Information & Training | SPC and Statistical Methods for Process Improvement.

Short Run SPC

In current production environments, there is a tendency to continually reduce batch, lot or campaign sizes. This is based on a philosophy of striving towards a Lean or Just-In-Time approach to processing where there will be reduced levels of inventory, faster response times to customer requests, etc.. While this brings many benefits, it can also make the task of controlling the process seem more difficult. This is particularly the situation, where decreasing production runs impact on an ability to gather sufficient data points to implement effective statistical process control. Many organizations struggle with the concept of maintaining statistical process analysis against short and continually changing production runs. How can you implement Statistical Process Control (SPC), where a batch of (say) 15 units of a product are produced, then a new product model with 20 units are produced, followed by 10 units of a further product, etc.? Is SPC realistic or beneficial is such a scenario?

The answer is “Yes”, SPC can be effectively applied to short and continually changing production runs.

Short Run SPC

SPC & Statistical Methods for Process Improvement.
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One approach is to utilize a Z-MR process control chart.
A Z-MR chart can be applied to short production runs by plotting the standardized process mean (Z chart) and variation (MR – Moving Range chart). Within a short production run, there will usually not be enough data points to allow an accurate estimate of the process parameters to be detailed. The Z-MR chart standardizes the data measured via subtracting the mean in order to center the data, then dividing by the standard deviation. This approach allows data from different runs to be reviewed and analyzed within a single control chart.

Statistical Process Control Full Details

Information & Training.

SPC & Statistical Methods for Process Improvement.

  • Process Capability. Variability Reduction. Statistical Process Control.
  • Pre-Control. R&R Studies. 
  • Process capability indices Cp, Cpk, Cpm, Capability ratio.
  • Performance indices Pp and Ppk.
  • Variable Control Charts.
  • Attribute Charts.
  • Pareto Charts.
  • Individual – X Charts.
  • Histograms / Process Capability Analysis.
  • Scatter Diagrams.
  • Etc. … Etc. …
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