Why Traditional Statistical Process control Monitoring does not work anymore – Part 2

International Quality Institute in US had innovated the SPC monitoring techniques known as short run SPC to address the needs of current production line with low volume high mix.   In this technique, one chart can be used across different models with different process center and control limits such as part A, B and C shown in chart below.

Short run SPC method transform data collected and can use predetermined the control limits to enable different process center and even standard deviation product can be plotted in one chart.  This is applicable for 
  1. Same model product  with different lot to lot process center 
  2. Different model product with different process center

There are 2 types of data transformation in short run SPC to get the plot points

  1. Target method - Calculating actual measurement readings and calculate the deviation from target point (either using specification or process control) for average chart
  2. Standardized method - Nominal transformation of actual measurement data to plot point for both average and range chart.

Unfortunately short run SPC is still not a widely used technique especially in the world of electronics part manufacturing which could due to lack of true quality engineering expert.  There is also limitation in software as currently there is only one commercial statistic software which is capable of plotting short run SPC, Stat soft Statistical.   

It is imperative to be able to monitor the critical quality parameter correctly to ensure that product  quality parameter is reflecting the actual product quality per customer requirement which is the method to consistently good quality product.  Short run SPC is one of the techniques that work in high complexity low volume environment.

Appreciation notes  :  I would like to thank my mentors in Dell who had introduced me to short run and enable me to go further in my journey of SPC discovery  and share with my audience.

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