ADVANCED MACHINING PROCESSES

ADVANCED MACHINING PROCESSES

UNIT I

Facts Trends and Challenges in Manufacturing The proof of the following dates and products is available in literature related to manufacturing5000-4000 BC Manufacturing started during 5000 4000 BC (Wood work, ceramics, stones, metal works, earth wares)2500 BC Sculptures produced by lost wax casting, jewelry Production, earth wares, glass beads 600-800 AD Steel production 800-1200 AD Sand casting of cast iron 1750 AD Machine tools run by the power of steam engine, resulting in growth of production and abundant availability of goods 1920-1940 Automation, mass production, interchangeable parts, die casting and lost wax methods for engineering parts 1940-1960 Computers development, Ceramic mold, nodular iron, semiconductors, continuous castings 1960-1990 NC, CNC machines, group technology, robotics and control, CAD / CAM, adaptive controls etc, squeeze casting, single crystal turbine blades, vacuum casting, organically bonded sand, compacted graphite, automation of molding and pouring, large aluminum castings for aircraft structures for rapid solidification technology, advanced manufacturing processes (advanced, casting, joining, machining, finishing processes) 1990-date Hybrid processes, micro-machining processes, nano materials, hard machining, lean manufacturing, agile manufacturing, etc In 1960s, the success of a manufacturing company depended on costIn 1980s, the success of a manufacturing company depended on qualityPresent day, the success of manufacturing company depends on cost, quality and lead time (lead time is time between placing the order and receiving it, alternatively, it is also known as time to market)

Manufacturing Challenges The emerging economies, the social and political transitions taking place and the new ways of doing business are changing the world dramatically. It is visualized through these trends that manufacturing environment of the future would be extremely competitive and significantly different from what it is today. In-order to remain successful in such an environment, the manufacturers needs to be updated with the latest trends and should possess dynamic capabilities, which need to be distinctly different.

The ability to innovate ideas and to develop a creative environment for such innovationsin manufacturing Development of effective and efficient training and education programs for the manufacturing workforce, as more skilled workforce is required The use and implementation of information technology in various areas of the manufacturing industries and their sub-functionsSustainability of small and medium scale enterprises to provide support to the large scale manufacturing organizations Focusing on clean and green manufacturing technologies, the environment and the society issues. The responsibility for the production process thus goes hand-in-hand with responsibility for the final disposal of products i.e. recycling in line with environmental policies. Need of Advance Manufacturing Technology Manufacturing is the basis for all economic activities and future growth of a country At the beginning of 20th century, mass production using efficient machine tools emerged in USA (Ford motors) After the second world war, new / advanced manufacturing processes came into Existence Since 1950s, new technologies have been emerged computerized numerical control,flexible manufacturing systems, lean manufacturing, green manufacturing, computerintegrated manufacturing are some of those. Newer materials have been developed and their processing requires special machine tools or special manufacturing process Therefore, there is a vital need to have more efforts to continuously advance manufacturing technology for a better-off and more stable future Description and Taxonomy of the Manufacturing Processes Metal Casting (Net Shape Processes) Metal Casting is one of the oldest known method for shaping the materials. It involves pouring molten metal into a mold having the required shaped cavity and then allowing it to solidify. When solidified, the desired metal object is taken out from the mold either by breaking it or taking the mold apart. The solidified object is called the casting. In this process, intricate parts can be given strength and rigidity which is frequently not obtainable by any other manufacturing process. The major metal casting processes are:Sand casting Permanent mold casting Continuous casting Die casting Slush casting Centrifugal casting Evaporative-pattern casting Lost wax casting Shell molding Vacuum sealed molding

Molding (Net Shape Processes)

Molding is generally used in plastics. A hollowed-out block in which liquid, plastic, molten glass or some ceramic material is filled is called a mold. The filled in material hardens and gets set inside the mold, replicating its shape. In order to remove the hardened substance, a release agent is used. There are about eight major processes in molding. Hot compression molding Transfer molding Injection molding Extrusion molding Laminating Vacuum forming Expandable bead molding Blow Moulding Material Removal Processes / Machining (Subtractive Processes) Metal removal processes in which we remove the excess material to give the final shape to the product, are often termed as secondary or machining processes. They are also termed as finishing processes; which are done to give the required finish or tolerance to the end product. This means that in both the cases i.e. either removal of material or finishing of part, the product to be cut or finished is made by one of the other processes described above. At instances, the product geometry is very complex, to be produced by other processes. In such cases the basic shape of the product is produced using other processes and the final shape is created by using some machining process. The major metal removal / machining processes are as given below:

Milling, Turning, Drilling Broaching, Shaping, Planning Honing, Etching, Grinding Finishing Processes Abrasive Flow Machining Abrasive Jet Machining Water Jet Machining Electro Discharge Machining (EDM)Wire Cut EDM Electro Chemical Machining (ECM) Ultrasonic Machining/Drilling (USM / USD) Electron Beam Machining (EBM) Laser Beam Machining (LBM) Electro Chemical Grinding (ECG) Hybrid Processes Abrasive Jet Machining (AJM)

Applications:Metal working: De-burring of some critical zones in the machined parts. Drilling and cutting of the thin and hardened metal sections.Removing the machining marks, flaws, chrome and anodizing marks. Glass: Cutting of the optical fibers without altering its wavelength. Cutting, drilling and frosting precision optical lenses. Cutting extremely thin sections of glass and intricate curved patterns. Cutting and etching normally inaccessible areas and internal surfaces.Cleaning and dressing the grinding wheels used for glass. Grinding: Cleaning the residues from diamond wheels, dressing wheels of any shape andsize.

Water Jet and Abrasive Water Jet Machining (WJM and AWJM)

Applications of WJM and AWJMThe Water Jet Cutting (WJC) process is mainly made used in cutting low strength materials like plastics, wood and aluminium EquipmentThe major components of Jet equipment (WJ or AWJ) are: Pump NozzleOrifice Control System

Process Parameters

1.Hydraulic parameters: Size of the orifice and required pressures.2. Abrasive Used: Type; Grit size and the flow rate required3. Target material: Composition of workpiece and mechanical properties such as hardness etc.4. Mixing: Inlet angle; tube length, bore diameter;5. Cutting: Angle of Attack; Stand of Distance (SOD); Traverse Speed