Machining PMMA-XT

PMMA belongs to the amorphous thermoplastics and therefore has no defined melting point, but softens above the glass transition temperature (around 105 °C). The extruded variant XT is drawn from the melt into sheets and rods; it has a tighter thickness tolerance and a lower molecular weight than cast PMMA (GS). This makes XT particularly well suited to thermoforming, bending and laser cutting, but somewhat more sensitive to stress cracking caused by solvents. PMMA is stiff, hard and crystal-clear, yet brittle and notch-sensitive.

PMMA-XT machines and laser-cuts excellently – milling, drilling, sawing and laser cutting produce clean, dimensionally accurate results; laser cutting delivers a glossy, flame-polished edge. We also offer bending, polishing, bonding and thermoforming. Because of its brittleness and stress-cracking sensitivity, we use sharp tools and adapted cutting parameters and avoid aggressive coolants. This is how we reliably produce transparent precision and visual parts – from single pieces to series production.

PMMA-XT is worthwhile whenever transparency, weathering resistance and economical processing are required – for example:

• Displays, POS and advertising media, signs and illuminated advertising
• Covers and diffusers in lighting technology
• Protective and partition screens, machine guards and sneeze guards
• Laser-cut transparent components with a glossy edge
• Weathering-resistant outdoor glazing and visual panels

PMMA-XT is an economical transparent plastic and is priced below polycarbonate and considerably below high-performance engineering plastics. As a rough guide, semi-finished stock prices are in the range of about 4–10 €/kg. The component price is determined mainly by the semi-finished shape and dimension, material utilisation (offcut), machining or laser effort and lot size. We are happy to quote binding prices on request based on your drawing. Note: extruded PMMA (XT) is usually cheaper than cast PMMA (GS) and particularly economical for laser cutting.

Equally important are the limits of the material:

• Impact- and shatter-resistant applications – PMMA is brittle; use polycarbonate (PC) for high impact strength
• Contact with solvents, alcohols or aggressive cleaners (risk of stress cracking)
• Continuous service above about 70 °C – then use more temperature-resistant materials
• Components with fire-safety requirements – PMMA is only normally flammable (B2 / UL 94 HB)
• Very tight tolerances on thick, high-optical parts – then cast PMMA (GS)

An honest assessment – and how the disadvantages can be mitigated in practice: Advantages:

Disadvantages:

Practical tip: PMMA-XT plays to its strengths wherever transparency, optics and weathering resistance matter – for example in displays, luminaires and glazing. Where shatter and impact resistance are the priority, we recommend tough polycarbonate (PC); for thick, high-optical or chemically more demanding parts, cast PMMA (GS).

• Crystal-clear with about 92 % light transmission, non-yellowing
• Very good weathering and UV resistance
• Hard, high-gloss, scratch-resistant surface
• Light (about half the weight of glass), well suited to laser cutting and thermoforming
• Economical and suitable for food contact
• Brittle and notch-sensitive – low impact strength (not shatter-proof)
• Sensitive to solvents, alcohols and esters (stress cracking)
• Continuous service limited to about 70 °C
• Only normally flammable (B2 / UL 94 HB)