Glossary of Acrylic Sheet Terms
Understanding acrylic sheet terminology is essential for professionals, fabricators, and enthusiasts working with this versatile material. This comprehensive glossary covers manufacturing processes, material properties, grades, finishes, and technical specifications commonly encountered in the acrylic industry.
A
Abrasion Resistance: The ability of an acrylic sheet surface to resist scratching, scuffing, or wearing when subjected to friction or contact with other materials.
Acrylic Cement is A solvent-based adhesive specifically formulated to chemically bond acrylic sheets by partially dissolving the surfaces to create a welded joint.
Annealing: A heat treatment process that relieves internal stresses in acrylic sheets, improving dimensional stability and reducing the risk of stress cracking during fabrication.
Anti-Static Surface treatment or additive that reduces the buildup of static electricity on acrylic sheets, minimizing dust attraction and handling issues.
ASTM American Society for Testing and Materials - an organization that establishes standards for acrylic sheet testing and classification.
B
Bending Radius: The minimum radius to which an acrylic sheet can be bent without cracking or failing, typically expressed as a multiple of the sheet thickness.
Biaxial Orientation: Manufacturing process where acrylic sheet is stretched in two directions simultaneously to improve strength and optical properties.
Brittleness: The tendency of acrylic to fracture with little deformation, particularly at low temperatures or high stress concentrations.
Buffing: Polishing process using rotating wheels and compounds to restore optical clarity to scratched or machined acrylic surfaces.
C
Cast Acrylic: Acrylic sheet manufactured by pouring liquid monomer between glass plates and allowing it to polymerize, resulting in superior optical clarity and machinability.
Cell Cast: Individual casting process where each sheet is formed separately, typically producing higher quality results than continuous casting methods.
Chemical Resistance: The ability of acrylic to withstand exposure to various chemicals without degradation, cracking, or loss of properties.
Coefficient of Thermal Expansion: A Measure of how much acrylic expands or contracts with temperature changes, critical for designing assemblies with dimensional stability.
Continuous Cast: Manufacturing method, where acrylic sheet is produced in a continuous process, typically more economical but with slightly lower optical quality than cell cast.
Crazing: A Network of fine surface cracks that can develop in acrylic due to stress, chemical exposure, or improper handling.
D
Desiccant: Moisture-absorbing material used in packaging to protect acrylic sheets from humidity during storage and transport.
Die Cutting: Process of cutting acrylic sheets using shaped steel rules or dies, typically for producing multiple identical parts.
Dimensional Stability: The ability of acrylic sheet to maintain its size and shape under varying temperature, humidity, and stress conditions.
Drape Forming: Thermoforming technique where the heated acrylic sheet is draped over a male mould using gravity and minimal pressure.
E
Edge Finishing: Various processes, including sanding, polishing, and flame polishing, to create smooth, clear edges on cut acrylic sheets.
Elongation: Measure of how much acrylic can stretch before breaking, expressed as a percentage of the original length.
Environmental Stress Cracking: A Failure mode where acrylic develops cracks when exposed to certain chemicals or solvents while under mechanical stress.
Extruded Acrylic: Acrylic sheet manufactured by forcing molten polymer through a die, generally more economical but with lower optical quality than cast acrylic.
F
Fabrication: General term for cutting, shaping, joining, and finishing operations performed on acrylic sheets to create finished products.
Flame Polishing: Edge finishing technique using controlled flame exposure to melt and smooth cut edges, creating crystal-clear surfaces.
Flexural Strength: Measure of acrylic's ability to resist bending forces without breaking, important for structural applications.
Frosted Finish: Translucent surface treatment that diffuses light while maintaining privacy, achieved through etching, sandblasting, or texturing.
G
Glass Transition Temperature: Temperature at which acrylic changes from rigid to rubbery state, typically around 105°C (221°F) for PMMA.
Glazing: Use of acrylic sheets as transparent barriers in windows, displays, or protective applications.
Grain Direction: Orientation of molecular alignment in extruded acrylic sheets, affecting strength and thermal expansion properties.
H
Heat Deflection Temperature: Temperature at which acrylic begins to deform under a specified load, indicating thermal performance limits.
Hot Knife Cutting: Cutting method using a heated blade to simultaneously cut and seal acrylic edges, preventing stress cracking.
Haze: Measure of light scattering in acrylic, expressed as a percentage of transmitted light that deviates from the incident beam.
I
Impact Strength: Measure of acrylic's ability to absorb energy during sudden loading, typically 10-20 times greater than glass.
Injection Moulding: Manufacturing process where molten acrylic is injected into closed moulds to create complex three-dimensional parts.
ISO Standards: International Organization for Standardization specifications for acrylic sheet properties, testing methods, and quality requirements.
J
Jig: Fixture or template used to hold acrylic sheets in the proper position during cutting, drilling, or forming operations.
Joining: Various methods of connecting acrylic pieces, including cementing, welding, mechanical fastening, and adhesive bonding.
K
Kerf: Width of material removed during cutting operations, important for maintaining dimensional accuracy in fabricated parts.
L
Light Transmission: Percentage of visible light that passes through acrylic sheet, typically 92% for clear cast acrylic.
Lubrication: Use of cutting fluids or lubricants during machining to prevent heat buildup and improve surface finish.
M
Machining: Cutting, drilling, milling, turning, and other mechanical operations are performed on acrylic sheets using conventional tools.
Masking Film: Protective plastic film applied to acrylic sheet surfaces during manufacturing and fabrication to prevent scratching.
Molecular Weight: Measure of polymer chain length in acrylic, affecting mechanical properties, processing characteristics, and performance.
Monomer: Basic chemical building block (methyl methacrylate) that polymerizes to form acrylic plastic.
N
Notch Sensitivity: Tendency of acrylic to concentrate stress at sharp corners, notches, or other geometric discontinuities.
O
Optical Clarity: Measure of acrylic's transparency and freedom from distortion, haze, or inclusions that affect light transmission.
Orientation: Molecular alignment in acrylic sheets resulting from manufacturing processes, affecting strength and expansion properties.
Outgassing: Release of volatile compounds from acrylic, particularly important in vacuum or enclosed applications.
P
PMMA: Polymethyl methacrylate - the chemical name for acrylic plastic, also known by trade names like Plexiglas and Lucite.
Polishing: Multi-step process of progressively finer abrasives to restore optical clarity to acrylic surfaces.
Pressure Forming: Thermoforming technique using positive air pressure to force heated acrylic against detailed moulds.
Q
Quality Grade: Classification system for acrylic sheets based on optical properties, surface quality, and dimensional tolerances.
R
Refractive Index: A Measure of how light bends when passing through acrylic, affecting optical applications and light transmission.
Residual Stress: Internal stresses remaining in acrylic sheets from manufacturing or fabrication processes that can cause distortion or cracking.
Router: A Power tool commonly used for cutting, shaping, and edge finishing acrylic sheets with appropriate speeds and feeds.
S
Stress Cracking: A Failure mode where fine cracks develop in acrylic under combined mechanical stress and chemical exposure.
Surface Hardness: Resistance to indentation or scratching, typically measured using Rockwell or Shore durometer scales.
Solvent Bonding: Joining method using chemical solvents to partially dissolve acrylic surfaces, creating welded joints upon evaporation.
T
Tensile Strength: Maximum stress acrylic can withstand when pulled in tension before breaking, typically 65-75 MPa for PMMA.
Thermal Forming: Shaping process where acrylic sheets are heated to a pliable temperature and formed over moulds or patterns.
Thickness Tolerance: Allowable variation in sheet thickness from nominal dimensions, typically ±10% for standard grades.
Transmittance: Fraction of incident light that passes through the acrylic sheet, affected by thickness, additives, and surface quality.
U
UV Resistance: Ability of acrylic to withstand degradation from ultraviolet radiation without yellowing, cracking, or loss of properties.
Ultrasonic Welding: A Joining method using high-frequency vibrations to create frictional heat and weld acrylic parts together.
V
Vacuum Forming: Thermoforming process where atmospheric pressure forces heated acrylic sheet against moulds under vacuum.
Viscosity: A Measure of resistance to flow in liquid acrylic systems, affecting processing conditions and final properties.
W
Weatherability: Long-term resistance to outdoor exposure, including UV radiation, temperature cycling, and moisture effects.
Weld Line: Visible line or weakness that can occur where flowing acrylic meets during moulding or forming operations.
Y
Yellowing Index: Quantitative measure of colour change in acrylic over time or under specific exposure conditions.
Yield Strength: Stress level at which acrylic begins to deform permanently, marking the transition from elastic to plastic behaviour.
Z
Zero Stress Temperature: Temperature at which residual stresses in acrylic are relieved, used in annealing calculations and stress analysis.
This glossary provides essential terminology for anyone working with acrylic sheets, from basic fabrication to advanced engineering applications. Understanding these terms facilitates better communication with suppliers, clearer specification writing, and more successful project outcomes.