A polycarbonate equipment case is a protective shell, and the specification that matters is not the flat sheet gauge but the wall thickness at the corners after the sheet has been drawn over a mould.
An instrumentation company shipped 2 000 cases formed from 3 mm polycarbonate. Field returns showed corners at 1.8 mm, and units arriving by air freight had cracked at the base corners where the case met the pallet.
Polycarbonate equipment case draw and wall
- Light instrument: 3 mm start
- Heavy or fragile contents: 5 to 6 mm start
- Draw ratio: 1.2 to 1 for predictable corners
- Corner radius: 10 mm minimum
Draw ratio is the number that decides the corner. A case 200 mm deep formed from a 300 mm wide blank draws material from all four sides, and the corners lose thickness fastest; a generous radius and a shallower draw keep them predictable.
Lid, gasket and transit
The lid land is the weather detail. A 6 mm flat land around the opening compresses a gasket evenly; a land that runs over a formed radius lets water in at exactly the point where the case is most likely to be stood in a puddle.
Transit is where cases fail quietly. Air freight depressurises and vibrates; a case with 1 mm of clearance between contents and wall transfers every shock to the equipment, and foam inserts are part of the case design, not an accessory.
For cutting the blanks for a formed programme, polycarbonate cut to size covers the tolerance.
Send your equipment outline, protection requirement and volume to oversales@rpplexiglass.com for a formed case quote.
Frequently Asked Questions
What thickness polycarbonate for an equipment case?
3 mm for light instruments, 5 to 6 mm for heavy or fragile contents. Wall thickness at the corners after forming is what protects, not the starting gauge.
Why choose polycarbonate over ABS for a case?
Impact strength and temperature range. Polycarbonate takes a drop without shattering and holds shape in a hot vehicle; ABS is easier to form and cheaper but brittle in cold.
How is the lid sealed?
By a gasket in a formed land plus two latches, not by a lip alone. A lip keeps dust out and lets water in; a 6 mm gasket land with latches keeps a case dry in a rain shower.