Question: 
Several hours of production was allowed to take place before a cracked seaming chuck was spotted and replaced. What should be done to reduce the risk of cracked seaming chucks and the quality problems this creates? 

Answer: (One of three answers published . . .) 
Two possible reasons for chucks cracking could be because the seaming rolls are set too close to the chuck or because they are set-up too tight.

A seaming roll that contacts or rubs against the chuck may cause excessive heat and wear, leading to chuck cracking. Chucks designed for EO ends for full-aperture EO ends tend to be more susceptible to cracking because of the thin flange required for clearance of the pull-tab.

Standard sanitary chucks are heat-treated to maximum hardness to achieve long-lasting wear. If this is done with an Easy Open (EO) seaming chuck while the metal is hard, it tends to become brittle and more susceptible to cracking on the thin flange area. While lowering the Rockwell hardness on the chuck during the heat treating process would make the material less brittle, it reduces the wear-life of the chuck. 

One solution is to heat-treat the chuck a few points below maximum hardness on the Rockwell scale and then coat the anvil (the working end of the chuck) with a coating of tungsten carbide or titanium. This provides a hard exterior while leaving the base material slightly softer and less likely to crack.

- - Patrick Chronis, VP Manufacturing
Tool Makers International, California, USA

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