Quality Drift Measured

Unevenness After Buffing CV%

Drift Rate CV% per 1000 h

Quality Limit CV%

Hours Since Last Buff h

Buffing Policy Schedule

Scheduled Buffing Interval h

Recovery per Buff %

Current Unevenness

— CV%

At the hours run since the last buff

Buffing Schedule

Hours to Quality Limit: — h
Unevenness at Scheduled Buff: — CV%
Interval Quality Requires: — h
Permanent Creep per Cycle: — CV%
Buff Cycles to Replacement: — no.

Compare the scheduled interval against the interval quality requires — where the scheduled one is longer, yarn is running out of specification for part of every cycle and the average Uster figure hides it. Linear drift is a reasonable fit through the middle of a cot life and understates both the rapid change on a freshly buffed surface and the acceleration once the rubber is genuinely worn. Unevenness is also not the only symptom and often not the first: imperfections, hairiness and lapping usually move before CV% does, so a cot condemned on CV% alone has been costing quality for a while.

Cot & Apron Buffing Frequency to Uster Unevenness Modeler — free, with the formula and a worked example, at Textile School.