A welding system from Heraeus Noblelight, Duluth, Ga., using special-purpose infrared emitters has helped a pipe-drainage company improve the production process of an inspection chamber assembly. The infrared system also eliminated the possibility of environmental problems often associated with the hot-melt adhesive technique that the company, Hepworth Drainage in Bristol, U.K., had been using.
One of Hepworth's major drainage-system product lines is a polypropylene chamber that provides surface access for inspection of below-ground drainage systems. The product consists of a base unit with multiple connections to clay or plastic drainage systems. The addition of two or four raising pieces creates the required depth of inspection chamber. An important step in the manufacturing process is the joining of the raising pieces, first to the chamber's base unit and then to each other. A hot melt adhesive had been used to join the pieces. Modern environmental protection requirements and the need to keep down costs led the British company to investigate more efficient solutions.
The infrared system has shortened to just 22 sec the complex automated process that uses a robot that brings various component tubes into an infrared welding cell and then welds them together. As a result, production cycle times for plastic inspection chambers at Hepworth have been reduced as has component quality. The heating process is environmentally friendly in contrast to the previous hot-melt adhesive system because there is very little fume production.
The process improvements were possible because quartz glass emitters can be shaped to match the product three dimensionally, so heat is generated only where it is required. In addition, infrared emitters only have to be switched on when the heat is actually needed, saving energy and money.
Technical data for the Heraeus contact-free weld-heating system include small custom-designed short-wave emitters, each delivering 15 W/mm; emitters distributed around the product surface; and cycle times of approximately 22 sec.