Cryogenic Treatment Improves Drill Bits Wear Resistance
By Benjamin Gorlick
Cryogenic Treatment of Drill Bits explained:
This article explains how cryogenic treatment improves the wear resistance and lifetime of drill bits.
When the cryogenic treatment process begins, metals are brought to deep cryogenic levels (-300F), causing the formation of untempered martensite throughout the metal, which is hard and brittle. If this were to be the last stage in a cryogenic process, the metal if it came in contact with a foreign object could easily chip and break. We avoid this problem completely by heat tempering the metal as the final stage of our process.
With the final step of heat tempering to +300F, the formation of carbides occurs in the metal, the technical description of this being called “precipitation of eta carbides”. Also, the untempered martensite is transformed into tempered martensite. These microscopic eta carbide particles enhance the strength and toughness of the martensite matrix. The metal is no longer brittle, retains its hardness, and experiences a dramatic increase in its wear resistance. This allows for a significant extension of the lifetime of the metal, up to 350% in many cases and in rare cases it can experience a ten fold increase.
In order for us to estimate the benefits a particular metal application will experience, we need to know two things:
A. What materials the metal tool are made of
B. What is the metal tool being used for during its normal process
Unlike cold treatment, cryogenic treatment promotes preferential precipitation of fine eta-carbides.
Q. Where are drill bits currently being cryogenically treated?
A. Global Engineered Products, LLC, representing the company 300 Below, Inc. who is actively providing cryogenics for drill bits and machining equipment in the coal mines throughout Illinois and Kentucky. They are also ser It’s uses range beyond drill bits to a wide range of industrial machine and tooling applications throughout the regions of Alaska and Washington state where large mining operations take place.
More information about eta-carbides and their effect on metals:
Steel is, at its most basic formulation, iron (Fe), a metal, and carbon (C), a non-metal. The carbon is dissolved chemically into the iron and is what provides wear resistance. In other words, high carbon content equates to high wear resistance. (The greatest amount of carbon that can be dissolved chemically is about 6% and a high carbon tool steel like A2 has about 1% carbon.) So just a little bit of carbon (diamond) or increase in carbides goes a long way in promoting wear resistance.
These changes to the carbon microstructure, through the precipitation of eta-carbides, have dramatic impact on the wear resistance of cryogenically treated steels and cast irons (brake rotors or cast iron drill bits for instance. Note that cast irons, such as rotors, are even higher in carbon content, 2% to 3%, for instance). That's why parts that are cryogenically treated typically wear 2X to 3X longer than untreated steels.
Another important benefit to realize that metals experience from Cryogenic treatment relates to stress relief. It is based on Einstein's (and Bose's) observation that matter is at its most relaxed state when it has the least amount of molecular activity of kinetic energy. When we freeze the components, we are actually removing heat, or reducing the molecular activity in the metal. This relaxes the metal and reduces residual stresses in the metal. It is these stresses that propagate when the part is put into service and causes failure due to fatigue. Hence, by reducing residual stresses, you greatly reduce failure due to cracking or what people term metal fatigue.
Global Engineered Products, LLC provides services described in this article for the cryogenic treatment of drill bits. You can visit their website:
About the Author
Benjamin Gorlick holds a background in Computer Science and Engineering and actively studies the effects of cryogenic tempering on metals and industrial equipment. He has visited the United States largest Cryogenics laboratory where he received training and experience in the field of Cryogenics and Metalurgy.
Article Source: http://www.simplysearch4it.com/article/34956.html
|If you wish to add the above article to your website or newsletters then please include the "Article Source: http://www.simplysearch4it.com/article/34956.html" as shown above and make it hyperlinked.|