A wire harness cell is a good place to learn what packaging materials can really take. The loads are trivial, which tempts people to specify light construction. Then the bins come back stained, cracked at the corners and slippery with oil mist.
Oil mist is the defining condition
Cutting oils, drawing lubricants and finger prints of assembly grease end up airborne and settle on everything. Polypropylene tolerates most of these reasonably, though aromatic content in some cutting fluids is the exception we described in honeycomb around solvents and degreasers.
The practical effect is not chemical attack, it is slip. An oily bin is hard to hold, slides on the bench, and eventually gets dropped.
Cut wire ends are sharper than they look
Offcuts of copper and aluminium with cut ends puncture thin sheet, especially at the base where they settle and get pressed by everything above. Base thickness and a smooth interior both matter: smooth so nothing catches, thick enough that nothing pierces.
Sharp offcuts also mean no open-flute edges inside the bin. A sealed or turned edge costs little and removes the catch point.
Bench-level handling sets the failure modes
These bins get lifted one-handed hundreds of times a day, slid along benches, and stacked three or four high when full. The failures concentrate in handles and rims – the parts people touch. Handles need generous radii and real material behind them; a handle that is a token slot cut in thin board tears out within weeks.
Colour coding does real work here
Harness assembly is variant-heavy, and the fastest error prevention is colour. Assign a colour per variant family and keep it consistent across cells. Where variants change frequently, colour the replaceable part rather than the bin, per the approach in colour coding without repainting.
Static considerations
Some components in harness assembly are static sensitive, and a standard insulating bin is the wrong choice for those. If your process includes any ESD control, ask specifically rather than assuming the standard construction is suitable – the definitions in what surface resistivity means in practice are the ones to measure against.
Cleaning reality
Solvent-wiped benches mean solvent-wiped bins, whether anyone planned it or not. If the cell uses aggressive degreaser daily, either accept shortened life and plan replacement, or move those bins to a material that tolerates it. It is cheaper to design around the cleaning habit than to change it.
Bin size versus replenishment frequency
Small bins need frequent replenishment and large ones occupy bench space that is usually the scarcest resource in the cell. The usual compromise – one size for everything – guarantees that some parts overflow and others sit half empty for days.
Two sizes, chosen from actual consumption rather than from what is available, solve this more effectively than any clever bin design. Fast movers get the larger bin, slow movers the smaller, and the bench stops being reorganised every week.
Bins that get wiped down daily
Solvent-wiped benches mean solvent-wiped bins, whether or not that was intended. Ask what the cell actually wipes with, because it decides bin material and bin life more than any load case in this environment.
What we can do
We cut small parts trays and bins from corrugated PP sheet and will ask what gets wiped across the bench before quoting. Tell us the variants, the cleaning method and whether any components are static sensitive, and we will specify accordingly – including telling you when a moulded bin is the better answer.