Armin Bijanzad 2.WEEK Definitions

1.High-speed steel

First introduced in 1900 by Taylor and White , high speed steel is superior to tool steel in that it retains it's cutting ability at temperatures up to 1100F.exhibiting good 'red hardness'.Compared with tool steel, it can operate at about double the cutting speed with equal life, resulting High-speed steels, often abbreviated HSS.
High-speed steels contain significant amounts of W,Mo,Co,V,and Cr besides Fe and C.W,Mo,Cr, and Co in the ferrite as a solid solution provide strengthening of the matrix beyond the tempering temperature,thus increasing the hot hardness.Vanadium(V),along with W,Mo,and Cr, improves hardness and wear resistance.Extensive solid solutioning of the matrix also ensures good harden ability of these steels. (MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.551)

2. Tool steels

Carbon steels and low/medium alloy steels, called tool steels,were once the most common cutting tool materials. Plain carbon steels of 0.90% to 1.30% carbon when hardened and tempered have good hardness and strength and adequate toughness and can be given a keen cutting edge. However, tool steels lose hardness at temperatures above 400F because of tempering and have largely been replaced by other materials for metal cutting. (MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.551)

3. Dynamic properties

In many engineering applications, materials are subjected to dynamic loadings. These may include (1) sudden loads (impacts) or loads that vary rapidly in magnitude; (2) repeated loading and unloading ; or (3) frequent changes in the mode of loading , such as from tension to compression. For such operating conditions , the engineer must be concerned with properties other than those determined by the static tests. (MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.51)

4.Casting terminology

The casting starts with the construction of a pattern, an approximate duplicate of the final casting. The modeling material is then packed around the pattern, and the pattern is removed to produce a mold cavity. The flask is the box that contains the molding aggregate. In a two-part mold, the cope is the top half of the pattern, flask , mold or core. The drag is the bottom half of any of these features. A core is a sand shape that is inserted into the mold to produce internal features on a casting , such as holes or passages for water cooling. A core print is the region added to the pattern, core or mold that is used to locate and support the core within the mold. The mold material and the core then combine to form the mold cavity, the void into which the molten metal will be poured and solidified to produce the desired casting .A riser is an extra void created in the mold that will be filled with molten metal. It provides a reservoir of molten metal that can flow into the mold cavity to compensate for any material shrinkage that occurs during solidification. Any shrinkage voids should then be in the riser and not in the final casting.
(MATERIALS AND PROCESSES IN MANUFACTURING 7th edition E.PAUL DEGARMO P.309)