Do knurls improve torque capability? A “pop-bottle” size lid (28 mm diameter, 15 mm high) was varied with six designs: 1) a smooth lid, 2) a lid with 13 knurls/cm, 3) a lid with 7.9 knurls/cm, 4) a lid with 3.9 knurls/cm, 5) a lid with 3.9 knurls/cm but for only 4 mm of height, and 6) a lid with 2 protrusions (“radiator type”). The 18 subjects rotated each lid. Using the smooth lid torque of 1.49 Nm as 100%, the lid with 7.9 knurls/cm had 170%, the radiator type had 164%, the 13 knurls/cm had 163%, the 3.9 knurls/cm had 141%, and the 3.9 knurls/cm for only 4 mm had 110%.
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References
1.
BernsT., 1981, The handling of consumer packaging. Applied Ergonomics, Vol. 12, No. 3, 153–161.
2.
NagashimaK.KonzS., 1986, Jar lids: Effect of diameter, gripping materials and knurling. Proceedings of the Human Factors Society, 672–674.
3.
SwainA.SheltonG.RigbyL., 1970, Maximum torque for small knobs operated with and without gloves. Ergonomics, Vol. 13, 2, 201–208.
4.
SharpE., 1962, Maximum torque exertable on knobs of various sizes and rim surfaces. MDL-TDR-62-17, Behavioral Sciences Laboratory, Aerospace Medical Division, Wright-Patterson AFB, Ohio.
