GlossaryKind of term: Cost and economicsTool cost per part
What is tool cost per part?
Tool cost per part is the cost of cutting-tool consumption allocated to one part, usually worked out from tool price, tool life and cutting time.
For each tool, take the price per cutting edge divided by tool life, times that tool's cutting time per part. For an insert, the price per edge is the insert price divided by the number of edges you actually use. For a solid end mill that is reground, purchase and regrind costs are spread over all its tool lives together. The sum over the tools in the routing gives the tool cost of one part. Holders and tool bodies last much longer and usually sit in the hourly rate or in overhead.
How does tool cost per part work in practice?
Many shops carry tooling as an average in the machine hour rate. That works as long as the work resembles the average. With short tool life and expensive tools, as in hard-to-machine materials, or with a special drill or a long-neck cutter, the average can be too low, and other work carries part of the cost. A line of its own allocates consumption to the part that causes it. On a one-off the wear share is often small beside setup and programming; on larger batches in such materials it can weigh more. How reliable the figure is depends on the tool life you assume.
What is tool cost per part often confused with?
Tool cost per part is not special tooling: consumption accrues with every part, buying a special tool is a one-off cost. If that special tool wears over a long batch, its consumption does come back per part.
Frequently asked questions
How do you calculate tool cost per part?
Per tool: price per cutting edge divided by tool life in minutes, times that tool's cutting time per part. Add up the tools in the routing. For an insert, the price per edge is the insert price divided by the number of edges actually used.
Should tooling go in the hourly rate or on its own line?
An average in the hourly rate is simple and suits work that resembles the average. When material or tooling differs strongly, consumption belongs on a line of its own, against the part that causes it. Choose one method per tool, so nothing is counted twice.