Infrared heaters weld transport boxes reliably
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| Infrared heaters weld contact free |
Complex wheeled trolleys are produced from injection moulded plastic panels quickly and in an automated process. Infrared emitters from Heraeus transmit heat without contact to suit the programmed production processes. This protects the material, improves the quality of the end product and so reduces final costs. Heraeus Noblelight will be showing infrared emitters at the K exhibition in Duesseldorf from 24th to 31st October.
Flat, blow moulded panels from thermoplastic HDPE are supplied basically as unfolded boxes, together with all the integral fixing lugs and holes and slots which would be used in subsequent assembly operations. The formed panels eventually form the rear section of a new lightweight, wheeled trolley intended for bulk deliveries to supermarkets and for transporting linen around hospitals
The lugs and slots, together with various mating faces, are used to weld the box together. However, their location is such that they are of different thicknesses and geometry. They are also of different shades.
The trolley designers considered that the welding would be impossible to achieve using contact methods, such as hot plate welding, as there would be unwanted scorching of the HDPE surface. However, they were aware that infrared had been used successfully in plastics welding and, consequently, Robot Units contacted Heraeus and tests were carried out at the company’s Neston Applications Centre. These demonstrated that the weld achieved using short wave infrared emitters was stronger than the parent material itself and that there was no burning of the HDPE.
As result, an array of short wave infrared emitters, of different lengths and power ratings, was fitted in the forming station of the Robot Units’ machine. When the flat moulding arrives at the forming station it is first clamped before the individual short wave emitters are fired up in a programmed sequence to comply with the geometry, thickness and colour of the plastic panel. The flat panel is then folded by the pneumatic tooling and the selected, softened faces and connection points are welded together. Cold air is then blasted into the station, the clamping force is removed and the box is removed from the machine. The cycle time is between 15 and 45 seconds, depending on the panel loaded.
Infrared radiation is transferred without contact and generates heat directly within the product. Consequently, it is superior to conventional methods such as heating by means of contact plates. In addition, unlike contact plate welding, there is no hot plastic left on the heating source. So plastic parts can be welded together in a way which is reproducible every time, without smell, in a matter of seconds. There is no need for time-consuming cleaning procedures. In seconds, infrared radiation can be targeted to melt the mating surfaces of a product, which then are joined by simply pressing them together.
Short wave infrared emitters react in matters of seconds so that they can be easily controlled. They transfer heat quickly and at high efficiency. As well as short wave emitters, Heraeus Noblelight offers carbon infrared emitters at a spectrum which is particularly well matched to the absorption properties of plastics. All Heraeus emitters are matched to the relevant process in their shape, size and spectrum. As a result, complicated heating processes can be replicated to allow automation.
Heraeus Noblelight GmbH
Reinhard-Heraeus-Ring 7
D-63801 Kleinostheim
Germany
Press: Dr. Marie-Luise Bopp
+ 49 6181 35 8547
marie-luise.bopp@heraeus.com
Heraeus Noblelight GmbH with its headquarters in Hanau and with subsidiaries in the USA, Great Britain, France, China, Australia and Puerto Rico, is one of the technology- and market-leaders in the production of specialist light sources. In 2006, Heraeus Noblelight had an annual turnover of 88 Million € and employed 651 people worldwide. The organisation develops, manufactures and markets infrared and ultraviolet emitters for applications in industrial manufacture, environmental protection, medicine and cosmetics, research, development and analytical laboratories.
Heraeus, the precious metals and technology group headquartered in Hanau, Germany, is a global, private company in the business segments of precious metals, sensors, dental and medical products, quartz glass and specialty lighting sources. With revenues of more than EUR 10 billion and more than 11,000 employees in over 100 companies, Heraeus has stood out for more than 155 years as one of the world’s leading companies involved in precious metals and materials technology.