Tanks that are cross-linked with polyethylene are designed to be able to withstand great pressure, and this is because they were manufactured with a rotational molding process. This process remains the best process that is now applied in creating cross-linked polyethylene storage tanks and other similar materials.
Basically, rotational molding begins with the cross-linked polyethylene resins, which are in actually in the powdered form. There are different molds that are used, depending on the tank size. A specified amount of resin is then included in the mold, and this also depends on the thickness of the wall.
There are three main things that influence the thickness of the take, and they include:
- The application that the tank is designed for
- Chemicals to be stored in the tank
- Temperature to be applied to the tank
The chemical process then begins immediately after the resin is added to the mold.
The Chemical Process of Rotomolding
The mold is first bolted and mounted in an oven before heat is applied, and this is with the aid of a gas burner. Once this is done, it is then rotated hydraulically at a speed of 4 to 12 rpm. The plastic melts, and this then creates layers of polyethylene, and this allows the plastic to assume the shape of the mold that is used.
After the formation process is completed, and mold is then removed from the heating source, and the tank is left to cool. The mold is then unbolted so that the final product can be seen and assessed. You might be wondering how long it will take for this process to be completed. It mostly takes between 20 minutes to 6 hours, and this depends on the size of the tank that is produced, as well as the thickness of the wall. Have a look here Grangerplastics.com to know more:
During the early days of this process, it mostly was done via trial-and-error processes, especially with respect to the timing of the processes. The steps in the manufacturing processes were done, after which the manufacturers would the subject the finished product to different impact tests. For a material that isn’t cured properly, it would not pass the impact test, but if the tank is cured properly, then it will pass the impact test and be considered to be acceptable.
However, that was only during the early days of rotomolding, and technology has advanced in many ways today.