The core issue is the lack of unified standards in the manufacturing and installation matching of different sensors. Specific reasons can be categorized into four types:
1. Inadequate precision of core components: Low-end sensors use low-precision sensing elements (such as ordinary PT100, with tolerances of ±3℃~±5℃). Their factory tolerances are inherently much larger than those of top-tier brand A-grade PT100 (tolerance ≤±0.15℃). Poor consistency in mass production naturally leads to excessive interchangeability errors.
Small manufacturers omit calibration processes, failing to individually calibrate each sensor. The inherent discrete errors of the components are not corrected, naturally amplifying the deviation after replacement.
2. Incompatible installation dimension tolerances: Different brands follow inconsistent dimensional standards:
Probe exposed length deviation exceeding 0.2mm: A probe that is too short will leave a gap with the hot runner detection surface, resulting in significant heat conduction loss and a lower detected temperature than the actual temperature; a probe that is too long will touch the bottom, and installation stress will alter the zero point, leading to excessive errors.
3. Loose mounting threads and outer diameter tolerances: A runout exceeding 0.1mm not only alters heat conduction but also causes zero-point shift in pressure detection.
4. Inconsistent output signal standards: Some niche brands do not adhere to the universal 4-20mA/0-10V output standard. Their output range is incompatible with the original sensor, naturally leading to deviations after the injection molding control system is converted.
Poor signal amplification circuit precision and large gain discrepancies between different sensors mean that even if the sensing element's precision is acceptable, the final output will still have significant errors.
5. Inconsistent calibration systems: Original sensors are calibrated according to a unified temperature/pressure benchmark, while aftermarket replacement parts have significantly different calibration benchmarks. For example, the calibration thermostat may be inaccurate, or the calibration points may differ from the original brand. After replacement, the overall detection results will shift, and the interchangeability error will naturally exceed the standard.
In short, smaller manufacturers omit precision control and calibration processes to reduce costs, resulting in significantly lower interchangeability compared to leading brands.
