What is the Difference Between a Hydraulic Press and an Injection Molding Machine?

Hydraulic presses are plastic injection molding machines that utilize hydraulic cylinders to clamp two mold halves together. Once filled with melted plastic, the press then cools and hardens it for solidification.

Though these machines have their uses, they may not always be the most cost-effective option for plastics processors. Injection molding can be an expensive endeavor and the machine you select will have a significant effect on your profitability.

Hydraulic Press

Hydraulic presses are commonly employed in industrial processes like forging, clinching, blanking, pressing, and molding. These machines use Pascal's Law to generate a great force by applying pressure to a closed liquid within a hydraulic cylinder.

On the market, there are various types of hydraulic presses to choose from - each with their own distinct advantages. Here's what you should be aware of about them:

A hydraulic press uses the plunger and ram together to compress material, similar to how a blacksmith uses a hammer when shaping metal.

This process can help you reduce downtime and boost productivity at your facility, as well as create more products with less effort.

When using a hydraulic press, there are several factors to take into account such as the material's size and how it will be placed between plates. Failure to do so could damage the machine and lead to injury if it becomes too big or heavy for it to handle effectively.

Electric Press

Injection molding machines utilize an incompressible fluid to apply force to the workpiece. This fluid is pumped via hydraulic system, which can be powered by either electric motor, pump, and oil reservoir.

Many injection press manufacturers utilize a hybrid design, combining hydraulic and electric functions. For instance, Krauss-Maffei offers several models with hydraulic screw drive but electric clamp traverse.

These hybrid machines have also been utilized for activating core pulls, ejectors and valve gates on electric presses from Boy Machines, Milacron, Ube and Niigata.

Injection presses can be equipped with energy-saving devices like servo pumps, barrel insulation and other controls that can reduce consumption by 30% to 70%. According to SKZ, the biggest opportunity for saving energy lies in plastification and barrel heating - two common machine functions that utilize energy - as well as platen movements, clamp force and injection force.

Hybrid Press

Hybrid presses harness the strength of hydraulics with the precision of injection molding machines, offering a cost-effective and high quality production solution for converting industries. They feature energy efficiency as well as cost effectiveness to make them an attractive option for companies.

These machines typically use an electric motor for clamping the mold and an hydraulic pump to circulate oil under high pressure, making them more energy-efficient than standard hydraulic injection molding machines - great news for your budget!

They are highly productive due to their capacity for filling molds faster than traditional injection molding machines, which reduces warping and boosts overall production.

These machines also feature a water saver valve, which reduces water usage from the chiller or tower. This is an effective way to save money on electricity bills and water expenses.

FANUC Injection Molding Machine

An injection molding machine consists of a material hopper, injection ram or screw-type plunger and heating element. Additionally, it contains the mold which is clamped to the platen of the machine.

When it comes to presses, there are plenty of options - from full hydraulic models to hybrid machines that combine hydraulic and electrical elements. But for large products requiring heavy molding, manufacturers tend to favor full hydraulic presses.

Electric presses are becoming more and more commonplace for high-volume, small parts that require less heat to shape, such as thin-wall plates for television screens or light guide plates for computers. Niigata's 715 ton electric model MD650S-IV AP can achieve mold gap positions accurate to +-0.02 microns using its Active Press control system.

All-electric presses use digitally controlled servomotors to operate all pressing and other auxiliary axes, providing precise injection, extrusion and clamping with up to 30% less energy consumption than comparable hydraulic machines - making them a green alternative for clean room environments.