How to Determine the Cause of Excessive Hot Runner Vibration?

You can troubleshoot in a methodical way, starting from the outside and working your way up to the most challenging, to identify the source of excessive vibration:

Step 1: Examine External Process/Equipment Causes (10 minutes)

Verify the parameters of the injection molding process: First, see if the holding pressure varies too much and if the injection speed is set too high. It is essentially possible to conclude that the vibration is generated by the process if the parameters are much greater than the suggested process values. Next, verify the speed at which the mold opens and closes. If the mold opens and closes quickly, the hot runner will likewise experience vibration.

Examine the injection molding machine's condition by noting whether the clamping force is uneven and whether the machine itself exhibits noticeable shaking. The high vibration is caused by external vibration sources if the injection molding machine is old and has wide clearances.

Step 2: Check Installation and Connection Issues (may be finished in 30 minutes; most typical causes) Once the system has been stopped and disassembled, check:

Verify whether the manifold and hot nozzle connecting screws are loose, whether the screws exhibit metal fatigue deformation, and whether the mounting surface is uneven or has leftover glue;

Verify whether the nozzle alignment is incorrect and whether the sealing gaskets between the hot nozzles and the manifold are old or distorted. If there are gaps, gap wobbling is what causes the vibration.

Step 3: Examine Problems with Structural Design

Verify the structural design if the installation is satisfactory:

Examine the manifold: Verify whether the spread of large-size manifolds is excessively large or if they just have supports at both ends. Resonance is mostly caused by insufficient stiffness if the span exceeds 800mm without intermediate support;

Examine the design of the flow channel: Examine whether there are several sudden changes in cross-section or if the flow channel turning radius is too narrow. Strong melt turbulence and pulsation caused by such designs will result in high-frequency vibrations coming from the source;

Verify Resonance: It can be concluded that resonance is the cause of the excessive vibration if the vibration frequency is near the hot runner's natural frequency.

Step 4: Check for damage and aging. Examine whether the hot nozzles and manifolds are distorted and whether the sealing components are outdated and inefficient if the hot runner is old and has been in use for a long time. As a result, the vibration will continue to rise and surpass the standard, and the gap will progressively widen.