Friction analysis at the glass/tool interface and the lubrication influence during hot forming cycles

In the hollow glass industry, specifically in the luxury perfume glass bottle industry, the success of the forming process depends on preventing the sticking at the glass/mold interface to make it easier to release the mold and prevent defects on the glass surface. This study concerns a new way to analyze the impact of lubrication on the glass/tool mechanical behavior. It is based on successive forming cycles performed on the experimental glass/tool interaction platform in the TEMPO Laboratory (Valenciennes, France). Each forming cycle combines a pressing phase, when the hot glass is pressed by the punch and a punch rotation phase in order to estimate the friction force. This article presents the analysis of the flint glass forming cycles using different punch lubrication conditions (i.e. bare punch, swabbed punch, coated punch, and coated/swabbed punch). The friction analysis is based on the evolution of the friction coefficient during forming cycles on the glass/tool interaction platform. The effect of ...