Quality loss

Quality loss commonly refers to the reduction in usable output or value that occurs when products, components, or processes do not meet specified quality requirements. It captures the impact of defects, rework, scrap, and performance variation on both production results and customer-facing quality.

What quality loss includes

In industrial and regulated manufacturing environments, quality loss typically covers:

• Defective units that cannot be used or shipped as-is (scrap or full rejection)
• Rework and repair effort required to bring nonconforming items back into specification
• Yield loss where only a portion of produced units meet acceptance criteria
• Off-spec performance such as reduced life, accuracy, or reliability even when within broad tolerance
• Inspection and sorting effort caused by unstable or low-capability processes

These losses can be tracked in quality systems (QMS), MES, or ERP, and are often translated into cost terms as part of Cost of Poor Quality (COPQ) or yield reporting.

Quality loss in operational metrics and OEE

In performance metrics such as Overall Equipment Effectiveness (OEE), quality loss usually corresponds to the share of produced parts that are not good at first pass. It is often expressed as:

• Quality rate: good pieces divided by total pieces produced
• Quality loss: the complement of the quality rate, representing scrap and rework pieces

Standards such as ISO 22400 define how quality loss contributes to OEE variants (for example, through a quality factor or a specific loss category). Plants may configure MES/SCADA to capture quality loss by shift, product, or equipment for continuous improvement and regulatory reporting.

What quality loss does not include

Quality loss usually does not include:

• Availability losses such as unplanned downtime or changeover time
• Speed or performance losses such as micro-stops or running below target rate
• Pure schedule or demand effects, like planned idle time

Those issues may interact with quality performance, but they are typically categorized separately in OEE and other KPI frameworks.

Common confusion

• Quality loss vs. COPQ: COPQ (Cost of Poor Quality) expresses the monetary impact of quality problems, while quality loss is the underlying physical or performance shortfall (e.g., defective units, rework hours) that COPQ quantifies.
• Quality loss vs. scrap rate: Scrap rate covers only units discarded. Quality loss usually covers both scrap and rework, and can also reflect degraded performance within tolerance.
• Quality loss vs. yield: Yield is a positive measure (percentage of acceptable output), whereas quality loss represents the fraction that fails to meet requirements or needs recovery.

Link to regulated manufacturing

In regulated industries, quality loss is often tightly linked to formal nonconformance records, MRB decisions, and CAPA activities. Systems may record each instance of quality loss with traceable data such as lot, serial, routing step, and test results to support investigations, audits, and continuous improvement.