Electromagnetic system speeds mould clamping

When Fusion Provida decided to invest in new injection moulding facilities at its Chesterfield factory, it turned to Staubli to provide an effective quick mould clamping solution.

When Fusion Provida, a world leading manufacturer in plastic pipe jointing techniques, decided to invest in new injection moulding facilities at its Chesterfield factory, it turned to Staubli to provide an effective quick mould clamping solution.

Fusion Provida is a manufacturer of automatic butt weld and electrofusion jointing equipment that is widely used for high integrity joints on gas, water and sewage pipelines.

To satisfy the growing demand for their range of electrofusion fittings from utility companies, both in the UK and overseas, investment was required in new production facilities.

In 2001, a GBP 7 million capital investment programme was agreed that is now being implemented.

Central to the investment was the purchase of a new Oima 380 tonne injection moulding machine, capable of producing electrofusion fittings ranging from 20 to 355mm diameter; 12 different sizes in total.

Operation of the moulding machine would require frequent mould changes to allow each of the 12 sizes to be manufactured on a JIT basis.

A quick and effective mould changing system was required to ensure that machine downtime was kept to a minimum.

Fusion Provida was already using Staubli's QMC 106 manual bayonet clamping system on its smaller injection moulders and requested Staubli to analyse requirements and recommend the optimum mould clamping system for the new 380 tonne machine.

Staubli specialises in quick mould change technology.

The company manufactures the complete range of quick mould clamping products, from simple mechanical systems suitable for machines typically up to 250 tonne capacity, through to high specification hydraulic or magnetic systems capable of operating on the largest moulding machines.

This breadth of experience ensures that the most suitable solution can be provided whatever the application.

Staubli recommended its QMC 121, a recently introduced permanent electromagnetic clamping system, which has the flexibility to accommodate the range of mould sizes and shapes required.

Hydraulic mould clamping was not the preferred choice due to the high extra cost of attaching uniform size backplates to each of the moulds.

Additionally, the ever present possibility of hydraulic oil contaminating the plastic joints being moulded was a crucial consideration since maintaining product cleanliness is an important requirement for Fusion Provida.

The QMC 121 system uses independent single pole, circular magnets which generate maximum clamping force right across the area of the mould including approaching the mould centre, an area that is often not adequately covered by other magnetic clamping systems.

An important feature of the system is the sensors built into the permanent electromagnet array.

These directly monitor the positioning of the mould as well as the actual clamping force that is being applied to the mould at all times.

It is the most sensitive mould clamping monitoring system in the world.

Fusion Provida agreed with Staubli's recommendation and the QMC 121 magnetic system was installed onto the first Oima machine.

Initial trials proved very successful.

Machine downtime on mould changing was reduced by 75%, to 15min from a previous 45min.

A second moulding machine is now being fitted with the same system and will shortly join the production line at Chesterfield.

Ian Gilthorpe, Senior Processing Engineer at Fusion Provida, responsible for the development of the new production line, commented: "The Staubli mould clamping system has exceeded all of our operating requirements, it was installed without any problems against a fairly tight schedule, is safe and reliable and offers excellent value".

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