Fisher: Commercial tire retreading world evolves

I love this time of the year, spring. Here in Michigan the temperatures are warming, daffodils and crocuses are popping up, trees are budding, and birds are chirping like crazy.

But April is a special time that always makes me nostalgic for days gone by. This issue of Tire Business that is dedicated every year to the Commercial Tire Industry and Retreading always has that effect on me because it brings back memories of the American Retreaders' Association (ARA), (which later became the International Tire & Rubber Association) Retread Show.

For more than 30 years up through 1999, this great show, dedicated to retreading and repairing, was held in Louisville usually about a week before the Kentucky Derby. (The last two shows were held in Nashville.)

It was guaranteed that the trees would be flowering, the sun would be shining and — like swallows returning to Capistrano — retreaders from all over North America would flock together to learn new things about running a retread business, visit with longtime friends, and network with new ones both on the exhibition floor as well as in restaurants and hotels all over town.

That show faded into the sunset as the retread industry changed, driven by consolidations and tire manufacturers expanding their proprietary networks of retreaders and retread shops.

Although there were as many as 3,000 retread shops in the 1960s, this number continued to dwindle, so that by 1997 only 1,316 remained, turning out about 17.5 million truck retreads annually.

By 1999, around 800 of the retread plants in operation were tied up with one or more retread system providers, leaving only about 300 shops under the control of truly independent retreaders.

Since a majority of retread equipment suppliers had good market coverage through retread system providers such as Bridgestone/Bandag, Goodyear and/or Michelin, which began holding their own retread exhibitions for their dealers, an annual national show became superfluous.

The industry continues to change. Today there are around 640 retread plants due to continued industry consolidation but with production improvements, these plants still have about an annual capacity of 15 million to 17 million units, and there are many plants that retread between 300 and 500 tires a day, which was unheard of 20 years ago.

When and how did this happen?

Well, change is a funny thing. It can really sneak up on you when you're not looking. Days, months and even years go by, and it seems nothing changes, but when you look back, everything is different.

I wouldn't say that the commercial truck tire retread industry has experienced revolutionary changes in the equipment it uses. It's more like a continual evolution of production equipment becoming less labor intensive, more accurate and faster.

In the 1980s and 1990s when I operated a retread plant, retread plant workers were strong, highly skilled craftsmen. They had to be because every station in the retread process required them to perform the task they were assigned manually, and as accurately and efficiently as possible, in order to produce consistent, high quality retreads.

Some equipment made the process a little easier or faster, but equipment at that time did little to factor out human error, so it was the skill and knowledge of each retread plant worker that determined the quality and performance of each retread.

Workers who were poorly trained or had bad attitudes produced crappy retreads. Today, with the integration of computers into production equipment, the level of accuracy has been greatly improved, the opportunity for human error has been reduced, and each shop employee is incredibly more productive.

In addition, the business of retreading has gotten a lot more sophisticated, too.

Back in the olden days, retreaders used manually recorded cards or other paper systems to record the work performed on each tire. A card stayed with each tire and the worker at each station in the retread process recorded the work that was performed on that tire.

Once the tires were loaded onto the truck for delivery to the customer, the cards were collected and given to accounting to generate the proper invoice. If you wanted to know where a particular tire was in the retread process, you'd have to manually look through all of the tires in the shop and warehouse to find it.

Billing was slow, and management had really poor visibility of how production was faring or what its material requirements were at any point in time.

Today's retread production systems have simplified tracking casings through the retread process, ensuring customers' requirements are followed, that all work is properly invoiced and customers get their own tires back.

They start by attaching a bar code to the tire. As the tire moves through the process, the bar code is read by the production machines in the shop, which then select the right program automatically to buff and build the tire, already knowing its make, model and size and the tread that the customer wants cured on it since the customers' business rules are also stored in the computer.

The bar codes also take hours off performing physical inventories in the warehouse and ensure the proper tires are put on trucks at the dock.

Retread production systems are supplied by Bridgestone Americas/Bandag, Continental Tire the Americas, Goodyear, Marangoni Tread North America and Michelin North America Inc. for their own dealers as well as by several independent software suppliers that can also interface with tire company proprietary software packages.

Technology has also had an impact on retread production equipment. Let's look at a few retread process stations that have evolved exponentially with the integration of technology.

The first big thing that impacted retread production was computerized buffers. Older buffers required operators to change templates that the buffing machine followed to provide the correct shape of the crown for varying makes, models and sizes of casings and required the operator to make several passes across the tread to remove all the tread rubber.

There was no way to determine how much undertread remained over the belt package unless the buffer operator made a skive into the buffed surface down to the top belt. Many casings were ruined when tires were buffed down too far.

Today's buffers are computer operated and use lasers to profile the tire automatically and determine the correct tread for each casing. These machines calculate all the parameters needed to buff a tire correctly and check to ensure the tread requested will suit the casing.

All the buffer operator has to do is load the tire on the chuck, enter the make, model and size of the tire into the computer (this can be done by scanning the bar code), and press a button.

The computer takes over and perfectly buffs the tire for the proper tread that will be applied, measures the circumference, ensures the shoulder circumferences are the same and uses technology to detect the steel belts to ensure the proper amount of undertread remains over them.

In addition, significant productivity advances have resulted by using twin hub buffers, which reduce mounting, inflating, demounting and deflation time.

Years ago tires had to be sprayed with a solvent-based adhesive to hold the cushion gum and tread in place until they were cured to the tire. Today, the need for cementing tires has disappeared with the use of cushion gum application machines that extrude hot cushion gum directly on to the buffed surface.

These automatic machines replace the process of stripping the backing off and wrapping a calendered sheet of cold cushion gum around the buffed casing. Cushion gum width is adjusted automatically to fit the tire, which reduces waste and labor required to trim the excess cushion gum off the shoulders and skives are automatically filled as well.

The latest advance in cushion applicators is the automatic setting of the wing formers with a laser camera to gauge the thickness of the cushion applied to the casing.

Older precure tread builders were largely manual operations that required the operator to straddle rolls of tread rubber on the floor and hold the tread in place as he centered it and, using only his eyeball, guided it around the casing while the tire rotated on the chuck

Depending upon how accurately the tread was cut prior to making the splice, retreads rarely achieved perfect straightness or balance. Today's builders are highly automated, measuring the tire circumference and the correct tread length to apply at an even tension so that a splice that matches the tread pattern results.

Lasers ensure the tread is centered and applied correctly every time. They then automatically stitch the tread rubber to the casing.

This results in better uniformity, balance and appearance. All the operator has to do is mount the tire on the builder's hub and press a button.

Builders for mold-cure retread systems have seen improvements as well. Extruder builders now automatically measure the casing and apply the correct amount of rubber based on the mold in which the retread is going to be cured.

There is no need for the builder to take measurements with a tape measure to ensure the final dimensions are proper. Also current-generation extruder-builders can extrude tougher rubber compounds that customers now require that older builders were not able to.

Enveloping in the precure process was a physically demanding job years ago. It would take one really strong guy or two weaker guys to install precure envelopes before the curing process and remove them after.

While today's vertical envelope spreaders are not computerized, they make this step in the process fast, easy and much appreciated by retread plant workers.

Another change in the precure process is the use of light-weight rubber sealing rings — known as ARC rings — and dedicated mounting stands.

In the old days, heavy metal curing rims were used and enveloped tires were installed on them on the floor along with a tube and flap. These then were put on a hook for transport to the chamber.

The light-weight rubber rings and mounting stand make this manual job much easier and faster as well.

Inspection techniques certainly have evolved over time. Back in the 1980s and early 1990s, ultrasonic inspection machines were the most common non-destructive inspection tools in use.

They measured sound waves passing through tires and if the uniformity of the sound waves was disrupted that indicated a separated or injured area. The reliability of this inspection technique proved to be problematic (i.e., a belt separation 360° around a tire would appear uniform) so other methods of inspection were needed.

Shearography was introduced around 30 years ago, but this process was expensive, time consuming, and it took an extremely well trained and experienced person to read the photos of anomalies in the tires and determine if casings were still usable.

Today shearography inspection technology — which compares "interferometric" images of the tire in a relaxed state with one under vacuum — is much cheaper, faster and automated and has increased the reliability of retreads tremendously by providing bead-to-bead inspection capabilities.

These machines are also equipped with evaluation software that grades casings automatically based on the parameters given for each tire. The grading can split the tire into zones so different parameters can be used in different zones.

Also, 3-D mapping of the tire is available, which makes the results more understandable for the operator and takes the guesswork out of interpreting the test results. This elimination of guesswork really made their integration into retread plants viable.

Since these machines can detect hidden problems missed in visual inspections, such as casing separations, blisters and undercuring, many retreaders use them not only in initial inspection but in final inspection, too.

This technology saves retreaders money by culling out bad casings at an early stage in the retread process, enable them to identify and buy casings made by tire manufacturers whose products are not disproportionately eliminated by shearography, and reduce their adjustment rates.

Looking into the near future, say within five to 10 years, every machine in the retread plant will be run by computers and connected digitally with the plant management software and with each other.

Autonomous and automated retreading lines that use robotic arms will move casings and materials through the retreading process so that machine operators will be elevated to a supervisory role and can save all that wear and tear on their button-pressing fingers and arms that currently must mount tires on hubs.

Only tire repairers and skivers will still need to be skilled craftspeople.

Each incoming tire will have either a barcode laser engraved on it or an RFID (radio-frequency identification) tag embedded in it that provides dealers and the manufacturer the ability to retrieve data throughout the life of the tire. This will include images of previous shearography photos and a 3-D mapped image of the retreaded tire that can be used to compare against current shearographic images.

Data on the tire's final inspection and repair information will also be included as will data from TPMS systems that provide a history of each tire's inflation pressure, temperature and mileage. Access to this data is what is going to have a major impact on retreading.

With the growth in automation, computerization, and advanced inspection technologies, the need for skilled retread plant workers will continue to decrease and fewer employees will be required.

Aside from tire repair craftsmen, today's retread plant workers just oversee machines that do most of the work. It is likely that tomorrow's retread plant workers must evolve as well and those of the future will need to be computer technicians.

Peggy can be reached via e-mail at [email protected]. Her previous columns are available at www.tirebusiness.com