PMMA Injection Molding for Optical-Grade Acrylic Parts
What tolerances does Fecision hold on PMMA injection molded parts?
Fecision machines PMMA injection molds to ±0.01 mm on critical dimensions using slow-wire EDM. Molds run for 500,000+ cycles before first resurfacing. Optical-clarity parts achieve light transmittance of ≥92%, meeting ASTM D1003 standards for lens and display applications.
ISO 9001:2015
ISO 13485:2016
AS 9100 Certified
DFM Review
Dimensional tolerance on mold cores (slow-wire EDM)
Mold cycle life before first maintenance event
Light transmittance — ASTM D1003, optical lens grade
Tooling lead time for standard PMMA molds
How It Works
Our PMMA Injection Molding Process
Each stage is documented, measured, and approved before the next begins. Acrylic is unforgiving — moisture, temperature, and gate location decide optical quality. We control all three.
DFM Review & Mold Design
Gate location, wall uniformity, and draft angles optimized before steel is cut. PMMA requires 1.5°–3° draft minimum; we flag any geometry that risks sink marks or birefringence.
Precision Tooling
Cavity steel (S136 stainless or NAK80) machined with CNC ±0.01 mm, then mirror-polished to SPI A1 for optical surfaces. Slow-wire EDM on critical shut-offs.
Material Pre-Drying
PMMA pellets dried at 80–90 °C for 4–6 hours to moisture content <0.1%. Skipping this step causes silver streaks — a failure mode we have never shipped.
Injection & Process Control
Barrel temperature 220–260 °C, mold temperature 50–80 °C, injection speed profiled to reduce shear stress on the polymer chain and preserve transmittance values.
In-Process Quality Inspection
First-article measured on CMM. Every 500-shot sample checked for dimensional conformance. Transmittance tested per ASTM D1003 on optical-grade batches.
Post-Processing & Packaging
Optional annealing at 70–80 °C to relieve residual stress. Parts individually sleeved in anti-scratch bags. Full traceability record shipped with every order.
Material Knowledge
PMMA Grades & Compatible Injection Molding Resins
Not all acrylic performs the same under injection conditions.
We can apply various grades and evaluate alternatives against your optical, mechanical, or chemical-resistance specification.
Optical-Grade PMMA
Plexiglas® 8N / Altuglas® V825T and equivalents
The standard for lens, light guide plate, and display cover applications. High molecular weight chains produce the optical clarity that defines this grade’s reputation.
| Light transmittance | ≥92% (ASTM D1003) |
| Refractive index | 1.49 (ASTM D542) |
| Tensile strength | 72–80 MPa |
| Vicat softening point | 103–107 °C |
| Mold shrinkage | 0.2–0.8% |
Impact PMMA
Plexiglas® Hi-Impact / Elvacite® blends
Core-shell rubber particles toughened into the PMMA matrix. Notched Izod impact strength increases 3–5× compared to standard grade, at ~8% transmittance cost — the right trade-off for enclosures subject to drop risk.
| Izod notched impact | 20–40 J/m (ASTM D256) |
| Light transmittance | 84–88% |
| Flexural modulus | 1,800–2,200 MPa |
| Mold temp range | 50–80 °C |
HR-PMMA
Röhm Plexiglas® HT — copolymer grade
Methacrylic acid copolymerization raises the Vicat softening point to 115–125 °C. Used in automotive lighting and LED housings where the standard grade warps under continuous thermal load.
| Vicat softening point | 115–125 °C |
| Light transmittance | ≥91% |
| HDT (1.82 MPa) | 100–110 °C |
| Mold shrinkage | 0.3–0.6% |
PC & COC/COP
Makrolon® PC | Zeonex® COC | Zeonor® COP
When PMMA’s stress-cracking in contact with solvents or its 1.49 refractive index is not optimal, Fecision can tool and run polycarbonate or cyclic olefin grades in the same precision cell.
| PC transmittance | 88–90% |
| COC/COP transmittance | 91–93% |
| COC refractive index | 1.53 |
| COP birefringence | <5 nm/cm |
Quality System
Precision & Quality Control for Optical Parts
PMMA injection molding fails quietly: a mold surface at Ra 0.02 µm versus Ra 0.05 µm is invisible to the eye until the part enters service under a backlight. We measure at every stage where measurement catches a defect before it ships.
Our quality system runs under ISO 9001:2015. Medical device parts produced in our Class 10,000 cleanroom area additionally conform to ISO 13485:2016, with full batch traceability and deviation records retained for 10 years.
CMM-verified tolerance on mold cavity dimensions
Optical-surface finish (SPI A1) — profilometer verified
Light transmittance measured per ASTM D1003 on every batch
Max moisture in PMMA pellets before barrel entry
Cleanroom molding cell for medical & optical assemblies
Batch record retention for medical device traceability
Application Areas
Industries Served with PMMA Injection Molding
Acrylic's combination of optical clarity, UV resistance, and dimensional stability makes it the material of choice across four distinct verticals — each with different tolerance and regulatory demands.
Medical & Diagnostics
Microfluidic chips, reagent cartridges, and optical flow cells require stress-free PMMA molded in a documented cleanroom environment. We hold ISO 13485:2016 and can supply material certificates traceable to resin lot number.
Electronics
Light-guide plates for LCD backlighting require thickness uniformity within ±0.05 mm across a 200 mm span. Camera lens covers and display bezels benefit from PMMA’s scratch resistance (Rockwell M97) and zero haze characteristics.
Aerospace & Defense
Instrument panel lenses and optical sight components demand zero internal stress — birefringence above 10 nm/cm causes polarization artifacts in HUD systems. Our slow-fill, high-mold-temperature process minimizes residual stress at origin.
Industrial Equipment
Flow-rate indicator sight glasses, machine guards, and sensor covers require PMMA’s weatherability (UV stability without coating for >10 years outdoor) paired with the chemical resistance needed in wash-down environments.
- PMMA (Acrylic) provides optical clarity and UV stability critical for dental tools, diagnostic cuvettes, and optical medical devices.
- Our PMMA medical molding process minimizes internal stress and maintains optical-grade surface finish, meeting the stringent requirements of laboratory and clinical environments. Discover how our medical injection molding expertise transforms PMMA into precision optical components for next-generation diagnostics.
PMMA Injection Molding FAQs
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