GlossaryKind of term: Manufacturing termUnattended machining
What is unattended machining?
Unattended machining means a machine keeps cutting with no operator present, for example overnight, relying on automatic loading and process monitoring.
Unattended machining is running a machine while nobody is there to load, measure or intervene. It ranges from a single long cycle that runs on after hours to a machine that takes new workpieces for hours from a pallet changer, bar feeder or robot. In between lies reduced attendance, where one operator tends several machines. Fully unattended running is also called lights-out machining.
What does unattended machining depend on?
Whether a process can run unattended depends on process reliability, not on batch size as such. Chips must break and clear, tool life must cover the unattended period or sister tools must be ready, and tool breakage must be detected. A proven program, automatic loading, on-machine probing, thermal stability, coolant, fire safety and an alert to someone on call all play a part. A one-off with a long cycle can run unattended too; the reclamping in between remains manned work.
How does unattended machining work in practice?
Unattended hours add productive hours per machine without adding the same number of operator hours. How you treat them in the cost is an estimating convention: a separate rate for unattended hours, or a machine rate without labour and operator time as its own item. Either way, labour is counted once. On the other side are the costs: automation, extra workholding, probes, sister tools and the risk that a fault is only found the next morning.
What is unattended machining often confused with?
Unattended machining is not the same as a night shift: a night shift can be manned, with a shift premium, and unattended running can also happen during the day, over a break. Nor is it a lower hourly rate as such: the rate is the amount per machine hour, and manned or unmanned says whether operator time belongs to that hour.
Frequently asked questions
When can a batch run unattended?
When the process runs reliably: a proven program, chip breaking that works, tool life or sister tools for the whole period, breakage detection and automatic loading. On a new part, a manned run usually has to show that first.
Do I count an operator when the machine runs unattended?
Not for the unattended hours. Labour belongs in the cost once: in a manned rate, or as its own item for loading, setup and inspection. The unattended hour carries the machine, tooling and energy.
Can a one-off run unattended?
Yes, if the cycle is long enough and the process reliable, for example a long finishing run on a 5-axis machine. Clamping, aligning and reclamping between setups remain manned work.