Industrial Designers and Engineers are continually developing new composite metal alloy materials and better approaches to mechanical product design. The new material is Nitinol. When choosing a material, the considerations are typically light weight, high strength with flexibility or toughness including chemical and mechanical and thermal stability and low cost to manufacture. The weight and cost factors may be out weighted by the product application and maintenance access costs.
In mechanical design the toughest or strongest product applications turn to carbide or nickel steel and titanium as the toughest materials, considering costs of the raw material and manufacturing process to achieve the desired part geometry. The most extreme design and material integrity problems today exist under water and in deep space requiring extreme toughness and corrosion resistance. For example, a deep water fluid pump or robotic motorized rotating solar panel arm in deep outer space may be exposed to hourly direct sun and or subzero freezing temperatures and maintenance is not an option.
For these applications carbide, nickel steel and titanium are the alloys of choice selected for the weight, strength and toughness. But traditional manufacturing of high grade steel and titanium alloys to high tolerance or exact measurements and like most materials under the elements of high heat and pressure fluctuations, have mechanical and corrosive wear longevity issues. Chromium steel ball bearings are traditionally manufactured in the cast molten steel into molds and then finished or polished to tolerance size. But manufacturing to tolerance is a costly process and even specialty steel alloys can not hold up to the extreme pressures and elements forever. Titanium is tough and lightweight, approximately as strong as steel but as light as aluminum at approximately half the weight of steel. Other than carbon, titanium has the highest tensile strength to weight and high melting point but it is relatively brittle and also costly to manufacture. Titanium is a common composite alloy component to increase the strength of steel but also hard to lubricate and chemically reactivity to lubricant oil or grease, leading to higher surface degradation, wear and loose tolerances.
The light bulb is Mr. Glen Glennon of Abbott Ball Company uncovered a possible new alloy solution, using an old school discovery and new rapid prototyping technology, powdered metallurgy or (FDM) Fusion Deposit Modeling or laser metal sintering. FDM is a rapidly developing metallic prototyping process used by producing the geometry in a molten, layer build process. Mr. Glennon approached and convinced NASA Glen Research Center in Cleveland, Ohio in a collaboration to look at his new materials application and perform some basic testing on provided prototype ball bearings in the new Nitinol- 60 alloy.
The results surprised everyone. Nitinol; (Ni) nickel and (Ti) titanium and (NOL) for the Naval Ordinance Laboratory, was discovered by Dr. William Buehler, a Laboratory Researcher in the 1960’s. Nitinol 55 then 60 is a metal alloy exhibiting properties of electrically conductive, with excellent hardness and toughness or elasticity or shape memory including extreme corrosive resistance making it ideal for outer space, deep water and new medical product applications.
Working with the NASA lab and further development, adding a third element has yielded outstanding results and several new patents. The new Nitinol-60 bearing material exhibited the conductivity, nonmagnetic, toughness and the corrosion resistance needed for extreme applications. The new alloy and to be refined manufacturing and rapid prototyping process opens the doors for markets of new hardware such as kitchen cutlery or invasive medical devices where hardness, sanitation or harsh chemical cleaning is used, like scalpels. Nitinol-60 is of course expensive, but it offers a new horizon when maintenance access is prohibitive. The battle field is deep water and outer space and the new material in the arsenal is called Nitinol, the new Designer Steel! We also work in titanium!
References
- http://spinoff.nasa.gov/Spinoff2015/ip_4.html Metalworking Techniques Unlock a Unique Alloy
- DellaCorte, 2010, “Nickel-Titanium Alloys: Corrosion Proof Alloys for Space Bearing, Components and Mechanism Applications”, NASA-2010-216334
- 60 NITINOL Alloys(Report). White Oak, MD: S. Naval Ordnance Laboratory.
- US patent 6,422,010, Gerald J. Julien, “Manufacturing of Nitinol parts and forms”, issued 2002-July-23
- “http://www.summitmaterials.com/sm-100/bearing-components/
- DellaCorte, 2009, “Intermetallic Nickel-Titanium Alloys for Oil-Lubricated Bearing Applications”, NASA-2009-215646
- http://www.abbottball.com/nitinol/