Content Definition , need and classification of machine tools Brief history and development, typical features, associated with cutting tools and Performance measure of machine tools. Theory of Metal Cutting General: Common features of machining processes, geometry of single point tool and tool signature, concept of speed, feed and depth of cut applicable to various machining processes. Cutting tool materials-types, classification, characteristics and applications .Manufacturing methods of cutting tools including coating of tools CVD,PVD). Cutting tool geometry and Surface finish Height of feed ridges and built up edges as primary factors effecting surface finish; effect of speed, feed, depth of cut, tool material and angles, and material variables on surface finish. Cutting Fluids, Tool Life and Machinability of Metals Functions and types of cutting fluids; effect on cutting force, tool life and surface finish, types of coolants, choice of coolant for various machining processes. Tool life definition. Flank wear and crater wear. Preliminary failure and ultimate failure, mechanism of tool wear, effect of speed, feed, depth of cut, tool material and geometry on tool life. Cutting force, tool life and surface finish as measures of machine ability.
Brief History of Manufacturing Earlier manufacturing remained in the hands of Artisans and their apprentices and earlier developments in manufacturing took place in their supervision. Probably copper is the first metal melted by man. Excavations of Mohanjodaroand Harappa (5000 BC) shows the metal and jewelry work. There are examples of in Greek and Roman civilizations that their craftsman used casting process. Invention of copper, bronze and then Iron age converted ancient civilization into Indus valley, China, Egypt, Mesopotamia and Babylon. The round groove marks on wooden bowls shows that turning was practiced as early as 1700 BC and was perfected before 6th century.
Brief History of Manufacturing The concept of tool angles is also not new. The primitive man started thinking of tools in which a proper shaped tool used to be tied with wooden branch. Later, stone piece was replaced by the metallic piece Idea of rotating stone wheel for producing sharp edges brought the concept of grinding. Wheels mounted on the spindle with crank for started appearing around 850 AD
Brief History of Manufacturing The earliest known machine tool: Lathe (1400 AD) Wooden plank lath, so name Lathe has derived.
Brief History of Manufacturing By the end of 18th century the steam engine power was available in large quantities at many locations which caused first Industrial Revolution. This led to the growth of Production and Mechanization. The Soho Foundry (LONDON) was established in 1796 AD with steam engines was considered as Engineering Workshop of that time. By 1820 AD steam power driven machine tools were ready for the sale. Now the need for high strength material was felt which was met by Carbon Steels. Liebig (1831 AD) could perfectly analyze and determine the effect of carbon on the strength of steel. This started age of Steels and it became possible to produce rigid and precision machines.
Brief History of Manufacturing Henry Maudslay (1771-1831 AD) brought several new concepts in machine tool design. He introduced the tool slide and rest with tool head in 1794 AD. It was equipped with lead screw and had provision for taper turning. He also produced number of screw cutting machines. In 1805 AD, first micrometer was designed by him. During 1825-1865 AD machine tools like planning, shaping, drilling, punching slotting, milling etc. were developed. The need for strong marine vessel led to introduction of rolling mills that produced iron flats for ships which crossed Atlantic in 1883 AD. These rolled material also met the requirements for multistoried buildings etc.
Brief History of Manufacturing By the mid of 19th century Britain became the leading country in science and technology. The war of America for independence proved surprisingly very relevant for the growth of manufacturing because, British govt. was trying to put them down in helping them in the filed of technology so they developed themselves up to an extent that Britain ultimately came down for mutual co-operation. True industrial revolution started when the concept of mass productionwas introduced in 1748 AD to lower the production cost so that the benefits of engineering could reach to common man. Proliferation of machines started and a large number of special purpose machines, automatic and semi automatic machines were designed and developed. The trend was to move towards mechanization and hard automation.
Brief History of Manufacturing Whitney introduced the concept of interchangeability in the end of 18th century. This needed more close tolerances therefore need for high speed stone tools (grinding) felt and development in precision grinding took place around 1900 AD. Significant improvement in welding processes also took place during this time. Use of metallic molds and patterns came into scene so that precise casting could be achieved. Polymer products were developed during 1925-1950 AD due to requirement of high strength to weight ratio. Introduction of hard, temperature resistant materials led to development of various unconventional machining processes during 1960 s.
Second industrial revolution started during mid of 20th century with the enormous growth in solid state electronics and computers, that can perform tasks very rapidly efficiently with lower cost.
In this age attempt was to enhance and sometimes even replace the mental efforts.
The trend was now to move towards flexible automation.
Today the era of mass production and hard automation is going away and is being replaced by batch production and flexible automation
The first step in this direction is Numerically Controlled machine tools in which the motion of slides is controlled by numerals and letters. The microprocessor based systems and feed back devices provide better accuracy and precision.
Manufacturing ? - Derived from the Latin Word MANUFACTUS MANUS – Hand FACTUS – Made
Practical Definition : Process of converting or processing raw material into usable products
Usable Products Raw Material Converting Process Adds Value to raw material by change in shape and properties Pins, Sensors, Valves, Cars, Ships Metals, Polymers, ceramics, composites
Manufacturing ? Imparting changes in material – Geometry – Material properties: • Strength • Hardness • Toughness • Etc. Systems Oriented Definition • Manufacturing as a system or enterprise – “A series of interrelated activities and operations involving design, materials selection, planning, production, quality assurance, management, and marketing of discrete consumer and durable goods” – A highly complex, interdependent activity that is dynamic in nature
Classification of Unit Manufacturing Processes • Based on: – process type e.g., shaping vs. nonshaping – state of workpiece material e.g., solid or liquid – processing energy e.g., mechanical, electrical,…
Classification of Unit Manufacturing Processes Shaping process classification – Mass conserving, dM ~ 0 examples: casting, bulk forming, powder processing – Mass reducing, dM < 0 examples: conventional and unconventional machining – Mass adding, dM > 0 examples: joining processes