Enclosures
8 min read
Designing an IP67 gasket path that survives assembly
A seal is only as good as its worst corner. How we size grooves, choose compression and keep the gasket in place on the line.
Author
Daniel Okafor
Role
DFM and suppliers
Published
Reading
8 min read
Start from compression, not from the gasket
An elastomer seals because it is squeezed. Too little and water finds a path; too much and the gasket takes a permanent set or the lid bows between screws. For most silicone and EPDM profiles we design for 20 to 30 percent compression at nominal, and check it at both ends of the tolerance stack.
Grooves, corners and screws
The groove holds the gasket in position and limits how far it can be crushed. Its width must leave room for the material to spread, and its corners need a generous radius so the cord does not kink.
Groove fill between 75 and 90 percent
Corner radius at least three times the cord diameter
Screws close enough that the lid cannot lift between them
A continuous path, with no gaps around bosses
Testing what matters
We test the assembled enclosure, not the gasket on its own. A first prototype goes through immersion at one metre for thirty minutes, then we open it and look for the first trace of water. The marks tell us exactly which corner or screw span needs work.
It is not glamorous, but it is the step that turns a drawing note into a rating you can print on the box.
More from the journal
→
Design for manufacture
6 min read
Draft angles are a conversation with the mould
Why one and a half degrees decides whether a part releases cleanly, and how we choose draft before the first sketch is dimensioned.
Tolerancing
7 min read
Reading a tolerance stack before it reads you
Four parts, four reasonable tolerances and one gap that can close completely. A worked example of worst-case and statistical stack-ups.
Electronics
5 min read
Board first, box second
Why we start an enclosure from the circuit board, its connectors and its antenna, and only then draw the plastic around it.