1.1 INTRODUCTION TO MANUFACTURING Manufacture Process of making raw materials into finished products (Machinery and division of labor) Food, drugs, textiles, chemicals, and everything made usable by the conversion of shape, form, or properties of natural materials 1.1 INTRODUCTION TO MANUFACTURING Metals and plastics Are of special interest: Durable goods, engineering materials Characteristics of this group are the properties of relatively high hardness, strength, toughness, and durability 1.1 INTRODUCTION TO MANUFACTURING Glass ceramics, woods, concrete, and textiles Compete with metals in many applications, but excluded from engineering materials Different in the combination of properties, processing requirements, and type of goods produced 1.1 INTRODUCTION TO MANUFACTURING Engineering materials includes most metals and those plastics that are solids and gave reasonable strength at room temperature 1.2 HISTORY OF MANUFACTURING Family units. Foods and shelter. Factory forms: excess goods were available for sale and trade. Early manufacturing. Agricultural and military. Industrial operations: reduction ore to metal. 1.2 HISTORY OF MANUFACTURING Interchangeability. Incentive for the manufacture of firearms. Resulted in rapid growth of production goods Importance of manufacturing. National Association of Manufacturers: 12.0% of the gross domestic product (2014). 1.3 INDUSTRIAL RELATIONSHIPS Competition in industry. Direct competition: sales volume depends on product quality, promotional activities, services policies, and price Cost of manufacturing. Lowest cost = larger profit per sale 1.3 INDUSTRIAL RELATIONSHIPS Direct personnel. Designer, operators with varying degrees of knowledge. Product engineers, inspectors, sales personnel Indirect personnel. Workers in administration, accounting, finance, purchasing, custodial service, and other support areas 1.3 INDUSTRIAL RELATIONSHIPS Nomenclature. The ability of personnel from one area of manufacturing to discuss and understand problems with people from another area depends directly on their knowledge of the nomenclature used in the area of concern A designer... to discuss intelligently with a production person the effects of various designs on the method and cost of production, must be able to understand and use the language of the production person… NDT personnel... must communicate with production and other personnel 1.4 DIFFERENT CATEGORIES OF MANUFACTURING PROCESSES Selection of materials. Property requirements dictate a specific material. Wide choice exists in the combination of material and processing that will satisfy the product requirements. The choice usually becomes one of the economic comparison. Processing. Consist of one or many separate steps producing changes in shape or properties, or both. 1.4 DIFFERENT CATEGORIES OF MANUFACTURING PROCESSES Shape changes. Shape changing of most materials can be accomplished with the material in one of several different forms or states: liquid, solid or plastic. Casting. Melting of material and control of its shape while it solidifies is referred to as casting. 1.4 DIFFERENT CATEGORIES OF MANUFACTURING PROCESSES Molding, forging, pressworking, rolling or extrusion. Reshaping of the material in the plastic or semisolid form. Machining. Shaping by metal removal or separation in the solid state is commonly performed to produce product shapes. Welding. The joining of solid parts by welding usually involves small, localized areas that are allowed to solidify to produce a complete union between solid parts. 1.4 DIFFERENT CATEGORIES OF MANUFACTURING PROCESSES Energy form. The energy may be supplied in the form of heat, mechanical power, chemical reaction, electrical energy, or even light sources. In nearly every instances, one principal objective is changing of shape. Process Effects on Properties. Many concepts and fundamentals in reference to materials are common to different kinds of processes. The metallurgical changes that take place during solidification during casting are the same nature as those that take place in fusion welding 1.4 DIFFERENT CATEGORIES OF MANUFACTURING PROCESSES Auxiliary Steps. The energy may be supplied in the form of heat, mechanical power, chemical reaction, electrical energy, or even light sources. In nearly every instances, one principal objective is changing of shape. Nondestructive testing (NDT). The dimensions and properties that are produced by any process are subject to variation, and, in practically all cases, some form of NDT is necessary for controlling the process and for ensuring that the final product meets certain specifications as to size and other properties 1.5 PROCESSING STEPS Manufacturing Usually a Complex System. Manufacture concerns mainly with shape changing. While the single operations might produce a product useful, a complex of series of shape-or property changing steps is required. 1.5 PROCESSING STEPS Figure 1.1 shows the basic processes that are used in shaping metals 1.5 PROCESSING STEPS Ingots are shown in Figures 1.2 and 1.3 1.5 PROCESSING STEPS The majority of manufacturing organizations specialize in one type of manufacturing operation 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES MATERIALS One or more materials are needed for any product, and most can be processed in a number of different ways Properties. The practical difference between various materials is in properties or combinations of properties. Compared to many other materials, steel is hard and strong and may be chosen as a manufacturing materials for these reasons. Tests: Standard Tensile Test, Hardness 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES MATERIALS Property Variations The properties of an element may be changed by the addition of even small parts of another element The properties of elements or combinations of elements (compounds) can be varied by the type of treatment given the material The properties are affected by the processes being used with the objetive of shaping the material 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES MATERIALS Property Variations Reducing the cross sectional size during the shaping of most metals results in an increase in hardness and strenght that may be undesirable if the metals must undergo further deformation processing. In many cases, this increase in hardness and strength that occurs as a result of the processing can be beneficial and part of the product design. 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES ECONOMICS Designers must not only know the functional requirements of the product but also have some knowledge of the probable market demands for various levels of quality and appearance. 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES ECONOMICS The designer’s choices of materials, shapes, finishes, tolerances, and other factors restrict the possible choices to be made in the manufacturing process. The designer may also specify the NDT criteria, thus influencing the choice of NDT method 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES ECONOMICS Choice of Materials Engineering materials, metals and others, have properties that vary over wide ranges with many overlaps. Costs also vary widely, but the cheapest material suitable for the product does not necessarily ensure the product will have the lowest cost. 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES ECONOMICS Quantity The number of a product that is made can have more influence on the cost than the design or the type of material used. The actual production time for each product is usually inversely related to the setup cost. 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES ECONOMICS Quality Quality costs money. Higher quality implies longer life, better finishes, better materials, quieter operation, and more precision. These factors all involve greater costs that may be justified by market demand. 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES ECONOMICS Inspection Inspection also costs money to perform, but, in another sense, like advertising, it pays; in fact, it is essential to ensure better quality product output and to improve customer relations. - Inspection equipment, qualified nondestructive testing personnel 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES DESIGN Appearance in Addition to Function Usually Important In the case of every product, the manufacturing process must be preceded by the design. The designer´s problems arise mainly from the fact that a single solution is seldom indicated. Of the many possible materials and shapes that may satisfy the functional requirements, some may have better appearance than others. 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES DESIGN Quality and Costs Must Balance It is generally true that costs will be different for different material and processing choices, and considerable screening of the alternatives can be done purely on a cost basis. However, the quality obtained with more expensive materials or methods may be superior to that of the cheaper choices, and decisions must often be made regarding some combination of quality and cost 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES DESIGN Availability of Facilities Affects Choices Obviously, the decisions made by the designer are far-reaching and of extreme importance. These decision are based on: – Materials and shapes, – Specified tolerances – The equipment and the trained personnel – Economical manufacture 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES DESIGN Availability of Facilities Affects Choices In many cases, the decisions that govern the choice of materials and processes must be made in an arbitrary manner. Designers cannot be expected to be experts in all the phases of production that influence the final quality and cost of a product. 1.6 MATERIAL CONSIDERATION IN SELECTION OF PROCESSES DESIGN NDT Design Similarly, the design engineering function must receive technical guidance from key NDT personnel in order to ensure that the design requirements can be met. Both the capabilities and limitations of the various methods of NDT must be considered in the design phases of the product life cycle in order to achieve optimum product effectiveness 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT STATES OF MATTER Material may exists in one of the three states of matter, gas, liquid, or solid, but except for some special processes with relatively small use, such as vapor deposition, or for zinc refining, the gaseous state is of small importance in manufacturing 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT Most Manufacturing Processes Are to Change Material Shapes For manufacturing purposes in which shape changing is the objective, the solid state may be though of as existing in two forms. Below the elastic limit, materials are dealt with as rigid materials. Above the elastic limit, solid materials may flow plastically and shape changing may be accomplished by application of external loads to cause permanent relocations within the structure of the material. 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT Most Manufacturing Processes Are to Change Material Shapes The end result of dealing with materials in the liquid form are similar to those with materials above the elastic limit. No appreciable density or volume change occurs, and the shape may be changed without loss of material. 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT SHAPE-CHANGING PROCESSES Shapes Changed with No Volume Change, by Additions, and by Subtractions. Shape changing is possible in any of theses states, but most manufacturing processes by definition or nature deal with materials in only one of these possible forms. Figure 1.4 shows the processes for shape changing without material loss and those in which material is added or taken away 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT SHAPE-CHANGING PROCESSES No volume Change. In those processes in which no volume change occurs, property changes are usually large and distributed throughout the material. 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT SHAPE-CHANGING PROCESSES No volume Change. In casting, the shape change occurs by melting and subsequent solidification to a prescribed shape. Casting is often the most economical method for producing complex shapes, particularly where reentrant angles exist 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT SHAPE-CHANGING PROCESSES No volume Change. Wrought materials, are produced by plastic deformation that can be accomplished by hot-working (above the recrystallization temperature) or cold-working. 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT SHAPE-CHANGING PROCESSES Additions or Combinations. New shapes can be produced either by joining pre-formed shapes mechanically or by any of various bonding means. Some examples are: welding, soldering and brazing, mechanical fastening, shaping, and powder processing. 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT SHAPE-CHANGING PROCESSES Subtraction or Removal. Shape changing may also be accomplished by taking material away in chip or bulk form or by material destruction. The property changes in theses processes are more localized, and energy requirements are generally smaller. Mechanical separation can be performed by removal of chips or by controlled separation along predetermined surfaces: machining, shearing. 1.7 EFFECT OF MANUFACTURING PROCESS ON THE PROPERTIES OF THE PRODUCT SHAPE-CHANGING PROCESSES Special Shape-Changing Methods. With the advent of new materials difficult to fabricate by convention means and of many designs requiring shapes and tolerances and material combinations difficult to achieve with conventional processes, a number of electrical and chemical processes have been developed for removing or adding material: metal plating, electrical discharge machining chemical milling, ultrasonic grinding, and electron beam machining.
