Rubber sticking to the rolls of an open mixing mill can result from excessive roll temperature, an unsuitable roll gap, compound formulation, or processing conditions. The first step is to identify the cause and adjust the temperature, roll gap, or mixing procedure accordingly. Release agents and changes to the compound formulation may also help reduce adhesion.
1. Adjust the roll temperature
Excessive roll temperature can soften the rubber and increase its tendency to stick to the roll surfaces. For natural rubber mixing, the source recommends maintaining the roll temperature at 40 to 50°C to help control tackiness.
If the temperature is too low and the rubber does not flow properly, a moderate temperature increase may improve its processability. The actual setting should be determined according to the rubber compound and the established mixing requirements.
2. Adjust the roll gap
An excessively narrow roll gap can increase shear and heat generation, causing the compound to overheat and stick to the rolls.
Increasing the roll gap may help reduce the pressure and heat generated during processing. However, setting the gap too wide can reduce mixing efficiency and affect compound uniformity. Make adjustments gradually and check the material condition after each change.
3. Use suitable release agents or plasticizers
Suitable additives may help reduce adhesion between the rubber compound and the roll surfaces. The source identifies stearic acid and talc as possible additives for this purpose.
Plasticizers may also be used to adjust the compound's processing characteristics and tackiness. Any changes to the formulation should be evaluated against the rubber's required physical properties and the intended application.
4. Keep the roll surfaces clean
Rubber residue and accumulated particles can contribute to sticking during subsequent mixing cycles. Clean the roll surfaces at appropriate intervals using a suitable cleaning agent or an approved roll cleaning method.
For frequent production, the source recommends cleaning the working surfaces every two hours. The actual cleaning interval should depend on the material, residue buildup, and production conditions.
Before cleaning, stop the machine and follow the manufacturer's safety procedure. Never wipe the rolls or remove stuck material while they are rotating.
5. Improve the compound formulation and mixing process
If sticking continues after temperature and roll gap adjustments, review the compound formulation and feeding procedure.
Adjusting the proportions of different rubber types or changing the carbon black loading may affect the compound's tackiness and processing behavior. These changes can also influence the finished rubber's properties, so they should be assessed through controlled trials.
The mixing procedure can also be reviewed. Adding ingredients in stages and adjusting the mixing cycle may help manage heat generation and compound consistency. Any reduction in mixing time should be validated to ensure that the ingredients remain adequately dispersed.
6. Custom machining for rubber processing equipment
Persistent roll sticking may also warrant inspection of the roll surfaces for wear or damage. If a machine component requires replacement, Hansheng Automation can assess custom machining based on customer drawings, material specifications, and dimensional requirements.
Our precision machining services also cover non-standard components for rubber processing, packaging, filling, and tobacco machinery. We can assess custom metal parts for yacht equipment and RC racing cars based on the supplied drawings and machining requirements.
