Introduction of Several Plastic Nozzles

Introduction of Several Plastic Nozzles

1. Nozzles for Low Viscosity Plastics Nozzles for injection molding of low viscosity plastics are usually needle-type shut-off nozzles, including spring brake and pneumatic/hydraulic pressure. Mainly used for PA, PPS, PE, POM and pp.

1.1 working principle The spring brake nozzle is opened directly under injection pressure and then closed by spring power. The axially moving needle in the needle-shaped shut-off nozzle is kept closed under spring force. The nozzle opening is usually closed and the melt flow pressure gradually increases. The nozzle is opened at 200bar when the exposed ring on the needle acts on the spring. If the melt pressure drops (80bar), the nozzle closes.

The pneumatic/hydraulic actuator controls the needle in the axial direction of the nozzle through a lever, so the melt flow is cut off at the nozzle mouth. The needle-shaped device is designed to ensure automatic opening of the nozzle under overpressure.

1.2 prevention Fine thread ○ Air pocket when rod retracts Material leakage occurs during dosing with the pull-out injection device.○ Leakage of raw materials during vertical injection molding 1.3 Special Applications Physical foaming ○ Melt flow preloading ○ Injection molding of hot runner (e.g. container, kettle) 2. Nozzles for Shear Sensitive Plastics For shear-sensitive plastics, bolt-type shut-off nozzles are generally used to adopt larger melt channels to reduce pressure drop. The so-called memory effect can be avoided by this one-pass melt channel principle. After adopting the single channel system, the cleaning of the device can be completed in a very short time (similar to an open nozzle).

2.1 working principle The integrally assembled actuating device (by pneumatic or hydraulic pressure) controls the radial screw through a lever device. Therefore, the molten stream is separated by this device. The design of the screw ensures that the nozzle will open automatically when overpressure occurs, which is different from that of needle-shaped nozzle, and the separation occurs later. Therefore, the hole between the nozzle opening and the shut-off device is longer. This feature may not be suitable for some applications.

2.2 prevention ○ Cavitation during thread retraction ○ Material leakage occurs during dosing with the pull-out injection device ○ Leakage of raw materials during vertical injection molding 2.3 Special Purpose Physical foaming 3.1 Nozzle for Injection Molding of Liquid Silica Gel The main application area of E-nozzle is LSR (liquid silica gel).

3.2 Main Features ○ The whole nozzle can be directionally cooled or heated, i.e. the part before the interface of the nozzle mould can be tempered; ○ simple structure; ○ Flexible connector (top, adapter).

3.3 working principle The E- nozzle adopts a very compact design. A two-way pneumatic cylinder controls the shut-off mechanism. At the same time, the integrated cooling system leading to the nozzle head ensures the normal and reliable processing function. The E- nozzle is made of highly anticorrosive production materials.

3.4 prevention ○ Silicone vulcanizes in nozzle ○ Cavitation during Screw Retraction ○ Material leakage occurs during batching with the pull-out injection device ○ Leakage of raw materials during vertical injection molding