1 reply to this topic

[AdamSmith]

I was wondering if anyone has any experience implementing SPC in a dry edible bean processing environment.  I have a dry bean processing/cleaning line with a sieve mill, destoner, gravity table, polisher, color sorter, two X-ray inspections and magnets.  QC samples and grades finished product hourly as well as sorts and catalogs the rejects from the X-ray inspections and color sorting.  My question is can we/should we implement SPC control charts on the reject data, and if so, what type of control charts would we use?  We sample rejects hourly and can both count the rejects (e.g. 10 stones, 5 dirt balls etc. etc) or we can also weigh the rejects and represent them as a w/w ratio of rejects/total product run. 

 

My theory is if the rejects are not highly variable, then the line is stable and in control. 

 

Any help or ideas would be appreciated.  I'm not convinced this is the best way to monitor the line for control.  

 

 

[mohamed ahmed yusuf]

Dear Adam,

Based on your simple description for your line, analysis of rejects will give you more control on your process and i think it will be mandatory if you applying any of food safety and quality standards (control of operations/ HACCP clauses) you should have two types of analysis:

1. Analysis for CCP's and PRP's that you have on your line like metal detector.

2. Analysis for steps like color sorter and things that could have an impact on product quality specs (Color- cut size-etc.).

 

For doing statistical analysis, you have 2 options:

1. If you have a history but doesn't have specs for your process then you will need to analyze this data to get the minimum and maximum specs and then put them on your control chart and then it will give you simply a chart disciplining your process status.

2. If you don't have a history but have specs for your products, then your upper and lower limit will help you in doing the control charts.

 

I recommend for you Minitab Program for doing these analysis or you can do it simply by Excel by entering data and generating charts.