We SPC our CCAs via PPM (Parts Per Million) defect level.  
     This has seemed to be a fairly good thermometer for 
     measuring how effective the machine is doing.  A word of 
     caution should also be interjected at this point to not rely 
     totally on this PPM reading and relate it directly back to 
     the performance of the machine.  Your machine could be 
     capable and in control, however, your design, layout, could 
     be causing the problem.
     
     We currently utilize two Hollis GBS Mark III machines.  We 
     SPC our Hot Air Knives (HAK) utilizing a Magnehelic gage.  
     We have modified our HAKs so our CFM output is fairly flat 
     across the face of the knife.  Tracking via SPC tells us 
     when it's time to refurb.
     
     We use SPC to track solder contamination level so we know 
     when to change the pot.  When a the pot is changed, we use a 
     special set of gages to assure that the rails, z-wave sump, 
     chip sump, and HAK are returned to their previous positions. 
     This includes HAK angle and conveyor angle.  We also check 
     the rail parallism and dwell time with a solder wave 
     analyzer.  We have ordered the newer solder wave optimizer 
     which allows you to measure z-wave and chip wave.  
     
     Most all the newer machines can do much of this from the PC 
     that controls the machine.  Hope this helps.

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