Automation overhaul boosts quality and efficiency

New moulding cell runs six times longer unattended

When Worksop-based electrical switchgear manufacturer Eaton found that the twenty year old Arburg injection moulding machine running its front shield component (a safety device for switchgear cabinets) was underperforming, it returned to Arburg as a project partner for plant renewal.

Eaton’s accompanying pneumatic three-axis robot was also proving unreliable and expensive to run. Overall, old equipment was causing poor repeatability, cosmetic damage and a high scrappage rate.

Eaton rigorously analysed the whole production path from moulding to automatic laser printing, highlighting key deliverables for specifying a new cell:

• Improved autonomy of operation;
• Reduced cycle time;
• Greater energy efficiency;
• Safety accreditation with a CE mark for the whole system;
• Turnkey solution from a single supplier;
• Repeatable positioning within the automation system;
• Operator-friendly control system.

Eaton selected Arburg as its project partner to meet these requirements. Autonomy of operation was improved by using a rotary table holding two identical sets of loading and unloading mandrels. This allows the parts to remain consistently oriented through the automation system to printing. Full mandrels are removed and replaced without stopping the machine, unlike the old system. The rotary table took the autonomy rating from the previous 50 minutes unattended on a good day to the current 6 hours on a continuous basis.

Cycle time was improved by 10% through deploying an Arburg Multilift Select three-axis servo robot, which also increased repeatability and reduced the rejection rate dramatically. The new robot has greatly improved overall equipment effectiveness (OEE) over the old cell, and the energy bill for the operation has been reduced as the new robot motors are more efficient than the old pneumatic actuation.

The final part of the jigsaw for Eaton was a control system common to both the moulding machine and the robot. Eaton’s Jimmy Keyworth comments: “There is no point in buying a solution with a control system that people are frightened of using.” The Arburg Selogica direct control system uses a single dataset for the machine and robot, with an easy-to-follow icon-based HMI.

Eaton regards the new system’s reduced scrap levels, improved efficiency and reduced energy costs as critical success factors for remaining competitive in today’s market.

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