How to Schedule Production Orders According to Priorities?

Scheduling production orders (POs) without a clear method inevitably leads to the same situation: several orders require the same resources at the same time. According to several industry studies, Excel remains the main production planning tool for more than 80% of small and medium-sized industrial companies and mid-sized businesses, yet its limitations quickly become apparent when priorities need to be adjusted in real time.

A production order (PO) is the instruction that triggers the production of a given quantity of an item, together with its operations, resources and associated deadlines. The challenge is to choose the right priority rules, apply them on a daily basis, and rely on a tool capable of handling unexpected events without disrupting the shop floor. Let’s see how to structure this scheduling process.

 

Why Is Priority Scheduling So Critical on the Shop Floor?

Several production orders are often launched at the same time and compete for the same resources: machines, operators and tooling.

 

The Difference Between Planning and Scheduling

Planning defines what needs to be produced, in what quantities and with which resources, over a medium- or long-term horizon. Scheduling operates in the short term: it determines the exact sequence in which POs are processed on available resources, based on the shop floor’s actual constraints. This is where day-to-day decisions are made: which PO goes first, and which one can wait.

The Pitfall of Managing by Urgency

Without clear priority rules, many orders fall behind schedule and eventually become urgent. Urgent orders then drive the shop floor, creating an overload that actual capacity cannot absorb.

To avoid this vicious cycle, it is not enough to accelerate urgent orders: less-priority orders must also be deliberately postponed according to a consistently applied rule.

 

Which Priority Rules Should You Use to Schedule Production Orders?

Several rules can be used to determine which PO should be processed first on a given resource from a list of pending orders.

 

The Most Common Priority Rules

Each rule serves a different objective: reducing lead times, meeting customer commitments or maximizing shop-floor throughput.

Priority Rule	Principle	Desired Outcome
FIFO (First In, First Out)	Process POs in the order they arrive	Simple and fair processing
SPT (Shortest Processing Time)	Prioritize the shortest POs	Maximize throughput and reduce average waiting time
LPT (Longest Processing Time)	Prioritize the longest POs	Limit delays on large-volume orders
EDD (Earliest Due Date)	Prioritize according to the nearest delivery date	Meet customer deadlines

How to Choose the Right Rule for Your Context

The choice depends on the criterion to be prioritized: lead times, work in progress (WIP), or workload balancing. The SPT rule, for example, maximizes throughput but can indefinitely penalize the longest work orders.

In practice, companies often combine several criteria, especially when multiple resources become bottlenecks. On this topic, you can read our dedicated article on the theory of constraints.

Group POs to Reduce Setup Changes

An often-underused criterion is to group POs that share the same machine setup or tooling, since each setup change ties up a resource without producing anything.

Sequencing POs to limit these changes, inspired by SMED* principles, saves production time without investing in additional resources. This criterion should be combined with traditional rules rather than replacing them.

 

How to Organize Daily Scheduling on the Shop Floor?

Once the priority rules have been defined, the next step is to determine how they should be applied in practice, workstation by workstation.

 

Centralized or Decentralized Scheduling

Centralized scheduling generates an overall schedule for all resources. Decentralized scheduling allows each workstation to manage its own queue independently. A shop floor with strong interdependencies between machines will benefit from centralized scheduling to avoid flow disruptions.

Take the Actual Capacity of Resources into Account

Reliable scheduling cannot ignore the shop floor’s physical constraints: machine capacity, operator availability and setup times. This is finite-capacity scheduling, as opposed to theoretical planning based on unlimited capacity. Without it, dates calculated by an ERP remain indicative and do not reflect shop-floor reality.

Handle Unexpected Events Without Disrupting the Rest of the Shop Floor

Urgent orders, machine breakdowns and supplier delays: dynamic scheduling makes it possible to adjust priorities locally and reposition the affected POs without disrupting the entire schedule. This ability to respond methodically is what distinguishes a responsive shop floor from one that is permanently overloaded.

Communicate Priorities to Operators on the Shop Floor

A priority rule only delivers results if it is understood on the shop floor. Too often, priorities defined by the methods department do not reach the workstation clearly, leading operators to reorder POs based on their own judgment. Making priorities visible at the workstation, through a displayed schedule or mobile access, helps close this gap.

 

How to Measure Scheduling Effectiveness

Defining rules is not enough: a few indicators can be used to verify that scheduling is delivering the expected results.

 

The key indicators to monitor

Indicator	What it measures
On-time delivery rate	Share of POs delivered within the customer’s promised deadline
Work in progress (WIP)	Number of POs simultaneously in progress on the shop floor
Average delay per PO	Average difference between the planned and actual completion dates
OEE (Overall Equipment Effectiveness)	Overall resource effectiveness, including the impact of setup changes

A continuously increasing WIP level or a deteriorating on-time delivery rate generally indicates that the chosen rules no longer match shop-floor reality.

 

What Role Does Planning Software Play in Priority Scheduling?

Beyond a certain volume of POs, Excel files quickly reach their limits: no automatic alerts, no scenario simulation and no consolidated real-time view.

 

Visualize Workload and Priorities at a Glance

Production management software such as Visual Planning provides a real-time view of each resource’s workload and priorities through customizable Planning or Gantt views, making it easier to make decisions between competing orders.

Integrate Scheduling with the ERP and Business Tools

Visual Planning interfaces with the main ERP and business management tools on the market (including SAP and Sage), ensuring continuity between upstream requirements planning and detailed shop-floor scheduling, without duplicate data entry.

Feature	Impact on scheduling
Real-time Planning / Gantt view	Immediate visibility of priorities and workload
Resource management by skill and availability	More accurate PO assignment
Overload alerts	Early detection of bottlenecks
ERP / MES integration	Continuity between upstream planning and shop-floor scheduling
Mobile access (VPPortal, VPGo)	Update priorities directly from the shop floor

 

Key Takeaways

Scheduling production orders according to priorities is not simply a matter of choosing a rule and applying it once and for all. It is a continuous balancing act between customer deadlines, actual capacity and day-to-day unexpected events.

A clearly defined priority rule that is visible to all teams prevents the shop floor from being driven solely by urgency. Combined with a tool capable of visualizing workload and handling unexpected events, it turns scheduling into a driver of industrial performance.

A well-scheduled shop floor no longer reacts to urgency—it anticipates it.

Request a Visual Planning demo and see how you can regain control of your production priorities.