How should a custom brush be tested before production?
In stages, from fit to endurance: dimensional fit, gentle first contact, cleaning performance, surface result, wear, contamination, and finally repeated production cycles. Between samples, change one design variable at a time. If two change together, you will not know which one helped or which one caused the failure.
Stage 1: does it fit?
- Check every brush and fitting dimension against the machine or the part.
- Check the assembly direction, access, clearance to fit it, shaft fit, thread, hub, keyway and the way it comes out.
- Turn it by hand or at low speed, with no contact, to check runout, balance and interference.
- Record the sample revision and the dimensions as actually measured.
Stage 2: what happens at first contact?
Start at the lowest speed, engagement, pressure or number of passes. Watch how the filament bends and whether debris leaves the face. Make sure the tips reach the intended zone and are not folding over, snagging or running on their sides.
Stage 3: what do you measure?
| Result | How to measure it |
|---|---|
| Cleaning | Residue mass, visual grade, particle count, swab result, pressure drop, or a defined cleanliness test |
| Surface | Roughness, gloss, scratches, coating damage, edge radius, dimensional change, or microscopy |
| Process | Cycle time, passes, line speed, motor current, pressure, fluid, temperature and operator steps |
| Brush | Loss of diameter or trim, filament set, loading, shedding, corrosion, runout and retention |
Stage 4: how long does it last?
Run enough cycles to bring out heat, permanent set, loading, chemical attack and uneven wear, and inspect at fixed intervals. Only estimate life once the wear rate has settled: the first cycles knock off the high spots and wear faster than the brush will in steady service.
How do you keep control of changes?
For every sample, record the revision, filament lot, dimensions, material, pattern, process settings, part lot, residue condition and result. Never change grit, filament diameter, trim, density, speed and engagement together. Run this way, the sample program ends with a configuration you can buy again and get the same brush.
What goes into the approval package?
The signed drawing, the approved sample, the inspection report, photographs, the process window, acceptance criteria, packing method and labeling. Mark which features are critical to fit and which are critical to performance.
