Machining time is a term used to describe the amount of time a machine spends actually cutting, milling, or otherwise altering a piece to be machined. It is part of what is known as the machine cycle time, which the total amount of time it takes to load and unload a piece of material as well as the amount of time it takes to actually cut that material. The machining time can be calculated automatically on many CNC, or computer numeric controlled, machines to help improve manufacturing efficiency and cost per cut.
Processing time is another term that is synonymous with machining time. This calculation measures only instances when the bit or cutting instrument of a machine is making cuts or otherwise removing material from a piece. If, for example, a board is to be cut on a table saw, the machining time would be the collective instances in which the blade is actually removing material; this means the blade is in motion and actively cutting the material for processing. Many machines, such as CNC lathes, will feature additional operating time, which is any instance in which the machine is active and the material is on the work surface, but no cuts are being made or no material is being removed. An example of such an instance would be when the bit is being moved to a new position over the material in preparation for another cut.
A company might try to calculate machining time for various machines in a shop to figure out where productivity has slowed and how it can be improved. A machine, for example, with a slow machining time may be upgraded or replaced with a more efficient tool that can complete the same job in less overall time. Some types of machines can combine functions to eliminate loading and unloading, thereby improving the efficiency of a machining process. Companies may also use this calculation to determine the overall cost of the finished product; it may be part of a formula that includes cost of raw materials, machining time, packaging costs, transportation costs, and so on.
Another important reason to determine the time spent machining is to prevent damage to the machines themselves and to know when maintenance may be necessary. A manufacturer may recommend a maintenance schedule based on how much time the machine is spent in operation, and replacement of bits may be required after a certain amount of use as well.