Question 8: What is the difference between producing with and without SPC?
The immediate practical differences when you start using SPC are:
• You measure at least three parts in succession coming off the machine (sample group). The mean value of the three readings for the three parts and the distance between the highest and lowest reading are noted on a control chart. From this you can easily see whether the process needs to be adjusted or not.
• Any adjustment is marked on the chart.
• A fresh sample group is taken after the adjustment has been made.
You usually find after a while that you have previously been measuring and adjusting the process needlessly. So the most usual effect of introducing SPC is that you measure and adjust the process less often than before, while rejects are down and quality is up.
Faq´s about SPC
1. Why should we use SPC in my company? »
2. Where should we start using SPC in our operations? »
3. What can we achieve with SPC? »
4. Can we start to introduce SPC without any preparation? »
5. What is MSA? »
6. What should we think about before starting to use SPC? »
7. What software should we use? »
8. What is the difference between producing with and without SPC? »
9. Where should the control limits be located on the control chart? »
10. What capability index should we have as a minimum requirement? »
11. We produce short runs. Is SPC any use to us? »
12. At what intervals should we measure the sample groups? »