Roller Coating Process
Carrying out a coating on a cylinder can be done as follows:
1. Cylinder preparation
2. Coating formulation
3. Coating application
This process is qualified in-house and can vary, depending on the coating type.
1. Cylinder Preparation
Right from receiving the new roller or a one which needs to be covered, we check the dimensions of the roller and ensure that they correspond to the order. We then assess the axles and bearing seats, to guarantee the proper roller operation.
In order to ensure optimal adhesion between the cylinder and the covering, the surface of the latter is cleaned of any substance and has a certain roughness.
Here are the steps which are carried out:
1. Mechanical uncovering
2. Chemical degreasing
3. Sand blasting/Shot peening
4. Chemical degreasing
5. Primer application adapted to the coating type
2. Coating Formulation
The mixture preparation is defined through the help of previous selection guide and technical choice, depending on your application. The mixture can be composed of more than ten different materials, to obtain the desired characteristics. These ingredients are mixed in a specific order using a cylindrical or pneumatic mixer.
- After approval, it is processed for application as a coating. It is processed into either:
Calendared sheet, a sheet of equal thickness wrapped around a mandrel with the rotations separated by an interlayer film
- Extruded strips that will be wrapped around the cylinder.
This preparation phase is almost identical when it comes to polyurethanes. In the case of polyurethanes, a more or less viscous paste is obtained. The application process of the elastomer is different.
3. Elastomer Application
ENRI uses 2 covering processes for rubbers:
- Covering the cylinder in calendared sheets to the desired thickness, ensuring to exclude air.
- The winding of extruded strips around the axis needs to be covered, using a special machine.
Once the rubber has been applied, the cylinders are wrapped in a bandage. The role of the bandage is to prevent the rubber from leaking or moving during the vulcanization process.
ENRI also uses 2 processes for polyurethanes:
- Quick-setting system without mold.
- Slow-setting system cast in a mold.
In the case of polyurethanes, the vulcanization phase is integrated with the cooling. The choice of one of the manufacturing processes is related to the mixture, which needs to be applied to the cylinder. Some elastomers are more suitable for one process or another.
Another rubber application process is known as vulcanization. The chemical bonding is carried out by a firing process, the polymers which are made, are known as hot rubber. Their chemical and mechanical resistance is increased.
The process and the duration of vulcanization are different according to the desired hardness, they guarantee an excellent adhesion and a homogeneity of the covering.
As a major operation, we pay special attention to finishing. A rigorous and very precise machining is carried out. It can be cylindrical, with a more or less high roughness, parabolic or hyperbolic. We can make axial, perpendicular, or helical grooves, but also embossing depending on your needs.
The dimensioning of the parts and their conformity according to your plans, is carried out by our quality department.
The packaging is the last stage in terms of our attention. We manufacture boxes that protect your parts from external aggressions and secure them during transport.