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MBA0044 : Differentiate between Automated flow line and automated assembly line with example. Write a note on Rapid Prototyping.

Posted on: September 17, 2011

MBA0044  : Differentiate between Automated flow line and automated assembly line with example. Write a note on Rapid Prototyping.
Answer: – Automated flow lines:

When several automated machines are linked by a transfer system which moves the parts by using handling machines which are also automated, we have an automated flow line. After completing an operation on a machine, the semi finished parts are moved to the next machine in the sequence determined by the process requirements a flow line is established. The parts at various stages from raw material to ready for fitment or assembly are processed continuously to attain the required shapes or acquire special properties to enable them to perform desired functions. The materials need to be moved, held, rotated, lifted, positioned etc. for completing different operations.
Sometimes, a few of the operations can be done on a single machine with a number of attachments. They are moved further to other machines for performing further operations. Human intervention may be needed to verify that the operations are taking place according to standards. When these can be achieved with the help of automation and the processes are conducted with self regulation, we will have automated flow lines established.

One important consideration is to balance times that different machines take to complete the operations assigned to them. It is necessary to design the machines in such a way that the operation times are the same throughout the sequence in the flow of the martial. In fixed automation or hard automation, where one component is manufactured using several operations and machines it is possible to achieve this condition – or very nearly. We assume that product life cycles are sufficiently stable to invest heavily on the automated flow lines to achieve reduced cost per unit. The global trends are favouring flexibility in the manufacturing systems. The costs involved in changing the set up of automated flow lines are high. So, automated flow lines are considered only when the product is required to be made in high volumes over a relatively long period. Designers now incorporate flexibility in the machines which will take care of small changes in dimensions by making adjustments or minor changes in the existing machine or layout. The change in movements needed can be achieved by programming the machines. Provisions for extra pallets or tool holders or conveyors are made in the original design to accommodate anticipated changes. The logic to be followed is to find out whether the reduction in cost per piece justifies the costs of designing, manufacturing and setting up automated flow lines. Group Technology, Cellular Manufacturing along with conventional Product and Process Layouts are still resorted to as they allow flexibility for the production system.

With methodologies of JIT and Lean Manufacturing finding importance and relevance in the competitive field of manufacturing, many companies have found that well designed flow lines suit their purpose well. Flow lines compel engineers to put in place equipments that balance their production rates. It is not possible to think of inventories (Work
In Process) in a flow line. Bottlenecks cannot be permitted. By necessity, every bottleneck gets focused upon and solutions found to ease them. Production managers see every bottleneck as an opportunity to hasten the flow and reduce inventories. However, it is important to note that setting up automated flow lines will not be suitable for many industries

Automated Assembly Lines: All equipments needed to make a finished product are laid out in such a way as to follow the sequence in which the parts or subassemblies are put together and fitted. Usually, a frame, body, base will be the starting point of an assembly. The frame itself consists of a construction made up of several components and would have been ‘assembled’ or ‘fabricated’ in a separate bay or plant and brought to the assembly line. All parts or subassemblies are fitted to enable the product to be in readiness to perform the function it was designed to. This process is called assembly.

The material goes from station 1 to 5 sequentially. Operation 2 takes longer time, say twice as long. To see that the flow is kept at the same pace we provide two locations 2a and 2b so that operations 3, 4 and 5 need not wait. At 5, we may provide more personnel to complete operations. The time taken at any of the locations should be the same. Otherwise the flow is interrupted. In automated assembly lines the moving pallets move the materials from station to station and moving arms pick up parts, place them at specified places and fasten them by pressing, riveting, screwing or even welding. Sensors will keep track of these activities and move the assemblies to the next stage. An operator will oversee that the assemblies are happening and there are no stoppages. The main consideration for using automated assembly lines is that the volumes justify the huge expenses involved in setting up the system.

Rapid Prototyping: Prototyping is a process by which a new product is developed in small numbers so as to determine the suitability of the materials, study the various methods of manufacture, type of machinery required and to develop techniques to overcome problems that may be encountered when full scale manufacture is undertaken. Prototypes do meet the specifications of the components that enter a product and performance can be measured on those. It helps in confirming the design and any shortcomings can be rectified at low cost. If serious defects or problems arise during the manufacture, a thorough change in design or even its replacement may be considered. To arrive at decisions to make use of the advantages stated above, it is important that the prototypes are made within the shortest possible time. Rapid prototyping facilitates this. It uses virtual designs from Computer Aided Design – CAD or animation modelling which transforms dimensional data to 3dimensional views. The physical space of the product is amenable to have cross sections made.
Cross sections taken at very close positions gives thin layers which enable the generation of a solid model of the designed product. The data that is thus created helps build a solid model exactly as per the drawings. Any shape can be generated in this method. Advanced technologies like – SLS (Selective Laser Sintering), FDM (Fused Deposition Modeling), LOM (Laminated Object Manufacture), EBM (Electronic Beam Melting) are some of Rapid Prototype Modeling Processes.
Since the basis data about the product is already available in CAD, the above processes can produce models in a matter of a few days. Conventional machines like lathes, milling machines, grinding machines, EDM (Electro Discharge Machining) also help in the production of prototypes. Because of their advantages Rapid Prototyping is being increasingly used.

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