Rotational moulding is a low pressure, high temperature manufacturing method for producing hollow one-piece plastic parts. The moulding process dates back hundreds of years to the Swiss use of the method to make hollow chocolate eggs. The technology involves aspects ranging from mould design to mould heating and cooling, and demoulding methods. Not all materials are suitable for the process - resin and additive selection are critical.

Rotational moulding is a very competitive alternative to blow moulding, thermoforming and injection moulding for the manufacture of hollow plastic parts. It offers designers the chance to produce stress-free articles, with uniform wall thickness and complex shapes. Typical moulded parts include bulk containers, tanks, canoes, toys, medical equipment, automotive parts and ducts.

There are many advantages associated with rotational moulding. Firstly, the moulds are relatively simple and cheap, because the process is low pressure, unlike injection moulding. The wall thickness of parts is more uniform and it is possible to alter the wall thickness without changing the mould. Complex parts with undercuts and intricate contours can be manufactured relatively easily. There is also very little waste as the required weight of plastic to produce the part is placed inside the mould.

This book - A Practical Guide to Rotational Moulding - describes the basic aspects of rotational moulding and includes information on the latest state of the art developments in the industry. A key feature of the approach is to use photographs wherever possible to illustrate the points that are being made. This book will be useful to those new to the industry, as well as those who are experienced in some aspects of the process.

The ever-changing nature of this industry means that it is very important for those involved in the manufacturing operation to keep abreast of the advances that are being made. The industry is becoming more competitive and customers are making increasing demands in terms of part quality and performance.

Rotational moulding is becoming a highly sophisticated manufacturing method for plastic parts. New mould and machine features, and advanced process control technologies, are being developed. This gives designers, and end users, access to new opportunities to create novel and innovative plastic mouldings. New technologies such as mould internal air temperature measurement, mould pressurisation and one shot foaming are now available.

Key features

About the Authors
Professor Roy Crawford obtained a first-class honours degree in Mechanical Engineering from the Queens University of Belfast in 1970. He went on to obtain a PhD degree relating to the processing and properties of plastics in 1973. He obtained a DSc degree for research work on plastics in 1987. Over the past 30 years he has concentrated on studying the processing behaviour of plastics. He has published over 250 papers in learned journals and conferences during this time. He is the author of 7 textbooks on plastics and engineering materials.

Roy Crawford is currently Pro Vice-Chancellor for Research and Development and Professor of Engineering Materials at Queens University Belfast. From 1997 to 1999 he was Director of the Polymer Processing Research Centre at Queens University. This Centre was established on the basis of the international reputation of the Rotational Moulding Research Centre that he initiated at the University.

He has been awarded a number of prizes for the high quality of his research work. In 1996 he received the prestigious Netlon Medal from the Institute of Materials for innovative contributions to the moulding of plastics. He is Technical Director for the Association of Rotational Molders in Chicago, USA and Technical Editor for the Rotation Magazine, published in the USA.