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ME Channels / Micro / Nano

Small Improvements in Medical

 

By Ilene Wolff
Contributing Editor

Medical device maker Donna Bibber put a client’s invention—a one-dose powder medication inhaler—on her web site hoping it might attract a pharmaceutical company interested in acquiring it.

After all, she said, her takeaway from a recent pharmaceutical show is that drug manufacturers are trying to eke out more revenue from medications with expiring patents by reintroducing them in new delivery systems.

“It seemed like inhalation is becoming a bigger part [of the pharmaceutical industry],” said Bibber, president and CEO of Micro Engineering Solutions (Charlton City, MA).

That kind of incremental thinking reflects the fallout from recent progress in her industry, medical micro and nano-manufacturing.

“It used to be just leaps and bounds,” she said of the progress in making increasingly smaller medical devices.

The Kern Micro is a five-axis machine designed to bridge the gap among milling technologies.

But once engineers reach the point where they can make one-atom layers of carbon, as University of Michigan research engineers did with 2D graphene for night-vision contact lenses, how much further will the laws of physics let micro and nano-manufacturing go?

Peter Liu, chief senior scientist for OMAX (Kent, WA) wrote in a 2013 white paper that nano-manufacturing with abrasive waterjet technology would happen by 2017, but he’s scrapped that objective.

“I don’t think we can get down to nano technology with waterjet,” he said. “Even with water only, we can get down to 10 or 25 microns at best” and not to the submicron level.

That limitation didn’t stop Omax from introducing Micro, a new five-axis milling machine for micro-manufacturing in 2014. Two other longtime competitors, Kern Precision (Webster, MA) and Makino (Auburn Hills, MI), also introduced new technology, and so did a relative newcomer to machine tooling, Chicago-based Microlutions (see sidebar). 


Plug and Play

Kern introduced its Micro five-axis milling machine in early 2014 to the United States, touting not only its reliability and precision, but also the size of its footprint, the capacity of its palletized toolchanger, its plug-and-play capability, its power, and its versatility in terms of the size of workpiece it can accommodate.

“In general, the ultra-high precision milling market, where high productivity and precision are key, lacked a highly reliable five-axis machining solution,” said Gary Zurek, Kern’s US managing director. “The combination of high productivity and achieving ultra-high precision on five-axis and three-plus-two axis parts has always been challenging to manufacturers.”

The Kern Micro offers medical device manufacturers a diversified five-axis machine that can bridge the gap among milling technologies, including high-speed machining, hard milling, graphite milling, and micro milling, he said.

With its rectangular footprint, occupying just shy of 5 x 10' (1.5 x 3 m) on the shop floor, the Kern Micro not only has a small footprint; the slim design also means several machines can be lined up like row houses with other Micros, for a highly automated work system.   

“In today’s economic climate, shop real estate is very expensive,” said Zurek. “Doing more in a Kern Micro is a prized attribute, but if a machine is taking up a lot of shop space then that can be a negative factor.”
These titanium and stainless steel orthopedic and prosthetic components were cut with abrasive waterjet technology from Omax.
If Kern’s Micro is small, its palletized toolchanger is just the opposite. The company has made the machine’s tool cabinet large enough to hold up to 209 tools, and convenient to use because of its glass front. Quick-change tool pallets can be assembled for individual jobs and stored separately.

“For years now, the industry has recognized the advantages of modular fixturing and management in automated situations,” said Zurek, adding that tool management can be a stumbling block in a highly productive environment. “Kern has applied this same technology to managing toolholders by palletizing them and managing them directly on the Heidenhain control.”

The advantage is an easily managed and trouble-free system that contributes to the efficiency of the entire production cycle by significantly reducing setup times, Zurek said.

If toolchanging is fast, so is setting up the Micro. It’s designed to be plug-and-play, with four connections required during setup for the machine, whose units are almost fully integrated: An optional water chiller is a stand-alone component.

“When the machine arrives, making it productive is a top priority for the company and its customers,” said Zurek. “Kern’s development team realized this important fact and made it possible for a remarkably quick, trouble-free installation by using the same philosophy behind plug-and-play technology.”

With its HSK 40 spindle with internal coolant lubrication, not only can shops achieve micron-level precision on micro-size parts, they can also cut more than 70 lb (31.5 kg) of steel in an hour. An HSK 25 spindle is available as an option.

Further, due to an integrated fourth and fifth axis table in a traveling column machine design, the Micro can handle workpieces up to almost 356 mm in diameter.


Horizontal Wire

For ultraprecision machining and the surface finish capability of small/fine wire operations, Makino offers the UPN-01 wire EDM.

The machine features the company‘s unique horizontal wire drive system that enhances wire threading performance, and is capable of reliably threading start holes as small as 0.03 mm, and can operate with wire diameter sizes ranging from 0.1 mm down to 0.015 mm.

Makino has specifically configured its horizontal wire system around the needs and requirements of micro-medical component manufacturing. The horizontal design provides significant versatility and advantages to extending productive untended operation, which is ideal for producing medical marker bands, as well as intricate grippers, augurs and clamps used in microsurgery. Maximum workpiece size is 150 × 150 × 40 mm, and maximum weight is 8 kg.

The UPN-01 can achieve accuracy at the submicron level in part because of its pneumatic slideway mechanism. The mechanism is made of lapped granite that uses a 10-µm cushion of air to make a frictionless bearing. Zero friction means the machine has a great degree of movement control.

“Its ten-nanometer minimum increment of movement is unmatched in the industry,” said John Bradford, micromachining research and development team leader.

The machine can achieve surface finishes as low as 0.1 µm Rz.

Because Makino incorporates its unique horizontal wire system in the UPN-01, slugs are not an issue. Instead of potentially falling into the lower head, they fall harmlessly to the bottom of the worktank without interfering with the machine’s operation. This eliminates the need for manual intervention, and extends the untended productivity of the machine.

The UPN-01’s CNC system is Makino’s Hyper-i, which features a 24" (610-mm), user-friendly touch screen that looks and works like many smartphones or tablets, with pinch, pull and drag operations.
For ultra-precision machining and the surface finish capability of small/fine wire operations, Makino offers the UPN-01 wire EDM.
The software includes digital manuals and an on-board training tutorial system for the operator, as well as many other streamlined and helpful functions that reduce the number of keystrokes and workload on the operator. Also, Hyper-i automatically records and translates production process data into pie and bar charts that make assessing machine utilization time quick and intuitive, essentially turning the Hyper-i into a piece of management software.

The UPN-01’s X, Y and Z-axes are 160, 160, and 50 mm, respectively; Its U and V axes are both ±7 mm.

Makino’s sinker EDM, EDFH-1, often sits side by side with the UPN-01 in medical manufacturing shops. With its machining guide arm, high-speed rotating spindle (up to 2000 rpm) and high-pressure pump, the company designed it to provide the capability and precision machining for both fine-hole EDM drilling and standard sinker EDM applications.

“It can machine start holes as small as 10 µm,” said Bradford.

The EDFH-1 can handle a workpiece up to 50 kg on its 350 × 250-mm table. The machine moves 220, 180, 300 and 220 mm on its X, Y, Z and W axes, respectively.

For manufacturers who need a sinker EDM that can handle larger parts and/or make larger start holes, Makino offers the EDAF-Series machine platform. The EDAF2 provides XYZ travels of 350 × 250 × 250 mm and workpiece weight up to 500 kg, while the EDAF3 provides 450 × 350 × 350-mm travels and supports up to an 800-kg workpiece.

“All of these machines are built for automation due to their software, innovative mechanical design, and high level of predictability and submicron repeatability,” Bradford said.


Taper-Free Cutting

Omax entered the world of abrasive waterjet micro-machining with its MicroMAX JetMachining Center, which promises taper-free cutting on a wide variety of materials. This versatility enables medical manufacturers to use abrasive waterjet cutting to make surgical clamps, orthopedic/prosthetic components, gears for electromechanical medical devices, and parts for laparoscopic tools.

The MicroMAX is the result of the commercialization of micro abrasive-waterjet technology developed under the support of a National Science Foundation Small Business Innovation Research Phase II grant.

MicroMAX comes equipped with a high-precision 7/15 Mini MaxJet5i nozzle with an 0.018-mm orifice and a 0.38-mm mixing tube, and is capable of cutting a kerf as small as 0.38 mm. The same nozzle body is available in a 5/10 beta version to cut thinner materials for spinal cages, for example, with a 0.13-mm orifice and a 0.25-mm mixing tube.

Omax entered the world of abrasive waterjet micro-machining with the MicroMAX JetMachining Center, which promises taper-free cutting on a variety of materials.

Omax is using an NSF SBIR Phase IIB Supplement to further downsize the nozzle and to incorporate 3-D machining capability. In addition, Omax is modifying its award-winning Tilt-A-Jet cutting head to mount it on the MicroMAX. The Tilt-A-Jet will be available as an option, which will minimize the taper of parts up to 40-mm thick.
 
The machine also has Omax’s advanced pressure controls for piercing delicate materials, minimizing the probability of delamination or cracking inside a blind hole.

“One of the problems with conventional waterjet is piercing delicate materials like laminates, composites or glass,” said Liu. “When you try to pierce with the waterjet, before it breaks through the material the jet decelerates, stops, and reverses its direction at the bottom of the blind hole.

“A large stagnating pressure develops inside the blind hole, and piercing-related damage results when the stagnating pressure exceeds the tensile/adhesive strength of the materials.”

The new waterjet machining center can also precisely cut stainless steel, titanium, nitinol, graphite, copper, and more, Liu said. In addition, laboratory testing using the MicroMAX to cut fiber-reinforced PEEK showed the fibers are cut cleanly, he said.

The MicroMAX’s table is 0.71 × 0.71 m (28 × 28") square, and has an XY cutting range of 0.61 m. It uses high-precision linear encoders, vibration isolation and intuitive software control systems for position repeatability of 2.5 µm and a positioning accuracy of about 15 µm.


Out of the Lab, Into the Industry: Microlution Finds a (Very) Small Niche

A little more than 10 years ago, Microlution’s founders were graduate engineering students at IMTS 2004, and facing an endless stream of visitors curious about the prototype micro-machining center they brought to demonstrate.

“We had many companies come by and ask if they could buy one,” said Andy Phillip about the machine he helped build in a lab at the University of Illinois at Urbana-Champaign with classmate Andrew Honegger.

Soon after, the pair co-founded Microlution and set up shop six miles away from IMTS’ McCormick Place location in Chicago.

“We’re very proud to be a part of the US machine tool industry, solving some tough manufacturing challenges,” said Phillip.

Microlution recently introduced its sixth machine line, has seen year-over-year sales percentage increases in the double-digits, and seems to have found its micro-niche in the global business of machine tools.

How’d they do that?

For starters, the interest at IMTS told them there must be a gap in the marketplace.

“We started with a clean sheet of paper and designed a machine optimum for small parts,” said Phillip, Microlution’s president. “What’s very special for us is we focus not only on small parts, but also small features where you run into the limits of the materials.”

Building a machine from scratch is an advantage vs. downsizing a large machine designed for macro-machining because you have freedom to design specifically for the application, said Lynn McPheeters, a Microlution investor and board member.

“Your chances of success are much less if you try to downsize,” said McPheeters, who retired 10 years ago as CFO of Caterpillar. “When we were most successful with new products [at Caterpillar], it was when we were designing for the special application we were getting into.”

Microlution’s platforms include the 363-S three-axis and 5100-S five-axis milling machines; ML-5 femtosecond laser precision drilling machine; FLP femtosecond laser cutting machine; MR-4 precision micro lathe; and MLDS multi-station femtosecond laser cutting and milling system, its newest technology.

The MLDS is designed for the laser to be working as much as possible, and with the capability to gang as many as three workpieces on the machine at a time.
All of Microlution’s machines, including the MLDS, can be outfitted with a camera or other sensors for inline metrology.

“What we offer is a very powerful capacity with the metrology,” said Phillip, noting that manufacturers sacrifice accuracy and speed when metrology is a separate step. “The smaller the parts get, it’s an advantage to have multiple functions in one machine and, in some instances, not an advantage but a necessity.”

In addition to guaranteeing accuracy on the micron scale, Microlution’s machines are also relatively small. Footprints range from 0.64 × 0.71 m for the 363-S to 1.9 × 1.9 m for the MLDS (including all ancillary components). They not only use less electricity and compressed air to do the job, they’re faster than the competition, Phillip said.

“When you scale a machine down, you’re making a machine that can be more productive in terms of dynamic performance,” he said. To illustrate, Phillip compared a racecar’s ability to follow a racetrack’s contours and turns compared with that of a lumbering double-decker bus.

“If you’re going to be making small parts, you’re going to have to achieve tight tolerances” like the racecar, he said.

In addition to the medical sector, the company’s machines are at work in the aerospace, automotive, consumer electronics and semiconductor industries. Its medical customers, which comprise 25–40% of their business, include companies using Microlution technology to churn out bone plates, spinal implants, cardiac and other catheters, neurosurgical devices, plastic hearing aid components and arthroscopic surgical tools.

As Microlution found its footing in the worldwide machine tooling industry in the last decade, it’s expanded to 24 employees and grown its client roster, with some customers coming back for additional machines.

“I think it’s in the repeat business that tells me we’ve got something here,” said McPheeters.


Published Date : 2/11/2015

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