Scrap Rate
Scrap rate is the percentage of materials or products discarded because they do not meet specification and cannot be sold or economically reworked. It is calculated as scrap quantity divided by total production quantity, multiplied by 100. Scrap can be measured by count, mass, or value, and excludes rework, which is recoverable through additional processing.
On the shop floor, scrap rate functions as a daily KPI for how much incoming material or work-in-process is lost to defects, setup errors, handling damage, and unstable processes. Operators capture scrapped units or mass at the operation level, then compare that quantity with total production or material input for the same period, line, shift, or SKU family. In warehousing, scrap tracking covers damaged inbound goods, obsolete pallets, packaging loss, and material rejected at incoming inspection; these events must be coded separately so inventory records reflect usable stock. In raw material planning, scrap percentage is built into BOM and route calculations so the planner orders more input than theoretical output requires. High scrap rate consumes material, labor, energy, and machine time without producing saleable output, reducing effective capacity, increasing cost of poor quality, and extending lead times.
What is the most defensible denominator for scrap rate in manufacturing?
It depends on the control objective: use total production quantity for unit-based quality monitoring, total material input mass for process-yield analysis, and material value consumed for financial cost-of-poor-quality reporting.
How should scrap be incorporated into planning?
Add a scrap percentage to BOM or route-based requirements so planned input quantity exceeds theoretical output. This is especially important where variable process loss is stable enough to model statistically.
Why can two plants report different scrap rates for the same product?
Because one plant may count only unrecoverable finished-goods rejects, while another includes in-process loss, inbound damage, trim loss, or material left over and unusable after manufacturing. The scope and denominator of scrap tracking must be defined consistently.