Fab reporter notebook: In lean manufacturing we trust

Yesterday I spoke with a production manager (on background) with a not-so-uncommon challenge. He had been brushing up on the basics of continuous improvement, including lean manufacturing methodologies adapted for the high-mix, low-volume environment.

All the talk of efficient part flow, shorter lead-times, and less inventory seemed great in theory. And the shop has made some initial steps. He had worked to reduce batch sizes to combat the large pile of work-in-process building up around the press brakes, a common bottleneck. The fabricator also revamped its material ordering to ensure raw stock for a job arrives a day or so before when needed, not a week or more.

But the fabricator had yet to launch a formal improvement effort. The shop is busy, to be sure, and managers expect the shop to be even busier next year. But this isn’t a reason not to launch a lean initiative. Indeed, improvement initiatives may make life easier. The shop performs numerous one-off jobs--a subassembly of, say, 10 or so components. All too often, jobs arrive at the assembly department incomplete, with one piece missing. Further improvement efforts may clear WIP, ease flow, and make it much less likely to lose a critical piece during an upstream process, like at laser cutting or punching.



The production manager wasn’t worried about implementing these inventory reduction efforts. What actually seems most daunting, he said, is 5S--sort, set in order, shine, standardize, and sustain. He specifically referred to individual workbenches. Many workers had complete sets of Allen wrenches other simple tools, all laid out for easy retrieval. Problem is, most of those tools sit unused most of the time. Press brake changeovers usually need just one or two Allen wrench sizes. At the grinding stations, many jobs call for a certain grit disk, but workers have entire range of grits, just in case an unusual job comes across their workstation.

Workers are hoarding tools, and for good reason: They want to ensure they’re never caught without the tool they need. It’s a basic mistrust. If they don’t have the tool, it could be anywhere, which means they need to go on a tool hunt. That will lower their productivity, which certainly won’t make them look good.

The production manager told me that instilling that trust will be the key to getting worker buy-in of lean manufacturing. This is a high-product-mix operation, so it’s almost impossible for every workstation to have every tool a worker is likely to need. This is why organizing workstations with commonly used tools makes sense. The remaining tools and consumable media (abrasive disks and such) could be stored in a central location, where inventory levels and usage patterns can be monitored.

In this shop, the manager said that to implement lean, the team will need to address this “just in case” mentality, which naturally develops in shop that processes literally thousands of different products. No matter how efficient one workcenter may be, the company won’t make any more money if overall part flow remains constrained at a bottleneck downstream.

Moreover, if workers hoard tools at their workstations--so they’re ready for everything--but can’t find the tool quickly, they waste time; the net effect is the same as looking for tools elsewhere in the shop. If they spend enough time looking for tools, they create yet another bottleneck and again inhibit part flow.

It’s not about the efficiency of one worker or one workstation, but the efficiency of the whole. If more products don’t ship in less time, the company isn’t making more money, landing more work, or making better margins. And without any of this, nobody wins.