What is Plastic Injection Moulding?

In plastic injection moulding(PIM) , a heated plastic material is injected into a mould cavity, where it cools and hardens to the desired shape. This process is repeatable and can be used to create large quantities of the same or similar objects. Injection moulding is a versatile manufacturing process that can be used to create a wide variety of parts and products, from small objects like bottle caps and toothbrushes to large objects like car body panels and washing machine drums.
It can be used to create objects of all shapes and sizes, and is suitable for both low-volume production and mass production. The process is relatively quick and easy, making it a popular choice for manufacturers.


There are four main steps in the plastic injection moulding process:

Step 1: Clamping the Mold Production The clamping unit is responsible for holding the plastic parts together while they’re being injected. The clamping unit consists of two opposing platens that hold the plastic parts together. The platens have pins that fit into holes in the plastic parts. When the pins are inserted into the holes, the parts are held together.

Step 2: Injection of Resin material The plastic material is fed into the injection machine in the form of “RESIN”. This process is known as “plasticization” and can consist of a single material or a combination of plastic resins and other additives. During injection, the material is forced through a heated barrel, where it is melted and mixed thoroughly. A ram or screw-type plunger is used to force the standardised material into a mould cavity through a gate and runner system.

Step 3: Cooling Phase In the mould cavity, the melted plastic is cooled and solidified. Without cooling, the plastic material would simply “short shot” – meaning it would not take shape. This is the key step to produce a quality injection moulded part. The strategically placed cooling system helps the material to solidify quickly without distorting its form.

Step 4: Ejection Process and finishing After cooling and solidifying, the moulded part is ejected using force, springs or mechanical techniques. The part is removed from the mold and it is trimmed of any excess plastic. The ejection process ensures that there are no imperfections in the part’s surface finish. Some machines may also incorporate a robotic system to pick up and transfer the parts onto a conveyor.

The injection moulding operation is now complete. This entire process can be repeated with a single system, making plastic injection moulding an extremely efficient production method. The injection moulding process requires minimal effort and is cost effective; it can produce accurate parts in large quantities. Not only that, but repeatable and interchangeable parts can easily be produced with this process.

Difference between Plastic Injection Moulding and Plastic Machining

Plastic Injection moulding involves expensive tool/die production.
Expensive process
 Ideal for mass production and intricate designs
Efficient method with repeatability among the batches
Plastic machining do not typically require expensive tools. In some cases, jigs are produced.
Less Expensive
Used for precision applications and custom parts
Greatest flexibility of design


Zastata uses a variety of materials for Plastic Injection moulding process to produce various types of products.The plastic used in the injection moulding process is typically a thermoplastic, composed of polymers, resins, and other materials each with its own advantages and disadvantages. The kind of material used to mold the part mainly depends on its application and utilization.

Plastic Injection moulding can be performed with a wide variety of materials, including different types of plastics, elastomers, nylon, rubbers, and most commonly thermoplastic and thermo setting polymers.

Thermoplastics – Thermoplastics are polymers, that can be melted and injected into a mold to create a part, and then melted and injected again to create a different part. Thermoplastics are the most used materials in injection moulding because they are easy to use and versatile.

Thermo setting Polymers – These polymers can be set or cure when exposed to heat or pressure. This means that they can be molded into any part but cannot be melted and reformed like thermoplastics. Thermo setting polymers are typically used for parts that require high heat or pressure such as engine parts.

Amorphous plastics – These plastics expand or shrink much less when heated or cooled since, they don’t have a sharp melting point. Acrylonitrile Butadiene Styrene (ABS), Polystyrene (PS), Acrylic, Polycarbonate.

Semi-Crystalline Plastics – Unlike Amorphous Plastics, these plastics have sharp melting point and under varying temperature conditions, they expand and shrink accurately depends on the temperature. Some of them are, Polypropylene (PP), Polyethylene (PE), Nylon (Polyamide), Polyoxymethylene (POM).

Mold components require thorough inspection due to their intricate parts and sensitive structure. The injection moulding machine must be inspected to ensure that all its components are functioning properly. It is essential to perform regular inspection through the process.

Zastata also performs number of inspection methods to ensure parts are made as per drawing.

The most common inspection methods are visual inspection, X-ray inspection, and ultrasonic inspection.

  1. Visual Inspection: Visual inspection is the simplest and most common inspection method and can be used to identify a wide range of defects. However, it is also the least accurate method, and can be affected by lighting and operator error.
  2. X-ray inspection: This is more accurate than visual inspection and can be used to identify defects that are not visible to the naked eye. However, it is more expensive and requires specialised equipment.
  3. Ultrasonic inspection is the most accurate inspection method and can be used to identify a wide range of defects. However, it is also the most expensive method, and requires specialised equipment.

By regularly inspecting parts and detecting any flaws prior to use, Zastata can ensure that their components meet the desired quality and help them produce reliable components for a variety of industries.

Quality Documentation

Zastata has good understanding and experience with Quality documentation like:

APQP – Advanced Product Quality Planning
FMEA – Failure Mode Effective Analysis
PPAP Level 3 – Production Part Approval Process
SPC – Statistical Process Control
MSA – Measurement System Analysis

Quality Certifications

We work with manufacturers who hold certifications like:

ISO 9001:2015 (Quality Management System)
ISO 14001:2015 (Environmental Management System)
ISO 45001:2018 (OH & SMS)
AS9100 Rev C (Aviation, Space and Defence)
ISO13485:2016 (Medical Devices)
IATF16949:2016 (Automotive Quality Management System)


Whilst High pressure casting is widely used casting method for high volume production, there are other casting methods which have their merits.

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Blow Moulding


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Over the years, Zastata has audited and worked with various die casting manufacturer across India for various casting types. Our pressure die casting company are selected and retained based on their quarterly quality performance on Cost, Delivery, Quality, Communication, Innovation and flexibility.


Over the years, Zastata has audited and worked with various die casting manufacturer across India for various casting types. Our pressure die casting company are selected and retained based on their quarterly quality performance on Cost, Delivery, Quality, Communication, Innovation and flexibility.











  • Plastic injection moulding process is extremely cost efficient compared to other production methods.
  • Parts can be manufactured with extreme precision and accuracy.
  • Complex shapes and intricate designs can be manufactured to exact specifications with ease.
  • Doesn’t require any additional post-processing.
  • Cost effective, more versatile, and repeatable, making it an ideal choice for mass production for various shapes and size.
  • Products made using plastic injection moulding are often very strong and durable.

Smooth Surface finish.

Plastic injection moulding is a manufacturing process used in variety of industries with greater design flexibility.

  • In the medical industry, plastic injection moulding is used to create components for diagnostic equipment and medical devices, including needles and tubing, blood filters, and drug delivery systems, etc.
  • In the automotive sector, injection moulding is used to produce countless components, such as wheel covers, trim, seatbelts, battery cases, airbag components and antenna covers.
  • It is also used to create electrical components and machine parts, as well as toys, sporting equipment and consumer electronics.

Plastic injection moulding [PIM] is a complex process with multiple stages that requires using a variety of materials. These materials range from the injection moulding machine and clamps to the molten plastic, moulds, and assembly and testing equipment.

Zastata ensures that parts manufactured by our manufacturers using this process are 100% compliant to the design spec and are inspected 100% for pilot production runs to ensure quality components are exported without any defects.




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