PC Sheet Is 250 Times More Impact-Resistant Than Glass: Grades and Selection
The short version
Impact strength is PC (polycarbonate) sheet’s headline property: PC sheet is almost unbreakable, and solid sheet is up to 250 times more impact-resistant than glass. But “250 times” is only the starting point — what actually drives selection is the graded test data behind the security-glazing and machine-guard standards. This article turns those graded test results into tables, so you know which table to read for equipment guards, sight windows and anti-vandal glazing.
1. Where “250 times” comes from
Solid PC sheet is up to 250 times more impact resistant than glass, tested in accordance with several standards and complying with the most stringent regulations. Two qualifiers matter:
- “Up to”: 250× is the upper bound of the class — actual performance at each thickness and duty is read from the graded tables below;
- It comes from the substrate: general-purpose (GP), UV-protected and AR hard-coated grades share the same result tables — the impact resistance belongs to the PC base material, not to any coating.
2. Security glazing classification: EN 356
EN 356 classifies security glazing by resistance to manual attack, on a scale from P1A to P8B — higher numbers mean stronger protection, and class B involves higher attack energy than class A. Measured results for the GP / UV / AR grades:
| Thickness | EN 356 class |
|---|---|
| ≥ 4 mm | P5A |
| 10 & 12 mm | P8B |
In practice: from 4 mm you get P5A vandal resistance; for the top P8B rating, specify 10 mm or 12 mm. Typical applications include display cases, public facilities, and the schools and hospitals named under the AR grade.
3. Flat-glass safety classification: EN 12600
EN 12600 classifies flat glass in buildings by pendulum impact, where class 1 is the best. Measured data for textured UV sheet:
| Thickness | Class |
|---|---|
| 5 mm | Class 3 |
| 6 mm | Class 2 |
| 8 / 10 / 12 mm | Class 1 |
8 mm is the entry thickness for the best class.
4. Vehicle glazing: ECE R43 (AR hard-coated only)
AR hard-coated sheet in 3–12 mm can reach Class B (ABG) and VIII/B/M (ECE R43) — ECE R43 is the regulatory framework for vehicle glazing. Wherever vehicle-glazing compliance applies (vehicle windows, observation glazing), AR is the grade to specify; its hard coat also delivers a glass-like surface hardness that uncoated PC cannot offer.
5. Machine guards: ISO 23125 and EN 12417 (the tables buyers should read)
Machine-guard and sight-window sheet is graded under two standards (ISO 23125 for turning machines, EN 12417 for machining centres). Graded data:
DIN EN ISO 23125 (guard classification):
| Thickness | GP / AR class |
|---|---|
| 4 mm | A2 |
| 6 mm | B1 |
| 8 mm | C1 |
| 10 mm | C2 |
| 12 mm | C2 |
| Titan 20 mm | C3 |
DIN EN 12417 (withstandable impact energy and projectile speed):
| Thickness | GP / AR |
|---|---|
| 4 mm | E = 370 Nm, 86 m/s |
| 6 mm | E = 510 Nm, 101 m/s |
| 8 mm | E = 720 Nm, 120 m/s |
| 10 mm | E = 1037 Nm, 144 m/s |
| 12 mm | E = 1110 Nm, 149 m/s |
| Titan 20 mm | E = 1531 Nm, 175 m/s |
E is the test impact energy (Nm) and m/s the corresponding projectile speed — the higher the values, the greater the ejected-particle impact the guard withstands. Selection is straightforward: match machine type and risk level to the table, and for heavy-duty use step up to 20 mm Titan — class C3, the highest in the ISO 23125 table.
Selection cheat sheet
- Anti-vandal glazing (display cases / public / schools): EN 356 → ≥ 4 mm for P5A, 10/12 mm for P8B
- Safety glazing replacement: EN 12600 → 8 mm and up reaches Class 1
- Vehicle glazing compliance: ECE R43 → AR hard-coated, 3–12 mm
- Machine guards: ISO 23125 / EN 12417 → 4–12 mm in GP/AR, 20 mm Titan for heavy duty
FAQ
Q: 4 mm already reaches P5A — is it enough for every anti-vandal application?
No. P5A and P8B sit several energy classes apart. Match the rating to the threat: 4 mm covers general vandalism, while the P8B rating requires 10/12 mm. The same logic applies to machine guards — 4 mm is only class A2, and class C starts at 8 mm.
Q: How does acrylic (PMMA) compare in impact strength?
Acrylic fails in a brittle manner under heavy impact and is far less impact-resistant than PC. For any rated security or machine-guard application, choose PC; acrylic suits static sight windows where surface hardness and optics come first.
Q: Does hard coating sacrifice impact resistance?
GP and AR share the same result tables with identical classifications at equal thickness — the hard coat changes surface hardness, while the impact resistance still comes from the PC substrate.
Closing
Selecting material for equipment guards and sight windows is essentially matching your duty case to the tables above. Wuxi Cremage Technology provides custom equipment guards and sight windows plus precision PC/acrylic machining, supporting the whole path from grade selection and thickness confirmation to mounting design. Further reading: chemical resistance and stress cracking of PC, PC sheet cleaning and maintenance guide.
References
- [1] Exolon® Technical Manual Solid (Makrolon® sheet, now Exolon®), Chapter 3: https://www.exolongroup.com/index.php/fuseaction/download/lrn_file/mf0261_e_210502.pdf