 275–305°C | 140–212°F / 60–100°C | 1.50 ∥ / 1.80 ⊥ constrained part 0.81 | — | 10 min | ISO plaque value is roughly double the real constrained-part value. |
| Nylon 66, 30–33% glass | 536–581°F / 280–305°C | 176–248°F / 80–120°C | — | 0.50 ∥ / 1.10 ⊥ | 10 min | 2.2× anisotropic. |
| Nylon 11 (PA11) | 480–555°F / 250–290°C | 105–195°F / 40–90°C | 1.1 ∥ / 1.1 ⊥ | GF30: 0.2 ∥ / 0.8 ⊥ | — | 4× anisotropy on GF30 — the largest in the nylons. |
| Nylon 12 (PA12) | 410–500°F / 210–260°C GF30 runs 250–290°C | 70–140°F / 20–60°C | 1.1 ∥ / 1.2 ⊥ | GF30: 0.2 ∥ / 0.7 ⊥ | — | Melt temp is grade-driven, not family-driven. |
| Polycarbonate (PC) | 536–653°F / 280–345°C | 158–248°F / 70–120°C | Covestro 0.70 / 0.75 SABIC 0.5–0.7 | 10–30% GF: 0.1–0.4 flow | 4–8 min | Residence has a real lower bound too — under 4 min gives an under-compounded melt. |
| PC/ABS | 428–610°F / 220–321°C | 120–210°F / 49–99°C | 0.5–0.75, isotropic | GF30: 0.15–0.35 ∥ / 0.30–0.50 ⊥ | 4–6 min | Covestro publishes identical parallel and normal values. |
| ABS | 425–525°F / 218–274°C FR grades never above 475°F / 246°C | 80–180°F / 27–82°C | 0.4–0.7 | — | — | Three suppliers agree on shrinkage and disagree by 55°F on mold temp. |
| SAN | 428–500°F / 220–260°C | 104–176°F / 40–80°C | 0.3–0.7 | 35% GF: 0.1 | — | |
| ASA | 464–536°F / 240–280°C | 140°F / 60°C | 0.5 ∥ / 0.9 ⊥ | — | — | The widely quoted “0.5–0.9%” is the two directions, not a grade range. ASA is not isotropic. |
| Acetal — POM homopolymer | Optimum 419±10°F / 215±5°C keep below 446°F / 230°C | 176–248°F / 80–120°C | 1.7–2.2 | — | >30 min at 419°F ~8 min at 464°F | Hot-runner steel capped at 374°F / 190°C. |
| Acetal — POM copolymer | 370–446°F / 188–230°C never above 460°F / 238°C | 140–250°F / 60–121°C | 1.2–2.4 | Glass fill inverts the direction sense | 15–20 min above 380°F | Suppliers disagree 6× on residence. See the decomposition warning below. |
| PET, glass-filled | 520–570°F / 271–300°C | 200–250°F / 95–121°C | n/a | 30% GF: 0.1–0.3 flow | Interruption >15 min: empty the barrel | No unfilled injection-grade PET exists in the Rynite or Impet lines. Never borrow bottle-resin numbers. |
| PBT, unfilled | 460–536°F / 238–280°C above 536°F = decomposition | 100–212°F / 38–100°C | 1.6–2.0 both directions | — | 5–10 min | ~70°F supplier conflict on mold temp. |
| PBT, 30% glass | 460–527°F / 238–275°C | 140–212°F / 60–100°C | — | 0.30 ∥ / 1.10 ⊥ (BASF) 0.3–0.5 / 0.4–0.6 (SABIC) | 5–10 min | The anisotropy ratio itself varies 3× between suppliers — 1.3:1 to 3.7:1. |
| PEI (Ultem) | 662–770°F / 350–410°C | 275–356°F / 135–180°C | 0.5–0.7, genuinely isotropic | 30% GF: 0.20–0.40 both directions | 2–5 min | Isotropic even at 30% glass — unusual and useful. |
| PEEK | 670–752°F / 354–400°C | 338–392°F / 170–200°C 170°C is a hard minimum | 0.9–1.3 ∥ / 1.1–1.5 ⊥ | GF30 cross-flow: 0.60 to 1.6 depending on supplier CF30 flow ≈ 0.0 | ~1 h at 360°C 30 min at 380°C | Largest supplier spread on the chart. Do not average Victrex, Evonik and Solvay. |
| PPS | 572–650°F / 300–343°C do not exceed 644°F / 340°C | 275–320°F / 135–160°C | 1.2–1.4 ∥ / 1.5–1.9 ⊥ | 40% GF: 0.20 ∥ / 0.50–0.80 ⊥ | Not published | Avoid 190–260°F / 88–127°C mold temp — unpredictable crystallinity. |
| PSU (Udel) | 626–734°F / 330–390°C | 248–320°F / 120–160°C | 0.6–0.7 | 30% GF: 0.29 ∥ / 0.46 ⊥ | 5–20 min | Filled sulfones are not isotropic, despite blanket claims to the contrary. |
| PPSU (Radel) | 662–734°F / 350–390°C | 280–356°F / 138–180°C | 0.6–1.0 | — | 5–20 min | |
| TPU | 374–455°F / 190–235°C indexed to Shore hardness | 50–158°F / 10–70°C | 0.60 ∥ / 0.70–1.0 ⊥ | GF: 0.05–0.2 ∥ / 0.1–0.5 ⊥ | Purge if the cycle stops >10 min | 60–80A runs 190–205°C; 98A–74D runs 215–235°C. A soft grade at the family maximum will degrade. |
| Acrylic (PMMA) | 340–520°F / 171–271°C | 100–205°F / 38–96°C | ~0.4 typical 0.2–0.7 at extremes | n/a | — | Add 0.1–0.3% for humidity expansion in service — most of the shrinkage budget. |
| GPPS | 356–500°F / 180–260°C | 50–150°F / 10–66°C | 0.3–0.8 | n/a | — | |
| HIPS | 356–480°F / 180–249°C melt should not exceed 464°F / 240°C | 50–150°F / 10–66°C | 0.4–0.8 | n/a | — | |
| PPO / PPE modified (Noryl) | 536–572°F / 280–300°C FR grades to 608°F / 320°C | 149–248°F / 65–120°C | 0.5–0.7 flow | 20% GF: 0.2–0.5 flow | 8 min | SABIC’s own guide contradicts itself on mold temp between body text and Table 3. |
| Polypropylene homopolymer | 374–525°F / 190–274°C | 50–203°F / 10–95°C | 0.8–2.5 | 20% talc 1.10–1.50 · 40% talc 0.70–1.00 30% GF: 0.24 ∥ / 1.15 ⊥ | Purge if idle >30 min | Glass-filled PP is the worst anisotropy here — up to 10:1. |
| Polypropylene copolymer | 392–500°F / 200–260°C | 59–149°F / 15–65°C | 1.2–2.0 | — | — | Measured 24 h after molding. |
| HDPE | 380–525°F / 193–275°C | 50–125°F / 10–50°C | 1.70–2.90 | n/a | — | ~120°F supplier spread on melt, and opposite mold-temp advice. Both positions are defensible. |
| LDPE | 320–450°F / 160–232°C | 68–150°F / 20–66°C | 2.40–3.10 | n/a | — | |
| Rigid PVC | 380–410°F / 193–210°C | 40–130°F / 4–54°C | 0.20–0.50 flow | Glass-reinforced: 0.05–0.15 | 15 min absolute | Degrades to gaseous HCl. Neutralize tools daily. |
| Flexible PVC | 325–395°F / 163–202°C durometer-indexed | 50–140°F / 10–60°C | 1.0–3.0 softer shrinks more | Filled 1.8–2.1 vs unfilled 1.5–1.8 (50–70A) | 10 min absolute | Soft PVC melt should not exceed 392°F / 200°C. |
| TPE-S (SEBS) | 370–473°F / 190–245°C | 59–140°F / 15–60°C | 1.1–2.1 ∥ / 0.7–1.3 ⊥ | Filled grades shrink less | ≤10 min | |
| TPV (Santoprene) | 350–450°F / 175–230°C | 50–151°F / 10–66°C | Hardness-indexed: 49A 4.1 ∥ / 0.7 ⊥ → 94A 1.5 / 0.7 | n/a | Purge if idle >20 min | Hardness changes the anisotropy, not just the magnitude. Cross-flow stays flat. |
Eight things worth knowing before you use these numbers
1. Amorphous and semi-crystalline behave differently — with two exceptions
Amorphous resins (PC, ABS, SAN, PS, PMMA, PEI, sulfones, Noryl) sit in a narrow 0.3–0.8% band and are close to isotropic. Semi-crystalline resins (nylon, acetal, PBT, PP, PE, PPS, PEEK) shrink 1–2.5% unfilled and are direction- and crystallinity-sensitive. Two exceptions catch people out: ASA is not isotropic — the commonly quoted “0.5–0.9%” is the two directions, not a grade range. And filled sulfones are not isotropic either, despite blanket statements to the contrary; BASF’s own 30% glass PSU is 0.29 along flow and 0.46 across.
2. Acetal decomposition is the highest-consequence line on this page
Celanese: Celcon acetal should never be heated above 460°F, nor remain above 380°F for more than 15 minutes without purging. Beyond that the resin degrades and releases formaldehyde — and if venting is inadequate, pressure builds in the equipment. DuPont on Delrin: decomposition is almost entirely to gaseous products, so pressure build-up can be rapid. Note the counterintuitive part: homopolymer is more permissive in the barrel (over 30 minutes at its 419°F optimum) even though copolymer is the more thermally stable chemistry in service.
3. Residence time and melt temperature are one parameter, not two
Every supplier that publishes seriously publishes a curve, not a scalar. SABIC puts it directly: residence time should be as short as possible when molding near the maximum suggested melt temperature. A “max residence” figure is only valid at the low end of the melt range. Covestro adds the opposite caution for polycarbonate — below about 4 minutes you get an insufficiently compounded melt.
4. Mold temperature sets crystallinity, and the trade runs both ways
Mold shrinkage rises with mold temperature; post-mold shrinkage falls. Cold-molded semi-crystalline parts measure fine out of the press and then move in service. Three specifics: PEEK needs a 170°C minimum tool surface or you get amorphous parts that crystallize later above Tg. PPS has a forbidden band — 190–260°F yields unpredictable crystallinity and should be avoided. And injection-grade PET needs a hot mold, the opposite of preform tooling, which is one more reason never to read bottle-resin numbers across. Delrin adds that annealing will not rescue a cold-molded part — it produces uncontrolled deformation instead.
5. Measure at 24 hours minimum, 48 for polyolefins
LyondellBasell: a polyolefin part reaches about 90% of total shrinkage after 48 hours, and shrinkage continues for days if parts are packed hot. SABIC anchors its published values to 24 hours after molding. Force-cooling parts to measure sooner — in a fridge or under water — measures thermal contraction, not shrinkage.
6. Hold pressure and gate freeze set the number as much as the resin does
Covestro: shrinkage begins the moment cavity pressure reaches atmospheric, and that point moves with the holding-pressure profile — so shrinkage can be influenced directly. INEOS notes polystyrene shrinkage may be effectively zero in zones under high follow-up pressure. Every published figure is conditional on a specific plaque geometry and set of conditions.
7. Nylon and acrylic grow after molding
DuPont: in a well-molded nylon part of moderate wall thickness, expansion from water absorption dominates the shrinkage from increasing crystallinity. Acrylic does the same — Trinseo publishes corrections to be added: +0.1% at 40% RH, +0.2% at 65%, +0.3% at 80%. On a 0.4% nominal shrinkage that is most of the budget.
8. ISO and ASTM values are not interchangeable
ISO 294-4 and ASTM D955 use different specimens, hold conditions and timing, and reference thicknesses differ (2 mm vs 3.2 mm). BASF publishes ISO plaque shrinkage of 1.50/1.80% for unfilled PA66 but a constrained real-part value of 0.81% — roughly half. Celanese says it flatly: shrinkage values measured on standard ASTM or ISO test bars should be used for material comparison only, not for tool design.
Some parameters aren’t indexed to the resin at all
A family-level row will mislead you in four cases. TPU melt temperature tracks Shore hardness — 190–205°C at 70A versus 215–235°C at 74D, so a soft grade run at the family maximum will degrade. Flexible PVC melt temperature and shrinkage both track durometer. TPV flow-direction shrinkage falls from 4.1% at 49A to 1.5% at 94A while cross-flow stays flat near 0.8% — hardness changes the anisotropy itself. And PA12 melt temperature is grade-driven: unfilled runs 230°C, 30% glass runs 270°C.
One thing that surprised us
There is no unfilled injection-grade PET in either the DuPont Rynite or Celanese Impet lines. Every injection PET grade is filled. If you find an “unfilled injection PET” shrinkage figure on a chart somewhere, it was almost certainly borrowed from bottle resin, which is processed under completely different conditions.
BASF Ultramid, Ultradur and Ultrason processing data sheets · DuPont/Celanese Zytel Molding Guide, Delrin Technical Molding Guide (2024), Rynite Molding Guide · Celanese Celcon and Hostaform product manuals, Polyester Technical Manual, Fortron PPS data · Covestro Makrolon and Bayblend typical-value sheets, TPU processing guide · SABIC ULTEM, NORYL, Cycolac, Cycoloy, Valox processing guides and datasheets · Solvay/Syensqo Ryton, KetaSpire and sulfones processing guides · Victrex and Evonik PEEK guides · Arkema Rilsan/Rilsamid · Envalior Pocan · Lanxess processing data · Polyplastics Duracon · INEOS Styrolution and INEOS Olefins · Trinseo · Trinseo/Röhm PLEXIGLAS · AmSty STYRON · Teknor Apex, GEON and Westlake PVC guides · HEXPOL · Avient GLS · ExxonMobil Santoprene · Lubrizol Estane · Asahi Kasei · Borealis · RTP Company · LyondellBasell · Mike Sepe, Understanding Postmold Shrinkage, Plastics Technology.
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