Before a measurement system can be purchased, a detailed engineering concept of the measurement process is developed. Using the purpose developed above, a cross-functional team of individuals will develop a plan and concept for the measurement system required by the design. Here are some guidelines:
The team needs to evaluate the design of the subsystem or component and identify important characteristics. These are based on customer requirements and the functionality of the subsystem or component to the total system. If the important dimensions have been identified already, evaluate the ability to measure the characteristics. For example, if the important characteristic of a plastic injection molded component was on the mold parting line, the dimensional check would be difficult and measurement variation would be high. One method to capture issues similar to these would be to use a FMEA process to analyze areas of risk in gage design both from an ability to measure to the part to the functionality gage (Design and Process FMEA).
This would aid in the development of the maintenance and calibration plan. Develop a flow chart showing critical process steps in the manufacturing or assembly of the part or subsystem. Identify key inputs and outputs to each step in the process. This will aid in the development of the measurement equipment criteria and requirements affected by the location in the process.
A measurement plan, a list of measurement types, comes out of this investigation.
For complex measurement systems, a flow chart is made of the measurement process. This would include delivery of the part or sub system being measured, the measurement itself, and the return of the part or sub-system to the process.
Next use some method of brainstorming with the group to develop general criteria for each measurement required. One of the simple methods to use is a cause and effect diagram.
source : Analysis of measurement systems
