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Hot runner system FAQ


Problem: The cavity is not filled

Cause: The melting temperature is too low; the injection pressure is too small; the gate is too small; the hot nozzle is too small; the mold temperature is too low; the nozzle opening of the melt cylinder is too small; the hot nozzle is clogged.

Treatment: Increase the temperature of the hot nozzle and the manifold, increase the injection pressure, enlarge the gate, increase the mold temperature, install large-size hot nozzles, increase the discharge port of the melt cylinder, and remove the blockage.

Problem: Hot nozzle casting

Cause: The back pumping (reverse cable) is not enough, the melting temperature is too high, the gate is too large, the gate is not sufficiently cooled, and the incorrect hot nozzle type is selected.

Treatment: Increase the amount of back pumping (reverse cable), reduce the hot nozzle temperature or mold temperature, and select the appropriate nozzle to process the correct gate size.

Problem: Hot nozzles do not work correctly

Cause: There is a problem with the heating wire or thermocouple, the hot nozzle is clogged, and the thermal nozzle expansion amount is not calculated correctly.

Handling: Check/replace the heating wire, check/replace the thermocouple, clean the hot nozzle, recalculate and process the expansion of the hot nozzle.

Problem: Poor color change

Cause: The color change operation procedure is incorrect and the hot nozzle type is incorrect.

Remedy: Refer to the operating instructions for the color change operation procedure and select the hot nozzle type correctly.

Problem: There are more flashes on the product

Reason: The injection pressure is too high, the temperature is too high, the flat template is of poor quality, and the clamping force is insufficient.

Treatment: Reduce injection pressure, reduce hot nozzle / sub-template / mold temperature, increase clamping force.

Problem: Produce coke marks on the product or in the gate area

Reason: The exhaust on the mold is insufficient, the injection speed is too fast, the size of the gate is not correct, and the material is not dried enough.

Treatment: Increase the exhaust, reduce the injection speed, increase the "J" size on the mouth size, and dry the material.

Problem: The tip of the mouth wears too fast when molding glass fiber material

Cause: The tip material is too soft.

Treatment: Replace with our carbide tip core.

Problem: The gate is too large

Cause: The gate is too large, the type of hot nozzle selected is incorrect, and the gate contour is not machined correctly.

Remedy: Reduce the gate, contact our company to select the appropriate hot nozzle type and check the gate processing contour.

Problem: The gate cools too early or begins to solidify in the middle of the processing cycle

Cause: The melt temperature is not enough, the gate is too small, the gate is overcooled, the direct contact area between the hot nozzle and the fixed mold is too large, and the gate profile is incorrect or the type is incorrect.

Treatment: Increase the temperature of the hot nozzle, increase the temperature of the mold in the gate area, check the nozzle hole of the hot nozzle to ensure the minimum direct contact area, check the contour of the gate, and correct the gate contour if necessary.

Problem: Moiré appears in the corresponding part of the product

Cause: The mold is too cold and the melt temperature is not enough.

Treatment: Increase mold temperature and increase melt temperature.

Problem: There is a cold block in the product

Reason: The type of hot nozzle selected is incorrect, and the hot nozzle tip is too cold.

Handling: Contact our company to select the correct type of hot nozzle and process the cold chute to ensure that the contact area of the hot nozzle head with the mold is minimal.

Problem: Occasionally squeeze cold spots from the mouth of the mouth of the mouth

Cause: Excessive heat loss from the hot nozzle head

Treatment: Reduce the direct contact area of the head to a minimum.

Problem: Plastic is stuck to the front end of the bushing head and the direct mouthpiece

Cause: The contact area of the bushing head and the mold is insufficient, and the heat dissipation is insufficient.

Handling: Increase contact area and enhance heat dissipation.

Problem: The thermal manifold does not reach the set temperature

Cause: The thermocouple has poor contact or failure, the heating wire is broken, and the heating wire is too loose or too short.

Remedy: Check if the thermocouple contacts are properly wired and check the heating wire circuit.

Problem: The heat splitter is heating too slowly

Cause: A certain heating wire is broken or the wiring is too loose, the air gap of the heat splitter plate is insufficient, the heat insulating gasket is excessively cooled, and the thermocouple is in poor contact.

Handling: Check all heating wires, increase air gap, require at least 10mm, or use heat insulation board, add heat insulation board on fixed mold fixing plate (floor) or reduce cooling to reduce fixed mold fixing plate, check thermocouple Is it good?

Problem: Thermal splitter temperature is unstable

Cause: Poor contact in the thermocouple.

Remedy: Check the thermocouple.

Problem: Metal fragments in the melt

Reason: Debris on the screw of the injection molding machine, metal fragments in the injection molding material

Handling: Remove metal debris to repair impurities in the screw filter plastic.

Problem: Thermal shunt plate and hot nozzle joint surface leakage

Reason: The calculation of the expansion amount is incorrect, the W-face machining height is inconsistent, the material of the fixed-mode fixing plate (floor) is too soft, the temperature of the heat-distribution plate is too high for a short time, and the "O"-type sealing ring is installed with problems.

Remedy: Recalculate and check the amount of expansion, check the height of the modified W surface, replace the fixed mold fixing plate (base plate) with appropriate hardness, replace the damaged parts and the "O" type sealing ring

Problem: Thermal splitter compensates for leaking glue

Reason: No padding.

Remedy: Install the spacer.

Problem: Oil (gas) cylinder does not work

Cause: No air/hydraulic oil enters the cylinder, the pneumatic/hydraulic cylinder system is stuck, and the system pressure is insufficient.

Handling: Check the pipeline and pump for leaks and blockages. Check the cylinder and piston to check if the feed pipe is excessively bent, and whether the piston and valve needle are flexible.

Problem: The cylinder system is bitten

Cause: The cylinder, the heat splitter plate, the hot nozzle, etc. are not the same, and the fixed mold fixing plate (floor) has too much heat.

Treatment: Adjust the concentricity of the cylinder, manifold and hot nozzle to increase cooling around the cylinder.

Problem: The cylinder is stuck after overheating

Reason: The cylinder, the heat splitter plate, the hot nozzle, etc. are different, and the excessive heat accumulated gasket of the fixed mold fixing plate (base plate) and the valve needle fixing nut generate friction.

Treatment: Adjust the cylinder, hot splitter, hot nozzle concentricity, add cooling around the cylinder, adjust the gasket and valve pin fixing nut

Problem: Leakage around the needle bushing

Cause: The valve needle bushing on the hot splitter plate is too loose.

Remedy: Check the hot manifold hole, needle bushing diameter and height.

Problem: Valve head head adhesive

Cause: There is not much heat on the valve needle.

Treatment: Reduce the temperature of the hot nozzle and gate and increase the cooling time.

More hot runner issues