The
benefits of machining implants produced using ceramics materials are becoming
obvious. Today the majority of implants are manufactured using titanium, cobalt
chrome or stainless steel. With lifespans typically ranging from 10 to 25
years, many younger recipients of these products will have to undergo a second
surgery to install replacements. It has
been projected that if these orthopedic components were made out of ceramic
materials, their life expectancy could reach as high as 75 years. The advantages to patients in terms of cost
and minimizing the number of times they must undergo the discomfort of rehab
are obvious. As an added benefit,
ceramic implants release no foreign particles into the body, while more common
metal implants do shed particles as they wear.
As
anyone who’s worked with ceramics knows, they’re incredibly challenging to
machine. Currently, components made from these materials must be produced using
diamond grinding wheels, making them expensive and limiting their design to
simple shapes. Contours and pockets
featured in many implants are difficult – if not impossible – to produce using
grinding techniques. This has substantially limited their presence in the
market.
The
appeal of ceramics to various industries has resulted in sizable investments in
R&D by cutting tool companies, manufacturers, universities and other
research institutions. These efforts have begun to yield fruit that will likely
shape the future of implant manufacturing.
In
the area of tooling, there have been breakthroughs in understanding the
importance of insert design and the proper use of materials like polycrystalline diamond (PCD) and cubic boron nitride (CBN). While Seco has
experienced success machining ceramics with these newly designed grades,
cutting these hard and abrasive materials consumes inserts at a rapid rate that
has kept the process economically unattractive. Until recently, that is.
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| Laser-assisted Machining |
To
boost insert life and achieve stronger results, Seco has worked with
manufacturers to combine extremely hard insert grades with laser technology. By
precisely positioning a high-powered laser just ahead of the cutting insert,
it’s possible to plasticize ceramic materials immediately prior to contact with
the tool. This greatly increases machinability, productivity and insert life,
achieving performance that substantially boosts the economic viability of
ceramics machining.
At
this point, applying the one-two punch of laser-assisted machining with the
latest Seco insert grades has allowed successful turning,
milling and threading
of materials such as silicon nitride, zirconia and alumina. This has resulted
in the production of ceramic components that were essentially impossible to
produce by any previous means.
Most
of the current laser-assisted cutting research has been focused on aerospace
engine components and bearings, but it holds tremendous promise for
applications in other industries, including medical
implants. Presently, aggressive analysis is being conducted to better optimize
insert edge preparations and more fully understand the chemical interactions
that occur between insert grades and specific ceramic materials. This work will
lead to refinements that allow the process to replace and outperform the
current approach of grinding, much in the same way that hard turning replaced
grinding for many applications over the past two decades.
While
all advances in cutting technology are exciting, it is especially inspiring to
see progress in an area that will directly improve the future quality of life
for a large portion of the world’s population. Thanks to progress in ceramics
machining, patients soon will be able to directly experience the benefits of
implants with higher levels of strength, wear resistance, smoothness and biocompatibility.
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| Don Graham |
About
the Author
Don is the manager of education and technical Services for Seco, responsible for all educational activities for the NAFTA market, new product testing and various other technical functions. Outside of work, he enjoys making maple syrup, restoring antique tractors and farming. Contact Don at dgraham@secotools.com.
Don is the manager of education and technical Services for Seco, responsible for all educational activities for the NAFTA market, new product testing and various other technical functions. Outside of work, he enjoys making maple syrup, restoring antique tractors and farming. Contact Don at dgraham@secotools.com.
