What are the solutions for excessive vibration in hot runner systems?

The main cause of excessive vibration in hot runner systems must be addressed first, beginning with the simplest fixes and working up to the more complex ones. Mature remedies for various causes are listed below:

1. Excessive vibration caused by mismatched process parameters (fastest solution): Lower the injection speed by 15% to 30%, smoothly adjust the holding pressure, lessen the pulsating impact of melt injection, and lessen vibration excitation at the source; lower the injection molding machine's mold opening and closing speed to lessen the impact force of mold closing and prevent the transmission of external vibration to the hot runner; and, for active vibration hot runners, directly lower the set frequency to less than 25 Hz to prevent the excessive range.

2. The most popular, low-cost solution for excessive vibration caused by loose installation connections is to clean the hot runner installation reference surface, remove any remaining glue and impurities, and correct flatness; tighten the connecting screws diagonally and evenly in stages in accordance with the manufacturer's required torque to eliminate connection gaps; replace the old and deformed sealing gasket between the hot nozzle and the manifold, realign and tighten, and fix the gap wobble issue.

3. Structural Design/Resonance-Related Excessive Vibration (Root Cause Solution)

Inadequate Stiffness/Resonance: Shorten the unsupported span, add high-temperature resistant auxiliary support blocks to the large-span manifold, boost system stiffness, alter the natural frequency, and stay out of the resonance range;

Absence of Vibration Damping Design: Use stainless steel damping fixing sleeves on the hot nozzles to reduce nozzle vibration amplitude; place copper-based, high-temperature resistant damping pads between the manifold and the mold plate to prevent vibration transmission and absorb excess vibration energy;

Defects in the design of the flow channel include grinding the inner wall, increasing the turning radius of the flow channel, smoothing out sudden changes in cross-section, lessening the disturbance caused by melt turbulence, and weakening the vibration source.

4. Excessive Vibration Caused by Aging Components

Replace worn-out and distorted hot nozzles and manifolds, fix distorted mounting reference surfaces, and address dynamic imbalances brought on by component deformation; modify the clamping mechanism's clearance, recalculate the clamping force, and remove vibration caused by the injection molding machine's own sway.