With all that can go wrong, the next person in the process should be inspecting the casing to catch these kinds of problems. If the designated inspector is the tire repair technician, he or she is well qualified to act as quality control for the skiver since skiving is part of the tire repair process, too.
Repair technicians also can be equally guilty of making mistakes. The ones that occur most often are caused by failure to remove all of an injury, making repairs that exceed limits, trapping air in the injury, using the incorrect repair unit, misaligning the repair unit and bridging the repair.
Repair technicians must know their repair limits, stick to them and pay strict attention to details. It's the little things that will make a repair last the life of a tire. Did you know there are more than 20 steps required in making a nail-hole repair and 30 steps in making a section repair? None of them can be skipped if a quality repair is to be made.
The really bad thing about repair failures is that they are lethal to the tire. When a repair fails on the road, the tire usually has to be scrapped.
Lots of retreaders are moving away from cement, but if you're still using it, know the type of cement you're using and what is required to apply it.
Never apply too much or too little. And above all, make sure it dries before applying the fill rubber, repair unit or tread. Wet cement is a failure waiting to happen since it prevents rubber adhesion.
The builder is in a good position to check the quality of the buffer.
This person can check the buffed surface for scorch as well as scrutinize the cement to ensure it is dry, the contour of the buffed casing to ensure it is buffed correctly for the precure tread it will get, or that the dimensions are correct for the mold for which it will be built, and that adequate undertread remains.
Since the builder is working on the foundation that the buffer supplied, it is imperative that the builder use specifications that are in concert with the buffer. Building is especially critical in mold cure retread plants. Casings have to be built within tight tolerances to fit the mold and match the buffed contour.
If the built tire is a little too small, tread surface porosity and tread non-fill result, which are usually caught in the plant and won't fail a tire. However, if the tread is too large, buckled treads will result-and that's a lethal tire condition.
While precure retreading processes are more forgiving of builder mistakes, errors can still be made. Improper tread width selection is a common mistake that usually occurs when the plant is out of the proper size tread.
Tread chunking at the splice is a common occurrence usually due to contamination at the splice or improper tread length. Misaligned treads are either offset to one side or snake around the tire.
These conditions may not fail a tire, but they will prevent the tread from achieving its optimum mileage.
Since curing always follows building, it is the responsibility of the technicians loading the chamber or the molds to check the quality of the builder. They should be looking for straight and centered treads when they envelope the tires as well as the right size tread to fit the buffed casing.
In mold cure operations, they should ensure that the built dimensions are proper for the designated molds and be looking for heavy splices that could buckle a tire.
As always, the right combination of time, temperature and pressure is needed to cure a tire properly whether it is being cured in a chamber or a mold. Therefore, it is imperative that this equipment is monitored continually with charts, timers and alarms to ensure that the cure specifications are achieved.
Heat studies with thermocouples should be conducted routinely several times a year. Hoses, envelopes or tubes should be checked for leaks on every shift or at least daily and repaired or replaced as necessary since leaks will affect the cure.
Tread separations are the result of improper cure conditions as is bond line porosity, which is a sponge-like appearance evident under the tread.
Of course the last quality control inspector is the person in final inspection.
Final inspection should always be done when the tires are hot and anomalies are readily apparent to a well-trained and equipped person in a well-lighted area. This person is your plant's last chance to catch mistakes before they become failures on the road and adjustments for your company. The final inspector is checking not only curing but everybody's work-especially tire repair since the spreader at this location provides the only chance after the repair station to check inside the tire.
Empowering every plant employee with the responsibility of quality control will reduce the number of adjustments and in-plant failures as well as reduce your processing costs since errors are corrected before they are cured. The commitment and constant attention to details that it takes to consistently produce a top quality product is hard work but well worth it.
Your retreads will be able to stand up to extreme temperatures-protecting your reputation and your bottom line.
Oh look, it's so hot now the trees are whistling for the dogs to come over!