What Is Production Routing? A Complete Guide to Optimizing Manufacturing Lines

What Is Production Routing?

Production routing is the defined sequence of operations a product goes through on the shop floor, from the first cut or mix to final packing. For each operation, the routing states where the work happens, which machine or work centre does it, how long setup and processing take, what skills are needed, and what quality checks apply.

If the bill of materials (BOM) answers the question "what is this product made of?", the routing answers "how, where and in what order is it made?". Together they are the two master records of manufacturing. Planning, scheduling, capacity checks, product costing and shop-floor reporting all depend on them. When routings are missing, out of date or kept only in a supervisor's head, every one of those activities becomes guesswork.

This guide explains the components of a routing, the main routing types, how routings drive capacity planning and cost, a full worked example, and how to keep routings accurate in an ERP system. Figures in the examples are hypothetical.

BOM and Routing: How They Work Together

The link in the last row matters more than it seems. If all components are issued at the start of a long routing, materials sit on the floor for days, get damaged or are borrowed for another job. Linking components to the operation that consumes them keeps work-in-progress cleaner and makes material variances easier to trace. You can read more about structuring the first half of this pair in our guide to the bill of materials.

The Components of a Routing

Operation number and sequence

Operations are usually numbered in steps of ten: 10, 20, 30 and so on. The gaps allow a new operation, say 25 for an added inspection, to be inserted later without renumbering the whole routing. The sequence also defines dependencies: operation 30 cannot start until 20 is complete, unless the routing allows overlap.

Work centre

A work centre is a machine, a group of similar machines, a production line or a manual work area that is planned and costed as one unit. Each work centre has:

• Available capacity: hours per day based on shifts and the production calendar, net of planned maintenance and holidays.
• Efficiency or utilisation factor: the share of available time realistically achieved after minor stops and changeovers.
• Cost rates: hourly rates for machine, labour and overhead, used to cost each operation.
• Alternatives: another work centre that can perform the same operation if the primary one is overloaded or down.

Standard times

Resources, skills and tooling

Some operations need a certified welder, a specific die or a calibrated gauge. Recording these on the routing lets the scheduler check availability before releasing an order, not after the job reaches the machine.

Quality checkpoints

Inspection steps belong in the routing itself, with the criteria and sampling rule stated. A failed check can route the batch to a rework operation, to scrap, or to a hold location for a decision.

Types of Routing

• Sequential routing: one operation after another in a fixed order. Common in simple discrete manufacturing.
• Parallel routing: separate branches run at the same time, for example two sub-assemblies, then merge at final assembly. This shortens total lead time.
• Alternative routing: the same product can be made on different equipment, such as a modern CNC machine or an older manual lathe with longer times. The planner chooses based on load.
• Rework routing: a separate path triggered when an inspection fails, so rework time and cost are recorded instead of disappearing into normal production.
• Process routing: in process industries such as food, chemicals and plastics, routings often describe stages like mixing, heating, cooling and filling, with batch sizes and yields rather than piece counts.

How Routing Drives Capacity Planning

When a production order is created, the ERP multiplies the routing times by the order quantity and loads each work centre in the right sequence. Comparing the load with available capacity shows bottlenecks weeks before they appear on the floor.

A hypothetical capacity check

A metal fabrication workshop plans next week's orders. Its CNC bending work centre runs two shifts of eight hours, five days a week, giving 80 hours. With a utilisation factor of 85%, realistic capacity is 68 hours. The planned orders require 74 hours of bending time based on their routings. The planner can see the 6-hour overload immediately and has options: move one order to the alternative press brake, authorise a Saturday half-shift, or move an order with a later due date into the following week. Without routings, the overload would surface on Thursday as a late delivery.

How Routing Drives Product Cost

Material cost comes from the BOM. Conversion cost, meaning labour and overhead, comes from the routing. Getting routing times wrong distorts product cost and therefore pricing.

A worked costing example

A hypothetical plastic container is made in batches of 2,000 units through three operations:

Run hours are units multiplied by minutes per unit, divided by 60: for example 2,000 × 0.6 ÷ 60 = 20 hours. Conversion cost per container is 6,112 ÷ 2,000 = about SAR 3.06. If the batch size dropped to 500 units, setup time would be spread over fewer pieces and the cost per unit would rise, which is exactly the kind of insight sales needs before quoting a small custom order.

Now suppose the real moulding run time is 0.75 minutes, not 0.6, because the routing was never updated after a change of material. Moulding run hours rise to 25, batch cost rises by 5 × 240 = SAR 1,200, and true conversion cost becomes about SAR 3.66 per unit, nearly 20% higher than the standard. Every quote based on the old routing has been underpriced.

A note on overheads

Under IAS 2, fixed production overheads are allocated to inventory on the basis of normal capacity. The amount allocated per unit is not increased because of low production or idle plant, and unallocated overheads are expensed in the period. Routing-based machine hours are a common and defensible allocation base, provided the normal capacity figure is realistic.

How Routing Drives Lead Time

Customers ask "when can you deliver?", and the honest answer comes from the routing. Manufacturing lead time is the sum of queue, setup, run, inspection and move time across all operations, adjusted for any overlap. In many plants, run time is the smallest part. Using the plastic container example, the batch spends about 30.3 hours in actual setup and processing. If each of the three operations has an average queue of half a shift (four hours) and each transfer takes an hour, the total is roughly 30.3 + 12 + 3 = 45.3 working hours, or almost three days on a two-shift pattern.

This tells you where to look for improvement. Cutting moulding run time by 10% saves two hours. Halving queue time between operations, through better scheduling or smaller transfer batches, saves six. Routings make this visible because each element is recorded separately rather than lumped into one "production time" figure.

Overlapping operations

Where the process allows, a routing can let the next operation start before the whole batch has finished the previous one. If trimming starts once the first 200 containers are moulded, rather than waiting for all 2,000, the two operations overlap and the batch finishes hours earlier. The ERP needs a transfer quantity or overlap setting on the operation to schedule this correctly.

Building Routings From Scratch: A Practical Sequence

Many factories that move to an ERP find that routings exist only partly, on paper travellers or in supervisors' notebooks. A structured approach avoids months of trial and error:

1. Start with your top products. Pick the products that account for most volume or revenue. A small share of items usually covers most of the load.
2. Define work centres first. Agree which machines and areas will be planned as separate work centres, their shifts and their cost rates, with finance involved in the rates.
3. Walk the floor. Follow a real batch of each product from start to finish and write down each operation, where it happens and who does it.
4. Time a sample. Record setup and run times on several batches, then use a representative figure rather than the best or worst run.
5. Add inspections and rework paths. Include every mandatory check, and define what happens if it fails.
6. Link BOM components to operations. State which materials are issued at which step.
7. Pilot and adjust. Run a few weeks of production orders on the new routings, compare actuals, and correct before rolling out to the rest of the product range.

Keeping Routings Accurate

1. Measure, do not guess. Set initial times from time studies or a sample of actual runs, not from the machine brochure.
2. Compare actual to standard. Record actual setup and run times against each operation on the production order. Barcode scanning at start and finish makes this practical.
3. Review variances monthly. Investigate operations where actuals differ consistently by more than an agreed threshold, say 10%.
4. Control changes. Routing changes should be versioned with an effective date and an approver, especially when they affect cost.
5. Involve the shop floor. Supervisors and operators know when a step has changed. Give them a simple way to report it.

Common Mistakes

• Using a single routing for all batch sizes without separating setup and run times.
• Leaving inspections out of the routing, so quality time and rework are invisible.
• Defining work centres too broadly, such as "the factory", which hides real bottlenecks.
• Never updating times after process improvements, so costs and lead times stay inflated.
• Ignoring the production calendar, including holidays and planned maintenance, when calculating capacity.

Routing in a Modern ERP

The term Industrie 4.0 was introduced at Hannover Messe in 2011, and much of what followed, from machine data collection to connected planning, depends on having accurate digital routings underneath. Saudi Arabia's National Industrial Strategy, launched in October 2022, targets 36,000 factories by 2035, so many plants are being built or scaled at a time when good master data is easier to set up from the start than to fix later.

Tranquil's manufacturing pages cover multi-level BOMs, material planning, production scheduling, quality checks, barcode integration and a production calendar, all connected to inventory and financial accounting in one cloud ERP. See production scheduling and quality check for details, and our article on ERP production planning for how routings feed the wider plan. To discuss your plant, contact the Tranquil team.

Frequently Asked Questions

What is the difference between a routing and a BOM?

The BOM lists the materials and quantities needed to make a product. The routing lists the operations, work centres and times needed to make it. The BOM drives material planning; the routing drives capacity planning, scheduling and conversion cost.

Why are operations numbered 10, 20, 30?

The gaps let you insert a new operation later, such as 25, without renumbering the whole routing. It is a long-standing convention in manufacturing systems.

Should setup and run times be recorded separately?

Yes. Setup is a fixed cost per batch, while run time varies with quantity. Combining them makes small batches look cheaper and large batches look more expensive than they really are.

How often should routings be reviewed?

Review actual versus standard times monthly for key operations, and update a routing whenever a process, machine or material changes. A full review of all active routings once a year is a sensible minimum.

Can one product have more than one routing?

Yes. Alternative routings are common when a product can be made on different machines or lines. The ERP should let planners choose the routing on the production order based on current load.