subject: The World Of Plastic Mouldings [print this page] Do you see your electrical outlets plastic covering? Ever wondered how these plastic moulds and materials came to be? Well, they did not just appear from out of nowhere, thats for sure. There are actually different methods and processes involved in creating a plastic mould and we will get to know them one by one.
One of the first things that you need to know is that, technically speaking, plastic moulding is the procedure by which organic materials are turned into non-organic material (plastic) for industrial use. The first plastic was produced in 1851 by Alexander Parks and was known as Parkesine. It was, however, John Wesley Hyatt who was able to create a way by which plastic can be manufactured into its finished form.
Plastic mouldings can be done in a number of different ways, some of which are injection moulding, blow moulding, compression, moulding, gas assist moulding, rotational moulding, and thermoforming.
Injection moulding is the most popular way by which plastics are processed. In this method, injection moulders force melted plastic into a mould cavity. Two types of mould are made us of an injection mould and an ejector mould. It is through an opening called sprue that the resin enters the cavity. This process is usually utilized in making kitchen utensils and bottle caps, among others.
The next most commonly used plastic mouldings technique is blow moulding, also known as blow forming, a process that is usually employed in creating hollow plastic parts. Blow forming comes in three forms extrusion blow moulding, injection blow moulding, and stretch blow moulding. It starts with the formation of the parison or preform and ends with a pressurized gas expanding the preform, pressing it against the mould cavity. Blow forming equipments are usually priced higher than those that are used for injection moulding.
The third most frequently used technique in plastic mouldings is the compression moulding. In this technique, a pre-heated moulding material is placed in an open, heated mould cavity. The mould is then closed with a plug member and then pressure is applied. This technique is usually makes use of vertical presses and is the preferred method in processing automotive parts as well as ultra-large basic shape productions. It is also considered to be one of the cheapest moulding techniques.
