1 Manufacturing Engineering: Basics of Manufacturing EngineeringChapter 2 Manufacturing Engineering: Basics of Manufacturing Engineering By Basanagouda Shivalli Dept. of Mechanical Engineering BVBCET, Hubli
2 Contents: What is manufacturing?Classification of manufacturing Processes Scales of production Advances in Manufacturing: CNC machines Mechatronics and applications
3 Definition Manufacturing can be defined as the conversion of raw materials into useful articles by means of physical labour or the use of power driven machinery.
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5 Manufacturing as we understand it today began in what is called the industrial revolution.The UK was the first nation to undergo the change from a largely agricultural economy to full-scale industrialization.
6 To create wealth To satisfy a demandManufacturing is a commercial activity and exists for two purposes: To create wealth To satisfy a demand
7 To create wealth There is no point in investing your money or other people’s money in a manufacturing plant unless the return on the investment is substantially better than the interest that your money could earn in a savings account.
8 To satisfy a demand There is no point in manufacturing a product for which there is no market. Even if there is a market (a demand), there is no point in manufacturing a product to satisfy that demand unless that product can be sold at a profit.
9 Classification of manufacturing processesPrimary Shaping or Forming Processes Deforming Processes Machining/Removing Processes Joining Processes Surface Finishing Processes Material Properties Modification Processes
10 1. Primary Shaping or Forming ProcessesCasting Powder Metallurgy Plastic technology
11 1. Primary Shaping or Forming ProcessesPrimary shaping or forming is manufacturing of a solid body from a molten or gaseous state or form an amorphous material. Amorphous materials are gases, liquids, powders, fibres, chips, melts and like. A primary shaping or forming tool contains a hollow space, which, with the allowance for contraction usually corresponds to the form of the product. Here, cohesion is normally created among particles.
12 Electromagnetic forming2. Deforming Processes Forging Extrusion Rolling Sheet metal working Rotary swaging Thread rolling Explosive forming Electromagnetic forming
13 2. Deforming Processes Deforming processes make use of suitable stresses like compression, tension, shear or combined stress to cause plastic deformation of the materials to produce required shapes without changing its mass or material composition. In forming, no material is removed, they are deformed and displaced.
14 3. Machining/Removing ProcessesTurning Drilling Milling EDM Grinding ECM Shaping and planning Ultrasonic machining
15 3. Machining/Removing ProcessesThe principle used in all machining processes is to generate the surface required by providing suitable relative motions between the work piece and the tool. In these processes material removed from the unwanted regions of the input material. In this, work material is subjected to a lower stress as compared to forming processes.
16 4. Joining Processes Pressure welding Diffusion welding BrazingResistance welding Explosive welding Soldering
17 4. Joining Processes In this process two or more pieces of metal parts are united together to make sub-assembly or final product. The joining process can be carried out by fusing, pressing, rubbing, riveting or any other means of assembling.
18 5. Surface Finishing ProcessesPlastic coating Metallic coating Organic finishes Inorganic finishes Anodizing Buffing Honing Tumbling Electro-plating Lapping Sanding
19 5. Surface Finishing ProcessesThese processes are utilized to provide intended surface finish on the metal surface of a job. By imparting a surface finishing process, dimension of the part is not changed functionally either a very negligible amount of metal is removed from or certain material is added to the surface of the job. Surface cleaning process is also accepted as a surface finishing process.
20 6. Material Properties Modification ProcessesHeat and surface treatment Annealing Stress relieving
21 6. Material Properties Modification ProcessesIn this type of process, material properties of a work piece is changed in order to achieve desirable characteristics without changing the shape.
22 Scales of Production: Popular makes of motor cars are mass-produced in large quantities by increasingly automated manufacturing techniques because of the large demand for such products. On the other hand large structures, such as bridges, are usually built on a ‘one-off’ basis mainly by hand. However some components, such as nuts and bolts, used in the construction of a bridge may well be mass-produced on automatic machines because of the quantity required.
23 Scales of Production The broad groupings are as follows:Continuous flow and line production; Repetitive batch production; Small batch, jobbing and prototype production.
24 Continuous flow and line production:
25 In continuous flow production the plant resembles one huge machine in which materials are taken in at one end of the plant and the finished products are continuously despatched from the other end of the plant. The plant runs for 24 hours a day and never stops. Plastic and glass sheet and plasterboard is produced in such a manner.
26 In line or mass production plants the manufacturing system plant is laid out to produce a single product (and limited variations on that product) with the minimum of handling. The product is moved from one operation and/or assembly station to the next in a continuous, predetermined sequence by means of a conveyor system. Individual operations are frequently automated. Such plants usually manufacture consumer goods such as cars and household appliances in large quantities in anticipation of orders. The layout of a typical flow or line production plant is shown below.
27 Layout for a flow production plant
28 Batch Production:
29 As its name implies, this involves the production of batches of the same or similar products in quantities ranging from, say, hundreds of units to several thousand units. These may be to specific order or in anticipation of future orders. If the batches of components are repeated from time to time, this method of manufacture is called repetitive batch production. General purpose rather than special purpose machines are used and these are usually grouped according to process.
30 Nowadays, the machines are often arranged to form flexible manufacturing cells in which the machines may be computer numerically controlled (CNC)and linked with a robot to load and unload them. To change the product, the computers are reprogrammed. The computer programs are kept on discs and are available for repetitive batches thus saving lead-time in setting up the cell.
31 Small batch, Prototype and Jobbing Production
32 This refers to the manufacture of products in small quantities or even single items.The techniques involved will depend upon the size and type of the product. For very large products such as ships, oil rigs, bridges and the steel frames of large modern buildings, the workers and equipment are brought to the job. At the other end of the scale, a small drilling jig built in the toolroom will have parts manufacture on the various specialist machining sections and will be brought to and assembled by a specialist toolroom bench-hand (fitter). Prototypes for new products are made prior to bulk manufacture to test the design specification and ensure that it functions correctly.
33 Workshops for small batch (100 or less) and single products such as jigs, fixtures, press tools and prototypes, are referred to as jobbing shops. That is, they exist to manufacture specific ‘jobs’ to order and do not manufacture on a speculative basis.
34 So far we have only considered an engineering example, but the same arguments apply elsewhere.For example when you order a suit from a bespoke tailor it will be manufactured as a ‘one-off’ specifically to your measurements and requirements. It will be unique and made mainly by hand in the tailor’s workroom. The tailor will not manufacture on a speculative basis. However, the suit you buy from a clothing store will be one of a batch produced in a factory in a range of standard sizes and a range of standard styles. The various parts of the suit will be cut out and made up by specialist machinists.
35 Advances in Manufacturing: CNC Machines:Definition of CNC Machine: Computer Numerical Control (CNC) is one in which the functions and motions of a machine tool are controlled by means of a prepared program containing coded alphanumeric data. CNC can control the motions of the work piece or tool, the input parameters such as feed, depth of cut, speed, and the functions such as turning spindle on/off, turning coolant on/off.
36 Applications: The applications of CNC include both for machine tool as well as non-machine tool areas. In the machine tool category, CNC is widely used for lathe, drill press, milling machine, grinding unit, laser, sheet-metal press working machine, tube bending machine etc. Highly automated machine tools such as turning centre and machining centre which change the cutting tools automatically under CNC control have been developed. In the non-machine tool category, CNC applications include welding machines (arc and resistance), coordinate measuring machine, electronic assembly, tape laying and filament winding machines for composites etc.
37 Advantages: CNC machines offer the following advantages in manufacturing: • Higher flexibility: This is essentially because of programmability, programmed control and facilities for multiple operations in one machining centre,
38 Advantages: • Increased productivity: Due to low cycle time achieved through higher material removal rates and low set up times achieved by faster tool positioning, changing, automated material handling etc.
39 Advantages: • Improved quality: Due to accurate part dimensions and excellent surface finish that can be achieved due to precision motion control and improved thermal control by automatic control of coolant flow.
40 Advantages: • Reduced scrap rate: Use of Part programs that are developed using optimization procedures
41 Advantages: • Reliable and Safe operation: Advanced engineering practices for design and manufacturing, automated monitoring, improved maintenance and low human interaction
42 Advantages: • Smaller footprint: Due to the fact that several machines are fused into one.
43 On the other hand, the main disadvantages of NC systems are:• Relatively higher cost compared to manual versions • More complicated maintenance due to the complex nature of the technologies • Need for skilled part programmers.
44 Elements of a CNC: A CNC system consists of three basic components:1 . Part program 2 . Machine Control Unit (MCU) 3 . Machine tool (lathe, drill press, milling machine etc)
45 Advantages of CNC machines when compared to Conventional Machines:Once the program has been written and proved, parts can be consistently machined to a high degree of accuracy and consistency. Production time can also be reduced due the fact that the tool can be feed at a rapid feed rate to the work. Also complex form tools are not required as the CNC machine can generate the required profile. Safety has also been improved as most CNC machines have safety features such as guards.
46 Mechatronics: Mechatronics basically refers to mechanical electronic systems and normally described “As a synergistic combination of mechanics, electrical, electronics, computer and control which, when combined, make possible the generation of simple, more economic, and reliable systems.
47 Disciplinary Foundations of Mechatronics:Mechanical Engineering Electrical Engineering Computer Engineering Computer/Information Systems
48 I. Elements of Mechatronics—Mechanical• Mechanical elements refer to – mechanical structure, mechanism, thermo-fluid, and hydraulic aspects of a mechatronics system. • Mechanical elements may include static/dynamic characteristics. • A mechanical element interacts with its environment purposefully. • Mechanical elements require physical power to produce motion, force, heat, etc.
49 II. Elements of Mechatronics—ElectromechanicalElectromechanical elements refer to: Sensors • A variety of physical variables can be measured using sensors, e.g., light using photo-resistor, level and displacement using potentiometer, direction/tilt using magnetic sensor, sound using microphone, stress and pressure using strain gauge, touch using micro-switch, temperature using thermistor, and humidity using conductivity sensor. Actuators • DC servomotor, stepper motor, relay, solenoid, speaker, light emitting diode (LED), shape memory alloy, electromagnet, and pump apply commanded action on the physical process. • IC-based sensors and actuators (digital-compass, -potentiometer, etc.)
50 III. Elements of Mechatronics—Electrical/Electronic• Electrical elements refer to: Electrical components (e.g., resistor (R), capacitor (C), inductor (L), transformer, etc.), circuits, and analog signals. • Electronic elements refer to: Analog/digital electronics, transistors, thyristors, opto isolators, operational amplifiers, power electronics, and signal conditioning. • The electrical/electronic elements are used to interface electromechanical sensors and actuators to the control interface/computing hardware elements.
51 IV. Elements of Mechatronics—Control Interface/Computing Hardware• Control interface/computing hardware elements refer to: Analog-to-digital (A2D) converter, digital-to-analog (D2A) converter, digital input/output (I/O), counters, timers, microprocessor, microcontroller, data acquisition and control (DAC) board, and digital signal processing (DSP) board. • Control interface hardware allows analog/digital interfacing communication of sensor signal to the control computer and communication of control signal from the control computer to the actuator • Control computing hardware implements a control algorithm, which uses sensor measurements, to compute control actions to be applied by the actuator.
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