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.
Buffing
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.
Skiving & Repairing
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.
Cementing & Filling
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.
Building
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.
Enveloping, Rim Mounting & Double Envelope System
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.
Curing by Chamber (Precure)
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.
The retreaded tyre is subjected to a final inspection. This
inspection insures that only tyres that meet industry quality standards
are allowed to leave the retread plant.
All retreaded tyres are encouraged to be returned with the sidewalls painted using a light coat of black tyre paint.
All retreaded tyres are encouraged to be returned with the sidewalls painted using a light coat of black tyre paint.
Source Vulkanisir-Dangstars Blog
