In order to facilitate ongoing skill and knowledge improvement, the Accident Specialist team took the initiative to arrange a detailed factory tour of the MaxT Solutions retreading (recap) factory in Westmead, Pinetown, where the full process from start to finish was carefully detailed. The tour was kindly facilitated by Mr. Gary Bushel, the factory technical manager and Mr. Wayne Camoin, the field Engineer.
The factory, one of very few in South Africa, prides itself on the major percentage of its casing being supplied through specific demand of their clients, where specific and ongoing intimate co-operation between the factory and the client ensures that good quality casings are supplied and retreaded, to the specific requirements of the client, to include specific tread for predominant road use or off-road use and other factors.
Although it was clear that various levels of safety and quality are carefully built into the entire retreading process, the initial receiving of the tyre (referred to as a casing), the logging in and attaching of a specific tag, identifying all the aspects and requirements of the casing through the process was highlighted.
This was followed by a detailed initial inspection of the casing to ensure that the casing, the basis of the retread, is suitable. We watched as a casing was carefully rotated in a rotating spreader system, inspected both inside and outside, with any blemishes marked off and noted.
Following the process to the actual buffing (a form of grinding) off of the old tyre tread surface to the appropriate finish in both texture and size, revealed an interesting machine that is specifically setup to the individual tyre size. The machine holds, inflates the tyre and buffs the surface to the appropriate finish, with a slightly convex finish. The inflation of the casing during this phase also has the advantage of revealing any further blemishes that might have been missed, such as pinholes, ply separations, ineffective repairs and other faults that may require treatment.
Once again, careful visual scrutiny of the casing post buffing was noted as being another step in the safety standards of the process, any blemished marked off and considered before the next process. It was also interesting to note that there is a “No touching of buffed surface” thereafter in order to ensure that the surface remains contaminant free to ensure the best possible surface for adhesion.
Further visual inspection is then undertaken, including the appropriate preparation, plugging and or patching of any minor cuts or holes both on the inner and outer side of the casing that can be suitably repaired.
Casings then move along the line keeping to a specific time period so as to ensure that no “bleeding” of the tyre from the buffing process has any effect on the further processing. To the casing the rubber bonding layer is applied, to the layman this would be the “glue” that secures the tread layer to the casing, this layer is specifically cut to size, both in length and width for the specific casing.
The specific tread length and type of tread to be applied is then cut from a roll, the end sections thereof are always a right angle butting joint, tread types used are specified on the specific tag for the particular casing, this tag following the specific tyre through the entire process. The casing also obtains specific tags and identifying markers that form part of the new complete new tyre as is specifically required to identify it.
All components used in the process, such as the tread itself and the rubber bonding layer are manufactured and supplied by Bridgestone, however not only Bridgestone casings are retreaded, most reputable tyre manufacturer casings are accepted for retread.
A process of rolling compression of the bonding rubber layer and tyre tread sections applied to the casing follows, this being the initial phase of the mating of the surfaces, rolled from centre outwards helping to remove air bubbles and to ensure the correct alignment and mating of the surfaces.
The casing is then enveloped in various specific layers of plastic and cloth in and at specific locations, followed by a tube type overall covering that is inflated during the subsequent heating and curing process to ensure that the correct pressures are held on the casing and new tread to see a successful bonding of the new layers.
The entire casing with its various coverings is then placed into one of various Kilns, there are many casings that are loaded at once. The temperatures and inflation pressures are all set to predetermined specific tolerances, after a preset number of hours the product is finally removed.
At this stage, a further inspection of the new tyre, whilst hot, is another safety system check in the process. The check while the tyre is hot sees imperfections, blemishes and bubbles being identified far easier, with any items identified either being repaired, or the entire casing disposed of.
The process is rather laborious and likewise it is crucial that the operators at the various process points are well versed with his or her duties, similarly, the inherent quality control of the line system and continuous monitoring has resulted in what MaxT say is exceptional quality control with statistics to clearly indicate this. Any warranty claims that do arise are meticulously examined. MaxT pointed out that they pride themselves on working to SANS 109 repair quality standards in each of their SABS approved retreading facilities.
Wayne also pointed out that they have made great strides in going green by reprocessing all of the off-cuts, the rubber from the buffing process and likewise that Casings are only disposed of through approved means.
It was of great interest for us to see and learn firsthand the entire process, and to be reassured that the products that we all too often see as “loose tread sections” (delaminated) strewn across our country roads, are usually there as a result of poor or improper maintenance of the tyre and not as a result of some backyard attempt at a recap.
Thanks once again to MaxT Solutions / Bridgestone, and in specific Gary and Wayne for their time taken to educate us on the process.