Infra-red emitters help produce cleaner welds

Edited by the Engineeringtalk editorial team Apr 18, 2006

Infra-red welding is fast gaining acceptance in the plastics sector, with CPR Automation of Tamworth firmly established as the leading supplier of equipment to satisfy the rising demand.

An infra-red welding system using Heraeus infra-red emitters has helped one the leading manufacturers of plastic pipe systems in Europe to double the welding throughput of two complex geometry drainage components, while eliminating the fume problems associated with the former hot plate welding process.

The pipe manufacturer operates within a culture which demands the production of best quality products, constant improvement of best-practice engineering processes, and continuous new product development.

In line with this continuous improvement philosophy, it was decided to investigate the possibility of speeding up the welding operation of two vastly different, complex geometry drainage products.

Both products are two-part assemblies and, formerly, the joining together of the two component parts had been carried out by hot plate welding, which was considered slow, cumbersome and requiring extensive fume removal.

Consequently, special purpose machine builder, CPR Automation, of Tamworth, was asked to design and develop an improved welding process.

Following extensive trials, a custom-built, three station infra-red welding cell was installed.

In operation, the relevant component parts are loaded into top and bottom jigs at the first station.

They are then indexed to the next station, where a cassette containing fourteen 2.4kW short-wave infra-red emitters is introduced between the bottom surface of the top component and the top surface of the bottom component and the infra-red emitters are powered up so that the surfaces are heated and softened.

Emitter power is controlled by pyrometer feedback of surface temperature.

The cassette is then withdrawn and the softened surfaces of the components are pressed together to effect the weld.

The welded unit component is then indexed to a cooling station before returning to the first station for unloading.

Change over between components is quick and simple and merely involves the removal of the existing top and bottom holding jigs and the fitting of new jigs to suit the new component.

Since installation, the infra-red welding system has shown itself to be far superior to the former hot plate system.

The welding process is twice as fast as before and current production requirements can now be met in one shift instead of the two shifts which were required previously.

Moreover, welding is much cleaner, as there are few fumes associated with the process and there have been gains in energy efficiency as the high power infra-red emitters are powered up only when necessary in the operating cycle.

Infra-red welding is fast gaining acceptance in the plastics sector, with CPR Automation of Tamworth firmly established as the leading supplier of equipment to satisfy the rising demand.

Being a noncontact method, IR welding suffers none of the disadvantages of hot plate methods, such as plastic adhesion to the heating surface which necessitates frequent tool cleaning.

It is also capable of handling large surface area products, as it is a simple operation to add more emitters to a heating bank.

In addition, infra-red heaters can be custom-built to match the geometry of the product to be welded.