For a shop running its own waterjet, hourly operating cost and cost per finished part answer different questions. The hourly model tracks the resources used to operate the equipment. The per-part model also accounts for the material, setup and work needed to produce an accepted part.
Define the hour before calculating its cost
Choose a reporting period and a consistent time boundary. Record whether machine hours mean powered-on time, jet-on time or productive cutting time. Keep the same definition when comparing jobs or periods; an hourly figure is hard to interpret without its denominator.
Use consumption and operating records from the machine. Separate measured running expenses from allocated ownership expenses so each can be reviewed on its own terms.
Build the hourly operating model
For abrasive waterjet cutting, running resources include abrasive, electricity, water and wear parts. Pump duty, cutting-head configuration and water supply conditions belong in that calculation. Include pump and head maintenance, operator attendance and the planned work for cleaning and handling spent abrasive.
Group the recorded costs under those headings, then divide the included operating costs by the machine hours recorded for the same period. State which headings are included. If maintenance or operator labor is already in this rate, do not add the same expense again to a job.
For a fuller ownership model, show equipment cost allocation, premises and other overhead separately. Use the shop's own accounting basis; do not mix an operating-only rate with a rate that already includes ownership expenses.
Convert the job cost into cost per accepted part
Apply the hourly rate to the job's machine time. Material type, thickness and required edge quality affect the cutting cycle. Include piercing, lead-ins, internal features and travel between cuts in that time estimate.
Add the stock used for the job and any programming, loading, workholding, inspection or finishing costs not already included in the hourly rate. Record usable offcuts and scrap according to the shop's material-accounting method.
Divide the resulting job cost by the number of accepted parts. Keep the acceptance standard with that result: a blank for later machining and a finished mating part have different scopes. Record rejected parts and rework in the job totals rather than counting them as completed output.
Keep the model traceable
Retain the drawing revision, material, thickness, machine configuration, operating hours, consumption records and accepted quantity. Review the cost headings alongside these inputs when the result changes. This provides a working model for the shop's own equipment and production conditions.
Continue with cutting speed and kerf control, or request a quote with the job details.