Shut Off Nozzle
Your Leading Shut Off Nozzle Supplier
We are committed to provide system solutions for plastic industry and offers high-end products like Shut off Nozzles, Plasticizing Screw Barrel, Tip Assembly and Tie Bar. After years of technical precipitation, Rootier is currently the only Chinese-based supplier providing full series injection nozzle solutions like shut off nozzle, mixing nozzle and filter nozzles. We have lot ready stock screw barrel for some commonly used IMM like Nissei, Sumitomo, Fanuc, Victor machines, which suitable for high Glass Fiber filled plastics processing with unique solutions to increase lifetime and performance.
Why Choose Us?
High quality
We have 100% quality guarantee to customers. We will be responsible for any quality problem.
Competitive price
Our products are complete in variety, good in quality, reasonable in price.
After-sale service
Good after-sale service, handling the customer complaint and solve problem for customers.
Fast delivery
Huge production capacity to ensure in time delivery and transport to the destination in the first time.
Shut-off nozzles are used in the manufacturing process of plastic injection molding. Machine shut-off nozzles serve as the connection between the plasticizing barrel (with reciprocating screw) and the mold. They are mounted on the machineside of the plastic injection molding process, unlike hot runner nozzles which are mounted on the moldside of the process. Machine shut-off nozzles differ from open nozzles because of their closable melt channel.
Benefits of Shut Off Nozzle
A shut-off nozzle helps prevent the nozzle from dripping or drooling molten plastic material after the injection process is complete. This can help maintain the cleanliness of the mold and prevent defects in the final molded product.
By using a shut-off nozzle, the flow of molten plastic can be more precisely controlled, which can help reduce cycle times by minimizing the time required for the material to cool and solidify in the mold.
A shut-off nozzle can help ensure that the molten plastic material fills the mold cavity completely and uniformly, leading to better part quality with consistent dimensions and surface finish.
By controlling the flow of material with a shut-off nozzle, it is possible to reduce material waste and improve the overall efficiency of the injection molding process.
Types of Shut Off Nozzle
Self-controlled
The needle keeps the nozzle orifice closed by spring pressure. When the injection pressure increases, the melt will push back on the needle head and try to open the nozzle. Once the melt inside the nozzle reaches a certain amount of pressure, it will succeed in pushing the needle back against the spring. There must, therefore, be a minimum pressure for the opening process to overcome the force of the spring. Once the nozzle opens, the pressure will drop again and the spring-operated needle will close the nozzle tip orifice.
Externally actuated
The nozzle is opened by external force, independent of the melt-pressure. The shut-off nozzle’s actuation is hydraulically or pneumatically driven. Externally actuated shut-off nozzles can have different ways of closing the melt stream. Due to the fact that they operate independently of melt-pressure, they can be used for a range of applications such as melt pre-compression, physical and chemical foaming and high-speed injection molding.
Needle
The melt flow is shut off via a melt channel-axis positioned needle moving back and forth according to actuation. This nozzle type shuts off the melt stream directly at the nozzle orifice-mold interface which prevents drooling.
Bolt
A shut-off bolt, positioned perpendicular to the melt channel moves up and down according to actuation, and thus shuts off/opens the melt flow. This nozzle type has a single melt channel. It therefore does not require rerouting of the melt around the shut-off mechanism. This makes it more suitable for processing of large volumes as well as shear sensitive materials.
Rotary
This nozzle type is fitted with a rotatable bolt assembly which has a cavity equal in size to the melt channel. In its open position, the bolt cavity is directly aligned with the melt stream. When the actuator rotates the bolt assembly, the cavity becomes misaligned and thus shuts off the melt flow.
Application of Shut Off Nozzle
Packaging, automobile and leisure industries, medicinal and electronic equipment.
Components of Shut Off Nozzle
External spring —External spring activated shut-off pin. During injection, material flow caused by injecting force overcomes spring tension, thereby pushing shut-off pin away from seat. During screw recovery and idle, the spring tension forces the pin forward restricting material flow.
Shut-off pin—Externally activated shut-off pin permits unrestricted material flow during injection. Completely seals off flow at point of removable tip seat during screw recovery and idle. Eliminates drool and stringing.
Replaceable tip—Special hardened tool steel tip can be changed in seconds. Reverse taper nylon design. Available with choice of radius and orifice 1⁄8”, 5⁄32” and 3⁄16” . Be sure to specify when ordering.
Automatic operation—Operation is fully automatic and mechanical, with activating force derived from natural machine action. During injection, the material flow and pressure force shut-off pin backwards, thereby overcoming spring tension through pin extension. Material flows unrestricted into mold. As soon as injection pressure is released, the tension of spring forces pin extension and thereby also shut-off pin forward, restricting material flow. Tip is of reverse taper design; hence, residue material is ejected with the finished article, eliminating the possibility of cold slugs and strings.
Assembly steps
1.Lubricate all the threads with high temperature resistant screw grease/anti-seize.
2.Screw the adapter into the cylinder/head (do not tighten).
3.Wait for the temperature to equalize between adapter and cylinder.
4.Tighten adapter to the torque shown in the machine manual.
5.Screw the nozzle onto the adapter by hand (wearing a glove) until it stops. (right-hand thread / do not tighten).
6.Align lever in required position; lever in downward position wherever possible. This alignment must be made to the left within one revolution (360°) of the body.
7.Screw in and tighten the head (right-hand thread) and hold the lever position on the body hexagon with locknuts. Make sure the temperature has equalized between adapter and nozzle.
8.Tighten the head firmly to the required torque: H0 = 200Nm H2 = 1000Nm
，H1 = 500Nm
9.Fit the pneumatic or hydraulic cylinder on the adapter with an attachment yoke.
10.Connect the pneumatic or hydraulic cylinder (cooling) to the energy source. Set the control signal.
11.Fit the strip heater and temperature sensor and heat the nozzle to operating temperature.
Make sure the bump’s tooth rings rotate normally; if not, replace them immediately.
Bumper: Make sure the bumper can rotate properly; if not, it might be stuck by foreign objects, which should be removed immediately.
Rotation patter sleeve: Make sure the flow adjustment loops rotate normally; if not, remove any objects or substances that cause the malfunction.
Shut off valve: Make sure the globe on/off valves function well; if not, find out what causes the jam for which the valve fails to turn on and off.
Gasket: Make sure the rubber pad inside the adapter attached to the hose is tight and intact; if not, replace it immediately.
Swivel adapter: Make sure the hose adapter at the far end can swivel normally.
How Do They Work?
There are two ways of operating shut-off nozzles:
Via injection pressure: The nozzle is closed in its standard state and opens once the injection pressure rises above a defined amount. This is known as pressure-dependent operation.
Via hydraulic or pneumatic actuator:The nozzle is actively opened or closed through a command from the machine’s control unit. This is a two-way control and is a pressure independent operation
Nozzle Leaks: Troubleshooting A Common Injection Molding Nozzle Defect
1.Low nozzle contact pressure
If the injection molding nozzle and sprue joint don’t have enough contact pressure, it can cause leaks during the injection molding process.
Solution: Make sure the machine has enough nozzle contact pressure (4 to 10 tons) to balance out the input pressure. Avoid machines with contact forces at the low end of the range when the input pressure is high.
2.Too much nozzle contact area
Many people think the nozzle tip’s radius should match the sprue bushing’s radius perfectly, but a larger contact area may cause problems.
Solution: Try a smaller contact ring (3/8-in. to 1/4-in.) on the inside of the sprue bushing to get a better fit without hurting the injection molding nozzle or sprue bushing.
3.Contact force on the edge of the nozzle tip
If the nozzle tip and the sprue bushing don’t have the same radius, the injection unit can leak and move backward.
Solution: Ensure the needle tip and the sprue bushing are properly aligned and have the same radius to stop leaks and push-back.
4.Misaligned injection unit and sprue bushing
If the injection unit and the sprue bushing are not in the right place, the needle tip or the sprue bushing can wear down, allowing high-pressure plastic to jet.
Solution: Make sure the injection unit and sprue nut align. Maintenance will need to fix the barrel if it isn’t lined up right.
5.Wrong molding orifice size on nozzle or hot runner
When the molding orifice size on the nozzle or hot-runner shape is wrong, injection pressure can push the injection unit back.
Solution: To stop push-back, ensure the opening molding orifice is the same size or slightly smaller than the hot-sprue-bushing molding orifice.
6.Radius mismatch of nozzle tip and sprue bushing
It is important to ensure that the radius of the nozzle tip is the same as that of the sprue bushing. This way, they can fit together and close well.
Solution: In this issue, you can stop the leaks by checking that the radius of the sprue bushing and the tip of the needle are the same.
7.Distorted Or Gouged Nozzle Tip
The sprue nut and nozzle tip can become damaged over time, which can cause distortions, burrs, or grooves.
Solution: Check the needle tip and sprue bushing often and take care of them so they don’t get bent or broken.
Our Factory
We have two factories with about 9000 square meters construction area located in Zhoushan. Our engineers are experienced in all kinds of plastic processing design and application. Our production capacities can reach 1500 screw barrel sets monthly that enable us to deliver products to our customers in a short time.
