Internal Setup Time
Definition
Internal setup time is the portion of a changeover that can only be done while the machine is stopped — such as removing and mounting dies, making adjustments, and running first-piece inspection — so it directly consumes production capacity.
In Practice
Internal setup is the true cost of a changeover: every minute of it is downtime on the resource. SMED (single-minute exchange of die) programs attack it in two ways — converting internal steps into external ones done while the previous job still runs, and streamlining what must remain internal with quick-release clamps, preset tooling, and standardized adjustments.
Cutting a work center's internal setup from 45 to 12 minutes changes the economics of the schedule: smaller lots become affordable, changeovers can happen more often, and the plant can follow a level, mixed-model schedule instead of long dedicated runs.
Frequently Asked Questions
How do you reduce internal setup time?
First separate internal from external work and move everything possible — staging, kitting, pre-heating — outside the stoppage. Then streamline the rest: quick-release fasteners instead of bolts, preset tool heights, parallel tasks with two operators, and standardized settings that eliminate trial-and-error adjustment runs.
Why does internal setup time drive lot size?
Because internal setup is pure downtime, long setups push planners toward big batches to amortize the loss, which inflates inventory and lead time. Shrinking internal setup lowers the cost per changeover, making small, frequent lots economical and the schedule far more flexible.
Related Terms
External setup time is the portion of a changeover that can be performed while the machine is still running the previous job — such as staging tools, fixtures, and materials — so it consumes no production capacity.
Idle TimeIdle time is time during which a worker or machine is available but not producing — waiting for materials, instructions, setups, repairs, or upstream work — representing paid capacity that generates no output.
Lean ManufacturingLean manufacturing is a management philosophy focused on maximizing customer value while systematically eliminating waste, such as excess inventory, waiting, overproduction, and defects.
Standard TimeStandard time is the time a qualified worker needs to complete a task at a normal, sustainable pace using the prescribed method, including allowances for fatigue, personal needs, and unavoidable delays.