CQI Special Process Audit in Practice —— Systematic Evaluation Methods from CQI-9 to CQI-27

1. Why Special Processes Require Dedicated Evaluation Standards

In quality management within the manufacturing industry, there is a category of processes that particularly challenge auditors and suppliers—special processes. According to the ISO 9000 definition, special processes are those "whose output cannot be verified by subsequent monitoring or measurement," and typical examples include heat treatment, electroplating, painting, welding, soldering, molding, and casting. Their common characteristic is that quality issues do not manifest in the current process but only appear after the parts are assembled into the final product and used for several months or even years.

For example, insufficient carburization depth in gears may result in all hardness tests passing during factory inspection, but early wear can occur after just a few thousand kilometers of driving; inadequate zinc plating thickness, coupled with insufficient salt spray testing, can lead to rusting within a few months at the customer site; insufficient welding penetration, if not detected during sampling inspection, can cause welds to crack under fatigue loads. These defects, once released, often result in batch recalls.

For this reason, standards impose stricter requirements on special processes compared to general processes. Clause 8.5.1 of ISO 9001:2015 explicitly requires that if the output results cannot be verified by subsequent monitoring or measurement, the organization should confirm such processes and, when appropriate, reconfirm them. IATF 16949 further strengthens the management of special processes in clauses related to control plans and process validation. Major OEMs have even incorporated the systematic evaluation of special processes into their customer-specific requirements. However, the challenge lies in the specialized nature of special processes: heat treatment, electroplating, and painting each have their own technical language, making it difficult for general auditors to delve deeply. Therefore, AIAG (the Automotive Industry Action Group) has published a series of special process evaluation standards—the CQI series—which translates the control requirements of each special process into auditable clauses using a unified framework. CQI stands for Continuous Quality Improvement, and this series of standards is often referred to as the "common language for special process audits."

2. Overview of the CQI Series Standards: Seven Core Manuals

The CQI manuals directly related to special processes are primarily seven, covering the seven most common special processes in the automotive supply chain:

Additionally, CQI-8 (Layered Process Audit) and CQI-20 (Effective Problem Solving) do not directly correspond to a specific special process but are often used in conjunction with the above manuals—CQI-8 provides a routine for daily layered audits, and CQI-20 provides a methodology for corrective actions for nonconformities.

The structure of the seven manuals is highly consistent, all following the overall framework of "management requirements + process sheets." This consistency is the reason they are widely accepted by OEMs. Understanding one manual can help you understand the others.

How to select the appropriate manual? The principle is simple: choose based on customer-specific requirements and your own processes. If a customer specifies a requirement in the CSR, it must be followed. When the customer does not specify, any process involving the seven categories mentioned should proactively establish a self-assessment mechanism according to the corresponding manual. It is also important to note that a single manual often covers multiple sub-processes—CQI-12, for instance, includes process sheets for electrocoating, powder coating, and liquid spraying. The company should ensure that the processes it involves are covered by the appropriate process sheets in the manual to avoid "selecting the wrong sheet and conducting a meaningless assessment."

3. Internal Structure of CQI Assessment: Three Major Sections and Four-Level Scoring

Opening any CQI manual, the content can be categorized into three major sections.

The first section is management responsibilities and quality planning. This section contains about twenty clauses, examining the "management environment" of special processes: whether the quality policy and objectives cover special processes, whether there is a clear process owner, how personnel training and qualifications are managed, whether equipment maintenance is adequate, whether changes (process, material, equipment) are reviewed, whether internal audits and management reviews include special processes, and whether nonconforming product handling and customer communication are smooth. Many suppliers focus entirely on process parameters, only to lose points on these twenty management clauses.

The second section is site and material handling requirements. Special processes are highly sensitive to the environment: ventilation and fire prevention in heat treatment furnace areas, storage and wastewater treatment of plating solutions in electroplating lines, temperature and humidity control in painting workshops, and zoning and labeling of chemicals. This section evaluates whether the "physical environment" where the process occurs is under control.

The third section is the process sheets, the most distinctive part of the CQI manual. Each manual is subdivided into several process sheets based on the process type. For example, CQI-9's process sheets cover different heat treatment processes such as carburizing, quenching and tempering, and induction heat treatment. Each sheet lists the specific control requirements for the process: heating temperature and time, atmosphere carbon potential, quenching media temperature, tempering curve, etc. During the audit, the process sheets corresponding to the actual process are selected and evaluated item by item.

The scoring method uses four levels: met, partially met, not met, and not applicable. "Partially met" indicates minor deviations that do not affect process capability, typically requiring rectification within a specified period. "Not applicable" must have a valid reason and be confirmed by the auditor; it should not be used as a shield to avoid addressing weaknesses. More importantly, CQI requires auditors to evaluate each clause from three dimensions: definition, implementation, and effectiveness—whether the requirement is clearly defined in the documents (definition), whether it is truly implemented on-site (implementation), and whether the implementation results are data-proven (effectiveness). A clause is only judged as "met" if it passes all three dimensions. This design prevents the loophole of "beautiful documents but chaotic on-site implementation." The final assessment conclusion is determined by the number and severity of nonconformities: a few minor nonconformities may be conditionally passed, but if there are serious nonconformities or systemic deficiencies, the assessment will not be passed, and re-evaluation is required after rectification.

4. Five-Step Method for Implementing CQI Audits

Treating a CQI assessment as a routine "document check and on-site inspection" is the biggest misunderstanding. A high-quality CQI audit should proceed in five steps.

Step 1: Define the scope and pre-assessment. First, confirm which special processes, production lines, and shifts are covered by the assessment, select the applicable process sheets, and send the assessment plan and document list to the supplier. During the pre-assessment stage, the supplier can submit a list of system documents, process flow diagrams, control plans, and major equipment records. The auditor can use this information to preliminarily identify risk points and develop a key checklist for on-site verification.

Step 2: Document review. Verify each item in the management section: whether the quality manual and procedure documents cover special processes, whether the control plan corresponds to the process sheet requirements, whether the work instructions quantify key parameters (temperature, time, concentration, current), whether the FMEA identifies failure modes of special processes, whether personnel qualification files and training records are complete, and whether equipment calibration and preventive maintenance plans are within their validity periods.

Step 3: On-site observation and personnel interviews. The auditor should enter the workshop to check if parameter records are filled out in real-time rather than retrospectively, if operators are clear about the key parameters and abnormal handling procedures of their positions, and if in-process products are randomly selected to trace their batch records. Observe material labeling, isolation areas, and chemical management. The on-site phase should avoid "accompanying personnel answering all questions" and instead interview operators, team leaders, and process engineers separately to cross-verify consistency.

Step 4: Data and record verification. This is the biggest difference between special process audits and general audits—data must speak. For heat treatment, review furnace temperature uniformity (TUS) reports, system accuracy (SAT) test records, thermocouple calibration certificates, and quenching media test reports. For electroplating, review plating solution analysis records, plating thickness, and salt spray test reports. For welding, review welding procedure specifications (WPS/PQR) and welder operation qualifications. For casting, review alloy composition reports and non-destructive testing records. Any data required by the process sheet must be supported by original records, and the records must match the on-site parameters.

Step 5: Scoring summary and improvement closure. Score each item according to the three major sections and four-level scoring, compile a list of gaps, confirm each nonconformity with the supplier, and develop a corrective action plan (CAP) with clear responsibilities and completion deadlines. Follow up to verify the effectiveness of the rectifications, and arrange a re-audit for major issues. The output of the audit is not just a report but a closed-loop list of "issues—actions—verification."

5. Practical Points for Preparing for CQI Assessment

For suppliers, CQI assessments often come from customer requirements, and a passive approach can lead to a constant struggle. Proactive preparation can be approached from six aspects.

First, establish a special process ledger. Clearly list all the company's special processes: process name, production line, execution standard, customer requirements, applicable CQI manual and process sheet. This ledger is the starting point for all preparations.

Second, conduct a gap self-assessment in advance. Use the CQI manual as a benchmark, score each clause, identify "partially met" and "not met" clauses, and rectify them three to six months in advance. Self-assessment should be honest; the worst scenario is a self-assessment showing all green, only to have a customer audit reveal all red.

Third, make parameter records "real-time, continuous, and traceable." Special process audits focus heavily on records: whether the furnace temperature recorder runs continuously, whether the plating solution analysis frequency is compliant, and whether parameter deviations have been reviewed and released. It is recommended to automate the recording of key parameters and clearly define the frequency and responsible person for manual records.

Fourth, strengthen equipment and metrology foundations. Each item, including TUS, SAT, thermocouple calibration, and gauge verification, should have a certificate, a cycle, and a ledger. Equipment maintenance plans should be truly implemented, not just patched up for the audit.

Fifth, improve personnel qualification files. Qualification, training records, and capability verification evidence for positions such as welding and heat treatment should be centrally archived to ensure "person-to-document correspondence and immediate availability."

Sixth, focus on high-frequency nonconformities. From extensive audit practices, the most common nonconformities fall into five categories: missing or retrospective records, parameter deviations without review, expired equipment calibration, incomplete personnel qualifications, and on-site operations not consistent with documents. Making these five categories the focus of daily self-inspections can prevent most deductions.

6. From Passing the Assessment to Enhancing Process Capability

The value of a CQI assessment should not be limited to just "passing." A strict CQI audit report is essentially a free special process health check: it tells you where the furnace is uneven, where the plating solution is out of control, where the records are inaccurate, and where personnel are weak. Smart companies will directly convert audit findings into improvement projects and include them in their annual improvement plans.

In practice, CQI assessments are closely linked with IATF 16949 certification audits, OEM second-party audits, and VDA 6.3 process audits: CQI addresses the issue of "whether special process controls are professional," VDA 6.3 addresses "whether the overall process operation is stable," and system audits address "whether management requirements are implemented." By using CQI as a tool to manage special processes, other audits in the special process section can almost always pass smoothly.

Special processes are the areas with the highest concentration of quality risks and are also the easiest to hide problems behind a "professional barrier." The significance of the CQI series standards lies in using a unified, transparent, and verifiable framework to transform the control of special processes from "the experience of skilled workers" into "auditable evidence." For quality professionals, mastering CQI audit methods is not just acquiring a new skill but also obtaining a key to unlock the black box of special processes—ensuring that every furnace, every plating tank, and every weld can withstand traceability and inspection.

Quality defects in special processes are always "late," and the significance of CQI assessment is to ensure that control precedes defects.

Knowledge code: 2.1.2

Version: v20260803

Author: Quality Think Tank The Quality Think Tank is dedicated to providing systematic knowledge, methodologies, and practical tools for quality management professionals, helping companies continuously improve their quality capabilities.