It is the first decision, and the most expensive one to get wrong. A payback calculation alone does not settle it.
What points toward subcontracting
Low or irregular volume. An idle machine produces nothing but still costs — space, maintenance, tied-up capital.
No process experience. Vibratory finishing and blasting have recipes. They are learnable, but they are learned on scrap.
No people. A machine needs a trained operator, not whoever is free that day.
You want to test. A few months of subcontracting tell you exactly which parameters you need, if you do end up buying.
Rare operations with heavy requirements. Shot peening to standard, with documentation, is the classic case.
What points toward owning
Constant, predictable volume. Here payback genuinely applies.
Short lead times. Every batch sent out adds transport and waiting.
Process control. When finishing is critical to your product, you want to intervene immediately.
Confidentiality. Parts that do not leave the plant.
Transport cost. On large or heavy parts, transport can exceed processing.
The calculation people get wrong
The usual comparison is “subcontracting price per part” against “monthly instalment”. It is incomplete.
For owning, add: consumables, energy, maintenance, wear parts, the operator, floor space, waste water treatment where applicable, and the learning period until scrap drops to an acceptable level.
For subcontracting, add: transport both ways, parts tied up during the cycle, and the risk of depending on someone else’s schedule.
How it is decided, in practice
Start with subcontracting. Measure. When volume becomes constant and the monthly cost approaches a machine instalment, you have your answer — and, in addition, you know exactly which machine you need.
An audit of your process, done before the decision, costs less than a badly sized machine.
Related reading
- Vibratory finishing subcontracting: how it works
- Blasting and shot peening subcontracting
- How to choose the right sandblasting equipment
- Free on-site process audit
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