Benefits of wheel-tool gap sensing in Conform/spl trade/ extrusion machinery

This paper presents the results from the successful production trials of a gap sensing system for Conform/spl trade/ extrusion machinery and associated benefits. It is critical to maintain a precise pre-defined wheel-tool gap for the efficient running of the Conform extrusion process and to maintain product quality. A high-temperature capacitive gap sensing system is designed and implemented on a copper Conform extrusion machine in a production plant. First, it is shown that machine setup times prior to production can be reduced from 35 to 5 min with active gap sensing. The sensors can be used for on-line direct gap measurement and control, and, for the first time, provide a detailed view of extrusion zone gap behavior during a full production cycle. From the experimental results, three different stages of a Conform extrusion cycle, start, slugs feed, and steady-state extrusion, can be clearly identified. The gap sensor is used to evaluate the relationship between gap size, and waste levels. It is shown that there is a linear reduction of waste levels from 20% to 2%, when the gap size is reduced from 1 to 0.15 mm.