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Statistical Process Control (SPC)

What is Statistical Process Control?

Statistical Process Control in manufacturing refers to the methodology of monitoring and measuring quality processes during the production process. As different processes deal with multiple variations, statistical process control (SPC) is a manufacturing analytics software tool used to pinpoint which areas of production need improvements or adjustments. 

SPC manufacturing works by collecting data on all your processes in real-time using a graph with set control limits to measure its efficiency. The best way to determine the control limits are by observing the capability of production lines. If the data you derive falls within your control limits, your processes and machines are running accordingly. However, if the data is outside of the control limits then it means there are issues that must be adjusted along the production line. 

Why Statistical Process Control Manufacturing Is Important:

As companies in the manufacturing industry continue to endure a highly competitive market, there are some factors that they simply cannot control – one of them being the cost of raw materials. This is why companies focus on what they can control in their factories, such as processes like shop floor control. Their goal is to improve manufacturing quality, enhance efficiency and reduce costs of materials and waste. Many companies still follow traditional procedures of inspecting quality issues only after production. SPC manufacturing is able to monitor performance in real-time, and thus can detect changes before there are any issues. 

Statistical Process Control Principles:

The purpose, or main objective, of adopting SPC analysis in operations management is to achieve more control over:

  1. Raw materials
  2. Customer requirements
  3. Handling of supplies
  4. Product defects

An accurate management of these SPC examples are a crucial part in improving the quality of your production. These are the exact direct performance indicators that are related to customer satisfaction and factory management. 

Variations in Statistical Process Control:

Variations in SPC manufacturing are distinguished by two sources: common or special. This process is the first step of evaluating whether the variation is natural (common), or special in which it’s caused by assignable sources of variation and can be adjusted or modified through a type of action. 

  1. Common Cause Variation in SPC – This variation comes from what manufacturers refer to as ‘normal sources’, and can be found in typical processes. 
  2. Special Cause Variation in SPC – This type of variation can be assigned to a cause other than the process itself. This is the target variation for SPC tools, so it can be removed and/or adapted.
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