Succeeding at Lights-Out
The list of considerations can be daunting, but the payoffs make it worth the risks.
Dad had warned me about leaving my machine. The warning, “Bad things could happen” ran through my head as I took my 10-minute break.
I had been running the same job on the VMC for weeks, and I had never left my station during operation. There were 36 aluminum manifolds loaded onto a trunnion fixture, and the complete cycle time was 2-1/2 hours. Everything had been running smoothly. I rationalized: If nothing had happened while I was standing nearby, wouldn’t it be more efficient to let the machine run while I walked away? Instead of putting the machine on feed hold, I let it continue to machine parts as I walked into the break room. My palms became sweaty and my heart began racing. Dad (who owned a tool and die shop in my youth) was in my head asking, “What are you thinking?” Of course, everything turned out fine, but this was 1992, and unattended machining was rare back then. I extended my absence to lunchtime. Successful. Eventually, I left the VMC running as I shut the lights off, locked the door and went home for the night. That pattern continued, and I consistently found finished parts waiting for me in the mornings.
That’s the story that began our shop’s journey into “lights-out manufacturing.” We routinely leave machines to run unattended during the day and again after hours. Large numbers of parts are machined with virtually no manual labor, and that’s a big upside for us. Lathes and machines are prepared, checked and loaded with raw material. During the day, counters are set, fluids are filled, inserts and cutters are replaced, and away we go.
Now that we are in the lights-out mindset, the particulars of our operation come naturally. But for someone new to our company or for an outsider, the long list of details that need to be considered can be daunting. Here are a few details that we consider essential to our success:
Equipment. We buy our equipment new and specify it with unattended machining in mind. All of our lathes have bar feeders, two spindles and live tooling. We produce parts that need little or no secondary operations so that they can be washed and packed up right off the machine. We look at all the machine options, and make our purchase with automation and future needs in mind.
Our production milling takes place on flexible manufacturing systems. These linear pallet pools allow one or two operators to tend a bank of four or five HMCs that can run 24/7. The best part? Tooling and fixturing are resident in the system, so setup time is virtually eliminated; precious time is spent on production, not setup.
Coolant and lubrication. We have a coolant management system that saves dozens of hours of labor each week. Every machine is plumbed into an automatic coolant delivery system that automatically mixes and delivers coolant to machines on demand. We use custom-built chip conveyor and tank systems that help filter, recover, and recycle coolant. Floating contaminants, way lube, and sludge are kept in suspension so they can be filtered out and removed. Way lube is topped off daily. We don’t want coolant or lubrication problems to stop an overnight run, so we spend time and effort up front to address these details.
Consistency. One of the most important conditions needed to run unattended is consistency. Tooling, material, and machine performance must be dependable. There are things that we can do to help ourselves, too. For example, on our lathes, we often turn down the ends on raw material in order to use the smallest channel set. This provides more support and rigidity to the bars as they are turning through the bar feeder and allows us to have more control over the machining process.
The only way to get consistent results is to build consistency into our processes. On machining centers, one important factor is consistent fixturing of raw material. We help our operators by providing torque-controlled screw guns, in which color-coded bits provide the amount of torque that is needed to hold parts securely.
Technology and automation. As advances in tooling, material and machine tool technology roll out, we need to be on top of them. That’s why you’ll always see us at IMTS and why we expect our vendors to be fluent in industry advancements. We always want to be aware of the newest technology, especially in automation.
We apply automation where it will have the greatest impact. Having robots—both traditional and collaborative—gives us the flexibility to run sensitive or irregular parts without a staff member tending to the operation. Our robots unload, wash, dry and package these special parts, allowing us to run production on our turning centers through three shifts while only staffing one.
I often wonder what Dad would think if he walked into our shop at 10 p.m. today. Unattended machining really does require a different approach. There are 168 production hours in a week, and I ask myself, “How can I charge for every one of those hours?” The answer lies in the details. This brief article barely scratches the surface. Hopefully, the details I mentioned will help spark ideas to increase the efficiency in your shop.
Anthony Staub is president of Staub Machine Company, which he started in his garage with a single lathe. Some 40 years later‚ the Western New York shop has grown to two facilities that provide precision machining for a range of manufacturers. More at staubinc.com.