Australia Business Information Hub : rubber moulding

Monday, 22 February 2016

Learn About the Process of Moulding Rubber to Form Objects of Daily Use

Rubber is an indispensable material in modern life and while it can be obtained from both synthetic and natural sources, do not come in the shape of usable things. Rubber is obtained from elastomers which is actually untreated and uncured and is a blob of rubber which has to be moulded in the shape of the object that one is trying to get. Rubber is great for manufacturing materials which are required to expand or contract according to the pressure forced on it. Elastomers can be derived from both natural and synthetic sources but it is mostly treated in factories and chemicals are mixed with it to make objects more durable and strong. Rubber moulding is the process by which this material is moulded to form objects and there are three main processes associated with it – compression moulding, rubber injection moulding and transfer moulding. All of the three processes mentioned include the same techniques as that of rubber moulding.

Steps of rubber moulding:

At first the blocks of elastomers are pressed together and put into a rubber moulding cavity. This cavity is made of metal which helps to keep the shape of the object intact.
This rubber is then heated and when the elastomers boil, they expand and contract accordingly to mould into the perfect shape of the object. These two steps are included in all the processes of rubber moulding.

Rubber Moulding

Different types of procedures for moulding of rubber:

Rubber injection moulding: In this process the rubber mould is heated and closed at first. Then the uncured elastomer is injected into this mould. In this process, the injection unit and the press unit have separate operating units or controls. It is advantageous if the opening of the feed for the rubber strip is placed at a height which is amenable to the whole process. The rubber mould is obtained by having a short injection time and high pressure while injecting the liquid rubber into the mould. The advantages of rubber injection moulding can be checked out below:
- Blanks are completely eliminated so the process is relatively easy to handle.
- The mould is completely closed which means that flash cannot be formed and thus the process becomes easier.
- Flow channels and complex cavities are easier to fill.
- The process is pretty amenable to automation.
Compression moulding process: This process requires the rubber or elastomer compound to be formed into a blank and this blank is then placed in the moulding cavity. The advantages of this process can be checked out below:
- It is the most primitive method for rubber moulding and has been there for centuries. This procedure is getting modernised now but it is still relatively simple compared to other processes.
- Other products can also be manufactured which does not contain rubber.
- It is the most suitable process to manufacture objects with large surfaces or large spreading surfaces.
- It can also be used effectively for rubber which has high viscosity and thus flow poorly.
Transfer moulding: The blanks are preheated and loaded into heat chambers and distributed into several cavities. The advantages of transfer moulding are as follows:

As manufacturers prepare blanks and handle them, it becomes difficult to keep control over the whole process. Transfer moulding makes it easier.
The curing time is much reduced as the rubber is manufactured from before.
Molten rubber flows into the cavities easily and fills them more efficiently.
This process is especially good for bonding of rubber and metal and a fresh surface is necessary for this to take place which is generated here.

If you still want to know more then, visit here and get more information about rubber moulding.

Saturday, 28 February 2015

All That You Want To Know About Rubber Moulding

By Mike On 18:20 In tool making

Rubber industry started to flourish just few decades ago, but now we can see its immense use across the globe. Rubber molds are one of the most consumable products supplied by the rubber industry.

As the name suggests, these are the moulds made up of rubber. In rubber material, these molds are manufactured in mainly four structures with different manufacturing techniques. This mainly includes pressing die, die-casting mould, injection mould and extrusion mould. Other moulds are inflatable mould, rubber dip mould and there are many other variations to it.

Here, we will try to discuss about these structures and techniques one by one and make an attempt to understand the theory behind their success in different stages.

Pressing die
It is famously known as general die. The material used in making this type of die is semi-finished rubber which is processed through mixing. The mixing technique is a type of manufacturing process which is used to make rubber moulds. In this process, the rubber and all other kinds of the necessary components are mixed together and improve the elastic property of rubber.

After the semi-finished rubber, it is put into the dye, pressurized and heated up in the plate vulcanizing machine. Then the die is molded by the means of heating and pressurization. As this type of die has simple structure and used in wide applications with convenient operation, it is considered as a useful product in the field of rubber molded parts.

Die casting mould
It is also known as transfer-type mould. The main material used in making it is the slab rubber. Simply put the material into the cavity of die-casting mold. By applying pressure on the die, the casting plug squeezes the sizing material. Then the sizing material enters the mould by the means of pouring system. Through this process, die casting mold is finally molded.

This type of mould posses some unique features as and is more complex than the common die, its consistency is excellent and much more. It is mainly used for the complex rubber products.

Injection mould
It is made by sizing material in the plastic state. Through the pouring system, in injection mould the sizing material is vulcanized. Then it is finally molded.

This mould also has a very complex structure. Therefore, it is widely used to produce the complex shaped, large sized, thick wall products. In addition, its efficiency of production is also very high and the quality is stable. Besides, it can also realize automatic production.

Extrusion die
It is a typical mould made by semi-finished rubber. Its manufacturing process is very complex as compared to the other die’s manufacturing process. Its characteristics are similar to that of the injection mould. It also consists of a stable quality and high production efficiency.

According to the varied field of utilization, different types of rubber molds are used in making different items or products. The key molding should be done only when the air is totally removed and mould cavity is filled up with rubber.

For instance, a ball made by using an elliptical shaped extrusion and cut up to an appropriate length with the help of a bar well. The weight of this would be chosen up to a few percent that is from 2% to 10% above from the weight of the final product. This ensures a fully formed product and gives an extra push to the air which is trapped residually.

In order to find the right type of rubber molds the dependency on the nature of the product is inevitable. Hope the information is beneficial for you!