TABLE OF CONTENTS Rotational moulding, also known as rotocasting or rotomoulding, is a low pressure, high temperature manufacturing method for producing hollow, one-piece plastic parts. As with most manufacturing methods for plastic parts, rotational moulding evolved from other technologies. The basic principle of forming a coating on the inside surface of a rotating mould dates back for many centuries, but the process did not gain recognition as a moulding method for plastics until the 1940s. The ceramic pottery process, known today as slip casting , is depicted in ancient Egyptian, Grecian and Chinese art. In Switzerland in the 1600s, the formation of hollow objects, such as eggs, followed the development of chocolate from cocoa. A British patent issued to Peters in 1855 (before plastics existed) cites a rotational moulding machine containing two-axis rotation through a pair of bevel gears. It refers to the use of a split mould having a vent pipe for gas escape, water for cooling the mould and the use of a fluid or semi-fluid material in the mould to produce a hollow part.
The earliest commercial application of the concept of rotational moulding for plastics used vinyl plastisols to coat the inside surface of a hollow metal mould. Typical products included play balls and toy dolls. This process using PVC is still in widespread use today. In the 1950s the use of the rotational moulding process expanded more quickly due to the introduction of powdered polyethylene grades specifically developed for the process. Nowadays polyethylene accounts for over 90%...
