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For Short Runs, Get Lean, Add Automation

Setup time kills productivity, especially when production runs are short. Here’s how a top press brake builder helps customers decide how to minimize lost time.

“Almost everybody now is doing short-run manufacturing,” says Scott Ottens, bending product manager of Amada America. “No one wants WIP (work-in-process). No one wants to build inventory.”

Ottens has a good overview, as the manager in charge of Amada’s press brake sales. When there’s an industry trend going on, few people are in a better position to put their finger on its pulse.

“Lean manufacturing is on the burner again,” he says, noting that the concept has resurged after the economic setback of 2008. At the risk of oversimplifying, it, lean manufacturing is about eliminating waste. And the biggest waste, particularly in press brake operations, is lost setup time.

“The press brake is one of the worst offenders in the entire shop, as far as setup time goes, and as far as green-light time [time spent making product] goes.”

Time Killer #1: Planning and programming. Done at the machine, it’s time spent not bending. The goal is to get it offline.

Only 28 percent of time is spent bending

How bad is it? “Typically what we see in a good shop is a green-light time of maybe 28 percent on the press brake. Twenty-eight percent of the day’s time, it’s running parts.”

Depending on where you stand, that either sounds appalling, or it sounds like an opportunity. Amada has seized on the issue and developed a systematic way to detect and analyze the “wasted” time – to add together all of the bits and pieces of time-consuming operations that rob time from actually bending parts. They call it VPSS, for Virtual Prototype Simulation System. The part of the system that’s relevant here is a step-by-step analysis of setup time, in a broad sense, that Ottens explains:

“This is how it goes. We go into a shop with a team of engineers, and, usually, one of my product specialists as well. They’ll do two things. One person will actually go around and just sample the timing of events. Every three minutes they walk through and look at a press brake, for example. They look at different machines. They have a chart that lists nine areas of processing setup: different setup functions, and then the actual production mode. They make a tick mark on the chart for what’s happening on that brake at that time. It gives a snapshot of what’s happening on the brake over the course of a typical day.

“Then they go in depth on one or two machines. They shoot video and watch setups, to show what’s going on in detail during those setups.”

Time Killer #2: Setting up tools. If it’s done manually, use tools that minimize adjustments. Or, automate.

Nine categories of setup time

“To create a tool to analyze it, we took the setup process and broke it into nine different categories. [see timeline sheet, page XX] When we put a video camera on that one machine; it’s on for the entire day while we watch them go through setups. While the video is being recorded, our engineers are writing down what goes on. They have a timeline sheet for noting the events. ‘What’s happening now? The operator is gone. He’s looking for tools. He’s been gone now for 20 minutes looking for this tool. He’s doing paper work. He’s test bending. He’s inspecting and checking parts.’

“We actually write down on each timeline what’s being done, in sequence, for the entire day. The video allows us to go back and review what the guy is struggling with, specifically. ‘Why is he spending so much time on, let’s say, test bending?’”

Time Killer #3: Machine adjustments. In a modern control system, this should be automatic, and some adjustments are unnecessary with tools that repeat, and with advanced crowning.

The Amada staff takes the recording sheets and the video back to their headquarters and they analyze it. They’re looking for operations and processes that can be improved, either through “lean” organization or through automation. From the analysis, they produce a report for the customer.

“If there is time being wasted by having to search for material, we can note it but we can’t address it ourselves,” says Ottens. “But from that point on, we’ll have solutions.”

Amada is in the business of selling machines and automation, and being able to identify and quantify the time-wasting steps is an important sales tool for them. But it’s also a tool for the customer. The whole data-accumulating process, and the analysis and report, are similar to what one gets from a consultant who you might call in to analyze ways to improve your operations. With actual reports showing the time it takes to complete each step, the [potential] customer has hard numbers and evidence. He can see what things are costing him, and where productivity is suffering.

There are a number of potential automation solutions. Amada can offer all, or almost all, of the components.As always, the first question is whether they’ll be cost-effective in a particular circumstance. Automation often is thought of as being primarily applicable to high-volume production, but, as Ottens points out, it can be even more effective in short runs. Again, that’s because setup and changeover time eats up a higher percentage of shop-floor time when runs are short and setup, therefore, is more frequent.

Time Killer #4: Test bending. Mechanical and optical bend gages not only do the measuring, but immediately feed back measurements to the controller, for automatic springback compensation.

Attack lost time with technology

“We attack all the areas that we can with technology,” says Ottens. “The whole goal is to externalize setup, to take everything you can off the machine and move it somewhere else. That’s the gist of it.

“Programming and creating a process; we can address that with offline programming software. Test bending, inspection; we can address that with a bend indicator.”

If it can be pre-programmed, the programs run the operation without leaving the machine idle: programs can always be ready to go. The obvious elements are the robotics, which, in Amada’s case as in some others, includes both loading and unloading tools, plus loading and manipulating workpieces. Part of the progress in automating press brakes for short runs comes from advances in programming, including programming that allows one robot, equipped with a couple of different hands or grippers, to change quickly from one job to another. Much of the rest is advances in the mechanics of the operation, including tools that can be loaded and located reliably using robotic means, and mechanical/optical/electronic devices that measure bend angles and feed springback-compensation information to the controlling computer. That’s the state of the art for press brakes, not counting the stock-handling and stock-staging steps, and the “rationalizing” of the machine locations to minimize footsteps, which are all part of “lean” manufacturing theory and practice.

Amada’s nine-category time sheet produces a detailed look at where time is being spent productively, and where it’s not.

The checklists that Ottens talks about actually are several pages long, for collecting the shop-floor information and for systematically analyzing and reporting the solutions that the company recommends. In order to make a cost/benefit analysis for the customer, they need to know what that shop’s costs actually are. Do the shops actually give their labor and other cost breakdowns to Amada?

“Yeah, asking for that actually is the first thing we do when we go in,” Ottens says. “It’s all confidential. We don’t share these reports with anyone else. Most people are willing to give it to us.” Armed with the costs, the steps, and the time those steps take, the VPSS analysis can show a customer where his opportunities are – in dollars and cents – to cut costs and to improve.

This 4:33 video demonstrates an Amada press brake tailored to automated, short runs, showing the features that appear as ‘solutions’ to the time-wasting steps uncovered in a typical shop-floor analysis.

”During the VPSS we will collect CAD drawings of the parts we observed,” says Ottens. “After we generate the report with the recommended machine(s) and features, we bring the customer to our facility for a live run of those parts. We take them through the whole ‘Print to Part Process,’ just as it would work in their shop. This proves out the programming, setup and run times generated in the report, giving them confidence to move forward with the recommended technology.”

We’ll assume that automating the steps usually demonstrates a payoff for the customer, or Amada wouldn’t go to the trouble. The nice things about it are that there is no arm-waving or blind faith. If you’re getting caught in a setup-time trap with short runs, it looks like a good way to measure where, and how much, you may save.

Amada America