INJECTION MOULDING
Sealing Solutions for Injection Molding Machines
Sealing Solutions for Injection Molding Machines
Hydraulic cylinders and other equipment on injection molding machines require complex sealing solutions to support challenging operating conditions. These cylinders are expected to operate continuously for long periods of time without any loss of efficiency. Therefore, the material and design of the seal, which is exposed to speed and friction, is highly important.
Alfa Sealing’s custom solutions for injection molding equipment include seals for:
- Injection Unit Cylinders
- Mold Stroke Cylinders
- Clampling Cylinders
- Ejector Cylinders
- Rotating Injection Unit
- Injection Unit Cylinders
Injection Unit Cylinders
The injection cylinder drives the linear movement of the injection screw and must deliver
consistent force to inject the proper amount of material into the mold during each cycle.
Mold Stroke Cylinder
The mold stroke cylinder brings the platens into position prior to the molding process, thus
allowing the clamping cylinder to provide the extension and retraction force for each cycle.
These cylinders may only actuate a few times a day, making low stick-slip seals an important requirement
Clamping Cylinders
The clamping cylinder maintains pressure on the mold to ensure parts are formed correctly
Depending on the speed of the molding process, this cylinder must work continuously in a short stroke environment. Special low friction seals can provide long life in these conditions.
Ejector Cylinders
Completed parts can be ejected from a mold in several ways: air, spring-actuation, hydraulic actuation, or even by a robotic arm. For hydraulic actuation, the ejector
cylinder moves a plate with mechanical components that are specifically designed to push
parts out of the mold. As this cylinder must operate on every injection cycle, low friction and long life are required
to ensure the fine movements are repeatable and that they fully remove parts each time.
Rotating Injection Unit
The rotating injection unit in an injection molding machine drives the molding material
through the injection screw, where the combination of movement and heat melts the material
prior to it being injected into the mold. This operation is continuous during the molding
process; therefore, seals must berobust and have low friction characteristics.