“Retreading” is the process of replacing the tread on worn tyres in which it is saved and reused the 80-90% of the material and by which you can save around 80% of the cost compared to the manufacturing of a new tyre. In tyre retreading industry brushes are fundamental in every re-manufacturing process in order to guarantee quality and safety of the retreaded tyre.
SIT offers a wide range of technical brushes in Liz brass-plated steel cord engineered and ideal for rubber brushing.

1. Initial inspection and preparation of the tyre to be retreaded

The worn tyre casing is initially cleaned from stones, nails, glass and debris using wheel and roller brushes in synthetic or metallic filaments. This process allows the operator to be more precise and safe during the initial inspection and avoids the machines to get dirty. After the initial automatic cleaning a closer manual and electrical inspection takes place to verify the feasibility of the tyre retreading. If this is the case the user repairs with brushes some spots before the buffing step.

2. Casing buffing

Buffing is the process by which all the old worn tread is removed before a new tread is applied to the casing. This is achieved with Liz steel cord wheel brushes (outer diameter from 100mm – 4” to 230mm – 9” and face width from 15mm – 5/8” to 65mm – 2-⅝”).
After a set of metallic rasp blades shaves off roughly the tread Liz steel brushes are used to round completely the case, improving it’s surface finishing and cleaning the sidewalls in order to improve the final retreaded tyre performance on the road. Special shaped wire brushes are used to clean the tyre beads.
The casing texture left by the buffing process is critical for the adherence of the new tread to be applied. Buff texture to be achieved is different for the type of vehicle/tyre and is controlled with an RMA (Rubber Manufacturers Association) texture chart (passenger tyre → RMA 1-2, heavy duty tyre → RMA 2-3-4).

Circular brushes for rasping machines

mminchmminchmminchmminchLiz steel cord
1004237/8117/16381-1/260001RW 41039600
1405-1/2321-1/4203/4582-5/1660001RW 61449603
1505-7/8237/8361-7/16381-1/260001RW 41539604
1505-7/8321-1/4361-7/16381-1/260001RW 41549605
1505-7/81811/16251582-5/1660001RW 61529606
1505-7/8251251582-5/1660001RW 61539607
1505-7/8321-1/4251582-5/1660001RW 61549608
1505-7/8431-11/16159/16773-1/1660001RW 81549609
1606-5/16431-11/16203/4773-1/1660001RW 81649610
1606-5/16451-3/4203/4773-1/1660001RW 81659611
1606-5/16502203/4773-1/1660001RW 81669612
1606-5/16572-1/4203/4773-1/1660001RW 81679613
1706-11/16227/8203/4773-1/1660001RW 81729614
1706-11/16381-1/2251773-1/1660001RW 81749615
1807-1/8451-3/4301-3/16773-1/1660001RW 81859616
2007-7/8391-1/2401-9/16773-1/1660001RW 82049617
2007-7/8502401-9/16773-1/1660001RW 82069618
2007-7/8441-3/4291-1/8100460001RW 102049619
2258-7/8301-3/16251773-1/1660001RW 82239620
2309-1/16502251773-1/1660001RW 82369621
2309-1/16572-1/4251773-1/1660001RW 82379622
2309-1/16441-3/4251100460001RW 102349623
2309-1/16552-3/16251100460001RW 102369624

Circular brushes for rasping machines

D = brush outer diameter
E = face width
S = trim length
C = arbor hole diameter
F = See page 75 for standard adapters. Special adapters can be realized on customer’s drawing.

3. Skiving and casing repair

During the casing repair the use of stem mount crimped wire wheel brushes with diameter from 40mm – 1-⅛” to 80mm – 3-⅛”, mounted on power tools is necessary to remove rubber imperfections and to round down small tyre holes before cement is applied.
The use of stem mount rubber bonded wheel brushes with diameters ranging from 50mm – 2” to 70mm – 2-¾” on the other side is recommended for skiving and cleaning of the steel cord belts inside the casing.

4. Precured tread buffing

For a perfect tyre tread rubber bonding treatment, it is essential to roughen the precured tyre tread inner side. This is possible using high density Liz steel cord roller brushes or single section wheels mounted in proper brushing machines. According to the incidental percentage of rubber inside the replacing band/tread, Liz steel cords in various sizes are available. For a more aggressive brushing the choice of a single brass-plated steel wire is recommended.

For pitched precured tyre tread other crimped wheel brushes 60mm – 2-⅜” wide can be recommended, especially for buffing the concave pitches located on the precured tyre tread band sides.
In order to get rid of rubber dust generated during the brushing session, it’s possible to use nylon filament roller brushes.

Cleaning the preprint

Rasping of the pre-printed material

5. Tyre building

Nylon cylindrical brushes, properly shaped, are used to build/add the lower layer on the tyre casing. Moreover, with other smaller sized roller brushes in nylon the anti-cracking sticky band can be applied on the casing sidewalls.

Other applications

Wheel brushes or stem mount end brushes on electrical or pneumatic tools are used for the vulcanization mould cleaning in the hot retreading process.

Moreover horse hair or thin brass strip linear brushes mounted on tapes are used in every tyre processing-retreading machine as smoke, dust and fragments of rubber or fluid sealing.