November 9, 2012
Seeing bins of parts lying around in your shop? Maybe it’s time to get away from the large-batch method and try one-piece flow. Rather than make a large quantity of Component 1, then Component 2, then Component 3, while a welder downstream waits for Component 3, you could set up a system of one-piece flow that sends a kit of three components. The key to implement this strategy is the bender software.
If you’re like most fabricators, you spend no small amount of time thinking about how you can improve your tube fabrication processes. Perhaps you have been talking to the folks on the shop floor, a few people in the office, and anyone who might be able to shed some light on the situation. You have some ideas, yet you are searching for the big one—the one that will really affect the bottom line.
As you walk out onto the shop floor, you see two large bins of fabricated components waiting to be welded.
Let’s say your main business is making patio furniture, and a chair requires three main fabricated components. Those two boxes of parts sit because the welder doesn’t have the third component and can’t get started on this lot.
Then it hits you … why wait? You have asked the critical question. You can solve several problems with one sweeping process change. It involves funneling all the necessary parts to the welder so that he can assemble one chair at a time, all day long. He doesn’t need bins of parts; he needs just three parts.
For this to happen, the welder must receive discrete kits, kits that allow the process to flow one chair at a time through the welding cell continuously. No more piles of components sitting around waiting. No more wasted floor space. No more bins. No more waiting on the third component to be formed before the welder can strike an arc and get to work.
To keep the discussion simple, let’s assume that all three of the parts required to build a chair are made from 1-in. aluminum tubing. The process starts at the CNC bender. For the process to flow, the bender needs to bend the three parts in kit fashion. Not a big batch of Part 1, followed by a batch of Part 2, followed by a batch of Part 3, but one of each in succession.
If the parts need some holes punched in them after bending, it would be a good idea to create a workcell with the bender and a punching machine.
After the three parts are bent and punched, the kit is passed to the welder, who assembles the components and sends the chair to the next process in line. The goal here is to keep the chair moving through the paint line and heading toward the loading dock.
The benefits of this approach are obvious. First, it frees up floor space, which can be used for something else. Second, and more important, it increases the number of chairs completed each day, which lowers the COGS (cost of goods sold).
The foundation of this project is the bender software’s ability to facilitate one-piece flow (see Figure 1). CNC tube benders that support this lean approach enable you to build groups (kits) of parts and process the individual parts in sequence. This technique, by definition, doesn’t allow piles of components to build up and wait.
This approach to forming a weldment lends itself well to high-volume products. Be aware that setting up the shop floor to produce a low volume, perhaps 20 chairs a month, would not work well with this process. That’s just one per workday, so it doesn’t make sense to go through the time and effort to set up the cell and program the bender for such a small increase in productivity.
However, for a high-volume application, this sort of strategy can provide immense improvements.
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