Down time refers to the period during which the operator cannot perform productive work due to various factors such as equipment breakdowns, non-availability of tools, or shortage of materials. This time is considered unproductive and contributes to inefficiencies in the production process.
Setup time involves the preparation of machines or tools before starting a production run, and unit operation time is the actual time spent on producing a unit. Allowance refers to additional time added for personal or unforeseen breaks.