Heat treatment is a special process, and records are the only evidence to prove that the process is under control. Temperature, atmosphere (carbon potential/nitriding potential, dew point, flow), time, quenching parameters, alarms and operations should be recorded for each heat and associated with part batches, process cards, equipment and operators. Electronic records ensure integrity and are tamper-proof, and support rapid traceability from any part to the heat curve, meeting CQI-9, AMS2750 and customer audit requirements.
- What to remember: temperature, atmosphere, time, quenching, alarm, operation, calibration
- What is associated: Part batches, process cards, equipment, personnel
- How to save: electronically, time synchronized, tamper-proof, backup
- How to use: traceability, analysis, early warning, audit
- Paper records are easy to lose and difficult to retrieve
Why records are so important
The quality of heat treatment cannot be completely guaranteed by final inspection. When a customer has a quality problem, whether he or she can call up the heat curve of the relevant parts within a few minutes and prove that the temperature, atmosphere, and quenching at that time were all within specifications often determines the definition of responsibility and the credibility of the company.
What needs to be recorded
| Category | Content |
|---|---|
| temperature | Temperature of each control zone, over-temperature alarm, heating/insulation/cooling curve |
| atmosphere | Carbon potential/nitriding potential, oxygen probe mV, CO%, dew point, enriched gas/ammonia/diluent gas flow |
| time | The start and end time of each process section, the time of entering and exiting the furnace, and the transfer time |
| Quenching | Quenching medium temperature, stirring, transfer time, medium detection results |
| Alarms and events | Alarm content, time, handling measures, operator |
| check | Carbon potential calibration results, process factor adjustment, TUS/SAT results |
| Batch information | Part number, batch number, quantity, furnace loading method, process card version |
Electronic records requirements
- integrity: The sampling frequency is sufficient and there can be no gaps;
- Time synchronization: The controller, software and detection equipment time are consistent;
- Tamper proof: The original data cannot be modified, and revisions must leave traces;
- Backup and retention period: Meet customer requirements;
- Easy to search: Query by part number, batch number, furnace number, date.
How to establish a traceability chain
Parts batch → Furnace loading record (basket/tray number) → Heat number → Process card version → Heat curve and alarm → Inspection results
The key is Bind the batch to the furnace when loading the furnace. Continuous furnaces (mesh belt furnaces, pusher furnaces) need to correspond parts to furnace conditions according to time or material tray position. This is exactly the problem that the charge tracking system needs to solve.
Data is not just for auditing
- Quality analysis: Compare the curve differences between qualified and unqualified heats;
- Equipment warning: The trend changes of probe mV, furnace temperature and flow rate prompt maintenance;
- Process optimization: Optimize time and carbon potential settings based on large amounts of data;
- cost accounting: Gas and energy consumption per heat.
Frequently asked questions
Can paper recorders still be used?
Yes, but there are problems such as lack of paper, unclear handwriting, difficulty in retrieval, and easy loss. Systems such as CQI-9 increasingly favor electronic records.
How quickly does the data need to be sampled?
Depending on the process and standard requirements, it should be able to clearly reflect the process and abnormalities. Key parameters (temperature, atmosphere) are usually sampled at short intervals.
Can old equipment be connected to the data system?
Most of them can be accessed by installing acquisition modules, reading instrument communication ports or PLC data. Communication protocols and on-site network conditions need to be evaluated.