injection moulding machine

Types of injection moulding machines

An injection moulding machine is a machine that injects molten raw material into a cooled mould cavity to produce plastic parts. Injection moulding machines can be categorized into three types according to the movement of the injection system: hydraulic injection moulding machines, electric injection moulding machines, and hybrid injection moulding machines.

• Hydraulic injection moulding machines

  Hydraulic injection moulding machines use hydraulic power to inject melted plastic into a mould. The injection speed of a hydraulic machine is adjustable based on pressure and flow, making it capable of producing complex and high-precision products. It is also suitable for making large products that require a lot of pressure. Nevertheless, hydraulic machines are often noisy and consume a lot of energy, which may lead to higher operational costs.

• Electric injection moulding machines

  An electric injection moulding machine employs an electric motor-driven system for the injection and clamping parts. This machine offers great repeatability and precision in producing plastic parts. It provides better energy efficiency and is environmentally friendly, making it a cost-effective option in the long run. However, the initial investment might be higher compared to hydraulic or hybrid machines.

• Hybrid injection moulding machines

  Hybrid injection moulding machines combine the attributes of hydraulic and electric injection moulding machines. Even though hybrid machines also consume a lot of electricity, their speed, efficiency, and precision are high.

Specifications and maintenance of injection moulding machines

Specifications

• Size and Clamping Force

  The size and clamping force of an injection moulding machine is measured in tonnes (t). For small machines, this weight can range from 14t to 65t. Larger forces will be seen with bigger machines - up to and more than 5,500t. The scale of a project will determine which size machine is used. For instance, cell phone cases use a machine that has 85t in clamping force and cars use the 5000t one.

• Screw Diameter

  The motor that drives the injection process uses a range of screw diameters between 25mm and 100mm. The size of the screw affects the amount of plastic it can push through the system at any given time.

• Thermal Control

  Modern injection moulding machines use heaters and air-cooled water chillers to manage the thermal control. This process ensures the flow and melt of plastic are consistent. The temperature can vary from 20 to 350 Celsius and sometimes reach more than 400 degrees.

Maintenance

• Greasing sliding parts:

  The parts of the injection moulding machine that require regular greasing are the guides. They have to be greased up to four times daily, depending on usage. The machine’s manual will indicate which locations need lubrication.

• Cooled water circuits:

  Regular maintenance of the cooled water circuits is vital. Workers need to remove the pipe and inspect it for mould or any blockages. Water must flow freely. The water temperature needs to be below 30 degrees and the pressure above 3 bars. Check that pumps and valves are working correctly.

• Moulds:

  Before starting production, the operator must inspect the mould closely. There mustn't be any plastic residue, rust, or moisture. Use air extraction, solvent, and lubricants to clean the mould thoroughly.

• Electrical components

  Vacuum and blow components assist in moulding electrical part crack inspection. Inspect all the electrical elements, controllers, sensors, and boxes. Check for oxidation or burnt areas on the control panels and use the manufacturer's manual to examine the relevant electrical parts.

Scenarios

Due to its versatility, the injection molding machine is extensively used in various industries, which are mostly creating the vast demand for the machine.

• Medical Equipment:

The production of medical devices and equipment demands precision, constancy, and cleanliness. Medical devices like syringes, scalpel handles, forceps, pill bottles, and insulin pen casings are made with the help of injection molding machines. The machines also create complex elements like implantable devices, diagnostic test components, and surgical instruments. The machine's aseptic environment helps to meet the high cleanliness standards required by the medical industry.

• Packaging:

In the fast-moving consumer goods (FMCG) industry, packaging is paramount. The food and beverage business requires containers that are both useful and aesthetically pleasing. Injection molding machines produce bottle caps, containers, jars, and other packaging accessories, of great volumes and with rapidity. In the cosmetics industry, airless pump bottles and aerosol container parts are created by this machine. Its productivity helps with the high demand in packaging.

• Automotive:

The automotive industry uses injection molding machines to create interior and exterior auto parts, bumpers, dashboards, trim, headlight housings, lamp housings, and switch panels. The industry relies on these devices for its need for precision and mass production.

• Consumer Electronics:

Because of the importance of small sizes and great functionality in consumer electronics, devices like mobile phones, televisions, laptops, tablets, computers, and gaming consoles require complex and perfect parts. These are achieved through injection molding machines. With the ability to create delicate details and small tolerances, the injection molding machine excellently fulfills the precision requirements of electronic accessories.

• Home Appliances:

Home appliances like refrigerators, washing machines, coffee machines, and microwaves often require plastic parts. The injection molding machine produces these plastic parts with efficiency, meeting the home appliance industry's high standards and vast demand.

In the construction business, polymer elements like windows, doors, piping systems, and insulation are achieved through the injection molding machine. Its regular parts guarantee that the assembly of buildings is safe and cost-effective.

How to choose injection moulding machines

Choosing the right injection moulding equipment requires a proper understanding of the production requirements, material characteristics, and other technical aspects. Here are some key factors.

• Know requirements for injection moulding machines in production

  Focus on the desired production capacity. Calculate the needed production volume per unit of time to determine the necessary capacity. Also, consider the complexity of the moulded parts, such as their size, shape, precision requirements, and whether they need additional features like assembly or insert inclusion. Furthermore, assess the desired part's quality, including its surface finish, dimensional accuracy, and mechanical properties. To achieve the preferred quality, select a machine that meets the moulded parts' precision needs.

• Material compatibility for injection moulding machine

  Consider the thermal conductivity, fluidity, and shrinkage characteristics. Select a machine that can handle the materials used in production. For instance, choosing one with a suitable barrel coating for abrasive materials like glass-filled nylon.

• Injection moulding machine control systems

  Consider the required automation level. Machines with higher automation levels increase productivity but may require more maintenance expenses and skills. Additionally, select an injection moulding machine with the necessary data interfaces for integrating production lines and other data systems.

• Injection moulding machine’s energy efficiency and environment

  Opt for energy-efficient injection moulding machines to reduce operating costs. Additionally, evaluate the machine's noise level and emissions within the environment where it will be used to comply with relevant standards and regulations.

Q&A

Q1 How does an injection mold work?

A1 The injection molding machine for plastic uses different molds as per the desired product shape. Initially, the plastic granules are heated and then injected into the mold cavity, where they cool down and solidify into the final plastic product. Finally, the mold opens, and the product is ejected.

Q2 What materials can be used with injection moulding machines?

A2 The materials that can be used with an injection moulding machine depend upon the machine type. Nonetheless, in general, metals, glass, ceramics, thermoplastic polymers like polyethylene, polypropylene, polystyrene, and many other materials can be used with the injection molding machine.

Q3 Who invented injection molding machines?

A3 The invention of the injection molding machine is attributed to several people and took place over many hundreds of years. But the modern injection molding machine was developed by The Englishman Hugh Lockwood in 1940. The machine worked on the screw principle and successfully molded plastic for the first time.