Interoperation Time
Definition
Interoperation time is the elapsed time between the end of one operation and the start of the next on a manufacturing order, made up of queue, wait, move, and staging time rather than actual processing.
In Practice
In most job shops, interoperation time dominates lead time: a part that gets 4 hours of actual machining can easily spend 10 days on the floor, with over 90% of that as queue and move time between work centers. MRP routings carry interoperation allowances so back scheduling produces realistic start dates.
Because it is mostly waiting, interoperation time is the first target for lead time compression — reducing queue through better shop loading, overlapping operations, or moving lots in smaller transfer batches can cut lead time dramatically without touching run time.
Frequently Asked Questions
What makes up interoperation time?
Four elements: queue time waiting for the next work center to free up, wait time after processing before the lot is picked up, move time in transit between operations, and staging time waiting for paperwork, inspection, or the rest of a batch. Queue time is normally by far the largest.
How can interoperation time be reduced?
Control shop load so queues stay short, overlap operations by sending partial transfer batches ahead before the full lot finishes, co-locate sequential work centers to cut move time, and give priority rules that keep hot orders from sitting. Each hour removed comes straight out of lead time.
Related Calculators
Related Terms
Back scheduling (backward scheduling) is a planning method that starts from a job's required due date and works backward through each operation's lead time to find the latest possible start date for every step.
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.
Job Shop SchedulingJob shop scheduling is the task of sequencing many different jobs across shared work centers in a job shop, where each job follows its own routing, so that due dates, queue times, and machine utilization stay in balance.
Lead TimeLead time is the elapsed time between initiating a process, such as placing an order, and its completion, such as receiving the goods. It is one of the most important inputs to inventory, planning, and customer promise decisions.