Polycarbonate and acrylic are the two most common transparent plastics in industrial use. Both machine well, both transmit light, and both cost far less than glass. The choice between them comes down to what the application demands, because the two materials perform very differently in impact, UV exposure, chemical environments, and temperature range.
Specifying the wrong one does not always fail immediately. A wrong specification shows up later as a shattered panel in a guarding application, a yellowed window after a season of outdoor exposure, or a crazing failure when a cleaning chemical contacts the surface. Getting the choice right at the start is less expensive than learning from a failure in the field.
The Core Trade-off
Polycarbonate has significantly higher impact resistance than acrylic. Acrylic has higher native surface hardness and better UV stability without a coating. Those two differences drive most material selection decisions in industrial applications.
If the application involves impact risk, safety guarding, or structural loading, polycarbonate is the starting point. If the application is primarily optical, decorative, or in a low-impact environment where UV stability is a priority, acrylic warrants consideration. Most demanding industrial applications, particularly those involving machinery guarding, robot enclosures, and equipment cabs, end up specifying polycarbonate because impact resistance is non-negotiable.
Impact Resistance
Polycarbonate absorbs impact energy by deforming. It bends before it breaks. Acrylic fractures under impact, and acrylic fragments are sharp. In any application where a panel is in the path of a dropped tool, an ejected workpiece, or a human body during an equipment interaction, the difference matters in the way it matters when things go wrong.
This is why polycarbonate dominates in machinery guarding, cobot safety barriers, equipment cab glazing, and anywhere safety is part of the design requirement. The higher upfront cost of polycarbonate relative to acrylic is a fraction of the cost of an incident caused by a material that could not absorb the load.
For low-impact applications such as instrument covers, display panels, and light diffusers in protected environments, acrylic's lower cost and slightly better optical properties can make it the right call.
Optical Clarity and Haze
Both materials are optically clear in standard grades. Acrylic transmits light at approximately 92% of visible wavelengths. Clear-grade polycarbonate transmits approximately 88 to 90%. The difference is perceptible in side-by-side comparison under precise optical measurement per ASTM D1003[1], but it is not noticeable in most industrial viewing applications.
Haze is the more practically important optical parameter in industrial use. Both materials start at low haze values. Both accumulate haze through abrasion during cleaning and handling. Coating selection drives long-term haze performance more than the base material choice. Five Star's Fusionite coating line is applied to polycarbonate substrates to deliver Taber haze below 2 to 3% through hundreds of abrasion cycles, maintaining optical performance across the service life of the part.
UV Stability and Outdoor Performance
Uncoated polycarbonate yellows when exposed to UV radiation. The yellowing is not cosmetic: it reduces optical transmission and signals material degradation that eventually affects mechanical performance. For any outdoor application or installation near windows and skylights, polycarbonate requires a UV-stable coating.
Acrylic has better native UV resistance. Standard acrylic grades maintain optical clarity through outdoor exposure without a UV protective coating, which makes acrylic a common choice for signage, display cases, and outdoor architectural glazing where impact loads are low and long-term appearance matters.
For industrial applications where polycarbonate is required for impact performance and the installation is outdoors or UV-exposed, UV-stable Fusionite formulations resolve the UV limitation without changing the base material's impact properties.
Chemical Resistance
The chemical environments in the application should be confirmed against the specific material's chemical compatibility data before finalizing a specification. The general pattern: polycarbonate is attacked by aromatic and chlorinated solvents, concentrated acids, and some hydrocarbons. Acrylic has better resistance to dilute acids and alkalis but is sensitive to ketones, esters, and aromatic solvents.
In practice, this means that cleaning protocols need to be verified against the panel material. A cleaning solvent that is safe for acrylic may craze polycarbonate, and vice versa. Installations in pharmaceutical, food processing, or chemical manufacturing environments should have the facility's cleaning chemicals checked against a compatibility chart for the specific grade being specified.
Coatings affect chemical resistance as well. Fusionite coatings provide an additional barrier layer that improves resistance to some cleaning agents over uncoated polycarbonate.
Scratch Resistance
Acrylic has higher native surface hardness than polycarbonate and scratches less easily without a coating. Polycarbonate is soft enough that an uncoated surface will abrade visibly with standard industrial cleaning tools.
For polycarbonate in applications involving regular cleaning, handling, or contact with abrasive particulate, a hard coat is not optional. Five Star's Fusionite CGII and CGIII coatings bring polycarbonate's abrasion resistance to the level required for industrial service life, eliminating the scratch disadvantage of the base material.
Operating Temperature
Polycarbonate handles a wider service temperature range than acrylic. Standard polycarbonate grades maintain structural integrity from approximately -40°F to 265°F. Standard acrylic grades have a lower heat deflection temperature and are not appropriate for high-temperature enclosures, near heat sources, or in applications that see significant thermal cycling.
In equipment cabs, engine compartment covers, and industrial enclosures near heat-generating machinery, polycarbonate's thermal performance is another reason it is the dominant choice.
When to Specify Polycarbonate
Polycarbonate is the right choice when any of the following apply: impact resistance is a design requirement, the panel is in or adjacent to a safety guarding zone, the application involves temperature extremes, the part needs to be thermoformed or machined to a complex geometry, or the installation is in an environment with aggressive cleaning protocols that require a hard-coated surface to maintain performance.
Five Star's polycarbonate fabrication capabilities cover sheet, formed, and CNC-machined components in a full range of grades and Fusionite coating options.
When to Specify Acrylic
Acrylic is the right choice when impact risk is low, UV stability without a coating is a priority, optical transmission is the primary specification driver, the application is in a protected indoor environment, and cost is a controlling factor. Instrument display covers, display cases, low-risk machine windows, and signage applications often justify acrylic on these grounds.
If the application could plausibly involve impact at any point in its service life, polycarbonate is the safer default.
Making the Right Call Before Fabrication
The material choice is easiest to change before a part is fabricated. After a panel is cut, coated, and installed, a material switch means scrapping the part. For applications where the requirements are unclear, Five Star's engineering team can work through the application environment, load case, and optical requirements to help identify the right specification before the first part is made.
Five Star Fabricating fabricates polycarbonate windows, guards, enclosures, and covers for industrial OEMs from its manufacturing facilities in Twin Lakes, Wisconsin. Material selection support, Fusionite coating recommendations, and custom prototypes are available through our engineering team.
Contact our engineering team to discuss material selection for your application.
References
1. ASTM D1003-21 — Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics