Saturday, March 30, 2013

Top Performance Grades Get a Laser Assist for Machining Medical Ceramics

By Don Graham, Manager, Education and Technical Services

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.

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.

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

1 comment:

  1. This is interesting. I never heard of ceramic being used before. I'd think that it would break as ceramic sounds pretty fragile. I've always put high trust in silver contacts for medical devices as silver is pretty durable and seems to hold up well.