Machining time (or machine time) is the time when a machine is actually processing something. Generally, machining time is the term used when there is a reduction in material. For example, in a drill press, machining time is when the cutting edge is actually moving forward and making a hole. Machine time is used in other situations, such as when a machine installs screws in a case automatically.
The machining time, combined with the loading and unloading time, yields the machine cycle time, or the amount of time that the machine must commit to each part, once it is set up to run that product.
Lean puts a strain on the total machining time that is available. Because we don’t like to run large batches, we must do frequent changeovers. Each changeover takes away some of the machine time available during the day. On the surface, this seems counter to production goals. But small batches have been proven time and time again to make work flow better.
Of course, to make sure enough machining time is available, you have two options. The first is to reduce the machine cycle time, whether the actual machining time, or the loading and unloading steps. This can be done with product redesign, or through kaizen.
The other option is setup reduction. It reduces the time that the machine is not processing a part, so more time is available to produce.