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The following question always arises when you purchase, retrofit or maintain machines and production equipment: “Is the performance of the machine or equipment established according to respective specifications?”
In the past, the geometrical specifications of equipment have been evaluated e.g. as described in ISO 282. Nowadays, real parts are normally produced first, then the relevant characteristics are measured and finally the measurement results are evaluated by means of statistical analyses. These results decided whether you accept the machine and equipment or not.
You can distinguish between machines producing different parts and production equipment manufacturing parts specifically for a limited product range (e.g. engine blocks, camshafts, etc.). Equipment purchasers define the specifications of the parts to be produced and define the most important characteristics of the part (one-sided or two-sided specification limits). The characteristics, if necessary, are allocated to different classes such as critical, significant, important or similar. Each class is assigned to a limit the capability index is not allowed to exceed. Machines and equipment are only accepted when each characteristic meets the required capability index. If a characteristic does not reach the defined limit, you have to take corrective action. The process owner can also decide whether the machine is accepted even though it deviates from defined specifications.
The manufacturer of the machine or equipment is usually responsible for initial acceptance. The process is repeated again when the equipment is installed at the customer’s. However, both cases apply different limits the capability indices have to meet.
In case of a universal machine, you first have to define the parts and associated characteristics the machine is supposed to produce. Otherwise, you proceed as described above.
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