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Demystifying demassification: The evolution of the proliferation of tire types and sizes, and its ramifications with the tire manufacturing process

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Demystifying demassification: The evolution of the proliferation of tire types and sizes, and its ramifications with the tire manufacturing process

Demystifying demassification: The evolution of the proliferation of tire types and sizes, and its ramifications with the tire manufacturing process

Jacques Bajer is alive and well. As the president of Tire Systems Engineering Inc., he specializes in the design of advanced manufacturing systems for the economical mass production of tires, power transmission belts, lathe-cut seals and air springs.

But his consulting business is "only" 34 years old; his influence on both the automotive and tire industries spans five decades.

He was an active participant in the evolution of both. His work at Ford Motor Co. from 1955 to 1970 led to the development of the tire uniformity grading machine (1962) and the low-profile tire (1964). Bajer also was a key figure in the radialization of America.

The French-born engineer doesn´t mince words when talking about the industries he loves. Never was that more evident than in his speech on "55 years of radialization" at the recent International Tire Exposition and Conference in Akron, Ohio.

After pointing out that long tire life was the primary promise of radialization, he questioned the viability of high performance tires and their trend toward low tire mileage.

"It remains to be seen... if consumers will accept radial-ply tires providing bias-ply tire mileage at radial-ply tire prices," he told the attendees.

With the continuing proliferation of tire sizes and the resulting impact on tire manufacturing, his voice has never been more relevant.

By Jacques Bajer

The traditional tire manufacturing process was originally developed to serve a market, which from the dawn of the automotive industry was based on the use of bias-ply tires, all of the same aspect ratio (1.00). This then initially small and "undiversified" tire market grew very slowly over a period of 75 years (1888-1963) because of:

1. the number of vehicles produced annually,

2. consumer demand, and

3. vehicle price affordability.

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For years nothing really changed in the tire industry in as far as tire design diversification was concerned.

However, in the United States in 1963, 14 years following the introduction of the radial-ply tire in France, the proliferation of tire types began when Ford was the first United States vehicle producer to use low section height bias-ply tires on the 1964 Lincoln and Thunderbird. Three years later, in 1966, the U.S. tire market continued its proliferation when bias, glass cord belted tires of the same aspect ratio as the non-belted (bias) version (.80) appeared at the original equipment level.

Finally in 1967, following years of tuning, Ford was the first U.S. vehicle producer to use Michelin low section height (.80) steel cord belted tubeless whitewall radial-ply tires, first as optional equipment on the Ford Falcon and the Mercury Colony Park station wagon, and in 1970 as standard equipment on the Lincoln Continental MK3. This significant U.S. automotive industry event marked the real beginning of the North American radialization, and the continuation of the proliferation of the North American tire market.

By 1987, bias-ply passenger car tires had vanished from the North American automotive market, having been replaced by steel cord belted tubeless radial-ply tires. Also by 1987, more tire shapes in terms of more tires of lower aspect ratios, together with higher speed rated tires became available, hence demassifying tire production.

Although the current U.S. mass small tire market appears to be stable, it is gradually declining. This segment of the tire market consists of S- and T-speed-rated tires of relatively high aspect ratios (by today´s trends) mounted on relatively small diameter wheels, essentially 13, 14 and 15 inches. Such tires are mass-produced in plants of 20,000-25,000 tires daily capacity, using tire manufacturing methods developed when tire types and sizes were not nearly as diversified as they are today, and when customization in the automotive industry was, for practical purposes, non-existent.

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By 1984, it became evident that due to the then emerging proliferation of tire types, a rethinking of the tire manufacturing process was required, in order to produce a greater variety of tires on a shorter production run basis per tire types and size, and this economically. Easier said than done. (Bajer addressed this topic in a guest editorial, "The tire industry: future shock?" in the January 1984 issue of Modern Tire Dealer.)

Michelin´s C3M and Pirelli´s MIRS tire manufacturing process represent such thinking. These facilities currently are designed to produce a relatively low total number of specialty tires per day (3,000), or one million tires per year. These mini-plants consist of small, software-driven automated tire assembling and curing systems featuring rapid installation and setting, as well as rapid tooling change. Of primary difference, as compared to traditional tire manufacturing methods, these facilities use the core built/core cured direct tire component formation and simultaneous application technology, with minimum human intervention, except for process monitoring, setting and programming according to the variety of tires scheduled for production.

With such a tire manufacturing system, the traditional tire assembling and shaping drums and their turn-up bladders, the tire belt/tread package assembling and their transfer rings, as well as the traditional tire curing presses and their curing bladders are eliminated. So are the traditionally massive, high energy consumption calendering and extruding lines, as well as the tire ply and bead preparation lines.

Also, and of major significance, with these new tire manufacturing systems, all traditional in-process storage of tire components, such as treads, sidewalls, innerliner, beads, bead apexes, belt wedges, belt and body plies, etc., are eliminated, making the process "inventoryless." The tire assembling module is merely fed by bobbins of compounds in strip form, as well as bobbins of steel and textile cords, and bead wire, all produced elsewhere and delivered to the mini-plants on a JIT (just in time) basis.

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The finished built tires, on their respective cores, are then prepared for insertion into the tire curing module, and at the end of the curing cycle the cores are extracted from the cured tires. The cured tires are trimmed, inspected and QC processed, and the extracted cores are prepared for the next core built/core cured tire production cycle.

The core built/core cured system minimizes in-process scrap generation, reduces the possibility of in-process contamination, and permits tires to be assembled on their respective cores with fresh components, which is an essential criterion among many others required to produce defect-free tires.

Finally, what is the capital investment needed to implement such "demassified" tire production methods? Theoretically, such capital investment should not exceed the one required to produce tires by traditional methods (in terms of dollars required per million tires produced yearly), keeping in mind that one cannot deviate from the fundamental principles of mass production from which, historically, high quality, reliable products have been manufactured on a consistent basis, and at affordable retail prices.

Sooner or later, tire field performance and economic data on these new tire manufacturing processes will become available, and judgement will be passed.

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