What is Job Sequencing? Definition & Manufacturing Examples

What is Job Sequencing?

Job sequencing is the process of deciding the order in which jobs or operations are processed at a given work center, machine, or production line. The chosen sequence directly affects setup times, throughput, work-in-process inventory, and on-time delivery performance. Job sequencing is one of the most impactful decisions a production planner makes daily, and getting it right can mean the difference between meeting every due date and chronically falling behind.

How Job Sequencing Works in Manufacturing

When multiple jobs are waiting at a work center, the planner or scheduling system must decide which one runs first. This decision is governed by sequencing rules — also called priority rules or dispatching rules. Common rules include:

• Earliest Due Date (EDD): Run the job with the soonest due date first. Minimizes maximum lateness.
• Shortest Processing Time (SPT): Run the quickest job first. Minimizes average flow time and WIP.
• Minimum Setup Time: Run the job requiring the least changeover from the current setup. Minimizes total setup time.
• Critical Ratio: Run the job with the lowest ratio of time remaining to work remaining. Balances urgency with workload.

No single rule is best for every situation. EDD works well when on-time delivery is the top priority. SPT is effective at reducing average cycle time. Minimum setup sequencing maximizes machine utilization. Sophisticated scheduling systems can blend rules, applying setup optimization as a secondary sort within due date groups.

Job Sequencing Example

A powder coating line has 5 jobs waiting. Setup time depends on color changes — switching between similar colors takes 15 minutes, while switching between light and dark colors takes 45 minutes. The current setup is white.

Due date sequence: White, Black, Red, Blue, White — total setup time: 15 + 45 + 30 + 30 + 45 = 165 minutes

Setup-optimized sequence: White, White, Blue, Red, Black — total setup time: 15 + 15 + 30 + 15 + 30 = 105 minutes

The setup-optimized sequence saves 60 minutes — an hour of productive capacity recovered just by reordering the jobs. If the due dates allow this resequencing without any job shipping late, it is clearly the better approach. If one of the jobs in the optimized sequence would ship late, the planner weighs the tradeoff: save an hour of setup versus miss one due date by half a day.

Why Job Sequencing Matters for Production Scheduling

Job sequencing is where scheduling theory meets shop floor reality. The right sequence simultaneously reduces setup time, improves due date performance, and lowers work-in-process inventory. The wrong sequence wastes capacity on unnecessary changeovers and pushes jobs past their due dates.

Scheduling software like Resource Manager DB (RMDB) automates job sequencing using configurable priority rules and optimization algorithms. Instead of manually sorting jobs in a spreadsheet, planners let the system evaluate thousands of possible sequences and select the one that best meets their objectives. The interactive Gantt chart then lets planners fine-tune the result, overriding the system where shop floor knowledge adds value.

Related Terms

• Priority Rules — The decision logic used to determine job sequence at each work center
• Setup Time — The changeover time between jobs that sequencing can minimize
• Dispatch List — The ordered list of jobs at each work center that reflects the sequencing decisions

Frequently Asked Questions

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