LOUISVILLE, Ky.-Associated Rubber Co. has introduced a new wrinkle to retreading: a treading system it promises is a ``new way of thinking'' about how replacement tread is manufactured. Unlike standard mold curing, with the firm's MARC-that stands for Mechanical Adjustable Retreading Computerized Cure-Treading System, a tread mold is adjusted to fit a tire.
This new process, the company claims, translates to better quality control and a lower cost product, hence the ``MARC of Excellence'' moniker it has bestowed on the process, which was unveiled at the recent American Retreaders' Association's World Tire Conference and Exposition in Louisville.
According to John D. Wingert, project manager for Associated Rubber, the system's uniqueness lies in its ``true segmented mold'' and matrix, adjustable not only to a tire's diameter, but also to its cross section.
That not only allows a retreader to be more adaptable, he said, but opens ``a lot of doors to the original equipment size changes that occur every year.''
``We've taken one stand and three matrices that can handle most of the popular medium truck casing sizes,'' he added. Mold dimension is accurate to within 1/32 of an inch to a tire.
The system also features an automatic start and stop with digital read out controlling a curing time of 55 minutes, about 20 minutes less than conventional mold cure. MARC's aluminum matrix, which has no vent holes, allows better, more even heat distribution to only the tread area, saving on energy cost, the firm said.
Tires are cured at 85 psi, meaning there's no heat transfer to the internal structure of the casing, Mr. Wingert said. ``Thus, a retreader gets the casing back more times than with an envelope cure because there's less fatigue and pressure put on it,'' and a fleet can reduce its tire maintenance cost.
Another advantage of MARC, he pointed out, is that it offers lower equipment costs, less maintenance than conventional systems, reduced labor and material costs, and more cycles per shift.
Less overhead is required, he noted, because all a retreader needs is a MARC road rim and radial truck tube, rather than the curing bags and rims utilized in a conventional mold cure system, or the envelopes and bags in precure.
In standard processes, curing bags or envelopes range in cost from $80 to $125 and are usable for 20 to 30 curings, he said. ``Our system eliminates that cost.''
Tread patterns offered with MARC are a G167 lug design Mr. Wingert called a replica of a Goodyear pattern, a highway tread resembling an XZA1 Michelin OE design, and a trailer design similar to Goodyear's G159 or Bandag's 4100.
``We'll have to (produce) other designs as well,'' he said, ``in order to keep up with the competition.''
While retreaders must purchase the MARC aluminum matrices, Tallapoosa, Ga.-based Associated is offering a three-year lease program-renewable every year thereafter-for the press, control and power units, Mr. Wingert said.
As part of its licensing agreement-and in order to control quality-the firm has specified that only its rubber compound be used with the system, and that a retreader meet both ARA and Associated's retreading standards.
MARC matrices are made by Associated's Chester Tire Mold Division, which the firm purchased about three years ago from Retreading Equipment Inc. A prototype of the MARC system has been set up and operational for about a month at Simmons Tire Co. Inc., a retread shop and retail/commercial center in Sheffield, Ala.