African Fusion March 2015

welding robots, effectively completing one part per rotation, but advancing the assembly of five other parts by one step,” Palmer explains. In a further refinement to robot cells, he says that modern CATs have an inner and an outer cone that are assembledwith a fibre-mat between them, which acts as a heat shield. Prior to welding, these parts are pressed together in an integrated ro- bot cell, which accuratelymeasures part tolerances andmates individual components to achieve the best possible fit. The outer seams are thenwelded in the same cell, producing excel- lent dimensional accuracies at exceptional production rates. “In addition towelding, automatic conveying, measuring, leak testing and quality certification are vitally important aspects of the catalytic converter production process. We therefore regularly team up with the systems’ integrators to make the best use of robotic solutions. Robots are no longer just a part of the welding system; they are now used for as- sembly prior to welding as well as for the quality assurance stages required after welding,” says Palmer. The manufacture of larger converters for the truck and bus industry, according to Palmer, has moved from Rosslyn near Pretoria to Port Elizabeth. In one relocated plant, a jig- less welding system is being used, where each welding robot is ‘assisted’ by a handling robot. The jigless system relies on a robot with a sophisticated gripper, which is used to pick up a pre-assembled CAT, reposition it and then regrip it to make sure it is heldaccurately in the reference position. The handling robot then becomes a six-axis manipulator that allows every seam to be accurately and optimally presented to the weld- ing robot – and travel speeds and heat inputs are seamlessly maintained regardless of path complexity. “Following welding, the handling robot presents the finished CAT to a checking fixture and, based on an accept/ reject decision, directs the component to the out line or the repair line,” Palmer informs African Fusion. “ This systemsaves a fortune on jiggingwhen switching tomodified or newdesigns. It also takes robotic welding to a whole new level of cost ef- fectiveness and productivity. To do all of this using dedicated automation and conveyorswould cost five timesmore and the robots are much more easily synchronised,” he says, adding that the process is “awesome to watch”. For catalytic converters, almost all of the welding is done using solid wire MIG welding processes, typically using 307 stainless steel consumables. “The SKS welding power source is used as the standard for Motoman robot systems that we supply, although many users would regard it as the ‘Rolls Royce’ of welding systems. We know the SKS system’s quality and reliability and we are able to offer an excellent back-up service. We are available to help customers at any time – day or night – to repair or replace a system and restore produc- tion,” Palmer notes. SKS power sources also offer a comprehensive range of output options, including synergic sloping options, spatter control and every type of pulsed waveform. “Different users have their preferences but, generally speaking, the most im- portant consideration is consistency. In this regard, the SKS system includes a database that can record the parameters of every completedweld. If there are any in-service quality come- backs, it is possible to interrogate this database to determine whether welding was performed according to the specified procedure,” he assures. While Yaskawa PE predominantly services the automotive

A view of Yaskawa PE’s demonstration, commissioning and repair facilities.

Testing of the critical dimensions of a catalytic converter weld for the automotive industry.

industry, Palmer reveals that it is not all about welding. “Our robots are used for hotmelt gluing operations to join the inner and outer components of a motorcar headlight; we apply an adhesive to the reflectors before the silver is applied; and a clear coat is spray-painted onto the outer lenses. We are also involved in welding wire seat springs; laser welding some of the critical seat under frames; pouring foam into seat moulds; and tending CNC lathes being used tomanufacture aluminium shock absorber components. “Any application that requires a repetitive task can be ro- botised economically,” he continues. “In the pharmaceutical industry, anti-retrovirals aremade inharsh environments from dangerous chemicals. Instead of putting humans in harm’s way to mix these chemicals, we use robots. It is safer and the application becomes cleaner, more consistent and the end product quality is higher.” Packing and palletising applications are also becoming more important. “We pack chlorine drums in the HTH factory, for example, put chlorine bottles into boxes and then pack boxes onto pallets,” he adds. “In the past, robots were seen as complicated and ex- pensive. This is no longer so. Today, a robot solution is a lot cheaper than a CNC machine – and which workshop does not have CNC machines?” Palmer asks. “We are currently talking to a small fabricator looking for a robot to meet its production needs. A robot might cost around R360 000, and a decent welding system can cost from R90 000 toR250 000, depending on the complexity required. So a R500 000 investment can offer a reliable production system that will run for 15 to 20 years, if maintained properly. Typical payback periods are less than five years and robotsmake very dependable employees,” he concludes.

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March 2015

AFRICAN FUSION