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MOTOMAN ROBOTICS (UK) LTD |
Press Release
ROBOTS ARE FOUR TIMES FASTER AT POLISHING
Following the successful installation of Motoman systems for robotic arc welding and more recently plasma welding and cutting, one of Europe’s leading stainless steel catering and sanitary ware equipment manufacturers, W&G Sissons, has embarked on a far-reaching programme to automate polishing at its Sheepbridge, Chesterfield factory.
The first cell, based on two Motoman 6-axis articulated-arm robots, entered service in January of this year (2001). Patrick Mason, production engineer in charge of the project, is planning to ensure that the polishing of all bowls, WCs and other products manufactured in batches over 20-off will be automated within the next two years.
Speed is perhaps the main benefit of robots over hand polishing. A WC which used to take 70 minutes to polish to a grained finish by hand now takes 18 minutes including six automatic tool changes. If a mirror polish is required, the saving is even greater – 30 minutes by robot compared with three hours manually. A further comparison was cited, whereby a 500 mm x 400 mm stainless steel bowl which used to take 24 minutes to polish is now completed in six. The success in polishing this and other similar bowls has allowed a reduction in work previously sub-contracted.
Not only are the robots faster at polishing, but they are also capable of operating ‘light out’ overnight. In six hours, the unmanned cell can polish 100 bowls and stack them for packing the following morning. Similarly, a batch can be run unattended on Saturday ready for Monday morning.
Continued Mr Mason, “The list of advantages of robotic polishing seems almost endless. For example, if six hand polishers are deployed on a product batch, we have to ensure that they polish to the same standard, which isd difficult and requires a high level of developed skill.
"However, the finishes are consistant when robots are used. The reason is twofold: first, the cycle is exactly reproducible each time; and secondly, robots can handle considerably larger tools than is possible by hand so there is much less overlapping between passes and sometimes none at all. Consistency of finish is a particular advantage if we have a large number of units going to one customer for a large project; or, say, a washroom is fitted with a range of our products that are viewed together but manufactured at different times.
“Hand polishing is by its nature repetitive heavy work, ideally suited for robotic application. In addition, dust and fumes generated in the polishing area are not a problem for a robot but there are Health and Safety issues when operators are involved, requiring efficient dust extraction plus individual safety equipment.”
Robotic polishing consumables are more environmentally friendly as they are dry abrasive wheels, whereas hand polishing involves the use of abrasive granules in a matrix of fat, predominantly of animal origin. The latter tend to be dirty in use whereas debris from the former is simply extracted through ducts at each robotic workstation. Moreover, unlike hand polishing tools, robotic consumables do not have to be dressed and prices are far lower.
Over 50 product variants are polished in the new Motoman cell. It is the result of a joint development by the equipment supplier and Sissons, which supplied the initial concept layout, jigs and fixtures and carried out its own integration. The cell comprises two Motoman UP-130 robots, one serving a rotary table and the other a fixed table. The robots not only handle the products into position, polish and unload them, but also exchange suction heads, abrasive tools and consumables automatically.