In this Industries there are three main processes were known to the industries Extrusion, Blow Molding, Injection Molding. In all these processes the main drawback is the tooling or die cost of the equipment against the single piece weight of the product. For the large Hollow component the Rotational Molding is most economical process.

 

The basic advantages of the process are as below.
• Economic tooling costs,
• One-piece construction,
• Weight reduction as compared to most metals,
• Uniform wall thickness
• Variety of finishes and coolers,
• the ability to produce multi-wall Moldings,
• Metal inserts as integral parts.
• Minor undercuts are possible with no draft angle required
• Short lead-time,
• Products from this process can offer excellent load-bearing properties and resistance to stress cracking and corrosion.

 

Some guidelines for the material for moulds:
• To produce the good quality water tanks by Rotational Molding, the material should have following properties.
• Good mechanical strength.

 

• Good material stability over a wide range of temperature and cycle time.
• Good resistance over warpage.
• High ESCR (Environmental stress crack resistance )