What are Split Operations? Definition & Manufacturing Examples

What are Split Operations?

Split operations involve dividing a single production operation into two or more sub-batches that are processed simultaneously on different machines or sequentially at different times. Instead of running 1,000 parts through one CNC mill over 40 hours, the batch is split into two lots of 500 and run on two mills simultaneously, completing in 20 hours plus an additional setup. Split operations are a powerful scheduling technique for meeting tight due dates and improving throughput at bottleneck work centers.

How Split Operations Work in Manufacturing

When a production order has a long operation that threatens to delay delivery, the planner can split that operation across multiple machines. Each sub-batch gets its own setup and runs independently. The tradeoff is clear: the split incurs an extra setup (and sometimes extra handling and quality verification), but the elapsed time for the operation drops significantly.

Split operations require that alternate machines are available and capable of performing the same work. If only one machine in the shop can perform the operation, splitting is not possible. The machines must also produce consistent quality — the parts from Machine A must be interchangeable with parts from Machine B.

The scheduling system must handle the logistics of splitting: tracking two separate sub-batches through the split operation, merging them back into a single order for subsequent operations, and managing separate quality documentation for each sub-lot. Not all scheduling systems support split operations natively, which limits this technique for some manufacturers.

Split operations can also apply across time periods rather than machines. If a machine is available for 4 hours today and 4 hours tomorrow but the operation needs 8 hours, the planner can split the run across the two available windows. The partial batch sits at the machine overnight, and processing resumes the next morning.

Split Operations Example

An aerospace parts manufacturer receives a rush order for 400 titanium brackets. The critical CNC milling operation takes 0.5 hours per part — 200 hours of run time plus 3 hours of setup. On a single mill running 16 hours per day (two shifts), this operation alone would take 12.7 days.

The due date requires completion in 7 days. The planner splits the operation:

• Mill 1: 200 parts — 3 hours setup + 100 hours run = 103 hours (6.4 days)
• Mill 2: 200 parts — 3 hours setup + 100 hours run = 103 hours (6.4 days)

Running in parallel, the milling operation completes in 6.4 days instead of 12.7 — well within the 7-day window. The extra 3-hour setup on the second machine is a small price for saving 6.3 days of elapsed time.

After milling, the two sub-batches merge for the deburring and inspection operations, which proceed as a single order.

Why Split Operations Matter for Production Scheduling

Split operations give planners a critical tool for schedule flexibility. When a single long operation is the bottleneck for an important order, splitting it across parallel resources can be the difference between meeting and missing the due date.

Resource Manager DB (RMDB) supports operation splitting, allowing planners to divide operations across multiple resources directly from the Gantt chart. The system manages the sub-batch tracking, recalculates downstream operation timing, and ensures the schedule remains feasible. This capability is especially valuable for job shops handling rush orders or large batch sizes on shared equipment.

Related Terms

• Bottleneck — The constraint resource where split operations are most commonly applied to increase throughput
• Finite Capacity — The scheduling method that identifies when operations need splitting to meet due dates
• Makespan — The total schedule duration that split operations help reduce

Frequently Asked Questions

Learn more in our complete manufacturing glossary or production scheduling guide.