Plastic Injection Molding – Advantages & Steps Involved In Manufacturing – Sujan Industries

By Sujan Industries In Automotive

21

May
2021

Plastic Injection Molding – Advantages & Steps Involved In Manufacturing – Sujan Industries

Plastic is the most common material for manufacturing goods and end-use parts, starting from Consumer Products, Medical Tools, Automotive, Electronic, Electrical Goods, and Appliances to various other industries Applications, etc. Plastic is mostly being used due to its versatile category of materials. Material Properties can be modified, optimize or customize as per application in various polymer options. Recycling & Re-use of Plastic material makes it more versatile among the other commodities. Considering the growing consumption of plastic in the Automotive, Industrial, Construction, Electronics, Electrical, Transportation & various other Industries, Sujan Industries Striving, Developing and Adopting state of art manufacturing and assembly facilities for producing and supplying premium quality plastic products to the Indian and global market and supporting the worldwide growth of the plastic industry.

What are the Various Types of Plastic?

There are hundreds of various grades of plastics material available in the market. Each material comes with unique property & different base chemistries. Compounded material with additives and derivatives make material cheaper & suitable for the end application. These are formulated to cover a wide variety of functional and aesthetic features. Mainly there are two types of plastics: Thermoplastic and Thermosetting. These types of plastics help to simplify the process of finding the material appropriate for a given product.

1. Thermoplastics
It’s the most commonly used type of plastic which has the ability to endure numerous melt and solidification cycles without any significant degradation. Thermoplastics are generally supplied in the form of small pellets or sheets that are heated and given the form of the desired shape using different manufacturing processes (i.e. Moulding, extrusion, thermoforming). The method is entirely reversible since there’s no significant chemical bonding and it eases out the melting or recycling and reusing of thermoplastics.

The common types of thermoplastic materials are as follows:

  • Polypropylene (PP)
  • Polyethylene (PE)
  • Polyvinyl Chloride (PVC)
  • Polyethylene Terephthalate (PET)
  • Acrylonitrile Butadiene Styrene (ABS)
  • Acrylic (PMMA)
  • Polystyrene (PS)
  • Polyamide//Nylon (PA)
  • Polycarbonate (PC)
  • Polyether Ether Ketone (PEEK)
  • Polyoxymethylene (POM)
  • Polyurethane (PU)

2. Thermosetting Plastics
Thermosetting plastics are also referred to as thermosets and remain in a permanent solid state after curing, in contrast with thermoplastics. Polymers in thermosetting articles cross-link during a curing method influenced by light, heat, or suitable radiation. This process of curing develops a chemical bond that is entirely irreversible. Thermosetting plastics are decomposed when heated and don’t reform after cooling. It’s not possible to recycle the thermoset materials.

The common types of thermosetting materials are as follows:

  • Epoxy
  • Cyanate Ester
  • Polyurethane
  • Polyester
  • Vulcanized Rubber
  • Silicone

Plastic Manufacturing Process at Sujan Industries

Plastic material is of versatile category. It has a lot of polymer options, each with its own specific mechanical features. Types of plastic manufacturing process include Injection Moulding, Extrusion, Blow Moulding, Rotational Moulding, Polymer Casting etc.

At Sujan Industries, we have our in-house workshop for the Injection Moulding process. The main advantage of this process is, it is most widely used for high volume & mass manufacturing of the products. Millions of high-quality parts can be produced at a fraction of time for various applications.

Steps of Plastic Injection Molding

The process starts with the design of the part and mould, selection of the polymer, and prototyping to ensure a premium quality result. The Moulds for injection molding are very complex and need to design and manufactured to tight tolerances to produce excellent-quality products. These critical stages take a few weeks to complete and the actual process of injection moulding is so efficient that a lot of parts can be entirely moulded in a few seconds. This process gives the result of highly complex & excellent quality products. Here are the steps involved in the injection molding process.

1 Material Pre-Drying: Many Plastic Materials (Hygroscopic Materials) i.e. Nylon, ABS, Acrylic, PET, PBT, PU, PC, etc. attracts moisture from the ambient/atmosphere and resulted in many defects while processing. Therefore it requires Material Pre-Drying before going forward to the next process.

2 Process Parameter Set-up: the First Step is mould loading on the machine after ensuring all electrical and cooling line connections followed by process Parameter Setup. Process parameters can be recalled from the system if the same tool set up data stored in machine systems previously.

3 Start of Moulding Cycle: After reaching desired Process Temperature at all zones of Barrel & hot runner (if applicable), Clean the barrel by purging the previous material, check the mould opening & closing, ejector function, clamping pressure, cooling line, etc. Start the moulding in Auto, Semi-Auto mode (as per requirements). A complete cycle can be understood in the below steps:-

4 Mould Closing: Mould Closing is the very first step of the Production Cycle, it will enable the mould to seal completely and lock with appropriate clamping pressure so that internal systems of mould (i.e. Gate, Runner and Vents) will start functioning. Gate is the entry point for the molten material where the runner is a channel to feed the material inside the cavity(s). A venting system allows the air to flow out of mould to prevent air marks, air bubbles and other visual defects.

5 Injecting Polymer: A barrel with a screw inside is filled with pellets of the selected polymer resin (with appropriate helix angle and clearance between barrel ID and Screw OD). The barrel refers to the barrel of the injection moulding machine, and some places are also called the material tube and the barrel. The function of the cylinder is to transport, compact, melt, agitate and press the plastic. All of these procedures are accomplished by the rotation of the screw within the barrel onset temperature.

6 Cooling: The melted plastic must cool and harden in the mould to retain its shape. Moulds are designed & made with channels to allow a coolant, normally water or oil cooling mechanism, cooling fluid to flow through and cooling channel of mould for a certain period of time.

7 Material Reloading: While the part is cooling, Material reloading starts, as the material feed inside the barrel it push the screw back and the barrel is reloaded material to prepare for the next cycle.

8 Mould Opening & Ejection: After cooling time reached mould opens and the cooled part gets removed from the mould by ejector pins which push it away from the surface of the mould where it is dropped into a box or conveyor system.

9 Finishing & Quality Inspection: At the end, the parts are checked to ensure that they are meeting given dimensions & other quality standards, and any finishing steps are executed, such as removing runner not separated to the part, excessive flashes or any rough corners left where the mould halves meet.

Materials Commonly Used at Injection Molding Process

With almost, any thermoplastic materials Injection Molding can be done. Plastics that are commonly used in the injection moulding process include the following:

  • Polypropylene (PP)
  • Polyethylene (PE)
  • Polyvinyl Chloride (PVC)
  • Polyethylene Terephthalate (PET)
  • Acrylonitrile Butadiene Styrene (ABS)
  • Acrylic (PMMA)
  • Polystyrene (PS)
  • Polyamide//Nylon (PA)
  • Polycarbonate (PC)
  • Polyether Ether Ketone (PEEK)
  • Polyoxymethylene (POM)
  • Polyurethane (PU)

At Sujan Industries, we have years of experience and expertise to produce plastic injection moulding components for various applications with high precision. Sujan Industries has an in-house R&D centre and an integrated lab to design the product and validation as per customer’s requirements considering the high performance of the product at end-use. We offer Various Rubber, Plastic, Rubber to Metal bonded products & Casting Components (Steel Casting/SG Iron). If you are looking for the best manufacturer from India for your critical application of plastic, rubber to metal bonded, and casting products, Get in Touch with us. We will assure you of the best service & solution always.

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