Abstract
A study of test results obtained by 50 operators, considered as a group, on meas uring the breaking strength of uniform twill fabric following a widely accepted "grab method" technique showed 26 percent of the operators to be out of statistical control.
It was found that those operators whose tensile testing was out of control had not met the two requirements of considerable experience and continual performance in textile testing.
Jaw breaks, which constitute about one-third of all the breaks performed, are shown to give more variable strengths and definitely lower average strengths than acceptable breaks, indicating that the jaws of the test machine contribute a weaken ing effect on the fabric and that jaw pressures should be known and regulated. Good operators (those in control) get practically the same number of jaw breaks as those out of control. A good operator will not necessarily get higher breaking strengths, or better types of breaks.
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