Making the Most of Machinery

On the other end of the telephone line, the bustle that colors the daily life of David Green is clearly audible. Green will surely tell you he’s busy—though there’s hardly a surplus of minutes to spare talking about making money instead of actually doing it—but there’s no need. The sound of machine tools doing what machine tools do really says it all.

Green, like all on the 60-or-so-member team at FMI Medical Instruments of Madison, Ala., is charged with providing innovative solutions to the most demanding of medical device manufacturing challenges. “The strongest element of our company would have to be the employees here,” says Green, a manufacturing engineer/programmer. “We make things that other people can’t make.”

Dedicated to manufacturing orthopedic implants, instruments, and devices, FMI’s 57,000 square-foot facility is designed to meet both prototype and production volume requirements and handily offers comprehensive machining—milling, mill-turn, wire EDM, and Swiss—and metal-finishing capabilities under one roof.

To tackle its to-do list, the company employs the usual suspects, i.e. materials, such as stainless steel, titanium, cobalt chromium, nitinol, polyether ether ketone (better known as PEEK), radel, phenolic, and acetal.

Founded in 1999, FMI historically programmed parts at the machine control until it realized that it was unable to maximize the potential of the increasingly complex machines it acquired.

In 2009, the company purchased ESPRIT^® computer-aided-manufacturing (CAM) software by DP Technology specifically to program its Mazak mill-turn and Citizen Swiss-turn machines.

“For a long time, we were just typing in programs. But as the complexity of the parts started to grow with the company, we needed something that could program multi-tasking machines, and that was ESPRIT,” Green says. “We now have software that generates complex toolpaths and can use existing geometry or surfaces to output correct code so that nothing has to be manually calculated.”

FMI serves a body of 50-plus customers who represent a range of one-time to repeat business and lot sizes of 25 to 1,000 pieces.

“The company started with just two people and has rapidly grown in the last decade,” Green says. “We’ve grown from one shift to three and we’re constantly adding machines and employees.”

To keep the gears of this well-oiled machine turning, it’s crucial to get jobs right the first time by maximizing the technology that drives it.

“Eliminating operations is a great way to eliminate mistakes from human error,” says Green, seen here on FMI’s shop floor.

“We’re trying to achieve on-time delivery for each customer and superior quality of parts,” Green says. “We have to have perfect setups, perfect programs, and maintain a good flow of products as a company.”

Among the lengthy list of medical parts being turned out by FMI are spinal hook, rod and screw systems and bone screws and hip stems, in addition to an assortment of surgical instruments like pliers, grippers, retractors, and spinal-screw insertion devices.

Many of these parts require tolerances of plus or minus .0002.

As is customary, Green and the crew begin with solid models supplied by customers. Though those models must sometimes be modified before they can be programmed, it’s not too tough a job in ESPRIT. Some of the modifications, he explains, relate to the way in which models tend to be “toleranced” to the nominal dimension versus the median dimension.

“We modify the geometry to make it closer to the median tolerance, and while we’d just like the model to be right, we have so many customers who all do it their own way, and we have to deal with that.”

Once the modeling is as close to perfect as FMI can get it, the company utilizes ESPRIT turning profiles to perform Swiss-style and multi-tasking machining. “If you have a part that has to be turned and milled, you want to do as much as you can to identify areas that first need to be turned, which makes our machining much more efficient.”

The elimination of manual calculation extends to reducing the number of programs required to get the job done. In the past, FMI used separate programs for milling and turning operations on the same part. With ESPRIT, the company is able to post both within the same program. “We would only post milling operations with the software and all other operations would have to be programmed at the machine,” Green says. “We can use ESPRIT to condense our whole process and do the programming offline. With a good program, you can just pull the program in.”

In addition to nixing the need for manual calculation, FMI has trimmed its number of required operations and maximized its complex machine tools.

“We have several parts that we used to make in multiple operations on different machines because we couldn’t utilize our machines like we wanted to,” he says. “With ESPRIT, we can make complex parts in one operation. This makes the manufacturing process smoother because, any time a part is loaded into a machine for another operation, you’re creating another opportunity for a mistake.

“Eliminating operations is a great way to eliminate mistakes from human error, and another benefit to making a part in one operation is that you can check the entire part for quality in complete dimensions instead of making guesses,” Green continues. “This dramatically improves quality because it eliminates mistakes made due to back-figuring dimensions that will be machined on a second or third operation.”

Green, who’s been a machinist for 12 years, credits FMI with both the best skillset and the best technologies—serious assets when it comes to delivering what customers want.

“Technology is a big part of what we do,” he says. “10 or 12 years ago, many of the parts were drawn on a piece of paper. Now it’s a CAD (computer-aided-design) file. With technology, what I’ve seen is that turnaround time is decreasing as technology is increasing.”

Because machines and software—and a powerful combination of the two—are capable of machining increasingly complex parts with tight tolerances, designers are designing parts with that increased capacity in mind.

It’s a busy day in the shop for this Citizen Swiss-turn machine, which is being maximized with the use of ESPRIT.