Ferrous material machining

Besides the ferrous materials, several large components of the submarine were manufactured from non-ferrous materials. These include the coning tower, torpedo tube and propeller. These were all manufactured from the same material, a two phase, a/ 3 brass (60% copper--40% zinc alloy) with lead additions to improve the machinability properties of the material. 

Cubic BN is the second hardest material after diamond. It does not react with iron in tribological contact [2] and can therefore (in contrast to diamond) be used to coat tools for machining of ferrous materials. 

Following the successful commercial synthesis of diamond in the 1950s, the second hardest material known, cubic boron nitride, cBN, was introduced to the market in the 1960s and is complementary to diamond. The iron, and its alloying elements, in ferrous materials has a tendency to react chemically with diamond under machining conditions and this can reduce the efficiency of the tool. cBN, however, although not as hard as diamond, does not react chemically with iron and is therefore particularly well suited to machining hard ferrous materials. 

Machining Ferrous Materials with Polycrystalline Boron Nitride... 

The invention of cubic boron nitride (CBN) is closely linked to the synthesis of artificial diamond. Cubic boron nitride synthesis was conducted first in 1957. CBN crystals are produced from boron and nitrogen at high pressures of 50-90 kbar, high temperatures between 1,800 °C and 2,700 °C, and in the presence of a catalyst (Klocke 2009). During the first years on the market, CBN was seen as a competitor to diamond. However, CBN proved to be a better material for machining of hard-to-machine ferrous materials than diamond due to the missing chemical affinity and the higher thermal stability. 

Figure 6 summarizes the most important grit characteristics in grinding technology. The reactivity of diamond with transition metals such as nickel and iron limits the use of diamond to machine these metals, especially steels. However, there are some abrasive applications with ferrous materials where diamond is the tool material of choice, e.g., honing of cast iron (Marinescu et al. 2007). 

The various PcBN compacts are mainly used for machining of a wide variety of hard and/or abrasive ferrous workpiece materials up to high temperatures exceeding 1000 °C. For example pearlitic gray cast iron hardened ferrous... 

For preventing corrosion of steel in ferrous-based materials, particularly in protecting machine parts and in storage and equipment, the use of volatile, or vapor phase corrosion inhibitors has been found to be effective. These materials are amine nitrite salts. These inhibitors are slightly volatile at room temperature protection results from the diffusion and condensation of the vapors on the surface of the items being protected. 

Although diamond is one of the most inert materials, it will rapidly graphitize in contact with ferrous metals at temperatures above 1,100 K, and as such, diamond is only by exception used in the machining of ferrous metals (and typically with relatively low cutting speeds). PcBN tools, however, have a greater inertness in the presence of ferrous metals at high temperature. 

Diamond is the hardest known material. For this reason, single-crystal natural-diamond tools have been used in industry for a great number of years, to dress grinding wheels and as cutting tools to finish-machine non-ferrous and non-metallic materials. 

A synthetic or man-made diamond material is now available which is extremely tough with a hardness approaching that of natural diamond. A layer of this synthetic diamond material is bonded to a tough shock-resisting base of cemented carbide for use in the form of tips. The range of application is on non-ferrous metals such as aluminium alloys, magnesium alloys, copper, brass, bronze and zinc alloys and non-metallic materials such as ceramics, porcelain and plastics. This material will also machine fully sintered tungsten carbide. 

The flank wear s tool-life curve of in dry turning of diamond tool for Al-20 mass% Si alloy is presented in Figure 11.2.12 1191. In comparison with the cemented carbide, the diamond tool shows superior cutting performance. This is due to extremely high hardness and superior thermal conductivity of diamond. The diamond is suitable material for machining such non-ferrous alloys. 

Applications of Diamond Tools. Most industrial machining operations are performed with coated cemented-carbide tools, usually as indexable inserts. Diamond (and PCD) increasingly competes with these materials, in particular in the machining of non-ferrous metals such as aluminum, copper, magnesium, lead, and theiralloys since it does not react chemically with these materials. 

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