The term cold retreading was developed long ago to differentiate the system from that of hot retreading.
Cold retreading was then a term used to describe a process in which the final curing of retread is done at temperature lower than 130c.
Precured retreading method is a system in which the tread is prevulcanized in a mould (matrix) either in a long slab form or a ring form before it is built onto the casing.
The Precure Tread system is a process by which a tread pattern is fully cured or vulcanized into the tread by using a press. The tread is then vulcanized onto a tire casing using a bonding layer of uncured natural rubber.
Precure rubber has the tread design cured into the finished shape before the rubber is shipped to the retreader.
A thin layer of uncured natural rubber is sandwiched between the buffed surface of the precure tread and the buffed surface of the tire.
The tyre is vulcanized with heat, time and pressure in a curing chamber that bonds the tread to the casing. This thin layer called precure cushion or bonding gum.Retreading Process
Each tyre received in a retread plant is subjected to a rigorous visual inspection. Inspectors are assisted by the use of non-destructive sophisticated inspection equipment.
We also purchase a new machine (Inspection Spreader).This Inspection Spreader designed to detect pinholes, nail holes, cuts, cracks, porosity,etc,Automatic tyre rotation stop when penetration detected with sparks.
The tyre’s old tread is mechanically removed on high speed buffers. Today’s buffers are extremely accurate and will remove the proper amount of old rubber while turning the tyre to an exact specified diameter and radius.
With advances in state-of-the-art repair materials and repair methods, many of these tyres can be routinely repaired and in most cases can be retreaded when the original tread is worn off. The repair station is where any surface injury is treated using effective material and tools for grinding and patching.
Even in small injuries it is critical that the injury is cleaned and filled. If this is not done, severe rust, separation and steel cable looseness could take tyre out of service. The injury should be inspected, and then cleaned out with a carbide cutter. After cementing the injury, a vulcanizing rubber stem should be applied to “fill” the injury. This would create a permanent repair that maximizes tyre life.
In the pre-cure system, the tread rubber has already been vulcanized with the new tread pattern design. The buffed tyre needs a thin layer of cushion gum to be wrapped around its crown area. The pre-cured tread rubber is then applied with the building machine. This is called the building process.
a) The built tyres are then mounted with envelops and rims to prepare them for curing.
b) For enveloping, tyres are first fitted an outer envelope at the envelope-mounting table before the inner envelope is fitted into them. The enveloped tyres are then vacuumed out for preparation prior to curing. Modern plants have their casings hoisted by monorail systems.
The Precure Tread system is a process by which a tread pattern is fully cured or vulcanized into the tread by using a press. The tread is then vulcanized onto a tire casing using a bonding layer of uncured natural rubber. The tyre is vulcanized with heat, time and pressure in a curing chamber that bonds the tread to the casing. This thin layer called precure cushion or bonding gum. Cold retreading was then a term used to describe a process in which the final curing of retread is done at temperature lower than 115c.
Hot Process (Hotcure)
Hot retreading is the term used to describe the retreading process in which the curing of retread is done at a temperature of above 140c. It employs a steel or aluminum mold with a tread design cast or machined into it.
Final Inspection (Presure Test) & Painting
- Tyre inflation pre-set at 2, 4 & 8 bar (max) for a better QC inspection.
- Enclosed by steel cage as safety protection.
- Testing cycle ended automatically to reduce supervision work.
- Well lighted within the cage for better visual inspection.
All retreaded tyres are encouraged to be returned with the sidewalls painted using a light coat of black tyre paint.