Defects

Where it comes from

One of Ohno's seven wastes; the Toyota Production System pairs it with jidoka and poka-yoke, the mistake-proofing approach Shigeo Shingo formalized in the 1960s.

What it looks like

• Scrapping parts that fall outside specification.
• Reworking or repairing units that failed inspection.
• Errors that slip downstream and trigger returns or complaints.

Why it matters

Every defect is paid for at least twice, once to make it and again to fix or replace it, and it can escape to the customer, so building in mistake-proofing to get it right the first time is far cheaper than catching it later.