Challenges of drilling exotic metals

Exotic metals present us with new challenges for drilling

In manufacturing, the expression “exotic metals” is applied to represent materials that exhibit superb wear properties, hardness, and service life in high heat, severe cold or corrosive conditions.
Such materials were intended to provide service for which conventional materials are not efficient. Exotic metals include Nickel and Nickel alloys, Chromium and Chromium alloys, Inconel, Hastelloy, Invar, Monel, and Haynes.

Nickel and Nickel alloys
Nickel and nickel alloys are applied to a broad range of applications that include corrosion resistance and/or high-temperature resistance. Nickel alloys are operated in industrial and marine applications.

Chromium and Chromium Alloys
For example, Chromium-Molybdenum alloy is an admixture of metals designed for high temperature and high-pressure industries. Chromium-Molybdenum is operated in the power generation industry and the petrochemical manufacturing considering its ductile ability and corrosion resistance

The corrosion proof Hastelloy alloys are broadly used in the chemical processing applications. The requirement for proper functioning influences acceptance and increased use of these metals in the fields of energy, health and environmental, oil and gas and pharmaceutical industries.

Very good oxidation sustainability and reduced heat distribution characteristics of Haynes are the most sought-after properties of the metal. Additional well-known attributes combine superior low cycle fatigue features, superior thermal firmness, and durability to high-temperature fluorine and fluoride environments. The material is used in aerospace and chemical processing manufacturing.

Inconel is a nickel-chromium alloy processed in applications which involve corrosion and high-temperature strength. Inconel has high resistance to alkaline solutions. Inconel is usually applied in the chemical, aerospace, nuclear engineering and heat treating industries.

Invar is an austenitic nickel-iron alloy. It has an exceptionally low index of thermal extension. The alloy is benefited from in the aerospace and die and mold sector.

Monel is a nickel-copper alloy mostly used when excellent corrosion resistance and mild temperature characteristics are required. Monel is usually used in electrical and electronic applications.

Other less common exotic metals are Kovar, Titanium, Waspaloy, Tantalum, Tungsten or Wolframite, and Zirconium.

Such metals present us with new challenges for drilling. The primary challenges to fabrication superalloys involve: the high strength of nickel-base superalloys at cutting temperatures produces high cutting pressures, creates more heat at the tool tip and bounds their velocity . The low thermal conductivity of these alloys transmits heat produced during machining to the tool. The whole process rises tool tip temperatures and reduces unnecessary tool wear, shortening tool life.

The high capacity for work compression in nickel-base alloys provoking cutting depth incision on the tool, which can damage the workpiece. The chip produced during such fabrication needs agreeable chip control geometry. Besides the above challenges mentioned, the metallurgical process also impacts their machinability. Exotic metals are easier to drill in soft form.

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