Subcontract and precision engineering packs face a problem the rest of engineering does not: you rarely know what happens to the part next. It may go straight onto a line, into stores for months, or out to a third party for finishing - and a pack specified for the shortest journey fails on the longest.
Packing for an unknown next step
A subcontract machinist despatches a part and loses sight of it. It might be fitted that afternoon, it might sit in a customer's stores through a damp winter, or it might be sent on to a plater and come back. Each of those is a different protection requirement and you will not be told which applies.
The practical response is to specify for the longest credible journey rather than the typical one, and to accept that this means a slightly more protective pack than the average despatch strictly needs. The alternative is a pack that works most of the time.
Surface-critical work
Precision work is frequently judged on a surface - a machined face, a ground finish, a plated coating. The packaging is in contact with that surface for the whole journey, which makes the pack itself one of the likelier sources of damage.
| Risk | Cause | Specification |
|---|---|---|
| Abrasion marks | Movement against board or other parts | Soft interleave or fitted pocket |
| Pressure marks | Hard material in contact under load | Non-marking foam, held by non-critical edges |
| Corrosion | Humidity over a long storage period | VCI paper or film, pack kept closed |
| Contamination | Fibre or dust from the packaging | Non-shedding materials |
| Impact to a projection | Leverage on an unsupported feature | Pocket supporting the body, projection clear |
| Part-to-part damage | Multiple parts loose in one pack | Compartmented or individually wrapped |
Protecting critical surfaces.
Corrosion over an unknown storage period
Corrosion protection is frequently specified and frequently undone. VCI paper and film work by maintaining a vapour within a closed pack, so a pack that is opened and re-taped at a goods-in desk has lost most of its protection without anyone noticing.
That makes the closure part of the corrosion specification, and it makes labelling that removes any reason to open the pack genuinely functional - see protective packaging.
Count accuracy on batch work
- Batch quantities are checked at goods-in and disputes are expensive in time rather than money.
- Bagging by line makes a count checkable without unpacking everything.
- Compartmented inserts make a shortage visible rather than counted - see Foam Inserts: When a Fitted Pocket Pays for Itself.
- Labelling the count on the outside removes the need to open the pack.
- Part-used batches need a reclosable pack, because they always occur.
One-offs versus repeat lines
The economics split cleanly. A repeat line justifies a fitted pack - the tooling or cutting setup recovers through pack time, consistency and damage that stops happening. A genuine one-off never will, and specifying bespoke for it is spending setup on something that ships twice.
Most precision businesses should run a short standard range with a good protective specification for the variable work, plus fitted packs for the handful of lines that repeat - see Bespoke Packaging: What the Tooling Actually Buys You.
Export and long journeys
An export despatch multiplies every risk: more handovers, longer storage, wider temperature and humidity range, and a far higher cost of failure because replacement means remaking and shipping again.
It is the clearest case for specifying up rather than to the average, and for closing the corrosion question properly - see export packing.
The storage constraint
Precision engineering businesses have machine space, not warehouse space. Packaging is bulky and nearly weightless, so buying properly - a full run of a right-sized carton or a batch of fitted inserts - competes directly with the floor the business actually earns from.
Holding the run centrally and calling it off resolves it - see packaging stockholding.
What to send us
The part or an accurate drawing, which surfaces are critical, whether corrosion is a risk, how long it may sit at the customer, whether batches are part used, and whether the line repeats. Photographs of anything arriving marked are particularly useful because surface damage shows its cause.
See industrial packaging and foam packaging.
A first step for subcontract engineers
The specification question here is about the journey you cannot see, so start by establishing what it might be.
- Ask two or three customers what happens to parts on arrival - fitted, stored, or sent on. The answers usually vary more than expected.
- Check whether VCI-protected packs are being opened at goods-in and re-taped.
- Count how many of your lines genuinely repeat. Those are the fitted-pack candidates; the rest need a good standard range.
- Look at a batch pack and ask whether a shortage would be visible or would have to be counted.
- Separate export despatch and specify it upward - see export packing.
The short version
- You rarely know the next step, so specify for the longest credible journey.
- The packaging is in contact with the critical surface for the whole journey.
- VCI protection depends on the pack staying closed, so closure is part of it.
- Compartmented packs make a shortage visible rather than counted.
- Fitted packs suit repeat lines; one-offs need a good standard range instead.
Frequently asked questions
How should machined parts be packed?
With nothing abrasive against the critical face and the part held so it cannot move. Where a projection exists, support the body and leave the projection clear rather than wrapping the whole item.
Do you supply corrosion protection?
VCI paper and film, barrier bags and desiccant, yes. The thing worth checking first is whether the pack stays closed, because an opened and re-taped pack has lost most of the protection.
Should subcontract work use bespoke packaging?
Only on lines that repeat. A one-off will not recover tooling, and most subcontract businesses are better served by a short standard range plus a good protective specification.
How do we avoid count disputes on batch work?
Bag by line, use compartmented inserts where the quantity matters, and label the count on the outside so goods-in does not have to open the pack to check it.
What changes for export despatch?
More handovers, longer storage and a wider humidity range, with a much higher cost of failure. It is the clearest case for specifying above the average - see export packing.