away with welding. In the standard process, up to two lugs are placed using an injection unit on a blow moulding machine. The process is carried out during the blow moulding cycle while the blown pipe is still hot, creating a high-strength bond between the pipe and the lugs that are formed by injection moulding. Traditionally, brackets, lugs and clips are injection moulded in separate machines and then attached to the blow moulded pipe in a third processing step through welding. In comparison with the multi-step process, the method is simple and avoids defects that result through welding. According to Röchling R&D manager Dr Fabrizio Chini, the company is using this technique to tap into a new field of metal substitution. He says it offers 25% lower cost and 30% less weight, in comparison to the aluminium tube used previously, while still meeting the 230°C and 2.8 bar workload requirements. The company also says that this process results in an extremely high strength component – about 20% stronger than that of the component produced by conventional method. Meanwhile, Pernoud’s Multitube also eliminates welding of automotive water pipes and air ducts by using overmoulding to apply additional parts through the use of a robot or rotary indexing mould plates. For instance, a cooling fluid duct would traditionally be made as two halves moulded in a 1+1-cavity mould, removed by a robot and vibration welded together. By using Multitube, a part is moulded in the first cavity o f a 1 + 1 - c a v i t y m o u l d , p i c k e d u p b y a ro b o t a n d placed in the second cavity of the same mould, where it is overmoulded. Hence, four production steps are integrated into one step. Benefits include 15% weight savings, faster cycle time and higher part rigidity. The robot can also be replaced with a three-station rotary index plate system, which will reduce the cycle time further. ◆
Three companies feature moulds and systems for multi-component production with cost savings and no welding.
erman toolmaker Zahoransky Formenbau i n t ro d u c e d a m u l t i - c o m p o n e n t m o u l d t h a t operates on a standard machine without the addition of rotary tables, indexing platens or stack turning technology, last year at the Fakuma show. In SCPS (servo-cavity positioning systems), the control sequence of the mould, including the drives for all other injection units, hot runner control equipment and core pullers, is handled by the mould’s own control s y s t e m . A l l t h e m o v e m e n t s a re s e r v o - d r i v e n a n d independent from the machine hydraulics. The mould is built with the progressive stages through the injection sequence stacked on top of one another. The indexing components move up through each stage and when they reach the top they are transferred from one mould half to the other and returned down to the first stage, operating like a paternoster conveyor. The indexing components are carried up by a spindle in the moving half of the tool. Injection takes place simultaneously at all stations. After the parts have passed through the final injection station they are removed by a robot. When the mould closes, each indexing component is transferred to a spindle in the nozzle half and on the next opening stroke is carried down to the bottom of the mould where on closing it is once more located on the upward spindle. The time taken to open the mould, index to the next station and close again is around 3 seconds. Automotive duct moulding Meanwhile, two methods that do not require welding come from automotive parts producer Röchling Automotive and French mould maker Georges Pernoud. Röchling used a patented manufacturing process it developed, known as Spritzfügen (injection bonding), to produce an air charge duct for the 125 Kw 2 l diesel engine of the Volkswagen Tiguan car. It used 30% glass fibre-reinforced PPS supplied by Ticona Engineering and won an award from SPE Central Europe last year. The modified blow moulding process, with an in-mould assembly system, allows brackets, clips, lugs and cable crommets to be produced and applied to a blow moulded duct pipe, doing
Air duct produced using Röchling’s patented method that does not require welding
3 I n j e c t i o n M o u l d i n g A s ia • F E B R U A R Y 2 0 1 0