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SPC - An Overview

• SPC is based on the fact that every process has some variation within it.
• There is no process that is so perfect that it produces exactly the same result every time.
• Some of this variation is natural, some is not.
• If you can operate the process so that only natural variation is present then your process is stable and you are in control.
• If the Natural variation is within agreed specifications then you are capable and your customer is happy.
         
• The more faults a process produces, the higher the cost of manufacture.
• If faults can be kept within the business and can be budgeted for, the costs are significant.
• As soon as the faults get to the customer, the costs escalate.
• With a poor reputation, you will eventually find your market share declining.
         
• Inspection has been the method used by virtually every manufacturer to prevent unacceptable product from reaching the customer. However, if the purpose of inspection is to detect and remove the presence of faulty product, then it doesn’t really work too well; if it did we wouldn’t need prevention techniques and your customer would never receive unacceptable product.
• Rather than detect the faults that you know your process is producing, you should be preventing these faults from occurring in the first place. To do this you need to gather relevant information from the process.
   
• SPC is one of the tools that helps you to do this.
• Capability Studies measure the natural variation to prove that the process is basically sound
• Control Charts then make sure that it remains stable.
• When variation appears that is not natural and yet significant, the control chart will find it.
• When you know why it exists you can eliminate this as a cause of variation.
• SIMPLE!

The aim of this part of the site is to give a little more information about elements of SPC.