What Is CQI-9? Heat Treat System Assessment and Audit Priorities

• Publisher: AIAG; Target: Automotive industry heat treatment (self-owned and outsourced)
• Core concept: Heat treatment is a special process and must be controlled during the process rather than relying solely on final inspection.
• Three major chapters: Management and Quality Planning, Site and Materials, and Equipment
• Process table: stipulates parameters and monitoring requirements according to process type
• Annual self-evaluation + homework review + continuous improvement

Why is there CQI-9?

The results of heat treatment (layer depth, structure, hardness gradient) are often not fully confirmed by non-destructive inspection of each part. Once the process is out of control, defects may appear in the form of fatigue fractures only after loading. The automotive industry therefore established CQI-9, requiring heat treatment businesses to use systematic process control to ensure quality.

Scope of application

• Internal heat treatment workshops of OEMs and parts companies;
• Outsourcing commercial heat treatment plants;
• Covering carburizing, carbonitriding, nitriding, nitrocarburizing, quenching and tempering, annealing, induction quenching, aluminum alloy heat treatment and other processes.

Main structure

Part One: Management Responsibilities and Quality Planning

• Designate the person in charge of the heat treatment profession;
• Failure mode analysis (FMEA), control plan;
• Internal audit, management review, continuous improvement;
• Personnel training and qualifications.

Part 2: Site and Material Management

• Parts receipt, identification, batch isolation and traceability;
• Furnace loading methods and parts transfer;
• Nonconforming product control and rework rules.

Part 3: Equipment

• High temperature measurement (thermocouple, instrument, TUS, SAT);
• Atmosphere control and monitoring (carbon potential, dew point, nitriding potential, etc.);
• Quenching system (temperature, stirring, medium detection);
• Equipment maintenance and spare parts.

Process Tables

List the parameters that must be monitored, monitoring frequency and tolerances by process type, such as carbon potential, temperature, time, quenching oil temperature, etc.

Review method

1. System evaluation: Check the above requirements item by item and assess compliance;
2. Job Audit: Select a specific part, track the entire process from receipt to delivery, and check actual records and requirements;
3. annual self-evaluation: Enterprises conduct self-evaluation at least once a year to formulate an improvement plan.

The most frequently asked questions during on-site audits

• Temperature system: Whether the TUS and SAT reports are within the validity period and whether the deviation is within the allowable range;
• Atmosphere: Whether the carbon potential is continuously monitored and recorded, and whether it is verified by backup methods every day;
• Quenching: oil temperature, stirring, medium performance testing records;
• Traceability: Can a part be traced back to specific heats and curves?
• Changes: Have process and equipment changes been reviewed and verified.

Prepare recommendations

1. First use the latest version of CQI-9 to do gap analysis;
2. Prioritize completing the three things of "continuous monitoring + recording + verification";
3. Electronicize records to reduce the risk of loss and tampering of paper records;
4. Designate someone responsible for instrument calibration and TUS/SAT planning;
5. Conduct regular internal work review drills.