Back in the ’80s, tin cans were pretty standard in the U.S. aerosol industry. Because the overall height accuracy of tin cans is very exact, a metal-to-metal seal with a tin aerosol valve using a laminate gasket between the crimp worked just fine with a 6-segment crimper.
Meanwhile, in Europe, they had already transitioned into using an 8-segment crimper, which made sense for their more common aluminum and tin cans. The aluminum-to-aluminum seal requires a rubber gasket between the crimp, to compensate for the less-precise overall height accuracy.
When aluminum started to become the norm in the U.S. in the early ’90s, usage of an 8-segment design became more typical, as you tend to have larger gaps between crimp points with a 6-segment because less valve-cup material is pushed under the can curl.
We have been using 8-segment crimpers since starting MBC Aerosol in 2008 and have never received a complaint. In fact, customers have shared they were pleasantly surprised by less if any, leakage compared with their older, 6-segment machines. Overall, the 8-segment just provides a more uniformed, radial crimp, and gives you a truly great seal on your product.