u/BreastHunter

We were looking at moving an assembly area from batch towards one-piece flow, but because it was mixed-model we ended up going round in circles a bit. The spreadsheet was fine for total work content and rough staffing, but it didn’t really help us land on whether it ought to be a line, cells, buffers between stations, people flexing, that sort of thing.

What I’m curious about is what people actually use to settle that in practice. Have you got something you trust, or is it more a case of mock it up, try it, and see what breaks?

Hi all, upfront: I’m asking this because I built a small app that helped us with a mixed-model assembly line project, and I’m trying to work out whether this is a common problem or just something specific to us.

Where I work, our engineering / production teams were looking at moving an assembly area from batch production to one-piece flow. We had lean consultants in to coach us through the line concept.

The frustrating bit for me was that most of the discussion was based around a spreadsheet. It was useful for total assembly time, customer demand, rough number of people, number of lines, etc. But it didn’t really show how the work should be split across separate workstations, which processes should happen where, or how the line would behave with a mixed product model.

Because different products needed different processes, it got confusing quite quickly. We understood the theory, but as a team we couldn’t agree on even a basic line layout. Some of us still felt an assembly cell might be better than a multi-station line.

The consultants then suggested buffer zones and operators “flexing” between stations. Interesting ideas, but again we couldn’t really see how it would work with our products.

I went home frustrated and built a simple web app to visualise it. The idea was to show the people on the line, how they would move between stations, and how the products would flow through the process.

By the next day I had something running with our processes and product mix in it. It showed the line running and gave a rough productivity view for the workers. From there we tweaked the layout, agreed on a concept, and then tested it on the shop floor. The trials backed up the simulation well enough for us to move forward.

I don’t see it as a perfect answer, but it helped us get from debate to “this is probably worth trying”.

I’d be interested to know how others approach this.

When you’re designing a mixed-model line or moving from batch to one-piece flow, do you rely mainly on Excel / line balancing, go straight to physical trials, use simulation software, or something else?