Calendering process of rubber calender

Rubber calenders mainly include calenders, rubber calender equipment, PVC calenders, small calenders, etc. The following will introduce you the calendering process of the rubber calender.

Here is the content list:

• What are the factors that affect the compression speed of the rubber calender?

• The quality problems and reasons that often occur in rubber calenders in tablet pressing.

What are the factors that affect the compression speed of the rubber calender?

1. Roll temperature: The roller temperature depends on the nature of the rubber. Generally, for rubbers with high rubber content or greater elasticity, the roller temperature should be higher (increase thermoplasticity); for rubbers with low rubber content or less elasticity, the roller temperature should be lower. In addition, to smoothly rubber calender the film between the rollers of the rubber calender machines, there should be a certain temperature difference between the rollers. For example, when the natural rubber wraps a hot roller when the film is moved from one roller to another, the roller temperature of the latter should be higher; while the general synthetic rubber is the opposite, it is easy to wrap the cold roller, so the order of the roller temperature should be the same at this time. Natural rubber is the opposite.

2. Plasticity of rubber material: The plasticity is large, the fluidity is good, the film is smooth, and the shrinkage is small, but when the plasticity is too large, the rubber calender is prone to sticking to the roller; the plasticity is low, the fluidity is poor, the film is not smooth, and the shrinkage rate is large.

3. Roll speed: The roller speed is fast, the production capacity is large, but the shrinkage rate is large, and the surface is not smooth. The roller speed of the rubber calender should be determined according to the plasticity and temperature of the rubber compound.

The quality problems and reasons that often occur in rubber calenders in tablet pressing.

The quality requirements of rubber calender tablets are smooth surface, uniform thickness, no crepe, dense internal rubber, no bubbles, etc. Common quality problems and their reasons are as follows:  

1. There are bubbles inside: because of the high water content of the compounding agent, the high volatility of the softener, the high calendering temperature of the rubber calender machine, excessive glue accumulation, improper film insertion, excessive moisture in the return glue, and too thick calendered film.

2. Surface shrinkage: Because the plasticity of the rubber is low, the shrinkage rate is large, the ratio of the rubber to the return rubber is uneven, and the heat refining is uneven.

3. The surface of the film is not smooth: because the plasticity of the rubber material is low, the roller temperature is low, the rolling speed of the rubber calender is fast, and the rubber material has self-vulcanizing rubber particles.

4. Uneven film thickness: Uneven shrinkage due to uneven plasticity of the rubber material, large fluctuations in rubber temperature, inconsistent roller distances on both sides, and different winding tightness.

Sheet pressing is to use a rubber calender to make a film with a certain thickness and width under the condition of equal roller speeds. It can be carried out by using a two-roller, three-roller, or four-roller rubber calender. Qingdao Huicai Machine Manufacture Co., Ltd. has developed a variety of rubber calenders. If you are in the rubber calenders, you can consider using our cost-effective products.