Fasteners and Sealing
Unless the depth of field is sufficient to tolerate variations in the distance between the laser and the workpiece, positioning and flatness are crucial for a good result. Most laser welding applications are therefore on components with a joint line that is in one plane. However, at the 2010 Lasys trade fair, LPKF exhibited its new Twinweld3D hybrid welding machine that is said to offer high-quality welds and fast processing times. Based around a robot, the Twinweld3D hybrid welding system enables designers to create freeform three-dimensional car headlights and taillights that LPKF says would be impossible to weld using conventional methods (Fig. 4). Further savings in time and cost are possible because tempering is not usually required after welding with this system. LPKF believes there is a market trend towards the use of
large, freeform three-dimensional mouldings, so it has developed the Twinweld3D to meet this need. Another trend, according to LPKF, is for a greater use of welding to join plastic micro- components, hence the company is also active in this area.
Versatile process
Laser welding is no longer the ‘space age’ technology that it once was, and it is certainly becoming a much more versatile process. At the same time, ultrasonic welding can now be used for a wider variety of applications than those for which it was suitable in the past. Design engineers looking to reduce manufacturing costs
Fig. 4. LPKF says its Twinweld3D robotic welding system enables designers to create three-dimensional forms that would be impossible to weld using conventional methods.
without compromising quality would do well to look at both of these joining technologies when considering both new projects and ways to remove cost from existing products. l
Conformally cooled mould tool inserts reduce cycle time by 20 per cent
A
key area of the injection moulding process, which significantly impacts the overall cycle, is the time required for cooling prior to de-moulding. It is clear therefore that finding ways to reduce the cooling cycle, whilst maintaining or better still improving product quality, is a prime target for mould tool designers.
An extensive study by the Vlaams Plastics Centre in Kortrijk Belgium, compared the time required to achieve a targeted de-mould temperature using mould tool inserts produced in different materials
Fig. 2. Multiple Loop Cooling Channels. Fig. 1. Single Cooling Channel. 30
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by conventional machining methods, with a conformally cooled insert produced using the LaserCUSING process. These tests were also conducted using two different polymers PP (polypropylene) and ASA (acrylic ester-styrene-acrylonitrile) The use of LaserCUSING technology, a process from the field of rapid tooling / prototyping manufacturing, allows tool and mould makers to produce mould inserts with individually configured close-contour cooling channels.
The results of this independent study
confirmed that inserts produced by LaserCUSING bring significant benefits. The cycle time required to achieve the target de-mould temperature of 65 degrees was just 24 seconds with the LaserCUSING insert compared to 31 seconds with a conventional steel insert, a saving of 7.0 seconds or 20 per cent. A further benefit was the reduction in component distortion, by as much as 36 per cent, when measured after de-moulding. With definitive results such as this, mould tool inserts manufactured by the LaserCUSING process and incorporating conformal cooling channels look set to become an integral and indispensable part of mould tool design in the future. These results were consistent across the two different polymers tested. l
Enter 30 or ✔ at
www.engineerlive.com/ede Concept Laser GmbH is based in
Lichtenfels Germany.
www.concept-laser.de
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