GlossaryKind of term: Manufacturing termMachine selection
What is machine selection?
Machine selection is the decision on which machine runs an operation or setup; it is tied to the setups, the route, the hourly rate and free capacity.
Machine selection assigns an operation or a whole setup to a machine in the shop's own machine park. Whether to subcontract the operation instead belongs to the wider manufacturing decision. It is part of manufacturing engineering and belongs to a part's route. For the same part several choices are often defensible: a shaft can go to a lathe and then a machining centre, or run in one go on a mill-turn centre.
What does machine selection depend on?
The choice depends on envelope and axes, access to the features, the tolerances between features, the spindle power and torque the material and operation call for, the workholding and tooling available, the machine's automation and the capacity at the time of planning. Machine selection and the setup plan shape each other: the machine decides which setups are possible, and a preferred setup can rule a machine out. They are worked out together, not in a fixed order.
How does machine selection work in practice?
The machine supplies the hourly rate of the machining line and affects setup time, programming time and the number of setups. Turning and milling on two machines means setting up twice and a handover; a mill-turn centre can do the same in fewer setups, usually at a higher rate. Which route is cheaper per piece depends on quantity, rates, setup time, programming time and how loaded the machines are. Record the chosen machine with the estimate and a colleague can check the price later.
What is machine selection often confused with?
Machine selection is not the machine fit. A fit check says which machines a part fits in terms of envelope and axes; selection is the decision which machine gets the work, with its rate, setups and schedule. Machine selection is also narrower than a manufacturing decision, which covers workholding, sequence and subcontracting as well.
How do you see machine selection in Blake?
In Blake each part shows a first check per machine on envelope and axes, with the limit that decides. You enter and accept the setups per route yourself. The machining line takes the hourly rate of the machine in the route; the result is labelled as an estimate.
Frequently asked questions
Who makes the machine selection?
Usually the manufacturing engineer; in a smaller shop often the cost engineer who also does the manufacturing engineering. At quoting it is a provisional choice; when the order is scheduled, machine load can lead to a different machine.
Why does another shop pick a different machine for the same drawing?
Because the choice depends on what is in the shop and what is free: machines, workholding, tooling and experience differ. Both routes can meet the drawing, with a different split of setup time, machining time and rate.
What if scheduling picks a different machine from the estimate?
Then the rate, the setup time and sometimes the number of setups shift. Post-job costing shows it as a difference from the estimate; that part of the difference comes from a different route, not from the time estimate.