Computer-Aided Manufacturing - Essay Example

?Computer Aided Manufacturing 528804) Introduction CAM or Computer Aided Manufacturing is the use of computer to automate the processes that take place in the manufacturing of a component. This can not only be used for manufacturing but can be used to cover the entire gamut of operations like transportation and storing of the product. Although the use of CAM is a costly exercise, it mitigates the number of errors that take place in a manufacturing process and also reduces the time for production. (Singh N, 1996) It also reduces the amount of scarp generated as optimum amount of raw material is utilized. The automation of machine tools using CAM can be used both in the production of small batches and large batches each of them offering its own set of advantages and disadvantages. The CAM Process The CAM process uses the same set of tools except that the computer applications have been linked to the manufacturing process to automate it fully. CAM is used extensively in NC, CNC machines. The NC system consists of the part program, MCU or machine unit and the tool. The machine control units have a number of degrees of freedom to facilitate better flexibility in construction. (Chris Voss, 1986) These include (i) Flexibility in tools used for locating purposes. Source: Singh N, 1996, CAM operations (ii) The different cutting speeds and the rate of feed of the product are also important contributions to the CAM (iii) The cooling pump also works in sync with the machining process and directs the cooling fluent very effectively to the work area. The control system in a NC (CAM) machine regulates the actual work done during operations and by it effective system of feedback negates any error that might arise during the manufacturing operations. (Rao.P.N, 1998) This can be described using a simple diagram used below Singh N, 1996, Control system The diagram shows the spindle which holds the cutting tool. A number of stepper motors is located to provide motion in each direction. Reduction gears are in place to allow the motors to be driven at required speeds. A tacho-generator put in place also provides the rpm of the cutting tool. (Singh N, 1996) Using the optical encoder which has a high resolution of close to 3500/revolution it senses the location of the motors and generates a feedback regarding the amount of positive or negative error of the tool with respect to its position from the desired location. This feedback facilitates an output which adjusts the tool by the required amount thereby maintaining accuracy of the process. Apart from these, the other significant advantages include (i) It offers a greater flexibility in design since minor changes can be incorporated in the design phase. (Singh N, 1996) (ii) The production is of a higher scale. (iii) Manufacturing Flexibility by re-routing product lines. (iv) The initial setup time or lead time is also greatly reduced. Advantages and Disadvantages of CAM in batch production 1. Production of small batches The advantages of using CAM in production of small batches is that (i) The amount of capital that needs to be invested initially is less. (ii) The manufacturer is given more time to work on the product and hence the software can be tinkered with to generate an optimum designed product. (Tanner J.P, 1991) Source: Rao.P.N, 1998, Yamazaki Mazak Corp having a 5-axis machining operation (iii) Meeting deadlines are relatively easy since the number of components manufactured is low in number. (iv) Although the initial investment for CAM is high, the production line can be stopped without any difficulty if the product is not working well in the market. The same CAM system can again be utilised to redesign the product. (Gardezi Syed et al, 2000) (v) Since a continuous line of products need not be generated, the production can be reduced during off season and picked up when there is demand or a custom made request for a particular product. (vi) It facilitates the incorporation of the Just in Time Technology (JIT) into the manufacturing process. This is a method that has been developed by Japan and tries to minimize the amount of stock that would be available at a given point of time. Too much of stock is wastage since material tends to deteriorate during the storage process and capital that could have been used for other purposes is lying as stock. (Lazol Ibrahim and Eker Melek, 2006) Too little of stock also causes delay in delivery as the raw materials are not procured on time. Therefore, having the optimum amount of stock facilitates manufacturing thereby minimizing wastage. This can however be incorporated only in small batches where the amount of units to be generated over a given period of time is less. Disadvantages (i) The lead time that is incurred when compared to the total time used in manufacturing the product is huge. (ii) The cycle time or the time that is taken between the productions of two batches is also high as the entire setup needs to be reworked and the new software for the new product needs to be written. (Mc Lean C.R, 2000) (iii) Use of CAM increases the rate of production to a considerable extent and if an error undetected by the Quality Control Department remains in the product after its launch to the customer, it would lead to a tremendous loss of goodwill for the manufacturer. The only option for the company in such a scenario would be to call back all the products that have sold and replace them with updated ones. (Tanner J.P, 1991) There have been instances in which products that have been manufactured using CAM like the cell phone batteries had to be called back after some of these generated high amount of heat leading to the customer complaints. (iv) Frequent interruptions between different custom made components leads to delay since the entire safety check list needs to be followed once again before the actual automated manufacturing process begins. Intermittent stoppages may lead to operators inadvertently forgetting a key safety aspect or overlooking the same to get the job done with. (Tanner J.P, 1991) 2. Production of large batches The advantages of using CAM in manufacturing large batches up to 500 units per month include (i) Minimum manufacture time required per product when compared to the total products produced in a month. (ii) Cycle time is minimised to a large extent. (Singh N, 1996) For example when a car manufacturer brings out a new variant of its car, it intends to promote that car for a few years down the line till a new variant is brought out. In such a scenario, the chassis for those complete set of cars would be identical and hence CAM can be very effectively used in continuous cycle of production. Source: Chris Voss, 1986, Degrees of Freedom (iii) The software need not be rewritten and the same tool setup can be followed in manufacturing. (iv) Since the cycle time is reduced all the associated costs also come down thereby reducing the unit cost of an individual product. (Tanner J.P, 1991) (v) The other advantage in using CAM for producing components in large batches is that once the process starts, it needs to be ascertained whether the operation and maintenance of a plant is taking place in the scheduled manner. The safety aspects related to working is taken care of since the process has already begun. Disadvantages (i) Large scale continuous production reduces the number of quality man-hours that the computer operator has to put in since the next major change of the product would be a long way off. This causes complacency and boredom starts to set in among the CNC operators. (Tanner J.P, 1991) (ii) Since the maintenance of a CAM process and its use in a factory involves lot of overhead expenses, these can only be covered after a significant number of components are produced as the rollout of the first variant. It is only after such a process that the next variant can be thought about. Therefore the number of different variants of the product at the same time is not feasible. Source: Singh N, 1996, CAD/CAM Integration Developments Recent developments involve the seamless interface of CAM with CAD. CAD or Computer aided design is used by the drafting engineer to draw the proposed shape in 2-D. (Compton W.D, 1998)These models can also be drawn in 3-D and the interface areas checked for possible areas of interference between surfaces. Once this is found the software is adjusted to revise the drawing to incorporate the changes. This 3-D model is linked automatically to the tool path and thus the product achieves a great degree of accuracy. The latest commercial product that assists CAD/ CAM includes CATIA, CADCAM and Pro-E. (Kang Xiumei and Peng Qingjin, 2009) Conclusion The principle of using the CAM for the manufacture of components forms an important part of this paper. Although the use of CAM facilitates the production of large number components, the batch size; whether a small batch or a large batch is to be produced is first ascertained. The idea to go in for total automation by incorporating CAD with CAM reduces the amount of skill that is required to manufacture the product. Therefore any change in design is automatically updated in the CAD drawing which alters the shape of the final product. Skilled operators that are employed in the machining sector slowly lose their importance since the works are automated using Computer Aided Manufacturing. Source: Singh N, 1996, coded program for a simple turning operation Reference List 1. Singh N, 1996, System approach to computer integrated design and manufacturing, John Wiley & Sons 2. Gardezi Syed et al, 2000, Small batch size metal products manufactured by single point incremental forming process: Economic Analysis, p. 52-53 3. Kang Xiumei and Peng Qingjin, 2009, Recent Research on Computer-Aided Fixture Planning, Recent patents on Mechanical engineering, Bentham Science Publishers. 4. Mc Lean C.R, 2000, Computer-Aided manufacturing System Engineering, Factory Automation System Division, National Institute of Standards and Technology, USA. 5. Tanner J.P, 1991, Manufacturing Engineering: An Introduction to Basic Functions, Marcel Dekker, New York. 6. Compton W.D, 1998, Design and Analysis of integrated Manufacturing Systems, National Academy Press. 7. Rao.P.N, 1998, CNC machine Tools and control systems, CAD/CAM principles and Applications 8. Chris Voss, 1986, Robot and its Standard movements, Managing New Manufacturing Technologies. 9. Lazol Ibrahim and Eker Melek, 2006, Computer-Aided manufacturing, Just in Time production, Total Quality Management and use of Balanced Scorecard Measures: An empirical study. Read More