Glossary of Plastics & Fabrication Terms

Base materials

PMMA (acrylic, acrylicglass, acrylic glass)

Polymethyl methacrylate — a transparent thermoplastic with the highest light transmittance among plastics (up to 92%). The industry uses several interchangeable names: acrylic, acrylicglass, Perspex, acrylic glass, organic glass.

Production variants:

• Extruded PMMA (XT) — less expensive, easier to machine, lower resistance to point cracking. Used for most standard applications.
• Cast PMMA (GS) — more expensive, superior optical and mechanical properties, can produce thicker sheets without internal stress. Preferred for structural elements.
• UV-stabilised PMMA — contains UV inhibitors. Maintains properties for 10–15 years in outdoor conditions.

Typical applications: POS display stands, showcases, interior signage, furniture fronts, decorative panels, LED lightboxes.

Polycarbonate (PC)

Polycarbonate — an amorphous engineering thermoplastic with the highest impact resistance among transparent plastics. Approximately 250× stronger against impacts than glass.

Variants:

• Solid (monolithic) PC — full transparency, maximum impact resistance
• Multiwall PC — honeycomb structure, high rigidity at low weight
• UV-coated PC — for outdoor applications
• Hard-coated PC — increased scratch resistance

Typical applications: CNC machine guards, anti-vandal shields, canopies, device enclosures in extreme conditions.

Dibond (aluminium composite panel)

Dibond — a sandwtheir composite consisting of two thin aluminium layers (0.3 mm each) bonded to a polyethylene or mineral core.

Typical applications: large-format facade signs, dimensional letters, exterior plaques, lightbox casings.

Process terminology

Bending plastics

The process of shaping thermoplastic sheets through localised heating and forming.

Springback — partial return of the bend angle after release from the forming tool. When designing a bent element, you must compensate for springback by overbending by the appropriate amount.

Kerf (cutting groove) — a groove milled into the material that facilitates bending at a sharp angle without heating.

Bonding plastics

Bonding PMMA:

• Dominant method: solvent cements (dtheirloromethane / DCM)
• Mechanism: solvent dissolves the surfaces, which then bond at a molecular level
• Joint strength: close to that of the base material
• Curing time: initial 5–15 min, full 24–48 h

Bonding PC:

• Use: silicone adhesives, two-part polyurethane adhesives
• Joint strength: 60–80% of base material

CNC / laser cutting

CO&sub2; laser cutting:

• Preferred for PMMA — clean, polished edge
• Polycarbonate: possible, but causes edge yellowing

CNC routing:

• Universal method for all materials
• Allows cutting, profile milling, and engraving

Thermoforming

The process of shaping a plastic sheet by heating it to its softening point and forming it in a mould (vacuum, pressure, or mechanical). Applications include complex-shaped enclosures, dimensional letters, domes, and convex guards. Limitations: requires a mould/die, material thins at stretch points.

Material properties

Thermal expansion

Plastics expand under temperature changes considerably more than metals.

Design implications:

• Mounting holes 2–3 mm larger than bolt diameter
• Expansion gaps when mounting in frames
• Avoid rigid fastening of large panels

UV degradation

Ultraviolet radiation causes degradation of plastics: yellowing, loss of transparency, and brittleness.

Recommendation: For all outdoor applications, use only UV-stabilised materials.

Chemical resistance

PMMA — resistant to: dilute acids and alkalis, salt solutions, low-concentration aliphatic alcohols, mineral oils.

PMMA — sensitive to: acetone, MEK, esters, chlorinated hydrocarbons, high-concentration isopropyl alcohol.

Polycarbonate — sensitive to: alkalis, alcohols (stress cracking!), ketones, ammonia, some disinfectants.

Cleaning:

• PMMA: water with mild detergent, pH 5–8
• PC: water with mild detergent, avoid alcohols

IP ratings (Ingress Protection)

Classification system for the degree of protection provided by enclosures against solid particles and water ingress (IEC 60529 / EN 60529).

Format: IP XY, where X = protection against solids (0–6), Y = protection against water (0–9).

Accessibility standards (informative)

In Europe, signage for people with disabilities is regulated by EN ISO 17049.

Key requirements:

• Tactile signs: minimum 0.8 mm relief
• Braille alphabet: dimensions per standard
• Contrast: minimum 70% between sign and background
• Mounting height: 120–160 cm above floor level

Term index

PlexiSystem Encyclopedia — Glossary
Last updated: January 2026