PMMA(Acrylic)
Polymethyl Methacrylate (PMMA), commonly known as Acrylic, is an amorphous optical-grade thermoplastic celebrated for its glass-matching light transmittance (up to 92%), superior UV weatherability, and exceptional scratch resistance. At Jucheng Precision, an ISO 9001 and IATF 16949 certified manufacturer, we specialized in high-precision optical PMMA injection molding for automotive lighting and luxury cosmetic packaging. Utilizing 35+ advanced molding presses (50-650T) and 25+ in-house 5-axis CNC machines, we build mirror-polished S136 stainless steel molds (SPI A-1 finish) to eliminate optical strain, haze, and birefringence, delivering pristine components verified by Zeiss CMM inspection.
Common PMMA / Acrylic Grades We Mold
We process high-purity Acrylic polymers from globally recognized synthesizers, optimized for optical clarity, high surface hardness, and outdoor UV resistance:
| PMMA Grade Class | Typical Brand & Grade | Key Characteristics & Advantages |
|---|---|---|
| Optical & High Flow PMMA | • Röhm PLEXIGLAS 8N / 8H • Sumitomo SUMIPEX MH / MG |
Exceptional light transmittance (92%), ultra-low haze, and easy melt flow. Ideal for thick-walled automotive light pipes, optical lenses, and LED diffusers. |
| High Heat PMMA | • Röhm PLEXIGLAS 7N • Arkema Altuglas HT121 |
Elevated Vicat softening point (up to 110°C) and superior scratch resistance (M-Scale 100). Specified for automotive tail lamp covers and high-temperature lighting bezels. |
| Impact-Modified PMMA | • Evonik PLEXIGLAS Resist zk6 • Chi Mei ACRYREX VH4 |
Toughened with acrylic elastomer domains to offer 3x to 5x higher impact resistance than standard PMMA, while maintaining high transparency for display covers. |
Applicable Molding Processes for PMMA (Acrylic)
PMMA’s high melt viscosity and amorphous optical sensitivity require strict injection parameter controls:
| Molding Process | Process Suitability & Application Details |
|---|---|
| Optical & Lens Molding | Excellent. Highly optimized for spherical lenses, light guides, LED reflectors, and optical prisms requiring zero light scattering and low birefringence. |
| Thin-Wall Cosmetic Packaging | Excellent. Produces luxury thick-walled cosmetic jars, perfume caps, and display boxes with crystal-like brilliance and scratch resistance. |
| 2K / Overmolding | Good. Extensively used in 2K multi-shot molding to co-inject clear PMMA over red or amber ABS/PC substrates for multi-colored automotive tail lamps. |
PMMA (Acrylic) Tooling & Optical Strain Control Guide
Molding an optical-grade amorphous thermoplastic like Acrylic demands precise temperature control and mirror-polished tool cavities:
- SPI A-1 Mirror Mold Polishing: Any microscopic surface scratch or pit on tool cavity walls will scatter light and degrade transparency. Jucheng’s tooling division uses premium S136 stainless steel hardened to 50 HRC, diamond-polished to an SPI A-1 mirror finish.
- Eliminating Optical Strain & Birefringence: High shear stress during injection creates internal molecular orientation, resulting in rainbow refraction lines (birefringence). We employ slow-to-moderate injection speeds, large gate channels, and progressive packing pressures to ensure low residual stress.
- Desiccant Pre-Drying Protocol: PMMA is moderately hygroscopic. Moisture causes severe silver streaks, bubbles, and loss of clarity. Raw material is strictly dried in desiccant dryers at 80°C–90°C (176°F–194°F) for 3–4 hours, maintaining moisture levels under 0.02%.
- Low Amorphous Shrinkage: PMMA features low and uniform shrinkage (0.4% to 0.7%). Our 5-axis CNC machining center cuts precise tool cavities with conformal cooling loops to speed up cycle times without thermal distortion.
Key Application Industries for PMMA Molded Parts
- Automotive Lighting & Optics (IATF 16949 Compliant): Tail lamp covers, ambient light pipes, instrument cluster covers, indicator lenses, and HUD display plates.
- Luxury Cosmetic & Retail Packaging: Thick-walled cosmetic jars, luxury perfume bottle caps, crystal-clear display boxes, and high-gloss compact cases.
- Medical & Diagnostic Devices (ISO 13485 Compliant): Optical diagnostic cuvettes, blood inspection chambers, light-guiding sensor housings, and laboratory fluidic wells.
Material Properties
| Density | 1.18 - 1.20 g/cm³ |
| Melt Mass-Flow Rate (MFR) (230°C/3.8kg) | 1.5 - 25 g/10 min |
| Light Transmittance (3.0mm) | 92.0 % |
| Refractive Index | 1.491 - |
| Tensile Strength at Yield | 65 - 80 MPa |
| Flexural Strength | 100 - 120 MPa |
| Flexural Modulus | 3,000 - 3,300 MPa |
| Charpy Notched Impact Strength (23°C) | 2.0 - 3.5 kJ/m² |
| Rockwell Hardness (M-Scale) | 90 - 100 - |
| Vicat Softening Temperature | 100 - 110 °C |
| Heat Deflection Temperature (HDT @ 1.8 MPa) | 90 - 100 °C |
| Linear Mold Shrinkage | 0.40 - 0.70 % |
| Maximum Part Size | 800 x 600 mm |
| Minimum Part Size | 1 x 1 mm |