Polycarbonate vs PETG Sheets: Which to Specify for Guards, Enclosures and Thermoforming
Polycarbonate and PETG are the two clear sheets specifiers shortlist when acrylic is not tough enough, and they solve different problems. Polycarbonate takes roughly 250 times the impact of glass, works to 120 °C and carries UL94 V-0 fire-rated grades; PETG forms at lower temperatures without pre-drying, offers superior chemical resistance, meets food-contact standards in unmodified form, and typically prices 10–25% below PC. This guide compares them on the numbers that decide machine guarding, equipment enclosures and thermoformed parts.
Quick decision table
| If your application is… | Specify | Deciding factor |
|---|---|---|
| Machine guards on high-energy equipment (CNC, presses, turbines) | Polycarbonate | Impact — PC’s toughness margin is the safety case |
| Light-duty guards, indoor barriers, hoppers, chutes | PETG | Adequate impact at a lower price, and it fabricates faster |
| Anything near heat — lamps, motors, hot process, dark roofing | Polycarbonate | PETG softens from ~65–70 °C; PC runs to 120 °C |
| Food-contact covers, medical device housings, POP displays | PETG | Food-contact compliant unmodified; deep-draw thermoforms cleanly |
| Fire-code interiors (transport, public buildings) | Polycarbonate | V-0 / B1 rated grades exist; standard PETG burns |
| Chemical wash-down environments, disinfectant exposure | PETG | Better resistance to cleaners that stress-craze PC |
| Outdoor glazing and roofing | Polycarbonate (UV co-extruded) | PETG weathers poorly outdoors; PC with UV cap is a 10-year material |
Property comparison with numbers
| Property | Polycarbonate | PETG |
|---|---|---|
| Impact vs float glass | ~250× | ~70–100× (well above acrylic’s 17×) |
| Continuous service temperature | −40 to +120 °C | −40 to ~65 °C |
| Light transmission (3 mm clear) | 88–89% | ~88–90% |
| Thermoforming | 190–205 °C, must pre-dry 4–12 h | 120–160 °C, no pre-drying — faster, cheaper forming |
| Chemical resistance | Sensitive to alkalis, many cleaners, solvents (stress crazing) | Noticeably better against dilute cleaners and disinfectants |
| Fire behaviour | Self-extinguishing; UL94 V-2/V-0 and EN 13501 B1 grades | Burns; only specialty FR grades improve it |
| Outdoor UV life | Excellent with co-extruded UV cap layer | Poor — yellows and embrittles; indoor material |
| Food contact | Selected grades only | Standard grades comply (FDA/EU regimes) |
| Scratch resistance | Soft surface; hard-coated grades available | Similar — both scratch without coating |
| Relative price (clear, like-for-like) | Baseline | Typically 10–25% lower |
Impact and safety: margin matters
PETG’s toughness surprises people coming from acrylic — it bends and whitens rather than shattering, and for hoppers, sight windows and light-duty guarding it is genuinely sufficient. The specification question is margin: a guard’s job is the worst day on the line, not the average one, and polycarbonate’s reserve against a thrown tool, a burst abrasive disc or an ejected workpiece is why standards-driven guarding on high-energy machinery stays with PC. A useful rule from our project work: if the guard protects against stored energy (spindles, presses, pressure), specify polycarbonate; if it mostly separates people from pinch points and splash, PETG earns its discount.
Temperature and fire: the hard limits
PETG’s ~65 °C ceiling is the most common disqualifier in industrial settings — enclosures over drive motors, panels near lighting, and any dark-colored panel in direct sun can all exceed it. Polycarbonate holds stiffness past 100 °C and offers certified fire-rated grades (UL94 V-0, EN 13501 B1) that PETG cannot match — decisive for rail, transit and public-building interiors. If the environment is hot, fire-regulated or outdoors, the comparison ends early in PC’s favour.
Fabrication economics: where PETG wins real money
PETG’s forming window is its commercial advantage: it thermoforms 40–60 °C cooler than polycarbonate and needs no pre-drying, which removes an oven cycle from every production run. For deep-draw trays, POP displays, medical housings and formed covers at volume, that is a per-part cost gap PC cannot close. PETG also die-cuts and cold line-bends in thin gauges where PC demands machining. For flat cut panels the two fabricate similarly — our fabrication services (CNC, laser cutting, bending, printing) run both — so the forming complexity of your part, not the sheet price, is usually what tips the total cost.
Buying guidance
Specify polycarbonate when any of these words appear in the requirement: impact-rated, fire-rated, outdoor, above 65 °C, safety glazing. Specify PETG when the driver is thermoformed geometry, food or medical contact, chemical wash-down, or budget on light-duty indoor panels. Mixed lines are normal — PC where the energy is, PETG where the forming is. For polycarbonate, our custom sheet program covers cut-to-size, colors and fire-rated grades from stock to container volume.
FAQ
Q: Is PETG as strong as polycarbonate? A: No — PETG reaches roughly 70–100× the impact resistance of glass, strong for a clear plastic but well short of polycarbonate’s ~250×. For light-duty guarding PETG is adequate; for high-energy machinery the PC margin is the point of the guard.
Q: Is PETG cheaper than polycarbonate? A: Usually 10–25% cheaper as flat sheet, and the gap widens on thermoformed parts because PETG forms cooler and skips pre-drying. On fire-rated or outdoor jobs the comparison is moot — standard PETG does not qualify.
Q: Can PETG be used outdoors? A: Not for sustained exposure — it yellows and embrittles under UV. Outdoor clear glazing belongs to UV-co-extruded polycarbonate (or acrylic where impact permits). PETG is an indoor material.
Q: Which is better for machine guards, PETG or polycarbonate? A: Match the material to the stored energy: polycarbonate for spindles, presses and anything that can eject mass at speed; PETG for splash guards, pinch-point barriers and enclosures on low-energy equipment. Many plants run both on the same line.
Deciding between materials for a guarding or enclosure program? Send us the application — we quote polycarbonate honestly, and tell you when PETG (or acrylic) is the cheaper right answer.
FAQ
Is polycarbonate better than PETG?
For structural and outdoor use, yes: polycarbonate has roughly 200× the impact strength of glass, higher heat resistance (up to 120°C continuous) and better UV stability. PETG is cheaper and easier to thermoform, but yellows faster outdoors.
What is the price difference between PC and PETG?
PETG is typically 10–25% cheaper per kg. However, PC panels last longer outdoors and carry higher impact ratings, so the cost per year of service is usually lower for polycarbonate in roofing and glazing.
Can PETG replace polycarbonate for greenhouses?
Not for long-life glazing. PETG is fine for indoor displays and thermoformed parts, but for greenhouse roofs with UV exposure and hail risk, polycarbonate multiwall is the proven choice.
Which is more scratch resistant, PC or PETG?
Standard PETG is softer than PC. With our hard-coated (flow-coated) PC sheets, scratch resistance is far better than both uncoated PC and PETG.
Is PETG food safe like polycarbonate?
Both are food-contact approved in many regions, but PC remains the standard for reusable food containers where impact strength matters. Confirm the specific grade with your supplier.
Polycarbonate vs PETG: Property Comparison Table
| Property | Polycarbonate (PC) | PETG |
|---|---|---|
| Impact strength (Izod) | 850–950 J/m | ~100 J/m (≈9× lower) |
| Max continuous temperature | ~120°C | ~70°C |
| UV stability outdoors | Excellent (UV-coextruded) | Poor — yellows in 1–2 years |
| Chemical resistance | Good (oils, alcohols) | Better (some solvents) |
| Thermoforming ease | Good | Excellent |
| Relative price per kg | Baseline | 10–25% cheaper |
| Outdoor service life | 10+ years | 2–4 years |
Bottom line: PETG wins on price and formability for indoor parts; polycarbonate wins on impact, heat and outdoor life. For roofing, glazing and guards, PC is the proven choice.
Can PETG replace polycarbonate in machine guards?
No — PETG lacks the impact strength (roughly 9× lower Izod) required by safety standards such as ISO 14120. Guards must use polycarbonate or equivalent impact-rated material.
Is PETG good for outdoor signs?
Only short-term — PETG yellows and becomes brittle within 1–2 years outdoors. Use UV-stabilised polycarbonate for outdoor signage that must last.