Machinist’s Corner: A look at D-O-W-N-T-I-M-E

Over the past couple of years, I’ve been heavily involved in lean manufacturing. Every other day at the company where I work, we conduct gemba walks where the work happens, plus we have monthly kaizen (rapid improvement) and 5S (workplace organization) events.

A lean item I’d like to explain is the “eight wastes of lean.” Look around your facility and I’ll bet that you can identify a few areas where waste occurs.

The acronym for the eight wastes is DOWNTIME: Defects, Overproduction, Waiting, Nonutilized talent, Transportation, Inventory, Motion and Extra processing.

Let’s look at them individually.

The most obvious example of defects waste is your scrap pile. But parts you must rework to make good parts are also defects. In addition, incorrectly given or taken information is a defect because someone has to verify and correct that information. The costs include wasted production time, wasted materials and wasted inspection.

Overproduction is more common in OEM facilities, where too many parts are made before they are ready to be sold. A machine shop, however, may run a bar of turned shafts and hope its customer will accept the lot. In either case, costs include wasted production time and materials.

How many times have you waited at a machine to perform a secondary operation because the prior operation was not completed? Or maybe you’ve waited for someone to bring raw stock so you can start production. These are scenarios where waiting wastes time.