Plastic Molding Ultimate Guide

Plastic Molding is a group of techniques used to form raw plastic materials to plastic parts using plastic molding machines and plastic moulds. Today’s world is using them in many applications.

We use plastics every day. Plastic products such as household plastic components, plastic parts of the vehicle, plastic toys are our daily necessities. Thus, the flexible design came across the world to make our everyday life more comfortable. Therefore, Plastic manufacturers brought up with different plastic manufacturing processes.

Plastic manufacturers invented how manufacturing companies can make plastic products with a profitable cost and ease of access. Most of the chemical companies are using this technology to inform their plastic production.

Mold (US Spelling) or mould (UK spelling) is the process of reshaping the plastic or metal from the melted stage to a final object by the cooling process. Plastic molding is one of the easiest and effective methods in chemical manufacturing.

In this article, we will discuss different mould-making processes and their pros and cons. Furthermore, we will discuss the mold maker machines, and plastic molding manufacturers across the world. Besides, we will explain the plastic mold techniques, CNC processes, and their categories. The following are some of the widely used plastic molding processes by different plastic molding companies.

Type 1: Injection Plastic Molding

what is injection moulding

Injection plastic molding is a molding process where the machine injects the melted plastic into the mold tool to make different shapes and sizes by cooling. Injection plastic molding produces solid forms such as bottle caps, toys, musical instrument parts, combs, containers, plastic gears, plastic chairs, mini tables, etc. Notably, the structure of an injection plastic molding machine generally has two parts:

Injection Unit

The injection molding Unit structure has a motor and gear. It provides the rotational speed of the screw ram in the barrel. On the other hand, the feed hopper contains the plastic raw materials and blends inside the barrel. After that, we will find a heater locates around the barrel. Undoubtedly, it melts the chemical raw materials. The temperature inside the barrel is usually from 180˚ C to 200˚ C. Following this stage; the screw pushes the melted plastic to go inside the nozzle. So, the main task for the injection unit is to keep the plastic, melt, and pass it to the clamping unit.

Clamping Unit

The injected plastic will now enter the mold. At this time, the clamping unit will work. In contrast, the mold or mould can be in different shapes. It depends on the product of the factory. By the cooling process, the injected molded plastic will form a solid shape. After that, the movable plate will let the final object pass away from the machine. And then, the produced plastic will go for the observation. Finally, it’s ready to travel around the globe.

However, am injection molding machine can be different in types—manually operated machine and A computer-operated machine. But CNC machines are faster than the manually operated device. Undoubtedly, it can produce a vast number of products in a day

For example, Ningbo Bole 280EKS plastic injection molding machine, PLASTIC INJECTION MOULDING MACHINE SERVO PLASTER, PSJ-150 Professional Plastic Injection Molding Machine2020, Haitian /CH/ JM /JSW Plastic Injection Machine. These are the best example of injection molding companies produced machinery.


  1. Ability to produce a huge quantity of plastic product.
  2. Except for the entry cost, this injection plastic molding machine costs comparatively very low.
  3. Low scrap rates.
  4. Repeatable.


  1. High tooling cost
  2. Large lead times.
  3. Difficult to make changes.

Type 2: Blow Molding

what is Blow molding

Blow molding generally manufactures hollow plastic products. Blow plastic molding is a process that is similar to the injection moulding process. But the only difference is, blow molding does not make solid shapes from the injected melted plastic, rather it makes hollow tube shape. Finally, the blower machine blows air inside it to make bottle-shaped products. Because of this characteristic, this process is named as blow plastic molding. Mainly, It produces products like bottles, tubes, etc.

In general, there are three main types of blow molding: extrusion blow molding, injection blow molding, and injection stretch blow molding.

All of them have similar activities but the structure and nature. Normally a blow molding starts from the feeding hopper. Similar to the injection moulding, it blends the raw material here. Due to the rotation of the screw ram, the plastic materials will get into the barrel. The barrel has 3 heating chambers. Here, the heater melts the raw materials. At this time, this melted plastic will enter inside the nozzle and this blow molds will make some tube shapes.

Later on, the blower will blow air inside the hollow mold. Subsequently, it makes the hollow molded plastic into the bottle-shaped. After that, The cutting tools reshape the size of the bottle. Then, the vacuum checking tool will check if there are any tiny holes inside the bottle. If they find any, they will reject them from the production line. Finally, the bottle will be ready for the discharge and move out of the factory.

Automatic PET Bottle Blow Moulding Machine, MG-S250L extrusion blow molding machine with an accumulator’s head, MG-D Series Extrusion Blow Molding Machine (Double stage) are the significant plastic blow moulding machines from the different blow molding companies.


  1. Large production quantities.
  2. The array of different products.
  3. Automation
  4. Blow moulding machine price is comparatively lower than other machines.  


  1. Waste of requirement precision.
  2. Petroleum Usage.
  3. It affects the environment.

Type 3: Compression Molding

what is Compression Molding

Buttons, cups, bowls, switches, handles, etc. are the few examples of the compression moulding products. Compression molding is one of the fabrication processes. Fabrication means giving the desired shape of plastic from different molding processes.

We can also use compression molding for rubber compression. Compression molding involves the molding of molten plastic through the compression process. Notably, the materials for this process is the thermoplastic or thermosetting polymers.

The compression molding machine consists of two parts, the Upper compression part, and the Lower compression. The lower part is fixed with the ground where the upper part can be moved upside down by the guide pins. The lower part of the system has a heating and cooling system.

The machine makes the plastics at the mold cavity in the lower part of the device into the desired shape. Then the Upper piston will pressurize the plastics at the mold cavity. The pressure measured from 100 – 500 kg/cm² and the heating scale measured at 130˚ C – 180˚ C. After that, when the heating and pressurizing is over the mold will form into a final shape. The cooling system will let the plastic compression to make a usable and solid-state product. Finally, with the help of the extraction pin, the upper part of the order will go upward, and the product is ready to go for packaging.

Ever fine compression molding models, Chongqing Qibiao Technology Co., Ltd, Yihui Compression molding machines, Dongguang Tian cheng machinery, Dongguan jieyang machinery are the top compression molding machine factory in the recent market.


  1. Low capital and tooling cost.
  2. Low mold maintenance.
  3. Stress has lower residual.
  4. Retains mechanical and electrical properties.


  1. Not economical making a small quantity of the products.
  2. Sometimes secondary machining (trimming, machining) of product is required after compression molding.
  3. Sometimes odd parting lines are observed.
  4. Limitation on molding depth.

Type 4: Rotomolding / Rotational Moulding

what is rotational moulding

Rotational moulding is also called roto moulding. It is also a  moulding technology for making hollow plastics. Comparing with the other technique rotational moulding process, It doesn’t need any pressure. Moreover, with a rotational movement of the roto-moulding machine, the plastic powder will fabricate into the hollow plastic.

This process can offer any sized or shaped plastic products. There are no limited measurements or sizes for this process. There are many rotational moulding products such as watercraft, automotive, agricultural products, kayaks, waste containers, roadway safety, lighting, toys are industrial products.

The rotational molding process has mainly four steps. They are:  

  1. Insert.
  2. Heating
  3. Cooling
  4. Demolding

The rotational plastic molding is very simple. The raw material plastics blended into powder form goes inside the barrel. With the rotation of the motor, the ram pushes the materials into the heating chamber. At this time, the machine provides 130˚ C – 180˚ C to melt down the powder. Subsequently, the rotomolded plastic will now reshape into the container size.

However, if we want to add other layers, we can give other raw materials into the container manually. It should be noted that the different layers will make different shape inside the box. After shaping, the cooling system works here. Hence the hot molded plastic will turn into the solid form. Finally, the product is ready for the packaging.

Wenling Rising sun roto-molding company Ltd, Shanghai yunyan Prototype and mould manufacture factory, Shandong jinxiu shanhe environmental Engineering company Ltd. are the noteworthy rotational molding machine companies in the new markets.


  1. Low-cost tooling
  2. Consistent wall thickness
  3. Double-wall construction
  4. High Durability
  5. High stability
  6. Strength is comparatively higher than others.
  7. Appearance


  1. High cycle times
  2. Limited material options
  3. The high cost of raw materials
  4. Low repeatability
  5. High labor costs.

Type 5: Extrusion Molding

what is Extrusion Molding

The plastic extrusion molding process can also be called as plastification extruding. We have seen the electric wire on the wall in our room, we have seen the charger, electrical cables, etc. These are the plastic extrusion products.

Extrusion moulding is for the thermoplastic polymeric materials. It manufactures long articles. Extrusion molding is partially the same as the injection and blows molding machines except for the later parts of them. The melted plastic surrounds the metallic wire to provide resistance from the electricity.

The plastic extrusion machine consists of a hooping container for inserting and blending the plastic powders. First, the screw conveyor mixes the chemical materials inside the barrel. The temperature is as usual as the other molding machines. Secondly, The heater keeps heating the plastic until the wire is successfully inserted into the plastic by the plastic extruder. Finally, in the end, with the help of the cooling process, the cable gets the room temperature into the solid form.

Micro machinery manufacturers, Extrmac Engineers, Extrusion blow molding machine are some significant plastic extrusion companies in today’s market. There are a few types of extrusion molding machines, such as PVC extrusion, pipe extrusion, polymer extrusion, polycarbonate extrusion, etc.


  1. The most efficient and rapid method for producing long articles.
  2. Low cost relative to other molding processes.
  3. Flexibility in manufacturing products.
  4. Plastic remains hot when it leaves the extruder, which allows for post-extrusion manipulation.


  1. It is used only for the linear polymers.
  2. When hot plastic exits the extruder, it frequently expands.
  3. The nature of the extrusion molding process places limits on the kinds of products it can manufacture.  

Type 5: Thermoforming

What is Thermoforming

Thermoforming plastic is a process where the molten plastics are formed into a pliable sheet to create a different shape by the vacuum molding process. Thermoforming is not similar to the injection, blow, or rotational moulding processes. The thermoforming products are container lids, blisters, trays, products for food, medicine and retail industries, disposable cups, etc.

The thermoforming process has typically two types, one is male form, and another is the female vacuum form. When the thermoforming plastic sheets come across, the potent shaping mold tool moves upward to make shapes. On the other side, the female vacuum machine manufactures with the vacuum forming process. After that, with the trimming process, the plastic body gets separated from the production line.

The male mold is a simple and stable structure. On the other side, female mold consists of a plug, clamps, mold cavity. When the preheated thermoforming plastic mold sheets come inside the female mold, the cap comes down due to the attraction of the vacuum force. And at last, it makes the desired shape. This process is also known as vacuum forming plastics. It makes the plastic the same as the female mold structure.

The thick thermoforming plastic preheated sheets usually are 3 mm in size, and the thin layers are generally 1.5 mm in size. Ruian City Litai Machinery Company Ltd., Nanjing Biy science technology company Ltd, Taixing Automu automation equipment company Ltd. Ruian ming yuan machinery company Ltd, etc are the thermoforming machine companies from the molding manufacturers in the market.


  1. Allows large sizes from plastic sheets.
  2. The tool requires a low cost.
  3. Easy and simple.
  4. Superior quality products


  1.  Frequently feeding the machine.
  2. Break at a certain temperature.
  3. It needs more plastic than other processes.


Plastic molding or moulding process has several kinds because of the different nature of the product we use every day. The product designers made easy for the moulding industries to manufacture the different products easily, fast, and hugely in quantity. Injection molding, blow molding, rotational molding, extrusion molding, compression molding, thermoforming are the notable processes that are widely used in today’s factories. Besides this, there are other moulding processes such as gas assist molding, structure foam molding, etc. There are lots of industries that are producing these machines. In this article, we described the basic knowledge about these molding or molding processes. Later, we will review different molding machines based on customer reviews, specifications, and prices. We will always be with you with complete knowledge and will provide the best suggestions.   

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