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
- Same model product with different lot to lot process center
- Different model product with different process center
There are 2 types of data transformation in short run SPC
to get the plot points
- Target method - Calculating actual measurement readings and calculate the deviation from target point (either using specification or process control) for average chart
- 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.
