What is Sequencing? Definition & Manufacturing Examples

What is Sequencing?

Sequencing in manufacturing is the process of determining the order in which jobs, operations, or tasks are processed at a work center, production line, or across the entire shop floor. While scheduling assigns work to time slots and resources, sequencing specifically addresses the order within those assignments. The sequencing decision — which job goes first, which goes second — has a profound impact on setup times, throughput, work-in-process inventory, and on-time delivery performance.

How Sequencing Works in Manufacturing

Sequencing decisions occur at every work center, every time a machine finishes a job and needs to start the next one. The simplest approach is first come first served, but this rarely produces optimal results. More sophisticated approaches use priority rules such as earliest due date, shortest processing time, or setup-dependent sequencing to find better orderings.

The mathematical challenge of sequencing is significant. For just 10 jobs at a single machine, there are over 3.6 million possible sequences. For 10 jobs across 5 machines, the number of possible sequences explodes into the billions. Finding the optimal sequence through exhaustive evaluation is computationally impossible for real-world problems. Instead, scheduling systems use intelligent heuristics and algorithms that find near-optimal solutions quickly.

Sequencing becomes especially impactful when setup times are sequence-dependent — meaning the changeover time depends on what was run previously. Switching from one part to a similar part requiring the same tooling might take 10 minutes, while switching to a completely different part might take 2 hours. A sequence that groups similar parts together can save hours of setup time per week.

Sequencing Example

An injection molding department has 8 jobs to run on a single press. Setup time depends on the color and material change required:

• Same color, same material: 15 minutes
• Different color, same material: 30 minutes
• Different color, different material: 90 minutes

Random sequence total setup: 8 setups averaging 55 minutes = 7.3 hours Optimized sequence (grouping by material, then sorting by color shade): 8 setups averaging 25 minutes = 3.3 hours

The optimized sequence saves 4 hours of setup time — half a shift of recovered production capacity. On a press that generates $200 per hour in revenue, that is $800 of additional output per day from better sequencing alone.

Over a year of 250 working days, if similar improvements apply daily, the shop recovers $200,000 in capacity without buying a single new machine.

Why Sequencing Matters for Production Scheduling

Sequencing is one of the most impactful levers a planner controls. It costs nothing to change the order in which jobs are run, yet the right sequence can dramatically reduce setup time, improve due date performance, and increase throughput.

Resource Manager DB (RMDB) automates sequencing using configurable priority rules and optimization logic. The system evaluates thousands of possible sequences to find orderings that minimize setup time while respecting due date constraints. Planners can review the recommended sequence on the Gantt chart and override individual decisions where shop floor knowledge adds value.

Related Terms

• Job Sequencing — A closely related term focusing specifically on the ordering of jobs at a work center
• Priority Rules — The decision logic used to determine optimal sequences
• Setup Time — The changeover time that sequencing decisions can minimize

Frequently Asked Questions

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