Plastic Injection Moulding - A Detailed Overview

The history of injection moulding dates back to around 19th century. Ever since the invention of the injection, moulding machines have undergone several modifications to attain the form widely used today. Initially, the injection moulding methods were based on the die casting technology where immense pressure was applied to obtain the desired shapes. The plastic injection manufacturing became widely popular after the Reciprocating Screw moulding machine acquired the patent rights in 1956.

Raw Materials

There are several kinds of raw materials used for the manufacturing of the plastic injections. However, the thermosetting plastic, elastomers and thermoplastic polymers (resins) are widely used in the production process due the presence of greater viscosity in these materials.

Equipment

The Plastic injection moulding machines have basic component parts such as material hopper, heating unit, plunger etc. These machine parts are used to build pressure and keep the moulds in proper order to give the perfect shape once the molten material is poured inside it. They are also called presses, working in accordance with the tonnage ratings. Tonnage is the capability of the machine to exert clamping force during the manufacturing process to keep the moulds in closed position. The tonnage may range between 5 tons to more than 9000 tons depending upon the rigidity of the raw materials and the projected area of the moulding parts.

Plastic Injection Moulding Process

Melting Polymers: There is a broad and cylindrical melting unit in the injection-moulding machine, where the polymer is converted into liquid under high temperature and pressure. The polymer is filled in an auger, which has an opening at the bottom. The auger is introduced into the melting unit using a hydraulic motor. A valve system at the bottom of the cylinder restricts the passage of the liquid into moulds.

Pouring the Liquid Material into the Moulds

Once the heating process is over, the auger is pushed further to pour the liquid polymer in to the moulds to give the requisite shape to the injections. The moulds are compressed under huge pressure to keep them intact and in proper position. During this process, the liquid is poured twice or more to ensure there are no air spaces left.

Cooling

 After the moulding, the entire mould is introduced to cooling for compact solidification of the plastic injections, which consumes the major time-period during the entire manufacturing process. The cooling is done by passing air or water over the heated moulds or introducing cold water through small holes on the mould surface.

De-moulding

Once the cooling process is over, the compact plastic injections are ready for removal from the moulds. The clamp on the mould is unlocked to open the mould and derive the injection. The entire process is completed and the mould is now ready for the next unit manufacturing.

Plastic injections are affordable compared to other forms of injection. The cost of production mainly depends on the type of machineries. In the long run, this is a lucrative business. The plastic injection moulds are widely used in the manufacture of a number of other plastic products.

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Injection Moulding - Guidelines and Advantages

Injection Moulding - What is this?

Injection moulding is one of the most popular ways to create plastic products. For example, you are having a manufacturing company and you need to manufacture a large amount of plastic products in a short time period, also those products should be in same size. Then you could use plastic injection moulding to manufacture your products faster than ever before. The best thing about it is that it is cost effective and this moulding also requires little supervision from staff. Injection moulding machine works in a few stages. In the first stage, the given plastic is melted and then that melted plastic is inserted into a mould machine. That mould machine is then squeezed together to create a shape for your plastic product. The second stage is cooling stage. Here, the moulding machine will cool all your formed plastic products.

Nowadays many people are using this type of moulding to make their product faster and also the injection moulding is more accurate. All the parts in the moulding machine are computerized that means all your work will run like clockwork and the outcome will be more accurate. Handmade plastic products can be a nightmare and sometimes will go wrong. Injection moulding products are always better than our handmade plastic products. Nowadays most of the car manufacturing companies use this injection moulding a lot. For example, the lid of your car's radiator will be manufactured using this technology. There are millions of cars made every year all over the world and therefore this sort of process is required to make sure accuracy and speed.

Some Design Guidelines for plastic injection moulding:

Now we are going to see 5 more design techniques for injection moulding.
1# You should avoid small holes when you are designing a perfect product. Because these small holes are too intricate to mould, these small holes also lead to tool breakage.
2# If you want any hole in your product, through-holes are best.
3# sometimes there will be a variance in surface consistency or angle. This variance is totally depending on the type of material used. Sometimes this variance is little consequence for some products. But if your moulding design requires an exact surface or angle then you should be careful when designing that product.
4# You should use the uniform screw sizes, because they will make your manufactured product much more accessible to many people.
5# Each additional component in your manufactured product will increase the risk of anything going wrong. So always you should make your product more and more simple. Then only it will be easy to handle.

Advantages injection moulding:

1# This injection moulding allows you to create more products within a short time period.
2# When manufacturing your product you may use fillers, these will increase product strength.
3# You can use more than one material.
4# Human work is reduced
5# Design flexibility
6# The outcome will be more accurate than handmade plastic products.

These are some design guidelines and advantages about injection moulding.

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