TYRE RETREADINGTYRE RETREADINGBY BY

PRE CUREPROCESSPRE CUREPROCESS

CH.PRAPULLACH.PRAPULLA

ABSTRACT

Topic: Study of Pre Cure Process It is a technology, where old tires are made serviceable by removing worn out and damaged treads (rubber belts) and replacing it with new treads. Similar to the new tires, the treated tires can be very well used on all vehicles, irrespective of light or heavy vehicles. Uncured rubber is added to a buffed casing and cured in the mold at temperatures of approximately 100°C.This temperature allows uncured rubber to flow in the matrix forming the tread design during vulcanization.This is one of the process in tyre retreading, comparing with the other tyre retreading processes this is more efficient as bonding of tread is strong due to heat treatment.

INTRODUCTION

Tyres It is estimated that over 290 million tires from cars and trucks are thrown away by Americans every year. About 55 million of these tires are either taking up space in our landfills

Burning of tyres releases toxic chemicals into the air that can also run off into our water sources. The best way to stop these discarded tires from carrying disease and toxic chemicals is to become involved in tire recycling. What is tire recycling?

Tire recycling is the process of recycling old tires that can no longer be used efficiently by vehicles into other types of products. In 1989 only about 10% of tires were recycled, but in 2003 over 80% of tires were sent to scrap tire recycling facilities.

Nomenclature of Tyre

What Is Tyre Retreading?

Tyre Retreading is a technology, where the old tyres are made serviceable by removing worn out and damaged treads (rubber belts) and replacing it with new treads. Similar to the new tyres, the treated tyres can be very well used on all vehicles, irrespective of light or heavy vehicles.

Why Retread?Retreaded Tyres are Great Value for Money! Retreaded tyres can and do perform as well as new tyres and they do it at a substantial savings over the high cost of new tyres. Retread tyres are proven to be as safe and durable as compared to new tyres.

Selection of Tyre For Retreading

To be suitable for retreading a tyre must:

●Be structurally sound· ●Be of an inherent quality suitable for retreading ("80% of some types of car tyres are not suitable for retreading)

● Manual/visual selection is the conventional process for acceptance, and is a highly successful method, carried out by well-trained inspectors.

●Different methods are employed for the selection process and the final quality check including manual, visual, ultrasonic, laser shearography and inflation testing. The choice of test depends to some extent on the throughput of the process.

Flow Procedure of Pre Cure Process

Inspection

Drying

Buffing

Building tread rubber

Enveloping

Fixing

Curing by pre cure pots

Final Inspection

INSPECTION The purpose of initial inspection is to verify that casing is acceptable for retreading or not using a thorough inspection of each tyre inside and outsid and the tyre surface should be intact, sidewalls should not over size.

After drying,the tyre's old tread is mechanically removed on high speed buffers.Then worker make second polishing and section repairs, including the sidewall of the tyre.

Buffing

ENVELOPINGENVELOPING

The built tyres are then mounted with The built tyres are then mounted with envelopes and rims to prepare them envelopes and rims to prepare them for curing.for curing.

FIXING STEEL RINGFIXING STEEL RING

After enveloping the tyre, fix them on the felly After enveloping the tyre, fix them on the felly on the working platform. And they are ready on the working platform. And they are ready for being made vacuum and vulcanizationfor being made vacuum and vulcanization..

BUILDING-TREAD RUBBER

The buffed tyre needs a thin layer of cushion gum to be wrapped around its crown area. The hot retreading tread(different from the cold retreading tyre tread, no flower patters is then applied with the tyre building machine).

A Tread with out any pattern represent the plane nylon sheet that is applied over the cushion gum.

FIXING INNER TUBE

The built tyres are then mounted with curing inner

tube to prepare them for vulcanizing.This is not necessary

for modern autonomous machinery use of this process is to

make the tyre expand after inserting into the mold.

AIRCRAFT TYRE RETREADING

All the processes mentioned above are similar to all types of tyre retreading except the thing that inflation of tyre is different depending on the accuracy and time available.

● Nitrogen is a inert gas and ensure maximum uniformity at high temperature

● Nitrogen is preferred by aircraft tyre retreaders working at high pressure because it assures the maximum adherence between the aircraft tyre (more rigid) and the mouldNitrogen reduces the curing time if used heated

CONCLUSION

●The retreaded tyres' life is almost equivalent as of the new tyre. But the expense of retreading is only 30 to 40% cost of the new tyre.

● Retreads are extremely environmentally friendly.

● Firstly, the production of a retread saves substantial amounts of fossil fuels. In fact, the manufacture of a passenger retread requires 4.5 gallons less oil than a newtyre.

● Retreading is also the best practical environmental option for tyre recycling. Every retread used means one less new tyre saving in natural resources. It also means that less tyres ultimately have to be burned, thereby reducing pollution. In fact, a recent study by the Environmental.

● An often named advantage of mold-cure retreading is the appearance of the retreaded tyre which is difficult to distinguish from a new tyre. With precure retreads, a bond line can be visible on the side wall.

● The look of a retread doesn’t tell you any thing about its safetyandperformance.

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