What are the common problems in hot runner sensor verification

Operational errors, judgment variations, and handling misunderstandings are the three primary types of common issues in hot runner sensor verification. These have a direct impact on how accurate the verification results are. The following are specific issues and ways to avoid them:

1. Typical issues with the verification process

These issues are the most likely to arise and directly cause measurement findings to be inaccurate:

Inadequate cleaning can result in errors. For example, residual material debris or oxide residue at the bottom of the hole or probe can cause the measured preload to be too small, leading to an incorrect assessment that the preload is insufficient and needs to be adjusted when, in reality, the debris has raised the probe. It can also result in a falsely high contact force during contact force verification, leading to an incorrect assessment that the preload is too large.

Inaccurate preload calculation: The preload calculation result will diverge by more than 0.1mm if the measurement reference is confused and the sensor flange end face is wrongly calculated as the thread end face. This will directly lead to an improper judgment.

Push-pull force gage testing done wrong: If the sensor is pulled at an uneven pace or in a non-perpendicular direction, the measured contact force value will deviate by more than 2N, incorrectly classifying it as unqualified rather than qualified.

2. Typical Issues with Result Judgment

These issues frequently result in improper adjustments being performed when they are not required or inappropriate changes being made where they are:

Ignoring the production scenario and strictly sticking to numerical ranges: For instance, big high-pressure molds need a preload of 0.2~0.3mm, but the threaded clamping standard of 0.15~0.25mm is applied incorrectly, misjudging the initially qualifying preload as being too large.

Ignoring uniformity verification and releasing production based only on single-item compliance can result in actual localized load imbalances and temperature fluctuations after production if the overall contact force value is only measured as being within the range.

Misjudging the cause of anomalies: When production temperature fluctuates, it is common to attribute them to a preload issue without first ruling out sensor age or loose wiring. This can result in faulty mold disassembly verification and cause production time to be delayed.

3. Typical Problems with Adjustment and Handling

These typical errors are easily committed during correction after evaluating and identifying deviations:

Inadequate Preload: Blindly tightening causes additional excessive contact force instead of relaxing, hastening sensor failure.

Inadequate Preload: When the preload is inadequate, adding shims thicker than 0.3mm directly results in an abrupt overtightening that transforms one deviation into another.

Slightly Uneven Distribution: Just 0.1–0.2 mm of thermally conductive copper foil are needed to forcefully remachine the hole bottom. The accuracy of the hole depth can be readily compromised by remachining, resulting in even larger variations.