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Plastic molding is the process involved in obtaining plastic products by using a mold. Over the years, molding techniques have been developing and improving to meet the market demand for plastic items. These items are supplied to various industries like appliances, medical, automotive, electrical, pharmaceutical, etc. Plastic molding companies around the world are rising to the challenge by incorporating various methods to manufacture plastics.
There are five main types of plastic molding processes that you can employ in manufacturing plastic goods. They are as follows.
Plastic Injection Molding
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Plastic injection molding is the most popular plastic molding. It is widely used due to its ability to make small and large products with high precision and complex designs. The working principle of plastic injection molding is simple; you need a mold, resins, and the machine to create the perfect plastic parts. The process starts with the designing and making of the mold according to the client’s specifications.
Mold-making is a delicate stage since the outcome determines how the product will look. It is usually made of metal, either steel or aluminum. After the mold is ready, the resins are melted and injected into the mold cavity under high pressure. The pressure ensures that every part of the cavity is filled with molten material to prevent defects on the part. Cooling and solidification take place, and the part is ejected from the mold. The process is done again to produce thousands of similar products.
Pros;
- Plastic injection molding is cost-effective.
- Mass production of similar parts is possible with plastic injection molding.
- It is a fast manufacturing process.
- There is minimal waste material from the plastic injection.
- It is versatile hence permits customization.
Cons;
- Although it is an economical process, the capital investment is pretty high.
- Machine repairs are expensive.
Compression Molding
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Compression molding is a manufacturing process that involves the compression of plastic material to form a product. Compression molding begins by preheating the desired plastic material then placing it on an open heated mold. The mold is then closed with a plug, and pressure is applied to the plug pressing the preheated plastic against the mold cavity. It is then left to cool in the mold and all the excess plastic removed, then it is finally ejected from the mold.
Compression molding is applied in industries such as automotive, where spare parts are needed. Products made from compression molding range from large to small items. The small products also have enough strength to act as spare parts for metal parts. Examples of these products are small auto parts, fenders, spoilers, hoods, and scoops. Compression molding has some advantages and disadvantages that you need to keep in mind if you are considering it.
Pros;
- Compression molding is among the most affordable plastic manufacturing processes.
- The process produces solid and durable products.
- Compression molding makes both small and oversized items.
Cons;
- There is a wastage of material during compression as some will overflow from the mold.
- Consistency in the product is not guaranteed.
Blow Molding
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Blow molding is known to produce hollow plastic products. Blow molding is a plastic manufacturing process that uses air, plastic, and mold to form hollow plastic items. The process is simple, plastic is melted, and the air is blown into it the same way as a balloon. The blowing is done when the liquid plastic is between two halves of a mold. The liquid plastic stretches and fills the cavity taking its shape. Blowing air is what forms the hollow space.
Blow molding is used to manufacture products such as bottles, cans, drums, and tanks. Blow molding can either be extrusion blow molding or injection stretch blow molding. In extrusion, the parison is placed into a mold (cold), and the air is blown to stretch it out. It stretches, forming a hollow item. On the other hand, injection stretch blow molding uses a perform formed through the injection molding process then put inside a mold for the blow molding process.
Pros;
- You can use various techniques for blow molding.
- It is inexpensive.
- You can conduct blow molding using advanced technology like 3D blow molding.
Cons;
- Blow molding requires a high degree of accuracy hence can lead to material wastage.
- The process uses a lot of petroleum which is not suitable for the environment.
Extrusion Molding
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The extrusion molding process is widely used to produce plastic items like pipes, straws, candy canes, insulators, hoses, etc. In simple terms, you can describe extrusion as squeezing out a product. The process commences with loading a heating machine with plastic pellets, and once molten, the liquid plastic is forced to pass through a shaped passage to adapt the design. Cooling then takes place, and the final product is a shaped rod-like item.
In the extrusion process, some thermoplastics are favored, especially those with greater strength and stability. These properties make these plastics adopt the desired design with ease and maintains it. Examples of these plastics are polyvinyl chloride (PVC), polypropylene (PP), acrylic, polyester, polycarbonate, and ABS.
Pros;
- Starting capital of extrusion molding is cost-effective.
- The cost of production is low, meaning profits will be higher.
- Setting extrusion machines is fast and straightforward.
Cons;
- There is a limitation in product variation as it can only produce one kind of product.
- Consistency may be problematic due to unpredictable factors like die swell (plastic expansion when hot).
- The production speed is moderate.
Rotational Molding
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Just like blow molding, rotational molding is a manufacturing method for producing hollow plastic parts. It is usually referred to as roto-molding. Unlike many plastic molding techniques, roto molding uses powder instead of resins. The process begins with the addition of plastic powder to a mold. The machine rotates while heating the powder simultaneously and eventually melts.
During the rotation, the liquid plastic attaches itself to the mold wall taking its shape. Rotational molding does not need the pressure to form products. The specific products obtained from rotational molding are kayaks, toys, tanks, recycle bins, car parts, etc. Roto-molding is a very diverse process as it permits the production of a variety of products.
Pros;
- Products from rotational molding are diverse in both size and shape.
- There is low material waste.
- Roto-molding equipment is affordable.
Cons;
- The process is labor-intensive, making production a bit costly.
- Although there is diversity in products, the design is usually regular as rotational molding cannot handle complex designs.
- The raw material is mainly plastics only.
Conclusion
Plastic molding processes are among the most utilized techniques in the world. Plastic items are always in demand, from consumer goods, medical tools, automotive parts to electricals. These items offer several benefits to consumers, and that is why the sector is snowballing. At RYD Tooling, we are experienced in designing, manufacturing, and secondary processes to make your products stand out in the market.
Our capabilities include injection molding, prototyping, parts design, among others done with high precision. Products from our factories are always high-quality withstanding the test of time. Don’t wait to work with us; click here to get in touch with our team of experts.
