Turning Technology | Lathe History

Talking turning technology

Chalmers, Raymond E

Customers demand reliability, productivity, and value. Here's how companies are responding.

Aside from the hammer and anvil, probably the most fundamental metalworking tool is the turning lathe. Turning machines are among the earliest known metalworking technologies, (the patent for the Wilkinson screw-cutting lathe with slide rest was issued in 1798). Turning and the products it produces shaped the infancy and growth of entire manufacturing industries, including automotive and aerospace.

The reason the lathe survives and thrives is that it's also among the most versatile of machine tools. Add machine rigidity, precision accuracy via computer-- numerical control (CNC), and 21st Century tooling advances, and CNC turning shapes the outer and inner diameters of countless products with precision, as well as providing such additional operations as threading, profiling, boring, honing, and polishing, to name but a few.

It's important to recognize there's a range of turning users as well. At one end are companies requiring high-volume, high-precision, high-speed automated turning centers, often incorporating multiple operations governed by leading-edge software and control technology, for dedicated, high-output operation. Making up most of the field, though, are smaller manufacturing operations of less than 500 employees producing on a make-to-order basis.

"Traditionally, we've been involved with the job shop/contract manufacturer customer of all sizes," says Dave Hayes, product manager/CNC turning for Haas Automation (Oxnard, CA). "The major concerns are reliability, service, maximizing productivity, and reducing setup times."

"We run the gamut of manufacturing companies we supply," says Dan Soroka, vice president of engineering at Hardinge Inc. (Elmira, NY). "We manufacture high-precision machines, conventional turning machines, complex multi-axis machines, Swiss-type lathes, and manual equipment. The areas of interest we hear about most from customers are speed (spindle, live tooling, and turret indexing), accuracy, and untended operation."

Haas is a relatively young company among machine tool manufacturers, incorporated in 1983 and supplying CNC lathes since 1994. In 1983, Haas entered the machine tool industry with the SC collet indexer, the first-ever, fully automatic, programmable collet indexer, a device used to position parts for machining with very high accuracy. Today, Haas manufactures four major product lines: vertical machining centers (VMCs), horizontal machining centers (HMCs), CNC lathes, and rotary tables, as well as a number of large five-axis and specialty machines.

Hardinge, on the other hand, was founded over 100 years ago, and is also a leading machine tool manufacturer. The company designs, manufactures and sells CNC metalcutting lathes, machining centers, and related tooling, as well as a wide range of collets, chucks, and other workholding products.

Productivity issues such as high-speed turning differ among various manufacturing customers. "We've had 7000-rpm capabilities for a few years now, and have sold maybe a dozen," says Hayes. "Total speed is not as important as time to maximum speed. We resolve this issue with horsepower rather than using integrated motor spindles as some manufacturers do. Although such integrated motor spindles provide a speed gain, they're fairly exotic and can cause significant downtime if there are any problems. Providing more horsepower as we do on a 5000-rpm option with 30 hp gets users to maximum speed faster."

Hardinge, for its part, sees a direct relationship between advancing spindle speed and improving machine throughput. "In the next five to 10 years, we can see supplying spindle speeds three times faster than today on conventional products, and maybe five times faster on niche machines," says Soroka.

Advancing speeds usually means thoughts of automating the turning process, whether by automatic loading and unloading or by integrating multiple operations in a single setup. "We surveyed our customers, asking them if they want to drop a part complete out of a machine or use secondary operations," Soroka explains. "It depends on the philosophy of the shop owner. Automation or combination machines can be a heavy investment, and it's not a generic solution. There is room for growth for highly automated combo machines, but that growth will be limited due to cost and cycle-time issues. So much depends on the nature of the application. And as tolerances get more restrictive, parts are subject to damage in handling," he adds. "Resolving this problem requires more than the conventional part-- catching basket."

Scott Easley, project manager at South Bend Lathe Corp. (South Bend, IN) brings up another issue: safety. "In our view, automatically loading parts or removing them from a machine is most favorable for high-speed operations, but this is motivated more by safety concerns, with the efficiency being an added benefit," he asserts. "When things are happening very fast, it is important to keep the operator out of the way. This factor will be even more important in years to come as things go faster."

On the controls side, Haas develops its own CNC system inhouse, everything from building its own servo amplifiers and servo drives to writing control software. "It's an advantage," Hayes says, "because setup can be simpler, we can provide custom displays, the control system is the same among our milling and turning equipment, and the learning curve is shorter."

Other suppliers embrace the non-proprietary type of machine controls, most often based on the personal computer (PC) platform. "We foresee a greater role for open machine control architecture in the design of turning machines," says Scott Easley. "The need to fine-tune the process, even in a standard machine tool like ours, facilitates using these types of controls. Furthermore, the need to accommodate a workforce that is not as traditionally trained in programming skills means the controls of the future will have to do more."

More sophisticated controls also will include more sophisticated process monitoring, where the machine monitors tooling and workpiece conditions online, and communicates that information constantly to the machine, he adds. Hard guarding and other safety systems will be integrated with electronic monitoring as well.

For example, the PC-based programming system on South Bend Lathe's Magneturn 1220 slant-bed CNC lathe can switch between conventional EIA/ISO G-- codes and conversational, menudriven formats. In setup mode, the operator enters safe zones and test modes to ensure machine/part protection.

"Manufacturing is getting more specialized, not less, and customers want a control that fits exactly with what they are doing," Easley says. "The PC platform lets you tailor things more easily, adding a robot for example. Extracting part information and generating resource reports is easier, too."

But the question of what constitues an open architecture depends as much on how a shop operates as on what machine builders or software companies supply. As with personal computer users, there are customers who want to plug in a machine and get to work, and there are others who want to customize their equipment with special cards and the like. As mentioned, Haas supplies its own servos, amplifiers, and control software in-house. "We've debated this for a couple of years and have come back to why supplying our own control is a highlight for us," says Dave Hayes. "Sure there are standards for PCs, but the last thing you want to do with a machine tool control is get in there and tear it up, adding or pulling out boards. There's nothing really forcing us to open-architecture controls, in fact it's quite the opposite. We hear of crashes and such from customers, and whenever that happens, the solution that gets them back up and running fastest is best."

"With the use of PC front-end controls, remote diagnostics is what people want," adds John Boulas, manager of the controls and software group at Hardinge. "They want to use a PC-based Ethernet network for uploading and downloading parts programs as well as monitoring machines."

Eliminating proprietary backplanes or motion-control cards is likely as open as a machine control gets, where everything is controlled by software alone and runs on off-the-shelf PCs. This is the environment championed by Manufacturing Data Systems Inc. (MDSI, Ann Arbor, MI), and admittedly one met with initial disbelief by manufacturers. "A software CNC with no motion control cards or proprietary hardware? I didn't believe it, not for a second," says Kevin Smith, process engineering manager at Dana Clark-Hurth's Spicer Off-Highway Products Division plant in Statesville, NC.

The software was given a try, though, for retrofitting a 20-year-old J&L two-axis lathe at a nearby Dana plant in Morganton, NC. According to Sammy Nguyen, manufacturing manager at Morganton, the original control was obsolete and unreliable. After retrofitting the lathe with OpenCNC, Nguyen reports improved machine capability according to QS9000 reporting requirements. "Uploading and downloading part programs is easier, and the software is easier to edit," he says. "I can go in and upgrade when I want, and change what I need to."

"We can literally look into the software and see what the spindles are doing, how fast it's turning, or what the encoders are doing," Smith adds. "There's all kind of things we can tap into."

Want More Information?

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