Common Mistakes When Using Camelback Hot Tread Rubber
Camelback hot tread rubber is one of the most popular rubber types used for re-building HCV and truck tyres. When used properly, it provides re-treaders a long-lasting tread layer with good load-carrying ability and long-haul performance. However, there are a few common problems in the storage, handling, and curing of hot tread rubber, which can make a good-quality rubber compound sheet a weak link in the tyre.
When using camelback hot tread rubber, knowing about these problems, and avoiding them, can mean the difference between tyre life, safety, and cost per km.
1. The use of the wrong grade or compound type
Not all hot tread rubber is created equal. Rubber compound sheets are engineered for various uses, such as high-mileage highway applications and mixed-load or off-road applications. One of the most common errors is selecting the wrong or out-of-specification camelback hot tread rubber for a casing or load specification.
For example:
- A soft, fuel-efficient compound for a heavily loaded truck tyre may tear out quickly.
- If a hard compound is used in a short-haul bus or delivery van, it can lead to a rougher ride and unnecessary expense.
A quality rubber manufacturing partner can help you determine which of the various rubber compound grades would be most appropriate for your fleet’s speed, load, and road conditions, so you wouldn’t waste money on a compound that doesn’t fit.
2. Wrong Storage and Handling
Camelback hot tread rubber is available in long, uncured rubber compound sheets that are sensitive to heat, light, and moisture. Common storage errors are:
- Storing the rolls in direct sunlight or hot, unventilated spaces can cause the rubber to soften, stick, or become uneven.
- Flat rolls on the ground in moist and dusty conditions for curing, which can cause contamination and non-uniform curing.
- Using rolls too roughly, causing wrinkles, creases, or uneven edges that may cause air pockets or weak areas after pressing.
The preferred storage position is upright with the rolls stacked in a cool, dry warehouse, away from direct heat and UV light, and without stacking the rolls too high or leaving them for extended periods without rotation.
3. Poor Buffing or Contamination of the Casing
The most important part of the hot tread process is a proper buffing of the casing before the camelback hot tread rubber is applied. Typical pitfalls at this stage are the following:
- Under‑buffing: Old hard tread or rubber left on the casing that results in poor adhesion and early separation.
- Underbuffing: Not enough rubber is removed, potentially leading to a weaker belt or carcass and weaker tyres.
- Contamination: Any dust, oil, or moisture that remains on the buffed area can affect bonding of the hot tread rubber to the casing.
The surface must be smooth and clean with even buffing and light application to have a lasting bond after being dust-free.
4. Inconsistent Application Pressure and temperature
In the hot‑tread (camelback) retreading process, the tread is applied cold and then cured under heat and pressure in the press. Rubber compound sheets may not vulcanize evenly if the pressure and temperature are not controlled properly. Common mistakes include:
- Not hot enough or long enough: This results in a soft, sticky rubber surface that can cause early wear or peeling.
- Too high temperature or too long: Over-curing may cause the tread to become hard, brittle, or even burned, which will affect the flexibility and safety.
- Camelback hot tread rubber: If the press does not hold the casing and tread evenly, the camelback hot tread rubber will deform and cause uneven tread or a poor footprint.
A properly designed curing press in combination with a good time/temperature profile will provide the optimum rubber manufacturing compound hardness, flexibility, and adhesion.
5. The use of old or damaged rubber compound sheets.
Rubber compound sheets and Camelback hot tread rubber rolls will have a shelf life. The rubber will over time lose its elasticity, harden, or even develop micro-cracks even before use. Mistakes include:
- The use of brick-hard or expired rolls, which do not fit the casing well and will not bond in a uniform manner.
- Using rubber that is heavily creased, folded, or improperly stored, which may cause weak spots or air pockets.
Rubber compound sheets should be examined for color, texture, and flexural properties prior to use, and any roll showing signs of dryness, cracking, or abnormality should be avoided. A good rubber manufacturing supplier will typically indicate or label their rolls and offer suggestions for storage and usage time.
6. Failure to use Cushion Gum or Adhesive Preparation
Many hot tread systems use a layer of cushion gum or adhesive between the casing and the camelback hot tread rubber. If this layer is:
- If too thin or uneven, it is likely to be weak.
- If it’s too thick, it will burn or expand too much when hot.
- The bond may become broken if it is applied to a dirty or oily surface.
The quality of the resulting tyre is significantly enhanced by treating the cushion gum in the same way as the rubber compound sheet—measuring thickness, keeping it clean, and carefully aligning it.
Also Read: Comparing precured cold tread rubber and conventional camelback hot tread rubber solutions
Frequently Asked Questions
- What are the differences between Camelback Hot Tread Rubber and precured tread rubber?
Camelback hot tread rubber is a rubber strip that has been applied on the casing and then vulcanized in the press, whereas precured tread rubber is rubber that is fully cured and patterned. The hot-tread method must be carefully managed in terms of heat, pressure, and time, and therefore good rubber production and process control are very critical.
- Is it possible to use the CamelBak hot tread rubber in all types of tyres?
It is very versatile, yet the proper grade and rubber compound sheet need to fit the tyre category, load, and road surface. Retreaders should be aware that the improper use of the wrong grade can result in rapid wear or early separation and should select the type of compound according to their fleet profile and the advice of the rubber manufacturing supplier.
- How can I determine whether I am using a good-quality CamelBak hot tread rubber?
A good quality hot tread rubber should be flexible, have no wrinkles, be of uniform color, and should be smooth and easily conform to the case without cracking or stretching. When it is difficult to roll, brittle, and/or shows visible impurities, it’s best to avoid these rolls.