The Work Order: The One Number That Runs Your Factory

What is a work order in manufacturing?

A work order is planning's written instruction to production to make one item: what to make, how many, to which drawing, by when, through which operations and with which material. Its number becomes the thread that links every other paper in the factory, from purchase to dispatch.

In many small plants, the order reaches the shop floor by word of mouth: "Make this one first, it is urgent." Nobody can later say why an order was late, how much material it used, or which operator made it. The work order fixes that.

One order, one number

When a customer's order is accepted, planning opens a work order and gives it a number. From then on, the same number is written on every paper connected to that order:

• the purchase requisition for the material it needs;
• the material issue slip when stores issues the material;
• the route card with the sequence of operations;
• the job card that travels with each lot;
• the inspection reports;
• the dispatch documents.

Six papers, one number. Ask for the number, and the whole history of the order is in front of you.

A simple numbering style works best: WO, the year, a running number. If your plant has no numbering today, start the series from a chosen date. New orders follow it, and old orders keep their old reference.

What a work order must contain

The delay block is the most important part. When the reason is written the same day, the plan can be corrected at once, and the monthly review shows the real causes of delay: material, machine, manpower or method.

Work order, route card and job card: who does what

These names are used differently in different factories, which causes confusion. Choose one set of names and use it everywhere:

• Work order: planning's instruction to production for one item.
• Route card: the fixed sequence of operations for one part and its drawing revision, with standard minutes.
• Job card: travels with one lot and records each operation as it is done: quantity in, good, rejected, reworked.

If your plant already calls the customer's order a "work order", don't use the same words for an order given to one of your own sections, such as heat treatment. Call that an internal work order.

Two kinds of work order

Most plants have both:

• Customer work orders. The customer reference is on the work order from the start.
• Internal work orders for stock. Some items are made ahead because the same customers order them again and again. These are made against an internal work order with no customer order behind it, and the customer reference is added only at dispatch.

Both are valid. What is not valid is production with no work order at all.

How the work order connects to purchase

Purchase should buy only against an approved purchase requisition (PR). Every PR has a type:

• Work order PR: raised for the net material need of a work order.
• Stock PR: raised when a stock item reaches its reorder level.

A PR without a work order number is not an error. It is a stock PR. A work order whose material need has no PR is an error, and it is the one that delays orders.

How to start in your plant

1. Choose the numbering style and the start date.
2. Agree the names: work order, route card, job card.
3. Make one simple work order format with the five blocks above.
4. Ask stores, purchase, production, quality and dispatch to write the work order number on their own papers from the same date.
5. Review the delay blocks every week for the first two months.