1.3 Change control & configuration management (ECR/ECO/deviation control)

Quality engineering is fundamentally about verifying that we are building exactly what we intended to build. Without robust change control, maintaining the integrity of our “Golden Sample” becomes incredibly difficult, and production quality can easily drift over time. A Quality Engineer acts as a thoughtful gatekeeper of the product’s validation status. Whenever a change is made to the product or process, a portion of the original qualification is effectively reset. The goal of this system is to precisely identify that gap and ensure it is closed before we allow mass production to resume.

Configuration management: the basis of inspection

You simply cannot inspect a moving target. Configuration Management (CM) is how we establish and lock down the approved product baseline. This specific baseline then serves as the definitive, single source of truth for both Incoming Quality Control (IQC) and Final Quality Control (FQC).

Baseline integrity

• Drawings & Specs: The physical drawings on the floor must always match the exact revision that is currently active in the PLM or ERP system.
• Approved Vendor List (AVL): Keep in mind that a resistor sourced from a new vendor is considered an entirely new part, even if the basic resistance value is identical. Different sub-tier materials can introduce unexpected reliability characteristics over the life of the product.

Revision logic

• Whenever a change impacts the inspection standard—such as altering physical dimensions or updating cosmetic criteria—the revision number must be incremented, and the corresponding Quality Plan should be updated to reflect the new reality.
• If a sub-component changes, such as a shift in the glue formula, it is important to re-validate the reliability compliance, even if the top-level drawing appears completely unchanged.

ECR & ECO: the re-validation trigger

An Engineering Change Order (ECO) is the formal mechanism we use to trigger a re-evaluation of the DFMEA (Design Failure Mode and Effect Analysis) and PFMEA (Process Failure Mode and Effect Analysis).

The quality assessment filter

When you review an Engineering Change Request (ECR), try to focus your attention primarily on the validation delta rather than just the commercial benefits or cost savings.

• When there is a material change, like switching from Plastic Resin A to Resin B, you should require new testing for flammability, chemical resistance, and dimensional stability.
• When there is a process change, like moving from manual screw insertion to an auto-feed system, it is crucial to require a torque consistency capability study (Cₚₖ) and a careful visual inspection to check for new scratch risks.
• When there is a tolerance change, such as loosening a gap from ±0.1mm to ±0.2mm, always verify the new stack-up analysis to ensure that the final assembly fit is not compromised.

Pro-Tip: When a critical component changes, do not just casually approve the ECO in the system. Require a formal First Article Inspection (FAI) and a localized reliability test—like a 5-piece drop test—specifically tailored to validate the new configuration.

Disposition of material

A good ECO always explicitly outlines the fate of any existing inventory to prevent quality issues stemming from mixed stock on the floor.

• Scrap: If parts must be scrapped, physical destruction is required. For high-value items, generating a clear Certificate of Destruction is a great practice.
• Rework: Any rework instructions should be thoughtfully validated by Quality Engineering before the line attempts them. Always remember to track the post-rework yield to verify the method worked.
• Use-As-Is: This disposition should only be permissible if the non-conformance has absolutely zero impact on product safety, long-term reliability, or the end customer’s experience.

Deviation control: managing risk exposure

A Deviation (often called a Concession) is a formal, documented agreement to accept a known non-conformance for a specific time period or limited quantity. It is important to remember that a deviation is not a structural fix; it is simply a temporary risk acceptance record.

Deviation rules of engagement

• If a proposed deviation affects a Safety Critical Characteristic (SCC), it should be rejected. Safety requirements are foundational and cannot be waived.
• If the deviation is purely cosmetic, it helps to establish physical Boundary Samples (often called Limit Samples) signed by the Quality Manager. These samples provide clear, visual guidance for the inspectors on the line.
• When a deviation is approved, it is generally wise to implement 100% screening or adopt tighter AQL sampling levels (such as Level III) for the duration of that deviation to protect the customer.

Traceability rules

Units produced under an active deviation must be fully traceable. Always record the specific Batch ID or the exact Serial Number range. Should field failures occur later, this data allows you to isolate exactly which units were built under the temporary concession.

Final Checkout: Change control & configuration management (ECR/ECO/deviation control)

Control Point	Quality Action
Validation Delta	The ECO should define the specific tests needed to re-qualify the change (e.g. Thermal, Drop, EMC).
Document Alignment	Ensure IQC/FQC inspection instructions are updated concurrently with the ECO release.
Stock Purge	Verify the physical segregation of old vs. new revision parts to ensure there is 0% mixed stock.
Deviation Containment	Approved deviations should generally include increased sampling frequency or 100% screening.
AVL Control	Alternate component sources should undergo the same qualification rigor as the primary source.
Rework Validation	Try to never release rework instructions without a verified method statement and a clear retest plan.