The short answer
Production scheduling sequences work orders against finite capacity — deciding when each runs and on which machine — and a Gantt chart makes that sequence visible. MRP produces a list of what to make and buy; scheduling turns that list into an order of operations the shop floor can actually run. It ranks the work by priority, sequences it so due dates are met and machines are not overloaded, and lays it out on a timeline where each bar is a job on a machine. The Gantt board is where a planner sees the whole shop at once, spots clashes, and levels work.
Scheduling is the control half of production planning and control. This guide sits under the pillar, what is production planning software?, follows machine loading (which sets the capacity limit scheduling works within), and connects to how MRP works (which produces the work orders). The product page is Scheduling & priority — Gantt.
What scheduling adds beyond MRP
MRP is powerful but deliberately blind to two things: capacity and sequence. It assumes infinite machine hours and it produces quantities and dates, not an order of operations. Scheduling supplies both. It takes the work orders MRP raised, respects the finite capacity of each machine, and decides the sequence — which job runs first, which waits, which moves to an alternate machine.
The Gantt board
A Gantt chart is the natural way to see a schedule. Each machine or work centre is a row; each work-order operation is a bar whose length is its run time and whose horizontal position is when it runs. In one view a planner sees the entire shop's sequence — where bars pile up (overload), where rows are empty (idle time), and where a late job pushes everything behind it. The board is not decoration; it is the interface through which the schedule is understood and adjusted.
The power of a Gantt board is direct manipulation: drag a bar to a different time or a different machine and the schedule re-sequences. Because the underlying loading stays finite, the board will not let a machine take more than it can run — an attempt to over-stack shows immediately. Fast Planning uses a DayPilot-based scheduler board for exactly this drag-oriented sequencing.
Order and resource priority
Sequence is driven by priority, set at two levels:
- Order priority ranks the work orders themselves. An urgent customer, a penalty-clause delivery or a tight due date is given a higher priority so it takes machine time ahead of routine work.
- Resource priority ranks which machine an operation should prefer when more than one can run it — steering work toward the faster or cheaper resource, or away from the bottleneck.
Together they produce the default sequence the board proposes. When a rush order lands, a planner raises its order priority and the affected machines re-sequence — the rush job moves forward, lower-priority work slides back — visibly, so the knock-on effect on other deliveries is understood before it is committed. This is what order and resource priority does in practice.
Forward versus backward scheduling
A schedule can be built in two directions, and the choice changes where the slack sits:
| Aspect | Forward scheduling | Backward scheduling |
|---|---|---|
| Starts from | Now / material-available date | The due date |
| Schedules each op | As early as possible | As late as it can run and still deliver |
| Result | Earliest finish, slack before due date | Just-in-time start, minimal WIP |
| Best for | Checking feasibility, quoting a date | Setting start dates, cutting inventory |
In practice planners use both: backward scheduling to work out the latest safe start date for each order, and forward scheduling to confirm that starting from today the work actually fits. If the forward pass finishes after the due date, the plan is infeasible as it stands and something must give — capacity, sequence or the promise.
Dispatch rules
When several jobs queue for the same machine, a dispatch rule decides which runs next. The common ones each optimise something different:
- Earliest due date (EDD) — run the most urgent job first. Best for meeting delivery dates.
- Shortest processing time (SPT) — run the quickest job first. Clears the queue fastest and reduces average waiting.
- Critical ratio — balance time remaining until due against work remaining, so jobs falling behind rise.
- Explicit priority — a planner forces a specific order or customer to the front, overriding the rule.
No single rule is right for every shop, which is why a schedule is proposed by the system using rules and priority, then adjusted by a planner who knows the customer and the constraint. The system does the arithmetic of feasibility; the planner supplies the judgement.
Re-sequencing as reality changes
A schedule is a living plan, not a Monday printout. Machines break down, material arrives late, jobs finish early or late, and rush orders land — every one a reason to re-sequence. This is where the drag-and-drop board earns its keep: a planner moves a bar to another machine or a later slot, changes an order's priority, and the board reflows the affected work while keeping capacity finite. The floor works to the current sequence, and the current sequence reflects what actually happened this morning, not what was assumed last week.
Continuous re-sequencing is also how the schedule stays honest against the plan-vs-actual feedback the floor books: if operations consistently run longer than their standard time, the schedule that assumed the standard was optimistic, and both the standard and the next schedule can be corrected.
Sequencing to cut setups
Sequence is not only about dates — it is about setups. Running similar jobs back to back can avoid a changeover; running them apart forces a re-setup that consumes bottleneck hours. A good scheduler weighs due-date urgency against setup savings: grouping colour, material or tooling families where it can without breaking a promise. On a bottleneck machine, an hour saved on setups is an hour of extra throughput for the whole plant, so setup-aware sequencing is one of the highest-leverage moves a planner makes — and the Gantt board is where the trade-off between grouping and urgency is seen and decided.
How Fast Planning schedules
Fast Planning Software, built by Improsys in Pune under the Fast Technology brand and deployable cloud or on-premise, schedules the work orders MRP raises on a DayPilot Gantt board, sequenced by order and resource priority against finite machine capacity. Planners set and re-sequence priority, drag operations across machines and time, and see overloads the moment they occur because loading stays finite. When a rush order lands, raising its priority reflows the affected machines visibly, so the effect on other deliveries is understood before it is committed. Because scheduling shares the platform with MRP and shop-floor booking, the sequence a planner builds runs on the same work orders the floor executes and books back against — one plan, from quantity to sequence to actual.
Frequently asked questions
What is production scheduling?
Production scheduling is the control step that decides when each work order runs and on which machine, in what sequence. Where MRP answers what to make and how much, scheduling answers when and in what order, sequencing the work orders against finite machine capacity by priority and laying them out on a timeline. A good schedule respects capacity, meets due dates, minimises setups and keeps the bottleneck busy — turning a list of what to make into a runnable order of operations.
What is a Gantt chart in production scheduling?
A Gantt chart is a timeline view where each machine or work centre is a row and each work-order operation is a bar whose length is its run time and whose position is when it runs. It makes a schedule visible at a glance — overloads show as bars piling up, gaps show as idle time, and dragging a bar re-sequences the work. In production scheduling the Gantt board is how a planner sees the whole shop's sequence, spots clashes, and levels work across machines and shifts.
What is the difference between forward and backward scheduling?
Forward scheduling starts from a date — usually now or the material-available date — and schedules each operation as early as possible, giving the earliest finish and revealing how much slack there is before the due date. Backward scheduling starts from the due date and works backwards, scheduling each operation as late as it can run while still delivering on time, which minimises work-in-progress. Many planners use backward scheduling to set start dates and forward scheduling to check feasibility.
What are dispatch rules in scheduling?
Dispatch rules decide which job runs next when several wait for the same machine. Earliest due date (EDD) runs the most urgent job first and is good for meeting dates; shortest processing time (SPT) runs the quickest job first and clears the queue fastest; critical ratio balances time remaining against work remaining; and explicit priority lets a planner force an order or a customer to the front. Real scheduling blends rules with judgement, which is why a schedule is proposed by the system and adjusted by a planner.
How does priority work in production scheduling?
Priority is set at two levels. Order priority ranks the work orders themselves, so an urgent customer or a tight due date jumps the queue; resource priority ranks which machine an operation should prefer when more than one can run it. Together they drive the sequence on the Gantt board. When a rush order lands, raising its priority re-sequences the affected machines so it moves forward and lower-priority work slides back — visibly, so the knock-on effect is understood before it is committed.
Can a schedule be changed after it is made?
Yes — scheduling is continuous, not a one-time act. Machines break down, material arrives late, rush orders land and jobs finish early or late, so the schedule is re-sequenced through the day. A drag-and-drop Gantt board makes this practical: a planner moves a bar to another machine or time, changes an order's priority, and the board reflows the affected work while keeping capacity finite. The schedule is a living plan the floor works to, refreshed as reality changes, not a printout fixed on Monday.