What is a routing and what is a work centre?

The routing is to labour what the BOM is to material. A work order copies the routing at release, so later changes to the master routing do not disturb jobs already running. Times on the routing are the plan; times logged by operators are the actual.

• Operation number and description, in sequence
• Work centre for each operation
• Setup time, run time per unit, and any queue or move time
• Instructions or a reference to a work instruction and drawing
• Inspection points and whether the operation can be subcontracted
• Alternate work centres, where the operation can move under load

A work centre is a planning and costing unit. It can be one machine, such as a laser cutter, a group of interchangeable machines, such as three manual lathes, or a manual cell, such as the welding bay. Each has a capacity, usually hours per day times the number of resources, and a rate per hour that covers the operator, the machine's depreciation and power and often a share of overhead. The rate is what turns logged hours into job cost. Setting work centres too fine, one per person, makes scheduling impossible; too coarse, one for the whole shop, makes the cost rate meaningless. One per distinct process or machine group is the usual rule.

Some systems combine the two into a single production template. That is fine for simple parts. When one part can be made on either the laser or the punch depending on load, you want one BOM and two routings, so keep the records separate in your head even if the software merges them.

A shop that runs on memory does not need routings written down until the day the person with the memory is away. Beyond that, routings and work centres earn their keep in three ways. They let a job card print with the steps in order, so a new operator can follow it. They let labour be logged where it happens, so a job cost shows that bending took twice the quoted time. And they let you see load by work centre, which is the first honest view of capacity most owners get. Start with the current method for your top products, use round numbers for times, and correct them from logged actuals rather than trying to time-study everything first.