Materials and Manufacturing Processes

There has been a major development in the material research and applications in industrial and commercial components or products. With the increase in demand of customers for various customized products that need to be durable, functionally reliable and low cost at the same time. These requirements motivate designers and manufacturers to tackle for the challenging task of optimizing the control factors that determines the quality of the final product. Material is one of the control factors that has been extensively analysed since the industrial revolution began using various material tests as described in Chap. 2. In this chapter, the properties, compositions and characteristics of different materials have been described in detail under the heading of all engineering materials used presently in industries and structural works. The production procedure of these materials, processes for heat treatments for altering properties of the material and applications of these materials are described in detail in this chapter.

Material is the most important aspect of research in all engineering domains which give us an understanding of the real physical structure of various products and objects that we come across in our daily life. The behaviour of these various products in their service life is very important to analyse as it might not be desirable to have a product fail at the most unexpected time. In order to quantify these behaviour of material, various properties have been described in detail in Chap. 1 which is determined by running few material tests. The procedure for carrying out these tests, feasibility of these test to be able to run for different materials and the behaviour of the part to be tested are some of the aspects which have been explained in detail in this chapter. Material tests have been detailed in two major branches namely, destructible and non destructible tests. Few other fracture surface behaviour in ductile and brittle material upon application of loads higher than their fracture strength and responses for plastic deformation in the form of heat generation and build up of residual stresses are described in this chapter.

Casting is the most widely used manufacturing process which involves melting of metal ores, scrap metals, carbonaceous material, alloying elements, fluxes and other additives in hot furnaces from where the liquid metal is collected by the ladle to be poured over the pouring basin, delivering the molten metal into the mould cavity. After pouring, the metal solidifies slowly inside the mould cavity. The solidification starts with the material phenomenon called nucleation which triggers growth of solid particles (transformation of liquid metal into solid crystals with release of energy) into fine/coarse grains possessing individual boundaries. During this solidification phase, all metals tend to shrink in their volume but which vary with different metals and alloys. This solidification phenomenon governs the design of various components of casting such as riser and gating system and also influences the dimensions of the mould cavity required for a particular metal cast. Allowances are provided on the patterns itself which are copies of the final cast. Moulding sand is prepared, the properties of which affects the quality of the final casting and that is dependent on different proportion of combinations of ingredients such as clay content, moisture content, carbon additives, etc. In this chapter, the basic understanding of the casting process, operations and design involved in the sand mould casting process, various metal mould casting processes and few other commonly used casting processes are described in detail.

Right from the advent of industrial revolution, forming process has been the most important and versatile operation in any manufacturing and metal working industries. Metals are needed to be deformed for a variety of functional requirements in the product or for enhancing the strength and hardness. This deformation produces a complex flow of material which basically is dependent on the amount of force application, ductility of the material, temperature of the material and modulus of elasticity. Deformation can be in the form of bulk deformation under compressive loads or bending, stretching, shrinking or shearing in the sheet metal operations based on which different tools (rollers in rolling, dies and punch) have to be designed accordingly for operations such as blanking, extrusion, wire drawing, rolling, etc. The temperature of the metal has to be maintained such that sufficient plasticity is induced and can be operated with the given capacity of the machine. Few positive aspects of forming processes include insignificant wastage of material, high output material strength, dimensional accuracy and simpler mechanism.

Welding is an important process in manufacturing which enables large and complex shaped products to be divided into small and simple parts to be manufactured independently and later can be rigidly joined by fusion of the material at the interface between two metal pieces, stiff enough to operate as a single piece. Welding process is mainly characterized by the melting of the interface material between the two metals, fusion or mixing of the material and then solidifying to produce a rigid and high strength joint. In some cases or applications, even an axial or shear pressure may accompany the fusion phenomenon to trigger a plastic deformation of material at the interface for tight bonding. Some other important materials used in welding are filler metals and fluxes. Filler metals are employed to provide the same material (as that of the base metals) at the interface gap between them in molten condition. Fluxes are employed to remove oxide formations in the weld pool and other impurities and form a layer of slag above the molten pool, protecting it from further oxidation. In this chapter, the fundamental concept behind the various welding processes and how are these classified based on different heat source utilization and techniques of utilization are explained in detail.

All metal parts, after being casted or formed has to be shaped into its final dimensions so that it could meet the required functionality, durability and aesthetic characteristics of a product. This shaping process requires metal removal which involves various complex phenomenon and factors, governed by a set of mechanisms that has been experimentally and analytically discovered and can be controlled by considering various tool geometry, optimized cutting conditions and better tool-work material combination. Merchant’s force model of the machining process recognizes the influence of the shear plane in determining all controlling factors such as the cutting conditions and inputs for optimized force and power utilization, good surface finish and longer tool life. In this chapter, these factors and conditions that govern the basic mechanics of metal cutting including the various type of chips and their desirability issues, crater wear and flank wear (that determines the limit of usage of any cutting tool) has been explained in detail. Turning is a fundamental operation (carried out on lathe machines) in any machining research due to its involvement of a single point cutting tool and the ability to reduce the complex problem (representing complex phenomenon) into 2 dimensional simple problems. Other operations involve either a single point or multi point cutting tool and includes boring, milling, drilling, reaming, etc.