Price Per Tool Is a Trap: Costing Carbide by the Part

Procurement is measured on price, so procurement optimises price. But the number that hits your P&L isn't the price of the tool — it's the cost of every part the tool produces. Those are very different numbers, and optimising the first can quietly inflate the second.

§The formula that matters

For any tooling decision, the honest metric is cost per part — or per metre drilled, per hole, per finished component:

Cost per part = (tool price ÷ parts per tool) + (machine & labour cost of every tool change, spread across those parts) + (scrap and rework attributable to the tool)

Sticker price is only the first term — and often the smallest.

§A worked comparison

Consider two inserts for the same operation:

*Machine time plus labour for each change. The “expensive” insert is 35% more per edge and roughly 40% cheaper per part — before you count the downtime, the end-of-life scrap, and the scheduling disruption the cheaper tool adds. In a high-throughput line, changeover time alone can dominate the entire comparison.

§What to actually track

• Parts (or metres, or holes) per edge — the single most important number, and the one quotes never show.
• Machine + labour cost per minute of downtime for a tool change.
• Scrap and rework rate as tools approach end of life.
• Consistency — a tool that lasts 900 parts ±5% beats one averaging 950 ±40%, because you can schedule the change.

§The procurement reframe

None of this means “always buy premium.” It means measure the right thing. Sometimes the budget tool genuinely wins; often it doesn't. Cost-per-part turns a price argument into an evidence-based decision — and usually pays for a modest tooling upgrade many times over.