New life for old iron

Retrofitting is an effective and economical option to make new money with old machine tools.

EDITOR’s NOTE: Click here for a video overview of several machines retrofitted by Machines in Motion Inc.

C.V. Tool’s six 1980s-vintage lathes were experiencing a combined 10 hours of downtime a week because of obsolete controls. The controls were difficult to repair and the wires were deteriorating.

The shop thought about replacing the three Cincinnati Milacron and three Mazak “turning workhorses” with new machines, but the units were well-maintained and took mostly light cuts, noted Kenneth Mattson, plant manager for C.V. Tool Co. Inc., Fitchburg, Mass., a manufacturer of hardware for various industries, including steam turbine, nuclear and aerospace. The shop typically cuts bronze, 400 series stainless, Ni-resist cast iron and mild steel.

Courtesy of Machines in Motion

A Pratt & Whitney Wolverine milling machine (top) that Machines in Motion retrofit cuts hardened steel (above).

Because the NC lathes were mechanically sound, retrofitting them with new controls, electrical systems and drive motors on the two axes made sense. Retrofitting the machines would prevent removing them from the shop and incurring rigging costs, so C.V. Tool decided to retrofit, Mattson explained.

The shop looked at several machine tool retrofitters, including one that wanted to move the machines to its facility to scrape ways and perform other rebuilding work. C.V. Tool ultimately chose AHS Machinery Service & Sales Inc., Tylersport, Pa., whose bid was only for retrofitting and therefore did not require moving the machines.

Like others interviewed for this article, C.V. Tool found real value in retrofitting, provided that the machines being retrofit met specific criteria. Mattson described AHS President Robert Sorensen as being the most “realistic” about the process, understanding that the fairly straightforward turning, boring and facing operations C.V. Tool performs on the lathes didn’t require all the “bells and whistles” that a new version of the machines’ old control would provide. Instead, Sorensen recommended a DynaPath CNC for the six machines, saving about $30,000 per machine compared to the new-version option. After discussing the pros and cons, the shop’s operators and maintenance personnel agreed with Sorensen.

Although the machines may be large, the retrofit price doesn’t have to be. “The one thing a lot of people don’t understand is the cost of the retrofit has very little to do with the size of the machine,” Sorensen said. “The CNC doesn’t know or care how big the machine is. A small machine with a complex toolchanger might cost more to retrofit than a very large horizontal boring mill with manual tool operation. There’s very little PLC operation to contend with there.”

To minimize production disruptions, AHS retrofit the six machines one at a time over the course of a year, with each taking about a week and a half to complete. AHS did most of the engineering and design work while the machines were still in service.

“The machines tools that weren’t getting retrofit were running around the clock [to maintain production],” Mattson said.

Meet the New Control

Except for some minor changes to the program format, such as positioning characters differently, programming stayed the same after the retrofits, according to Tony Botti, NC programmer at C.V. Tool. The existing programs required some tweaking to run correctly, he added, but then “ran right off the bat.”

Although change can be intimidating—especially after running the same control on the same machine for more than a quarter of a century—the operators found the new DynaPath CNCs were user-friendly and significantly more reliable than the old ones, Botti said. “After a couple days of working with the control, they were able to increase their setup speed.”

In addition, the DynaPath is efficient, requiring fewer buttons to push and screens to navigate through compared to the old CNC. “Each screen can do quite a few operations vs. having a bunch of knobs and buttons like the old control did,” Botti said. “Operators are able to do their work quite quickly.”

Courtesy of International Tool Machines

Retrofitting often involves removing electrical clutter, such as this “rat’s nest” of wiring in a machine’s electrical cabinet.

The retrofits also streamlined the equipment, eliminating a stand with a computer and monitor on it, an electrical cabinet and a lot of wiring from each machine. The original computer and monitor measured about 4 ‘ high × 2 ‘ wide × 1½ ‘ deep, and the cabinet was about 5 ‘ high × 3½ ‘ wide × 3½ ‘ deep, Mattson pointed out. Each retrofit machine has a control pendant that measures 2 ‘ high × 2 ‘ wide × 6 ‘ deep and hangs in front of the machine. “It opened up everything,” he said. “Even the airflow is better because a couple of these machines are in corners.”

The increased space enables setting fixtures and other tooling closer to the machine, enhancing operator efficiency, Botti added.

One thing that didn’t change is the speeds and feeds for the machines. “Downtime is what we’re saving on now,” Mattson said.

Retrofit Benefits

“A retrofit is going to give you first and foremost reliability and repairability,” AHS’ Sorensen said. “When some of these old controls fail, you can’t find the parts for them or, if you do, it takes a long time.”

He added that customers often inquire about putting bigger motors on a machine to boost cutting speeds, but that’s a mechanical function rather than an electronic one. Besides, getting a machine to cut at 1,000 ipm isn’t the challenge. “The problem is the machine wasn’t built to operate at those speeds. You’re going to have excessive wear at least and you might have more serious problems with heat buildup,” he said. “I tend not to promise improvements in cycle times.”

Other benefits retrofitting provides include the ability to monitor machine conditions, such as tool load and oil and bearing temperatures, that the old control might not have offered. The control can then be somewhat interactive and change the feed rate based on tool load, Sorensen explained.

A retrofit can also provide new control features, such as the ability to write and edit programs at the machine, graphically plot on the control screen what the part is going to look like and enable conversational programming. According to Sorensen, those features enable an operator with fewer skills than a machinist to run the machine.

Nonetheless, a retrofit will not radically alter a machine’s capabilities. “If I was building a new machine today, I could take full advantage of the CNC,” Sorensen said. “On a retrofit, unless we add sensors and some hardware, the new control is limited to doing the same machining operations the old control was doing. It just does them in a more user-friendly manner.”

Upgrade to Familiar

Doug Laursen, president of Machines in Motion Inc., agreed that ease of programming is a significant retrofit benefit. The Chino Hills, Calif., company retrofits machines with Centroid CNCs, which come standard with the Intercon conversational part programming language. “It’s essentially a fill-in-the-blank processor where you’re going to pull up a canned cycle for making a rectangular pocket, for example,” he said. “Then only questions that pertain to defining that rectangular pocket appear on the screen.”

Laursen noted the requirements and expectations for a retrofit vary by customer. “For the most part, every machine we do is a one-off, and every customer we interface with is a one-off,” he said, adding that the list of machines the company retrofits includes lasers, waterjets, grinders, lathes, mills, punch presses and specialty machines.

For example, Laursen noted reducing cycle time is important for a production shop, possibly requiring a retrofit to include an upgrade to AC brushless motors to increase cutting speed. An aerospace manufacturer, however, might be primarily concerned with improving machine accuracy and may want to add linear encoders and scales. A typical job shop may just want to make a machine it was struggling with easier to use.