Types of Injection Molding Machine, Their Advantages and Disadvantages

Types of Injection Molding Machine is the basic plastic injection molding machine knowledge. We will talk about the injection molding machine types topic in two directions: injection molding machine driving technology and mechanism constructions.

Fistly, we will talk the types of injection molding machines named by driving system`s technologe or method. There are Hydraulic Injection Molding Machines, Electric Injection Molding Machines and Hybrid Injection Molding Machines. Below table will show you these three types of injeciton moulding machine`s characteristic:

Hydraulic Injection Molding Machines Electric Injection Molding Machines Hybrid Injection Molding Machines All Hydraulic Injection Molding Machines is the only type of plastic injeciton molding machine before 1980s. until the year of 1983, a Japanese company introduced the first all-electric injection molding machine in the world. Electric Injection Molding Machines is available in the 1980s and quickly became popular in high precision plastic parts manufacturing industry. The full electric servo drive injection molding machine`s positioning accuracy is extremely high (of ± 0.0001 in) in nowadays but with very expensive price. Hybrid Injection Molding Machines combines hydraulics and electric motor drives into a single variable-power AC drive power source that operates on-demand. It have both benefits of two types of injeciton moulding machines: Electric Injection Molding Machines and Hybrid Injection Molding Machines. Advantages of Hydraulic Injection Machines:

• Lower initial price: The base price of these machines are significantly less than its alternatives.
• Cheaper parts: If a part on the machine needs to be replaced due to damage or the parts life-span reached its limit, the replacement parts are lower cost and easier to find.
• Stronger parts: The hydraulic parts of the machine are more resistant to wear and tear—they are built to last.
• Power: Hydraulic molding machines have exceptional clamping force.
• Simple: Hydraulic molding machines have simple structure and with easy maintenance.
• Easy Using: Hydraulic injection machines mostly are easy to set high-pressure clamping force.

Advantages of Electric Injection Machines

• Energy efficiency: Electric injection molding machines only use energy when in action—meaning the motor output is only equal to that of the load requirements.
• Less-down time: There is no chance of leakage from oil. Also, no oil use means no filters to be replaced, which means consumable expenses are less.
• Faster process: These machines are digitally controlled, meaning the process is entirely repeatable and needing no supervision.
• Clean operation: Since there is no use of oil for this machine, it is safe for use if you are manufacturing medical and food packing parts. Typically, these parts should be created in a clean-room area.
• High precision and high reproducibility:Injection control (such as pressure and speed) can be controlled in fine units, the control of the injection device is accurate and the molding conditions can be stabilized,highly accurate control and highly accurate monitoring system. It can perform difficult operations such as multi-stage extension of the hydraulic system, and can control the extension
• Quiet & Eco-friendly

Advantages of Hybrid Injection Machines

• Diversity: the possible combinations for hybrid injection molding machines open up new degrees of design flexibility.
• Best of both: Hybrid molding machines combine the energy savings and accuracy of electric molders with the force-generating capacity of a hydraulic unit.
• Replaced motor: Hybrids have replaced fixed-speed DC pump motors with variable-speed AC drives so the pump only operates when required and uses the necessary amount of oil for process efficiency.
• Less downtime: These require less maintenance and experience less downtime than an all-hydraulic or all-electric molding machines.
• Price point: Falls nicely between all-hydraulic and all-electric molding machines, making it an affordable option. Especially for medical device manufacturers.
• Energy-efficient,low-temp, closed-loop process
• Exceptional clamping force
• High-precision production and repeatability
• Accommodates thick-and thin-walled parts/design variety

Disadvantage Hydraulic Injection Molding Machines:

• It costs higher running costs
• It takes time to start (warm-up operation)
• High power consumption
• Maintenance takes time
• Difficult to precisely control
• Compared with servo motors, not good at fine control
• Risk of oil spill

Disadvantage of Electric Injection Moulding Machines

• The molding machine itself is more expensive than the hydraulic machine
• Difficult to increase injection speed
• Can not run beyond the limit of the servo motor
• Need routine maintenance
• Wear-and-tear parts that require regular replacement

Disadvantage of Hybrid Injection Moulding Machines

• Substantial differences exist machine-to-machine
• Risk of product mismatching
• Questionable replacement machine accuracy and availability
• Requires hydraulic and electric maintenance procedures

Secondly, There are two types of injection molding machines that are classified primarily by the mechanism construction: horizontal type of injection molding machines and vertical type of injection molding machines. The current mainstream of injection molding machines is horizontal, and one of the factors is the difference in clamping pressure. The clamping force of the vertical type of injection moulding machine is between 5t and 300t, while the clamping force of the horizontal type of injection moulding machine is between 3ton and 8000ton.

Horizontal injection molding machine

• Since the main frame of the host is very low, there is no height restriction on the installation factory
• If the product can fall automatically, no robot is needed, and the product is automatically formed
• The horizontal injection molding machine has a low body, simple feeding and easier maintenance
• The mold should be installed as a crane
• When multiple units are arranged side by side, the molded products can be easily collected and packaged by the conveyor belt
• There are two-platen design and 3 platen toggle design for horizontle injection molding machines

Vertical injection molding machine

• The floor area is small, only about half of the horizontal machine
• The surface of the mold faces upwards, it is convenient to place the inserts, and the insert molding can be easily inserted
• Due to the phenomenon of gravity, the mold is supported by a horizontal template to provide durability to maintain the accuracy of the machine and mold
• A simple robot with precise control can retrieve each plastic part cavity
• Open universal clamping device, easy to configure, suitable for various types of automation devices, there is no difficulty for the automatic forming of complex and delicate products.
• The vertical injection molding machine is equipped with a transmission device, which can realize automatic production and molding.

What is the most common injection molding machine?

After knowing the plastic injection moulding machines types, you may have a new question like what is the most common injection molding machines. Well, I would said the horizontal type servo driven hydraulic injection molding machines is the most common injection molding machines in these years. To be understand it better, we should talk a bit more about plastic injection molding machines industry.

In 1846, the first injection molding machine patent is applied by Charles Hancock, the British inventor.

In the year 1872, the brothers John Wesley Hyatt and Isaiah applied the first injection moulding machines patent in American. This machine is actually the first injection molding machine and it is quite simple comparing to current injection press with thounsands of parts and components. At that time, the injection molding machine is like the injection cyringe in medical field. Just heated barrel to melt the plastic and the injection into a mold. No screw and mold clamping parts. So it can produced simple products only like our home molded made products.

About 15~25 years ago, the common injection molding machine is driven by fixed speed motor and fixed constant delivery pump.

In about 2000 to 2010, the varible hydraulic pump is seen in most plastic injection machines. And after that, the injection molding machines manufacturing is developed very fast. Servo motor become the standard driven parts and the servo injection molding machine share the market more than 75%. But they are still hydraulic type injection molding machines. So the most common injection molding machines are the horizontal type servo driven hydraulic injection molding machines.

In about 2018, hybrid injection molding machine is become more and more popular. But the cost is still high comparing to the servo driven hydraulic injection molding machines, though it`s cheeper that all-electric injection machines. Lots of people thought the hybrid type plastic molding machines is the great trends in the following years. And the all-electric will be a bit far future unles the cost of servo motor and servo driven system go down a lot.

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