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# What is Statistical Process Control (SPC) | SPC Tools

## What is Statistical Process Control (SPC)?

Statistical Process Control (SPC) is an industry-standard methodology for measuring and controlling quality during the manufacturing process. Quality data in the form of Product or Process measurements are obtained in real-time during manufacturing. This data is then plotted on a graph with pre-determined control limits. Control limits are determined by the capability of the process, whereas specification limits are determined by the client’s needs.

**Steps Involved In Using Statistical Process Control :**

**Plan **– Identify the problem and the possible causes.

**Do **– Make changes designed to correct or improve the situation.

**Study **– Study the effect of these changes on the situation. This is where control charts are used – they show the effects of changes on a process over time. Evaluate the results and then replicate the change or abandon it and try something different.

**Act **– If the result is successful, standardize the changes and then work on further improvements or the next prioritized problem. If the outcome is not yet successful, look for other ways to change the process or identify different causes for the problem.

Statistical Process Control (SPC) is an industry-standard methodology for measuring and controlling quality during the manufacturing process. Quality data in the form of Product or Process measurements are obtained in real-time during manufacturing. This data is then plotted on a graph with pre-determined control limits. Control limits are determined by the capability of the process, whereas specification limits are determined by the client’s needs.

Statistical process control (SPC) is the application of statistical methods to the monitoring and control of a process to ensure that it operates at its full potential to produce conforming product. Under SPC, a process behaves predictably to produce as much conforming product as possible with the least possible waste.

* Seven* Statistical process control (SPC) Tools:

**Pareto Diagram****Process Flow Diagram****Cause and Effect diagram****Check sheets****Histogram****Scatter diagram****Control charts**

**Pareto Diagram**

PARETO DIAGRAM:

- The Pareto diagram is a graphical overview of the process problems, in ranking order of the most frequent, down to the least frequent, in descending order from left to right.
- Thus, the Pareto diagram illustrates the frequency of fault types.
- Using a Pareto, you can decide which fault is the most serious or most frequent offender.
- The basic underlying rule behind Pareto’s law is that in almost every case, 80% of the total problems incurred are caused by 20% of the problem cause types; such as people, machines, parts, processes, and other factors related to the production of the product.
- Therefore, by concentrating on the major problems first, you can eliminate the majority of your problems.
- The few items that have the largest amount of occurrence is your more frequent problem, than are the many items that only happen once in a while. This is called the “vital few over the trivial many” rule.
- Quite often, once you cure several of the “big hitters” you also eliminate some of the smaller problems at the same time.