Injection molding is an essential process in plastics manufacturing. It is widely used to create plastic products, including toys, medical equipment, automotive parts, and more. To achieve this, injection molding machines are used to inject the melted plastic into a mold. There are different types of injection molding machines, each with its own advantages and disadvantages. This blog post will explore the different types of injection molding machines and how they work.

Types of Injection Molding Machines 

Hydraulic Injection Molding Machines

The hydraulic injection machine relies mainly on hydraulic power for injection. It is an affordable option for producing large items like car bumpers and multi-part molds. However, the downsides include high production and maintenance costs, as the machine must be kept running constantly to avoid breakdowns. Precise temperature control is also necessary during plastic component production to prevent the creation of defective products.

Pros

  • Consistently performs injection and ejection functions
  • Enables production of large parts with its high clamp force and shot sizes
  • Durable machine construction ensures long-lasting use
  • Affordably priced, and replacement parts are widely available

Cons

  • Consumes excessive amounts of energy during operation
  • Molding results may lack precision
  • Susceptible to the risk of fluid leaks

Electric Injection Molding Machines 

The all-electric injection molding machine is more expensive than its hydraulic counterpart, but has advantages such as not requiring standby mode or temperature adjustments during operation. This leads to greater efficiency and stability in the resulting injection molded products. Additionally, the all-electric machine lacks a hydraulic system, eliminating the risk of liquid leakage.

Pros

  • Energy efficiency
  • Reliable precision
  • Versatile for a wide range of applications
  • Low operating and maintenance costs
  • Flexibility for easy reconfiguration between projects
  • Advanced controls and design for quick tool changes and start-up times
  • Safety features and ergonomic design for operator focus

Cons

  • Higher initial investment
  • Regular replacement of wear-and-tear parts
  • Requires routine maintenance.

Hybrid Injection Molding Machines 

The oil-electric hybrid injection machine combines the benefits of hydraulic and all-electric types, resulting in high efficiency and economic benefits. The servo oil-electric injection machine is equipped with a high-precision servo motor, achieving the same cost-effectiveness as all-electric types while also having simpler, more accurate, and more durable table and mold clamping mechanisms, reducing maintenance costs. The hybrid type also offers higher injection and holding pressure than all-electric types, representing a major breakthrough in the hybrid injection molding machine industry.

Pros

  • Energy-efficient closed-loop process with low temperature
  • Exceptional clamping force
  • High-precision production with excellent repeatability
  • Accommodates design variety including thick and thin-walled parts

Cons

  • Substantial machine-to-machine differences
  • Risk of product mismatch
  • Questionable accuracy and availability of replacement machines
  • Requires both hydraulic and electric maintenance procedures.

Vertical Injection Molding Machines 

Vertical injection molding machines position the mold vertically, allowing for insert molding and overmolding. Vertical machine is suitable for small-scale production and has a lower mold cost. However, it has limited clamping force, less suitable for large-scale production, and is more difficult to access and maintain.

Pros

  • Cost-effective and more affordable than horizontal machines
  • Compact and take up less space, making them ideal for small facilities
  • Operate and require less training and expertise
  • Better access to components, making maintenance and repairs easier
  • Energy efficient and consume less energy

Cons

  • Lower production rates and are not suitable for mass production
  • Efficient in using material, leading to higher waste and costs
  • Not be as stable or precise, resulting in lower quality and consistency
  • Difficult to access in tight spaces, making maintenance and repairs more challenging
  • Complex and require more training and expertise to operate and maintain

Horizontal Injection Molding Machines

Horizontal injection molding machines position the mold horizontally, allowing for high clamping force and easier access for maintenance. This type of machine is suitable for large-scale production, but it has a higher initial cost and limited flexibility in mold design.

Pros

  • Handle larger and heavier parts than vertical machines
  • Use a wider range of materials and colors
  • More parts per hour and reduce cycle time
  • Accommodate more complex molds and multi-cavity molds

Cons

  • More consistent and correct injection pressure to fill the mold cavities
  • Take a larger footprint and need more floor space
  • Inefficient and difficult for insert molding and overmolding
  • More risks for operator safety and product quality

Thermoplastic Injection Molding Machines

Thermoplastic injection molding machines use thermoplastic materials that can be melted and re-melted for reuse. This type of machine is widely used and offers high production efficiency, but it has limited durability and heat resistance and a lower precision than thermoset machines.

Thermoset Plastic Injection Molding Machines

Thermoset plastic injection molding machines use thermoset materials that are cured and cannot be re-melted for reuse. This type of machine is highly durable and offers high precision but has limited flexibility in mold design and a longer curing time.

Pros

  • Produce high-quality and accurate parts with complex geometries and fine details
  • Low material waste and increased material re-use through recycling of excess or defective material
  • Fast cycle times and high production rates due to rapid cooling and solidification of thermoplastic materials
  • Wide range of thermoplastic materials with different properties and colors can be used

Cons

  • High initial costs for both the machines and the molds, which require precision and durability.
  • Long turnaround times initially, as molds take time to make and test.
  • Difficult and expensive to change the unit design, as molds are difficult to modify or replace.
  • Reliant on non-biodegradable plastics, posing environmental and health risks.

Powder Metal Injection Molding Machines 

Powder metal injection molding machines use a mixture of metal powders and binding agents to create metal parts. This type of machine offers high precision and is suitable for complex shapes but has limited material availability and higher initial cost.

Pros

  • Ability to produce complex and intricate metal parts with high dimensional accuracy and tight tolerances.
  • Capable of working with multiple metal materials and alloys, such as stainless steel, titanium, and tungsten.
  • Highly repeatable and reliable due to the metal mold being specifically designed for the part.
  • Fast production times as powder metal material can be injected and solidified quickly.
  • Low material waste, as excess or defective material can be reused.

Cons

  • High initial costs for both the machines and the molds, requiring precision and durability.
  • High operational costs due to expensive powder metal material and high temperature and pressure requirements.
  • Difficult and expensive to change the unit design, as molds are difficult to modify or replace.
  • Requires additional steps such as debinding and sintering to remove the binder and densify the metal part.
  • Reliant on non-biodegradable plastics for the binder, posing environmental and health risks.

Multiple Cylinder Direct Pressure Injection Molding Machines

Single-cylinder, double-cylinder, and four-cylinder direct pressure injection molding machines use different numbers of cylinders to create high injection pressure. These machines offer high injection pressure, wide range of applications, but have higher energy consumption and maintenance costs.

Toggle Type Injection Molding Machines

Toggle type injection molding machines use a toggle mechanism to create high clamping force. This type of machine offers high clamping force, faster cycle time than hydraulic machines, but has higher initial cost and energy consumption than electric machines.

Multi-color Injection Molding Machines (Multi-Component Injection)

Multi-color injection molding machines use multiple injection units and molds to create multi-color and multi-component products. This type of machine is suitable for complex shapes and designs, reduces assembly cost, but has higher initial cost and more complex operation and maintenance.

Plunger Type Injection Molding Machine 

Plunger type injection molding machines use a plunger to create injection pressure and force the material into the mold. This type of machine offers high injection pressure, wide range of applications, but has limited injection speed and higher material waste.

 Screw Plunger Type Injection Molding

Screw plunger type injection molding machines use a screw to create injection pressure and force the material into the mold. This type of machine offers high injection pressure and speed, suitable for large-scale production and wide range of applications, but has higher initial cost, energy consumption, and more difficult to maintain and repair.

Plunger-Plunger Type Injection Molding

Plunger-plunger type injection molding machines use two plungers to create injection pressure and force the material into the mold. This type of machine offers high injection pressure, wide range of applications, but has limited injection speed, higher material waste, and limited flexibility in mold design.

Reciprocating Screw Injection Molding

Reciprocating screw injection molding machines use a screw that moves back and forth to create injection pressure and force the material into the mold. This type of machine offers high injection speed and precision, suitable for small to medium-scale production and wide range of applications, but has higher initial cost, more difficult to maintain and repair, and limited flexibility in mold design.

Tie-bar-less Injection Molding Machine

A tie-bar-less machine design in injection molding eliminates tie-bars, allowing for a smaller machine footprint and a mold that can be placed on the entire platen face. This results in increased efficiency, easier mold change and maintenance, and improved automation capabilities.

  • same mould -a smaller machine
  • same production floor space
  • freedom for automation
  • save energy 
  • quick mould changes
  • force distribution

Desktop Injection Molding Machine

Desktop injection molding machines are small-scale machines designed for prototyping and small-scale production. This type of machine offers lower initial cost, compact and easy to use, but has limited injection force and volume, less suitable for large-scale production, and limited flexibility in mold design.

How to Choose the Right Type of Injection Molding Machine for Your Needs?

Determine the product requirements

Understand the desired production output, product complexity, material type, and quality standards of the product you intend to manufacture.

 Consider the available space

Consider the space requirements for the machine, including the height, width, and depth of the machine. This will help ensure that the machine can fit into your production facility.

 Identify the required clamping force

The clamping force of the machine determines the amount of force that is required to hold the mold shut during the injection process. It is calculated based on the projected area of the part and the pressure required to mold the material.

 Determine the injection rate, injection weight, and shot size

The injection rate determines the speed at which the material is injected into the mold, the injection weight determines the amount of material that can be injected in a single shot, and the shot size determines the maximum size of the molded part.

 Consider the type of injection molding machine

There are different types of injection molding machines available, such as hydraulic, electric, and hybrid machines. Each type has its advantages and disadvantages, so it’s important to consider which type best fits your production needs.

 Research and consult with experts

Conduct thorough research to understand the technical specifications and capabilities of the machines that are available. Consult with experts in the field, such as machine manufacturers or injection molding experts, to gain insight into the best options for your specific application.

 Consider the cost and financing options

Finally, consider the cost of the machine and the financing options available to ensure that the machine fits within your budget.

By following these steps, you can select the right type of injection molding machine for your needs, ensuring optimal production output, efficiency, and quality, while also taking into account the injection weight, which is an important parameter for determining the suitability of the machine for your specific application.

Conclusion

Injection molding provides a highly efficient and effective manufacturing process for plastic products. The different types of injection molding machines offer varying advantages and disadvantages, and selecting the right machine for your needs can make a significant difference in the quality and efficiency of your manufacturing process. By understanding the different types of injection molding machines and their advantages and disadvantages, you can make an informed decision and choose the best machine for your specific requirements.