Abstract
This paper studies the opening characteristic of aluminum bottles with screw caps. In order to examine the opening characteristic, opening experiments and measurements of friction coefficient and contact state between the bottle and cap have been performed. An analysis technique of estimating the 1st torque when unscrewing the cap is proposed in consideration of the experimental results. The estimation agrees with the measurement of the 1st torque in general. It is necessary to take the relation between the friction coefficient and contact pressure into consideration to improve the estimation accuracy. This studies result was able to show the directivity for good openability of an aluminum bottle.
