MEDICAL MACHINING Photo courtesy Iscar Metals
Iscar Metals Pico Ace tool allows for repeatability of 5 µm, both radially and axially.
Medical Machining Tightens Up Regulations, competition are causing part makers to tighten profit margins, part tolerances and cycle times
T
he medical device market finds ways to stay in the headlines in one way or another, whether it’s because of big mergers (such as Medtronic’s acquisition of Covidien) or tax-inversion moves (such as Medtronic’s
subsequent relocation of its headquarters to Ireland). Medical
Michael C. Anderson
device companies and their lobbyists continue to push back
Senior Editor
against the US medical device tax used to cover some of the costs of the Affordable Care Act. And recalls of medical products certainly get into the media. But away from the front page of the business section, manufacturers in the medical device field are feeling the effects of a shift in health care practices. “The regulatory environment in North America and Europe has driven a shift to value-based healthcare solutions, which in turn has resulted in increased competition, changing business models, and innovative strategies to achieve sustainable growth,” medical market analyst Bryan Hughes of P&M Corporate Finance LLC (Chicago) said. March 2016
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MEDICAL MACHINING
The ripple effects from all of these developments are reaching the medical device side of the machining business, resulting in a tightening of a number of parameters, from profit margins to part tolerances and more. Tighter Margins Scott Walker, president of Mitsui Seiki USA Photo courtesy Mitsui Seiki
Inc. (Franklin Lakes, NJ), gives an example of the way hospitals do business has changed—and how that change affects medical manufacturers and their suppliers. “Ten years ago, a hospital used to go in and buy the entire range of components,” Walker said. “For knee replacements, for example, a hospital would buy a box and in it would be, say, 15 sets of knees. They didn’t know until they cut your leg open what size would fit in there, so they were ready with a range of sizes that they had purchased.” ARNO Medical Solutions ®
The Mitsui Seiki Vertex 55X II model series features XYZ positionin accuracy of 0.001 mm.
No longer, he said. “Today the way it works is, a kneereplacement salesman goes into the room with the surgical team, he brings in a box of knees, and the hospital only buys and uses what goes into the patient.” That kind of practice means a lot fewer knees get sold, and so the manufacturers are hard-pressed to cut costs wherever they can. Walker recalled selling a dozen highend five-axis machines to Johnson & Johnson for making knee replacements and eight more to Zimmer for making
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hip replacements some years ago. More recently, he said, the machines sold to Johnson & Johnson have been sent to Ireland and the Zimmer machines sent to Puerto Rico. “They went outside the US to reduce costs, and then started buying more commodity-based machine tools,” he said. Other Mitsui Seiki customers—still in the US—are making smaller components, such as titanium intervertebral implants, as well as surgical tools and molds for plastic accessories. Walker said that their most popular machine with these customers is the Vertex line of five-axis vertical machining systems. The new Vertex 55X II model series, comprising six distinct models, was announced in February
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2015. Linear axes strokes are 550 × 600 × 500 mm. “The line is designed for tight-tolerance work,” Walker said, and features XYZ positioning accuracy of 0.001 mm. Spindles are available in 15,000; 25,000; and 30,000-rpm speeds.
Tighter Tolerances
features the company’s multiturret technology and has the
Even tighter than the profit margins in this business
capacity to machine components ranging in size to 38 mm.
are the tolerances required for increasingly smaller, more
The machine’s triple-turret design capitalizes on simultane-
detailed components.
ous capabilities to reduce overall machining time, which is
“The medical industry is very innovative, and is coming to us with more and more complex components,” said George
beneficial given the medical industry’s tight margins. The machine also offers deep-hole drilling on both the
Bursac, general manager of Star CNC Machine Tool Corp.
front and rear ends of components, as well as high speed and
(Roslyn Heights, NY), a specialist in Swiss-style machin-
universal control. To further improve accuracy and productivity,
ing solutions. “Over 50% of our total business is in medical
the machine is equipped with the company’s custom “Motion
manufacturing. We work with a number of well-established
Control” feature. A flexible toolpost design enables the incor-
medical companies and, you know, they always come back
poration of additional tools to increase functionality.
for more. Parts are becoming smaller and more intricate, with a lot more detail on them—and you can’t make them any other way than by using a Swiss-style machine.” The type of parts Bursac is talking about include those
Tighter Cycle Times The tight margins in medical manufacturing demand the fastest cycle times possible while maintaining qual-
from implants, surgical instruments, cardiovascular compo-
ity, affirms Mazak Corp. (Florence, KY) VP Rick Ware. For
nents, dental equipment and more, he said. “Some of the
medical shops making a range of precision parts, that
parts they’re manufacturing now are sometimes so tiny that
calls for a five-axis system with speed, accuracy and flex-
you cannot see them with your eyes alone—you have to use
ibility, he said.
a jeweler’s loupe to see certain details on these parts.” Quality and repeatability are other requirements for machining these ever-smaller components, according to Bursac, which is a reason for automating more of the procedures.
“Any handling of precision parts by people introduces variables that could create problems. The machine doing everything makes for a more accurate, repeatable process.” “With smaller parts, a lot of people used to make different fixtures to hold them. Today, we don’t have to do this on our machines. We make parts out of bar stock from scratch,” Bursac said. “You put a rod in the machine and out will come a finished part. All details are added right in the machine. The part is picked up with a subspindle and finished on the back end as well.” Bursac stresses the advantage of being able to start and finish a job on a single machine without human intervention. “Any handling of such precision parts by people, it introduces variables that could create problems. With the machine doing everything without a need to stop for fixturing and so on, it makes for a more accurate, repeatable process.” The ST-38 model from Star CNC is popular with the company’s medical customers, according to Bursac. It March 2016
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To illustrate, Ware shared the example of Mazak cus-
According to Ware, for every job the shop has moved
tomer OneSource Manufacturing Technology (Leander,
to the VCU 400A 5X, it has immediately reduced cost per
TX). OneSource manufactures primarily medical implants—
part by at least 15% through shorter cycle times. In some
knees, hips and a variety of spinal components—along
instances, cycle times were reduced by more than 25%.
with some associated supportive instrumentation. Parts
“The small-footprint VCU VMCs feature trunnion-style ro-
range in size from 3.2 mm2 up to 457 mm2. Typical toler-
tary/tilt tables that make it possible for shops like OneSource
ances are ±0.227 mm and as tight as ±0.0127 mm, and
to cost-effectively add full-axis machining to their operations,
materials include stainless steels, titanium, cobalt chrome,
especially for producing medical components,” Ware said.
PEEK and others. When the company first moved into medical work a few
‘That’s the Priority’
years ago, they did their five-axis machining with three-axis
At toolmaker Iscar Metals (Arlington, TX), the focus is
VMCs outfitted with fourth and fifth-axis trunnion units. They
also on reducing cycle times—a more important concern
soon discovered that such an approach hindered their part
than increasing tool life, according to Grip Systems Product
processing speed and cost-effectiveness. The communica-
Manager Clay East.
tion between the trunnion units and the VMCs on which
“Tool life is important, East said, “But what Swiss-style
they were mounted caused lags in positioning; the units’
machining shops and medical shops realize is that if we
additional mounted weight restricted how fast the machine
can extend their tool life by 20%, that’s great—but if we can extend their productivity by 20%, well, they’re jumping over buildings at that. That is going to allow the customer to get 20% more usage out of their machines. It frees up their machines—by 20%!—for other jobs. “That’s the priority,” East said. “You want to squeeze every penny out of every machine you’ve got when you’re in the medical industry.” East offered two examples of recent innovations at Iscar that are helping to increase productivity for their medical customers. The first is an
Photo courtesy Mazak
update to a decade-old product called Swisscut. In its original design, a user would have to completely remove a screw in order to index the tool The stages of machining done on titanium spinal cages at OneSource Manufacturing.
insert or remove the insert completely. “It sounds like a small thing,” East says, “but I used to work in a Swiss machine shop and I can tell
tables could rapid traverse; and the extra inertia involved with
you firsthand that when you drop a screw, it’s very frustrating”
moving the added weight also accelerated machine wear
as your work comes to a halt while you search for it. “And if it
and tear as well as generated vibration that affected part
happens several times a day, and 52 weeks a year, that adds
surface finishes. But what really hindered operations was the
up to real loss in productivity.” So about two years ago the
amount of time and effort it took to achieve required levels of
Swisscut was redesigned so that the user need not completely
machining accuracy.
remove this screw in order to index or remove the insert.
OneSource purchased a Mazak VCU 400A 5X VMC that
“About three turns and you can take the insert off,” East
features an integrated tilt/rotary trunnion table with roller gear
said. “It’s accessible from either side of the tool. This allows
cam technology. The machine has as 40-taper 12,000-rpm
you to change that insert without removing the tool from the
spindle, automatic toolchanger and 30-tool storage capacity.
machine, saving time.”
With an X-axis stroke of 505 mm, the VCU 400A 5X handles parts up to 400 mm in diameter and 304 mm in height.
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His second example involves precision boring an inner diameter with solid carbide tools such as boring bars or
grooving bars. Iscar has developed a secondary bar holding
cal scanner can quickly confirm a MBD profile tolerance has
solution for use with their Pico line of tools, he said. “By go-
been met,” he said.
ing from what used to be the industry standard of two-screw
According to Goodrich, the latest iterations of Master-
clamping of the tool to three-point-contact clamping,” East
cam are further addressing the productivity concerns of the
said, “we were able to take our repeatability on this ID boring
medical market through an ongoing project the company
operation from 50 to 5 µm, both radially and axially.”
calls “Rest Machining—a quick way for manufacturing
To put that into perspective, a human hair is about 100-µm thick. “It was the move to three-point clamping that allows us to
engineers or programmers to target material left behind in a machining operation.” He explained that Mastercam’s Stock Model feature can
get to that level of precision,” East said. “To this day I have
calculate the shape of the stock—the material from which
yet to see any of our competitors publish anywhere near the
a part is being machined—anywhere in the process the
5-µm repeatability axially and radially. The closest any have
programmer desires. So, when referencing a Stock Model
gotten that I’ve seen is 50-µm axially and 20-µm radially.”
and a finished part model, Mastercam’s toolpaths can be set to only machine areas where material protrudes from the
Model-Based Definition The connection between part designers and manufac-
finished part model. “Taking this approach saves our customers time and
turers has also become much tighter with the advent of
money by efficiently targeting only the stock left on the part,
software-aided designing for manufacturability. “One big
and not having to waste machine time ‘air-cutting’ over
change the industry has seen is the move toward MBD, or
already finished areas,” Goodrich said.
model-based definition,” said Keith Goodrich, a product specialist at CNC Software Inc. (Tolland, CT), the makers of Mastercam software. “Although not specific to the medical industry, the effects are felt strongly in this corner of manufacturing,” Goodrich said. “Designers and their customers weigh aesthetics heavily in the medical industry, smooth transitions from one feature to the next are increasingly more important and always difficult to define on 2D blueprints. Using MBD, a profile tolerance to a supplied model or individual feature of a supplied model is extremely simple to convey from the designer to the manufacturing engineer.”
“Medical shops realize that if we can extend their tool life by 20%, that’s great—but if we can extend their productivity by 20%, well, they’re jumping over buildings at that.”
LIFTING
PERMANENT
CLEAN UP
• Flat lift ratings of 220 to 4,400 lbs.
• For OEM applications & machinery
• Push, hang & trailer-type sweepers
This move to MBD has a further impact on the task of
Booth 1644
machining medical components, Goodrich explained: It has streamlined the process from manufacturing to inspection. “Instead of a machine operator requiring custom gaging to check 2D blueprint callouts—which is cumbersome, time consuming, and often unnecessary with respect to a part’s design intent—a first-article inspection using a CMM or optiMarch 2016
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Further clarifying the condition of the in-process stock
of this project. In the end, however, the customer was able to
relative to the finished part profile is Mastercam’s Compare
avoid a lot of risk and save time by working with the simula-
feature, Goodrich said. “This feature compares the machined
tion to optimize their new machining cells.
material to the finished part model with userspecified tolerances and clearly displays any material remaining as well as any over-cut, gouged features.” The result is a better use of machine time as well as of stock. Photo courtesy Star CNC
Tight Simulations Multiaxis machining equipment and the tools and automation needed to meet customer demand are a big investment for medical manufacturers and the thought of the cost of downtime and repairs if a program goes wrong can bring night sweats to the most hardened of executives. For this reason, a growing number of companies are first trying out their machining programs on virtual machines by way of simulation software.
Star CNC ST-38 model features the company’s multiturret technology and has the capacity to machine components ranging in size to 38 mm.
“The trend in medical device manufacturing is going to-
While that customer’s machines used FANUC controls,
ward more and more use of complex multitasking machines,”
Proisy pointed out that this simulation system can work with
said Silvère Proisy, general manager of Spring Technologies
machining programs from any software package.
Inc. (Boston, MA, and Paris), a developer of NC simulation
“Another medical client asked us in 2012 if we could sim-
and verification software for optimizing CNC machines. “Ma-
ulate and optimize an operation that used a legacy program
chines that are complex enough to do everything, and this is
that was written with software that doesn’t exist anymore or
where simulation can have a crucial impact on a company’s
programmed manually,” he said. “We said yes because ulti-
return on investment.”
mately we are reading G code. As long as a program comes
Proisy offered the example of a major medical-device OEM that recently invested in some five-axis machining
down to G code moves, we can simulate it no matter what the software was.
centers that feature dynamic offsets to allow the completion
“People at that company told us later on that just by
of a complex part in a single operation as well as in robotic
putting that operation into our software, they were able to
loading/unloading equipment.
significantly cut machining time,” he said. “After a year they
The company “needed to make sure that when they set up a new program, its going to execute correctly without any crashes or any part issue,” Proisy said. “We have to take into account all of the parameters that reside in the real machine. When we set up the simulation, we ask the customer to give us all of the knowledge about the subroutine macros from the machine—we extract these from the real machine and put it into the simulation.” The more abilities a machine and its CNC software have, the more parameters need to be reflected in the simulation’s virtual machine, according to Proisy. “It can be very complicated,” he said. “It took us a couple of months to set the virtual machine up properly” in the case
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had saved half a million dollars just through time saved.” CNC Software Inc. 800-228-2877 / www.mastercam.com Iscar Metals 817-258-3200 / www.iscarmetals.com Mazak Corp. 859-342-1700 / www.mazakusa.com Mitsui Seiki USA Inc. 201-337-1300 / www.mitsuiseiki.com Star CNC Machine Tool Corp. 516-484-0500 / http://www.starcnc.com/ Spring Technologies Inc. 617-401-2197 / www.ncsimul.com
