Case study
400,000 euro a year in a twenty-machine shop
What happens when measurement moves into the machine
A mid-sized manufacturer producing spare parts and moulds for a sector where a measurement record must be kept and traceable for every part runs twenty CNC machining centres. Their problem was not technical: the machines ran and the parts were in tolerance. The problem was how long the machines were not running.
Before
At every new setup the operator found the datum by hand. Tool lengths were also set by hand, by the operator, at the machine. For inspection the part was unclamped and sent to the measuring room, and the machine waited for the result.
A broken tool was usually noticed at the end of the program; every part machined in that program then became suspect. When and why the machines stopped was not recorded at all.
What was done
CNC Probing software, a measuring probe and a tool setter were installed on all twenty machines. CNC Control monitoring software was connected to the same machines. Installation took one macro per machine; the control units were not modified.
Result
Finding the datum went from about twenty minutes per setup to two. Tool length and diameter are now measured automatically on the machine instead of by hand.
Because the part is measured on the machine, the unclamp-reclamp cycle and the wait for the measuring room are gone. Broken tools are caught within the cycle; no bad part moves to the next operation.
Measurement results are reported in Q-DAS format as they are taken, so traceability is unbroken at part level. The investment paid for itself in less than a year, and the largest item was not scrap but machine downtime.
Annual saving — worked example
| Item | Calculation | Per year |
|---|---|---|
| Datum and tool setting time | 20 machines × 35 min/day × 250 days = 2,917 h | 175,000 € |
| Downtime for inspection and re-clamping | 20 machines × 15 min/day × 250 days = 1,250 h | 75,000 € |
| Reduction in scrap and rework | about one third of the annual scrap cost | 90,000 € |
| Damage and suspect parts from broken tools | one incident a month instead of one a shift | 60,000 € |
| Total | 400,000 € |
A machine hour rate of 60 euro has been used. The figures come from the company’s own records and vary from shop to shop. Recalculate with your own machine hour rate.
Before and after
| Datum | By hand, ~20 min per setup | With the probe, ~2 min |
|---|---|---|
| Tool length and diameter | Set by hand at the machine | Automatic, straight into the offset table |
| Part inspection | Unclamp, wait for the measuring room | On the machine while clamped |
| Broken tool | Noticed at the end of the program | Caught within the cycle |
| Measurement record | Compiled by hand | Automatic, in Q-DAS format |
| Reason for downtime | Verbally, at the end of the shift | Live, recorded, with alerts |
Production manager
Machine operator