Incoming Source of Variation & Source of Variation in Process Flow Chart

[manojdparab]

can anyone please tell me what is INCOMING SOURCE OF VARIATION & SOURCE OF VARIATION in PROCESS FLOW CHART?
i am confused in incoming source of variation in PFC. i guess it means variations from previous process, which will effect the next process. Example, variation in hole diameter in previous process, which will effect my assembly in next process, so shall i consider these hole diameter as incoming source of variation?
Also in some PFC only source of variations is mentioned, i think these must be the variations in process characteristics like temperature, pressure, cooling time etc., which will effect the product characteristics. Again if these are the sources of variation then do we need to address all the sources of variation (i.e. process characteristics) in PFC or only the critical ones??
Please answer waiting for your feedback.

 

[Stijloor]

Can someone help?

Thank you very much!

Stijloor.

 

[Marc]

Another quick "Bump". Can anyone help with this one? My Thanks in advance!

 

[Rob Mcfee]

can anyone please tell me what is INCOMING SOURCE OF VARIATION & SOURCE OF VARIATION in PROCESS FLOW CHART?
i am confused in incoming source of variation in PFC. i guess it means variations from previous process, which will effect the next process. Example, variation in hole diameter in previous process, which will effect my assembly in next process, so shall i consider these hole diameter as incoming source of variation?
Also in some PFC only source of variations is mentioned, i think these must be the variations in process characteristics like temperature, pressure, cooling time etc., which will effect the product characteristics. Again if these are the sources of variation then do we need to address all the sources of variation (i.e. process characteristics) in PFC or only the critical ones??
Please answer waiting for your feedback.

I think your question is, 'should variation from previous processes be considered as inputs to process variation considerations in subsequent processes'.

The general guidance when conducting a process study is to assume that all parts from previous processes are being manufactured within defined process tolerances. However when you are establishing receiving inspection criteria consideration should be given to process characteristics that if outside of tolerance would critically affect subsequent process capability. The level and extent of these controls should be based upon risk. Mainly the process capability of the previous process and the degree of impact the out of tolerance condition will have upon subsequent processing and historical data from the process owner as to their performance.

Do not fall into the trap of conducting a second PFMEA type study on a previous process, to try and understand the likelihood of impact on a subsequent one. If process characteristics are critical then they should be identified as 'special', allowing the previous process owners to exercise an enhanced level of control. This is the primary method that should be utilized to communicate criticality of process control. When the previous process owner is creating their PPAP, PFMEA CP package, you as the subsequent process owner should be heavily involved ensuring that any characteristics that could impact your subsequent operation have been clearly addressed, to a point where you have confidence as the the likely conformance of parts that you will be receiving.

Hope this helps.