PMMA is the clearest thermoplastic you can mould. At 92 % light transmission it outperforms polycarbonate, it resists UV without yellowing, and its surface hardness means it survives cleaning that would haze PC. It is brittle under impact, so it is chosen for optical and cosmetic duty — lenses, light guides, display windows — rather than for anything that has to take a knock.
Typical values for standard moulding grades. Exact figures depend on the specific compound or grade — confirm against your drawing before quoting.
Key properties
| プロパティ | Typical value |
|---|---|
| 密度 | 1.18 – 1.19 g/cm³ |
| Tensile strength | 65 – 75 MPa |
| Flexural modulus | 3.0 – 3.3 GPa |
| HDT at 1.8 MPa | 85 – 100 °C |
| Mould shrinkage | 0.4 – 0.8 % |
| Light transmission | 92 % at 3 mm |
Values are typical for unfilled moulding grades at 23 °C unless stated. Glass-filled and specialty grades differ.
Typical applications
- Optical lenses and light guides
- Display windows and control panel covers
- Automotive tail and indicator lenses
- Lighting diffusers and edge-lit panels
- Cosmetic packaging and premium display items
Processing notes
- Dry 3 h at 80 °C. Moisture produces silver streaks that are impossible to polish out of an optical part.
- Melt 230 – 260 °C, mould 60 – 90 °C. For optical parts, a hotter mould reduces flow stress and birefringence.
- Polish the tool to SPI A1 or better for lenses. Every tool mark is reproduced faithfully — PMMA hides nothing.
- Packing pressure matters more than for opaque parts: shrinkage voids show up as optical distortion, not as a visible sink.
Frequently asked questions
PMMA or PC for a transparent cover?
PMMA for optical clarity and scratch resistance where impact is not a risk. PC where the part must survive impact or heat above 120 °C. If you need both, the usual answer is a PC substrate with a hard coat.
Can you mould a lens to optical tolerance?
We mould to mechanical tolerance and specify the optical surface from the tool. For imaging-grade lenses the tool needs optical polishing and the process needs a mould-flow study — send the drawing and we will tell you what is achievable.
Related materials
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Send us your PMMA Acrylic drawing
Upload a 3D model or a 2D drawing and we will come back with a DFM review, a tooling cost and a piece price — usually within two working days.
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