PMMA-Optical Cast
Grade
Cast = as cast
Pick for large optical windows, laser-cut/engraved parts and thick blanks needing best surface flatness and machinability.
Values for the Cast condition
Other PMMA-Optical grades and fills
PMMA-Optical is listed in 7 conditions; see the grade overview at PMMA-Optical.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified optical grade | Pick when parts must survive handling/drop loads and a small loss of clarity and stiffness is acceptable. | — | 50 | 30 | 65 HRM |
Flame-retardant transparent grade | Pick for lighting diffusers and display housings that must meet a UL94 V rating; expect some haze and lower clarity. | 60 | 62 | 3 | 88 Shore D |
Light-guide plate grade | Pick for thin backlight light-guide plates where long optical path length and thin-wall filling dominate. | 66 | 68 | 3.5 | 88 Shore D |
UV-transmitting optical grade | Pick for UV curing windows, tanning/analytical optics and sensors needing transmission down to ~300 nm (no UV absorber added). | 68 | 70 | 4.5 | 89 Shore D |
Optical fibre / light-pipe core grade | Pick for POF cores and long light pipes where attenuation per metre, not mechanics, is the limiting property. | 72 | 74 | 4 | 90 Shore D |
Heat-resistant optical grade | Pick for LED/lamp optics or lenses cured near 110–130 °C where standard PMMA distorts. | 73 | 75 | 3.5 | 90 Shore D |
CastThis page As cast | Pick for large optical windows, laser-cut/engraved parts and thick blanks needing best surface flatness and machinability. | 74 | 76 | 5 | 92 Shore D |
What is PMMA-Optical Cast?
PMMA-Optical Cast is PMMA-Optical in the Cast grade — pick for large optical windows, laser-cut/engraved parts and thick blanks needing best surface flatness and machinability. PMMA-Optical Cast has a yield strength of 74 MPa (10.7 ksi) and a tensile strength of 76 MPa (11 ksi) — stronger than 83% of polymer grades. Elongation at break is 5% and the elastic modulus is 3.3 GPa (0.479 Msi). PMMA-Optical Cast has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 105°C (221 °F).
Advantages
- Polishes to a fine finish — 98/100, better than 100% of polymer grades
- Good UV / weathering resistance — 88/100, better than 90% of polymer grades
- Easy to machine — 80/100, better than 84% of polymer grades
- High strength — 74 MPa (10.7 ksi), better than 83% of polymer grades
- Stiff — 3.3 GPa (0.479 Msi), better than 80% of polymer grades
Limitations
- Low fracture toughness — 1.2 MPa·√m (1.09 ksi·√in), worse than 77% of polymer grades
PMMA-Optical Cast properties
Typical room-temperature values for PMMA-Optical Cast; 25 are specific to this condition. Other listed values are PMMA-Optical reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
PMMA-Optical Cast has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 105°C (221 °F).
Mechanical16
PMMA-Optical Cast has a yield strength of 74 MPa (10.7 ksi) and a tensile strength of 76 MPa (11 ksi) — stronger than 83% of polymer grades. Elongation at break is 5% and the elastic modulus is 3.3 GPa (0.479 Msi).
Thermal11
PMMA-Optical Cast is rated for continuous service to 80°C (176 °F). It conducts heat at 0.19 W/m·K (0.11 BTU/hr·ft·°F), worse than 68% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical7
PMMA-Optical Cast is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (72/100), worse than 70% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of PMMA-Optical Cast takes about 105 MJ of energy and emits 6.2 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 0%.
Manufacturability8
PMMA-Optical Cast's machinability is very good (80/100, better than 84% of polymer grades); weldability good (55/100); formability very good (70/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PMMA-Optical Cast
Is PMMA-Optical easy to machine?
Machines and diamond-turns to optical finish with sharp positive-rake tools, high speed and low feed; use coolant/air blast and avoid dwell to prevent crazing, and anneal (~80 °C) before and after cutting to relieve stress.
Can PMMA-Optical be welded?
No fusion welding — join by solvent (dichloromethane/MMA cement), UV-cure acrylic adhesive, ultrasonic or laser welding; avoid solvent vapour on stressed parts to prevent crazing.
Can PMMA-Optical be formed, bent or molded?
Dry 4–6 h at 80–90 °C to <0.05 % moisture, inject at 225–265 °C melt with 60–95 °C mould, slow fill and high holding pressure for low birefringence; thermoform sheet at 150–180 °C.
What surface finishes work on PMMA-Optical?
Flame or diamond polishing gives near-optical edges; hard-coat (siloxane/UV-cure) for scratch and chemical resistance, vacuum AR/metallic coatings adhere well after plasma treatment.
PMMA-Optical chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| methyl acrylate / ethyl acrylate comonomadded for thermal stability and flow in injection grades | 0 – 6 | 3 |
| chain transfer agent / residual monomer mercaptan CTA, mould release, antioxidant; UV absorber only in UV-cut grades | 0 – 1 | 0.3 |
| methyl methacrylate (MMA)polymerized MMA backbone; optical grades use high-purity, low-metal monomer | ≥ 92 (balance) | — |
PMMA-Optical Cast — frequently asked
What is PMMA-Optical Cast used for?
PMMA-Optical Cast is typically used for light guide plates (LGP), optical lenses, plastic optical fiber and camera/display components. In short: lowest-birefringence PMMA; diamond-turnable optical grade; costliest acrylic grade.
What is the yield strength of PMMA-Optical Cast?
PMMA-Optical Cast has a typical yield strength of 74 MPa (10.7 ksi) and a tensile strength of 76 MPa (11 ksi) — stronger than 83% of polymer grades. Strength varies by condition: see the 7 listed tempers.
Is PMMA-Optical Cast easy to machine?
Yes — machinability is rated very good (80/100, better than 84% of polymer grades). Machines and diamond-turns to optical finish with sharp positive-rake tools, high speed and low feed; use coolant/air blast and avoid dwell to prevent crazing, and anneal (~80 °C) before and after cutting to relieve stress.
Can PMMA-Optical Cast be welded?
Yes — weldability is rated good (55/100). No fusion welding — join by solvent (dichloromethane/MMA cement), UV-cure acrylic adhesive, ultrasonic or laser welding; avoid solvent vapour on stressed parts to prevent crazing.
What surface finishes work on PMMA-Optical Cast?
Flame or diamond polishing gives near-optical edges; hard-coat (siloxane/UV-cure) for scratch and chemical resistance, vacuum AR/metallic coatings adhere well after plasma treatment.
Can PMMA-Optical Cast be formed, bent or molded?
Dry 4–6 h at 80–90 °C to <0.05 % moisture, inject at 225–265 °C melt with 60–95 °C mould, slow fill and high holding pressure for low birefringence; thermoform sheet at 150–180 °C.
What is the maximum service temperature of PMMA-Optical Cast?
PMMA-Optical Cast is rated for continuous use to about 80°C (176 °F), and briefly to 95°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ISO 8257-1/-2 Plastics — Poly(methyl methacrylate) moulding and extrusion materials — ISO (2021)
- JIS K 6717 Poly(methyl methacrylate) moulding materials — JSA (2019)
- Engineered Materials Handbook Vol.2: Engineering Plastics — ASM International (1988)
- Acrypet optical / light-guide grade data sheets — Mitsubishi Chemical (2023)
- Plexiglas / Altuglas acrylic resin and sheet data — Röhm / Trinseo (2023)
- CAMPUS plastics database — PMMA property profiles — CWFG (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.