04. What Is a Process Indicator? Why It Is Not a Defect and How to Document It 04. Qu'est-ce qu'un indicateur de processus ? Pourquoi ce n'est pas un défaut et comment le documenter

The Exact Definition — Word for Word

IPC/WHMA-A-620E §1.5.1.3 defines a Process Indicator as follows:

Three phrases in that definition deserve special attention because they are routinely misread in practice.

The Three Critical Phrases

1. "Does not affect the form, fit, function, or reliability"

This is the fundamental test. A Process Indicator is a condition that passes the form/fit/function/reliability test — it simply does not fully satisfy the written acceptance criterion. If you can demonstrate that a condition affects any of those four properties, it is a Defect, not a Process Indicator. If you cannot demonstrate that it affects any of them, you cannot reject the assembly.

2. "Neither fully meets the acceptance criteria nor is a defect"

This is the zone between Acceptable and Defect. The standard defines three possible conditions — Acceptable, Process Indicator, Defect — and deliberately creates a middle zone. A condition in this middle zone does not trigger rejection. It triggers monitoring.

This distinction is intentional. The standard's authors understood that real manufacturing processes produce conditions that sit between "perfect" and "broken." The Process Indicator category exists specifically to handle those conditions without creating unnecessary rework, cost, and disruption.

3. "A process indicator is not a defect"

The standard makes this statement explicitly because the error of treating a PI as a defect is common enough to warrant a direct statement. When you see this in §1.5.1.3, read it as a prohibition: you may not reject, rework, scrap, or require disposition of an assembly solely because of a Process Indicator condition.

How Process Indicators Appear in the Standard

Throughout IPC/WHMA-A-620E, Process Indicator conditions are coded with the letter P in the bracket notation. The position in the bracket tells you which class the PI applies to.

The most common notation you will encounter in heavy equipment harness inspection is [A1P2D3]. This means the condition is routine for Class 1, warrants monitoring for Class 2, and is a reject for Class 3. Since most heavy equipment harnesses are Class 2, this notation appears frequently and is the one most often misapplied.

Real Examples from Heavy Equipment Harness Inspection

Here are specific conditions from IPC/WHMA-A-620E that are coded as Process Indicators for Class 2. These are conditions that inspectors frequently and incorrectly reject on Class 2 assemblies.

How to Document a Process Indicator Correctly

The standard does not require disposition of individual Process Indicators — but it does require monitoring. This creates a documentation obligation that is separate from your NCR system. Here is the correct documentation structure.

The Connection to Statistical Process Control — §1.6.1

The Process Indicator system and the SPC requirements of §1.6.1 are designed to work together. The PI is the signal — SPC is the framework for interpreting it.

Section 1.6.1 element (b) requires that when SPC is used, quantitative methodologies and evidence must be maintained to demonstrate that the process is capable and in control, and that improvement strategies define initial process control limits with the goal of reducing the occurrence of process indicators. This means PI reduction is an explicit quality objective under the standard — not just a side benefit of good process control.

Element (e) requires a system to initiate corrective action for the occurrence of process indicators, out-of-control processes, and discrepant assemblies. This confirms that PI data must feed into your corrective action system — not to generate NCRs against the assemblies, but to improve the process that produced them.

Manufacturer-Defined Process Indicators

Section §1.5.1.3 explicitly states that not all process indicators are specified by the standard, and that it is the Manufacturer's responsibility to identify process indicators unique to their assembly process.

This means your quality program should include a list of Manufacturer-defined PIs — conditions specific to your assembly methods, tooling, or materials that you have determined do not affect form, fit, function, or reliability but that you want to track as process signals. Examples for heavy equipment harness operations:

• Connector mating force slightly elevated but within tool capability — may signal seal degradation before it becomes a functional issue
• Wire insulation surface marks from routing fixtures — cosmetic, no effect on function, but frequency signals fixture wear
• Label placement offset within readable range — not an IPC defect, but frequency signals a placement process issue
• Protective sleeving end slightly frayed but sealed — within acceptance, but frequency signals cutting tool condition

Defining these in advance — before an auditor asks — demonstrates a mature quality program and shows your customer that you manage process quality proactively, not reactively.

Summary — The Seven Rules of Process Indicators

• Rule 1: A Process Indicator is not a defect. The standard says so explicitly. Stop treating it as one.
• Rule 2: The assembly passes. No disposition, no rework, no NCR, no hold tag required on the individual assembly.
• Rule 3: Record it. Every PI occurrence goes into your PI tracking log, not your NCR system.
• Rule 4: Monitor frequency. A single PI is information. A trend is a problem signal.
• Rule 5: Act on trends, not occurrences. When frequency indicates abnormal variation or out-of-control process, investigate the process — not the shipped product.
• Rule 6: Document your process response. Your corrective action records are objective evidence of process control per §1.6.1.
• Rule 7: Define your own PIs. The standard only specifies some of them. A mature quality program identifies Manufacturer-defined PIs for your specific assembly process.

La définition exacte — mot pour mot

L'IPC/WHMA-A-620E §1.5.1.3 définit un indicateur de processus comme suit :

Comment les indicateurs de processus apparaissent dans la norme

Comment documenter correctement un indicateur de processus

Les sept règles des indicateurs de processus

• Règle 1 : Un indicateur de processus n'est pas un défaut. La norme le dit explicitement.
• Règle 2 : L'assemblage passe. Aucune disposition, retouche, NCR ou étiquette de retenue requise.
• Règle 3 : L'enregistrer. Chaque occurrence d'IP va dans votre journal d'IP, pas dans votre système NCR.
• Règle 4 : Surveiller la fréquence. Un seul IP est une information. Une tendance est un signal de problème.
• Règle 5 : Agir sur les tendances, pas les occurrences. Investiguer le processus — pas le produit expédié.
• Règle 6 : Documenter votre réponse de processus. Vos enregistrements d'action corrective sont une preuve objective per §1.6.1.
• Règle 7 : Définir vos propres IP. La norme n'en spécifie que certains. Un programme qualité mature identifie les IP définis par le fabricant.