What are some successful cases of the interchangeability verification method?

In the dual-sensor hot runner injection molding scenario, the interchangeability verification technique is well developed. It has been used by numerous injection molding facilities in China to promptly identify and resolve false alarm issues. Here are two examples of successful cases:

Case 1: A Guangdong precision electronic injection molding plant (many false alarms following new installation)

Problem: The initial deviation of a recently installed pair of hot runner pressure sensors was 0.12%FS, which was higher than the permitted range of 0.05%. Direct replacement was planned because it was suspected that the sensors themselves were incompatible.

Operation: Testing was conducted using the interchangeability verification method. The deviation continued to follow the mounting hole after interchange (the initial hole #1 consistently had a higher deviation), indicating that the mounting hole coaxiality mismatch was the root of the issue.

Result: The variation decreased to 0.02%FS after reinstalling, calibrating, and reaming the holes to fix the coaxiality. The issue was resolved without the need to replace the sensors, saving around 2000 yuan on the expense of buying new ones.

Case 2: After a year of operation, a Zhejiang auto parts injection molding facility experienced unexpected false alarms.

Problem: Three to five false alarms per week have recently been reported for a pair of sensors that have been in use for eighteen months. Loose installation was suspected, but numerous shutdowns and inspections were unable to identify the problem.

Operation: The deviance continuously followed one of the sensors after the sensors were switched, indicating that the sensor was drifting and aging. Individual testing showed that the other sensor's zero-point drift was normal, but this sensor's had reached 0.08%FS.

As a result, only one outdated sensor was changed. The false alarms vanished entirely after recalibration, saving half the replacement cost and removing the requirement for pair replacement.

Case 3: A Jiangsu medical injection molding facility (sporadic false alarms with no known reason)

Problem: Dual-sensor comparisons frequently resulted in sporadic false alarms. During inspections, deviations were always within allowable bounds, and the underlying cause could not be identified.

Operation: It was found that the deviation followed the acquisition channel by switching the sensors and acquisition channels. Unstable contact resistance and output fluctuations were ultimately determined to be caused by a loose connection termination on one channel.

Result: The sporadic false alarms were totally eliminated by re-crimping the terminals, saving money by avoiding the needless sensor replacement.

These examples show how the interchange verification approach may find issues fast, prevent blind replacement, and save an average of more than 70% of troubleshooting time and around 50% of repair expenses. It is an extremely useful on-site troubleshooting technique.