AKRON-Behind all the details, patents, secrecy and technology of Goodyear's Impact tire production process is a single-minded pursuit: Precision.
``Precision is our drummer,'' said Rick V. Vannan, director of advanced process and product technology. ``The company that is able to produce a tire that has all its components placed exactly as the engineers designed it will be the winner.
``Precision manufacturing will yield a lighter, thinner tire that will run cooler-and therefore with less rolling resistance-longer and smoother,'' Mr. Vannan said during a recent tour of Goodyear's advanced research and development center in Akron, where the elements of the Impact system have been under development for the past five years.
``We expect tires built with the full complement of Impact technologies to be so uniform as to require no wheel weights for balancing,...and that would apply to any tire, built anywhere in the world,'' Mr. Vannan said.
Goodyear's use of Impact technologies to date is more advanced with truck tires than with passenger tires-owing to the more significant cost benefit.
And the company feels its use of several new technologies will yield a truck tire that should bring the million mile casing closer to reality.
Based on statements by Goodyear Chairman Samir Gibara and other Goodyear executives, Impact also should yield lower-cost tires, but those involved with the process won't say to what extent buying prices will be affected.
For instance, Goodyear has stated the hot-former alone is expected to reduce the cost of manufacturing tire casing components by about 20 percent and, expressed another way, will reduce labor costs for truck tires by as much as a third.
Two key pieces of the Impact-Integrated Manufacturing/Precision Assembled/Cellular Technology-puzzle already in place and contributing to enhanced precision are the hot-former and injection molding of beads.
The hot-former is a series of computer-controlled, extruder-fed contoured-roll calenders linked by a conveyor belt that pre-assembles up to 12 truck tire casing components-things like the inner liner, the barrier layer, sidewalls, chafers etc.- into what is called a ``composite laminate.''
Calenders squeeze rubber between counter-rotating steel rolls. Standard calenders produce sheet rubber and are often used to help mix the compounds used in tire making. The contoured rolls used in the Impact hot-former have the shape of the various components cut into them, allowing these strips to be laid down in a continuous process.
Goodyear maintains that laminating these various components together while they're still warm achieves several improvements: increased uniformity; greater precision in terms of component thickness and placement; and reduced use or even elimination of processing chemicals designed to retard the vulcanization process until the cure cycle.
The other aspect of Impact now undergoing final evaluation is injection molding of components, principally the bead package for now, but eventually also the tread.
``Injection molding will be the breakthrough technology'' for tire building, according to John Jentgen, head of manufacturing at Goodyear's Colmar-Berg factory in Luxembourg, Germany. Injection molding is a process where molten rubber is injected under high pressure into heated and clamped molds.
By injection molding the bead package, Goodyear is able to assemble and partially cure a number of different compounds into an easily handled component.
This package streamlines the tire assembly process and allows for greater precision in the design of tires since layers of rubber and reinforcements no longer are subjected to bending forces around the bead in the curing press, Mr. Vannan said.
This is particularly true in the case of truck tires, he said. By increasing the precision of component placement in the building process, Goodyear engineers believe the cured tire will perform more optimally, yielding a smoother rolling tire and-especially in the case of truck tires-will deliver even longer mileage.
To achieve increased precision, Goodyear is turning its manufacturing into a continuous process-involving continuous mixing of rubber, conveyor-belt assembly of components, ``on-the-fly'' size and type changeovers of assembly equipment, and curing without a press.
The price tag thus far
With several aspects of Impact now operating and protected by global patents, Goodyear executives have begun to speak more openly about a project the company has spent more than $500 million developing, with another $200 million budgeted this year for Impact-related activities. The company spent $2 million alone on securing patents, according to Bradley P. Bruggeman, director of facilities planning and corporate services.
Hot-formers already are in place at three Goodyear plants. The company is expanding the network to seven plants by 2004 when a third of Goodyear truck tires and 10 percent of passenger tires will be made using Impact systems, Mr. Bruggeman said.
Goodyear's Lawton, Okla., plant is the next in line to receive a hot-former, with production from the Impact-based system to start early in 2002. After that, Goodyear will add a hot-former line for passenger car tires at its Philippsburg, Germany, plant in 2003, and another in 2002 for truck tires at an as-yet-undisclosed site in North America, company executives said during a recent briefing on the IMPACT system.
At the same time, Goodyear recently pulled the plug on a new plant in Brazil that was to have been built from the ground up using Impact principles.
A superior process?
Calendering tire components is far superior to extruding them because of the precision, Mr. Vannan said. He explained that in traditional tire manufacturing, components are extruded under high pressure through a die, and a dynamic characteristic of all rubber processed this way is die swell-the tendency for the rubber to expand after it has passed through the die.
To ensure that these components are the proper size and gauge prior to their assembly into a finished tire, the extruded rubber is stretched by varying the speed of the conveyor that takes the pieces away.
``Extruding tire components means we have to deal with die swell of up to 15-20 percent,'' Mr. Vannan said, ``and that means constantly adjusting the take-away conveyor speed to compensate.
``We figure calendering the components is three times more accurate in terms of gauge variation.''
Goodyear claims hot-forming is superior to both extrusion and strip lamination-the latter the focal points of Group Michelin's C3M and Pirelli S.p.A.'s MIRS systems-in terms of precision component placement. Compared with its own extrusion operation, hot-forming offers improvements of more than 50 percent in gauge variation and 40 percent in placement variation.
Once the casing components are calendered on the hot-former, they are wound on a huge spool-dubbed ``King Kong'' by the tech center staff-holding material for up to 100 truck tires.
This spool, which is designed to keep the material from sticking to itself and keep contaminants out-is then delivered to a building station that has been adapted to take the spool; existing building equipment can be used.
At the building station, the spool is unwound and cut to length automatically by a sonic knife that can slice the hot-formed components at a steep angle-typically 8 degrees in current practice-yielding a tire with no perceptible splice in uniformity tests.
Upstream from the hot-former, Goodyear hopes to perfect the continuous mixing process-using extruders to mix rubber without interruption instead of the conventional method, which involves batch processing of rubber, carbon black and other chemicals and fillers in capital-intensive internal mixers.
Continuous mixing also offers the chance to eliminate a number of stabilizing materials needed to keep rubber fresh between processing steps, both Goodyear and independent analysts noted. This change offers measurable cost savings by reducing purchases and eliminating the storage and handling of these materials.
On the other hand, committing to continuous mixing means a company has a lot of faith in the uniformity of its raw materials supply, consultants said. If for any reason the compound's not right in continuous mixing, there's a lot of potential waste.
Downstream of the hot-former, Goodyear is evaluating the effectiveness of manufacturing cells, especially for shorter-run tire types that require more frequent dimension changes. Cells are in place in several factories now, and the conversion is ongoing.
Goodyear also is experimenting with precuring the tread and then matching this to a green casing.
In the case of new truck tires, using premolded beads and treads would allow the company to pursue non-traditional curing methods-i.e., press-less curing-and eventually cut cure times in half, according to a Goodyear patent on the subject.
How exclusive is it?
Is the Impact process unique?
One tire manufacturing engineer-a 20-year industry veteran who asked not to be identified-said the Impact process appears to be more a novel use of familiar technologies than something revolutionary.
That is not to say the process is less effective than other automated technologies-such as the robotic-oriented toroidal building systems touted by Group Michelin or Pirelli S.p.A.-the engineer said. But Impact is a different way to achieve improvements.
Goodyear itself acknowledges that some elements of Impact trace their roots to a manufacturing system proposed more than 15 years ago by Eric Holroyd, an engineer with Dunlop Holdings Ltd.
Goodyear bought the rights to the Holroyd system in 1986 from BTR P.L.C., which had purchased the assets of Dunlop Holdings a year earlier.
The company also is developing a highly automated tire building system-dubbed Flexible Manufacturing System II-that is scheduled to go into full-scale production next year at the company's Fulda, Germany, tire plant, which emphasizes high-performance tires.
The company declined to discuss FMS II in detail, other than to say it would be 100-percent automatic and highly flexible.