In our last article (Nadcap Accreditation Part One: The Basics) we discussed the fundamentals of Nadcap accreditation: what it is, how it works, why we should do it, what will be addressed in the audit, and how we should prepare. Here, we will talk about pre-audits, how to review the audit’s findings, how to analyze the root cause of a major or minor nonconformance, how to apply corrective actions, and what we should do after the audit is complete.
Pre-audits (aka internal audits, self-audits) are commonly misunderstood – they are not a recommended practice but a mandatory one, to be conducted prior to the formal Nadcap audit process. Failure to perform a pre-audit will result in the Performance Review Institute (PRI) auditor reporting a major nonconformance with accreditation standards. Completion of the pre-audit should be done within the 90-day period of the formal audit. This is considered best practice and will give ample time to resolve any issues that come up and to avoid surprises during the formal auditing process.
Whenever possible, an internal team should be assigned to perform the pre-audit so that no important details of the checklist requirements will be missed. Hiring an independent auditor who was properly trained in Nadcap accreditation is an option worth considering as it offers an outsider’s impression of the heat treat department’s performance that internal people may have overlooked. While PRI has put considerable effort into keeping the audits consistent regardless of the company, the different skill sets of auditors and their experience will influence the audit process.
Corrective actions from previously performed audits will need to be verified as still being effective and in place as part of the pre-audit process. If the PRI auditor notices a repeat finding that has not been fixed, it will automatically be noted as a major nonconformance. Each audit includes checklists to examine all pyrometric equipment including their calibrations, certifications, preventative maintenance and periodic test results (e.g., SAT, TUS, vacuum leak rates, dew point measurements, etc.). Often times, auditors will pay close attention to the calibration of instruments and may ask questions about how they are set and about the manufacturer’s requirements. Furthermore, it is important to make sure all of your thermocouple certifications and calibration points (process T/C, SAT T/C, TUS T/C, quench-oil T/C, etc.) are up to date since auditors tend to give them a close inspection.
With any defined procedure, the required documentation must be present. Failure to have this documentation readily available is also a nonconformance. If a requirement is listed as an industry standard, procedures and documentation must fully comply with the standard in order to avoid a nonconformance during the audit. Support staff should also be on hand during the formal audit, and the work they do should be discussed in the pre-audit. These disciplines include (but are not limited to): hardness test inspectors, metallurgical lab personnel, and TUS/SAT checkers (if applicable). Be sure that all support staff is properly trained. In addition, it is mandatory for Nadcap accreditation to have a heat treat training program that is compliant to SAE-ARP-1962 (latest revision).
It is important to note that the company assumes responsibility for all aspects of compliance, even for those processes that may be performed by outside heat-treating or support companies. Any and all documents that certify compliance, such as those for the calibration of instruments, the certification of thermocouples, or quench-oil test results, must be reviewed and verified. The documentation should be signed by an authorized individual (e.g. metallurgist, quality engineer, technician, supervisor, etc.). Failure of a sub-supplier is the failure of the company.
In addition, the company has the responsibility of gathering all compliance paperwork from any outside service provider and must verify that the paperwork is accurate. Nadcap accreditation requires attention to detail, and companies must show full-time commitment, especially when it comes to acquiring or issuing revision and/or changes including up-to-date documentation on instruments, changes to internal procedures, periodic testing, preventative maintenance and record control/verification. The checklist for the quality system is kept to a minimum if the supplier has AS9100 accreditation (or equivalent).
Tolerances for temperature, ramp rates, preheat and soak times, cooling rates, carbon potential and all other recorded data that follow the company’s internal procedures must be carefully checked. This data should also be consistent with industry standards and specific customer requirements. If a tolerance is not specified, companies should specify the tolerance. A failure to provide a reference to tolerances will again result in nonconformance during auditing (due to the actual values having a tendency to vary during the process).
Think like an auditor! You should be prepared to have sample jobs available to the auditor that are representative of each type of work that is heat-treated at the plant (by customer, material, process, configuration, etc.). Remember, long audit jobs may require more than one audit. The auditor might start with one process that will begin on the audit’s first day and then continue while on-site. In addition, there should be at least one other similar job that was previously run within the months prior to the audit. Other jobs are often selected at random by the auditor.
Reviewing up to eight jobs is not uncommon for short duration job audits. Many times, half these jobs are ones that the auditor will want to see on-site and the remainder can be previously completed jobs. Auditors have a tendency to select jobs that touch on multiple customers if such jobs are available. If the scope of the audit includes a process like carburizing, a carburizing job must be ready for processing during the time of the audit. If no such job is available for processing, the auditor will typically select one that has been recently completed. The collection of job paperwork, ranging from purchase orders to prints, routings, records, product and/or test results, etc.) can be a time-consuming process. It is advised to have resources available to help with the gathering of this information when necessary.
Once the pre-audit is performed, it is critical to follow the proper steps outlined by PRI in preparation for the official audit. These steps include:
- Reviewing, correcting and documenting any nonconformances
- Performing root-cause analysis
- Implementing corrective actions
A nonconformance is a finding that has been identified during the internal audit or one that the auditor identifies during their official audit. Nonconformances can fall into one of two categories: major or minor. A major nonconformance is either “the absence of, or systemic breakdown of, the process control and/or quality management system,” or “any nonconformance where the effect impacts or has the potential to impact the integrity of the product.” A minor nonconformance is “any single system failure or lapse in conformance with the applicable standard or audit criteria”. In other words, a major nonconformance suggests there is a lack of control over the process or product quality, or that the safety of the product might be compromised while a minor nonconformance is any deviation from Nadcap/AMS specifications or customer standards that does not impact the product (e.g., a typographical error). If a minor nonconformance could affect the product (e.g., not having a thermocouple calibration document on hand), then it becomes a major nonconformance.
After the audit is complete, nonconformances should be addressed quickly and completely, starting with any major nonconformances so that product quality is not compromised. Nonconformances should be prioritized and grouped together, if possible. Remember, in order to address a nonconformance, one must determine its root cause, a process that may take time to determine and correct. Clearing audit nonconformances is a painstaking and time-consuming process, which is why so much effort is put forth to avoid their issuance.
Performing Root-Cause Analysis
A common mistake when trying to find the root cause of a nonconformance is to list contributing factors or simply attribute the problem to “human error” (e.g., the operator did not adhere to the correct procedure). However, the root cause in this example is training, which must be conducted and verified as having been done.
Applying Corrective Actions
Implementing corrective actions for any findings discovered during the internal audit is one of the final steps in performing the pre-audit. This must be submitted to PRI at least 30 days before the official audit.
For example, during the internal audit, let’s say you identified a nonconformance due to a typographical error in the calibration report for the overtemperature controller. This has no product impact. However, if the root cause is a lack of quality resources for reviewing calibration reports and if the calibration service provider is not available to correct the root cause within the 30 days before the scheduled audit, you should note in the internal audit report that the corrective action will be fully implemented and verified during the next calibration with the future date. After the official audit, the auditor will then verify that the corrective action was implemented by the aforementioned date.1
Be sure to document the implementation of any corrective action after the internal audit, as auditors will verify that these corrective actions are in place during the official Nadcap audit.
What to do after the formal Nadcap Audit is Complete
Whether the Nadcap audit was successful or not, the steps outlined below are necessary to complete the audit and prepare for the next audit or plan for the re-audit process.
In order to correct a nonconformance, one must review the finding with the auditor while he/she is on-site to make absolutely sure there is an understanding what the finding was and how it was interpreted. When the audit is complete, it is necessary to respond to all findings in writing. Take this step very seriously. This should include a detailed explanation including:
- A nonconformance statement
- The root cause
- The corrective action is taken
- The impact of the nonconformance on the product(s)
- The action is taken to prevent future reoccurrence
- Objective evidence that the corrective action will provide a complete and thorough solution to the problem at hand.
Performing Root-Cause Analysis
First, it is critical to understand that there is only one root cause to any given problem. It’s identification often requires a company to dig deep into its assumptions, procedures and methods to understand the true nature of the problem. PRI and other groups often can support this effort with training classes. Depending on the auditor’s findings, it may turn out that multiple findings can be grouped together reducing the time required to solve them.
Applying Corrective Actions
The last and most important step is applying the corrective action in the real world. For example, if there was a finding for improperly located load thermocouples and you determined the root cause was a lack of operator training, the corrective action would be to provide operator training at a specific frequency; you should then note the training schedule that has been followed since the corrective action was implemented.
After the audit is complete, and within 21 calendar days, it is necessary to submit an initial response to the audit findings. After the initial response, one has 7 calendar days to provide a detailed response. PRI will accept or reject the company’s explanations. Only 4 total responses are allowed. Thirty extra days may be allotted if more time is needed; however, utilizing these extra days can affect a company’s merit score and, if unsatisfactory, could lead to an audit failure.
The simplest advice anyone can give regarding any audit process is to “say what you are doing and do what you say”. In other words, have clearly defined procedures in place and documentation that demonstrates that these procedures are being followed. Be thorough, be open, be honest, and be prepared. Surprises are not what either the auditor or the company want. Contrary to popular belief, auditors are not out to fail you, but rather to evaluate your words and actions toward a goal of total commitment to quality.
Finally, keep track of what worked well and what didn’t so you will be prepared for the next audit cycle. Continuous improvement with respect to processes, equipment and methods will enhance the quality and safety of the products you produce and your reward will be a successful audit!
1. Ipsen USA (https://www.ipsenusa.com/processes-and-resources/articles-and-white-papers/obtaining-nadcap-accreditation-helping-you-pass-your-audit)
2. Herring, Daniel H., Vacuum Heat Treatment, Volume 2 (Chapter 38.4), BNP Media, 2016
3. Arrow Cryogenics (https://www.arrowcryogenics.com/nadcap-certified
4. Quality (https://www.qualitymag.com/articles/90405-the-role-of-nadcap)
5. Aston, Jerry “The Heat Treatment Task Group Offers Its Top Tips in Order to Prepare for a Successful Nadcap Audit”, Thermal Processing, August 2019