BARCELONA, SPAIN — Rotational molders have been challenged to reduce their manufacturing cycle times by up to 80 percent if they want to remain competitive in market sectors they traditionally have called their own.
Rotomolders must reduce their manufacturing costs and expand the range of plastics materials they use if they are to counter a fierce assault from competing processes, warned Roy Crawford, director of the Polymer Processing Research Centre at Queen's University in Belfast, Northern Ireland.
Challenges to rotomolders include new techniques to make hollow parts using thermoforming, injection molding and blow molding, he said.
Crawford spoke to nearly 300 rotomolders from more than 25 countries at the spring meeting of the Association of Rotational Molders in Barcelona.
``As process technologies and methodologies continue to evolve, the clear distinction or boundaries that separate them begin to blur. Hollow objects, once the domain of blow and rotational molding, can now be produced by thermoforming or injection molding.
``As this overlap gets greater, we need to be very careful in the rotational molding world that we are aware of the competition these other people will bring,'' said Crawford, who also is director of technical services for the association, which is based in Oak Brook, Ill.
He said an ARM survey this year demonstrates clearly that the rotomolding industry has failed to deal with its key deficiencies.
A similar, 1992 survey showed the same key problems — reducing manufacturing costs and introducing new or improved materials.
``We haven't taken a sufficiently structured approach to try to solve the problems so that seven years later these are still things that people feel should be addressed,'' Crawford said.
Crawford challenged rotomolders to find ways to reduce cycle times by 80 percent. He said that if rotomolders average just a 50 percent cut, ``that would be excellent.''
Crawford said that some rotomolders prefer to ignore the challenge from other processors in the hope that it will go away. But that, he said, is ``not a sensible strategy.''
Molders need to think seriously about taking advantage of the greatest benefits of rotomolding: the capacity to make products with little or no residual stress; control of wall thickness; the ability to add inserts relatively easily; and little orientation in the mold.
Crawford said injection molders have accelerated their use of newer technologies, including gas-assisted injection molding and lost-core molding.
Thermoforming makes good use of its range of suitable resins. Like injection molders, thermoformers have stepped up their use of a newer technology: twin-sheet forming, which can make thin, yet extremely stiff, parts such as refrigerator panels.
Meanwhile, blow molders can create complex shapes by partial inflation of the parison or movement by the mold platen. They also can make multilayer or multimaterial parts, and can incorporate solid skins with foam cores, he said.
ARM is adopting a role ``to motivate, to encourage and to coordinate'' rotomolding's research effort to meet the challenges, Crawford said.