Hello there,
No doubt you are using a fixed factor such as +1/4% to account for the stranding helix.
First you must know the exact length of wire on each of the pay-off bobbins by accurate weight measurement each and every time and on each frame (bay) of the strander. If you don't know this, everything else is meaningless.
Second, you must know the exact scrap length again by by accurate weight measurement on the pay off bobbins when only the scrap is left. This you must know by each stranded layer or by each frame (bay) of the strander.
Third, you must understand the scrap left on each the bobbins keeping in mind:
- The 6 wires stranded around the center wire require excess length for that helix. (7 wire strand)
- The 12 wires stranded around the 7 wire core require additional length for that helix. (19 wire strand)
- And so on.
Fourth and as a result:
- The center wire bobbin should have the most scrap. Analyze the the scrap per bobbin and use SPC to understand your results.
- The 6 wire helix bobbins should have the next most scrap. Analyze the the scrap per bobbin and use SPC to understand your results.
- The 12 wire helix bobbins should have the least amount scrap. Analyze the the scrap per bobbin and use SPC to understand your results.
Make sure you use representative samples and get all the operators and production foremen involved so everybody understands and are all working together.
Fifth and once you know you are on a firm statistical footing, carefully cut back the fixed factor number.
SPC is the only practical way to accurately control these issues.
Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641- 3212
