The technical paper session of the PMA meeting is always lively, Sarah Houlton reports on some of the key papers
The first technical paper, presented by managing engineer Sara Sina and chief executive Linda Katz of Wisconsin-based Molded Dimensions, looked at the work of the company’s cross-functional Urethane Restoration Team in reducing scrap.
The team includes a wide group of people from across functions. ‘We’re not just looking for a quick fix, but at the root cause of problems,’ Katz explained. ‘There are lots of tricks involved in making a good part, and it is a long training process. The aim was to remove the need for these individual tricks.’
One issue that commonly causes problems is mould temperature variation, Sina said. ‘It causes defects in parts such as air cracks, low durometer and uneven surface finish,’ she said. It turned out that the electric hot tables for open casting at her firm had up to a 30°C temperature variation across them, and casters would instinctively know which part of the table to use. The hot table covers were not always insulated, and some were in poor condition.
To address the problems, they replaced most of the electric hot tables with water-based ones that had much thicker platens to maintain the heat, and built new, insulated hot table covers that were lifted using a winch-and-pulley system to protect them from damage. ‘There is now a 1°C variation across the…