2.5 PLANT LAY OUT In addition to the organizational structure, firm engage in manufacturing must also be concerned with its physical activities. the term plant lay out refers to arrangement of these physical facilities in a production plant. A lay out suited to flow-type mass production isnot appropriate for job shop production, and vice versa.
Fixed position lay out Process lay out Production flow layout
We will see that are there is a considerable correlation between the type of plant layout and the types of production previously classified according to quality. FIXED-POSITION LAY OUT. In this type of lay out, the term “fixed-position” refers to the product.
Because of its size and weight, the product remain in one location and the equipment use in its fabrication is brought to it. Large air craft assembly and ship building are example of operation in which fixed-position layout is utilize. Fixed-position layout is illustrated in figure 2.5(a). Another arrangement of facilities, similar to the fixed position type, is project layout.
this is used for construction jobs such as buildings, bridges and dams. As with fixed-position layout, the product is large and the construction equipment and workers must be moved to the product. Unlike the fixed-position arrangement, when the job is completed, the equipment is removed from the construction site.
- In fixed-position layout, the product is eventually move out of the plant remains for the next job.
- This type of arrangement is often associated with job shops in which complex products are fabricated in very low quantities.
- PROCESS LAYOUT.
- In process layout, the production machines are arranged into group according to general type of manufacturing process.
The lathes are in one department, drill presses are in another, plastic molding in still another department, and so on. The advantage of this type of lay out is its flexibility. Different part, each requiring its own unique sequence of operations. can be routed through the respective departments in the proper order.
- Forklift trucks and hand carts are used to move material from one work center to the next.
- Process lay out is typical in job shops and batch production.
- It is also used in quantity type mass production.
- The process layout is illustrated in Figure 2.5.(b).
- PRODUCT-FLOW LAYOUT.
- If a plant specializes in the production of one product or one class of product in large volumes, the plant facilities should be arranged to produce the product as efficiently as possible.
For complex assembled products, or items requiring a long sequence of operations, this efficiency is usually best achieved with product flow layout. with this type of layout, the processing and assembly facilities are placed along the line of flow of the product.
the work in progress is moved by conveyor or similar means from one workstation to the next. the product is progressively fabricated as it flow through the sequence of workstations. As the name implies, this type of layout is appropriate for flow-type mass production. The arrangement of facilities within the plant is relatively inflexible and warranted only when the production quantities are large enough to justify the investment.
Figure 2.5.(c) illustrates a product low layout. These three layouts (fixed-position, process, and product-flow) are the conventional types found in manufacturing plants today. As we shall see in Chapter 16. a fourth type, called group technology layout, represent an attempt to combine the efficiency of flow layout with the flexibility of process layout.
What are the different types of dams?
- Gravity dam: a rigid dam, made of masonry or concrete, withstanding water pressure by means of its own weight.
- Arch dam: a masonry or concrete dam that transfers reservoir pressure to the valley banks by means of its horizontally arched shape.
- Spillway: a special part of the dam that allows floods through or above the dam.
Roller compacted concrete (R.C.C.): a cost- and time-efficient construction method for concrete dams. Hardfill: natural soil treated with cement at low cost, which allows the soil to take on some of the qualities of concrete.I.C.O.L.D.: the International Commission on Large Dams. Created in 1928, I.C.O.L.D. consists of 80 associated national committees
What is the basic shape of a rigid dam?
1. Masonry Dam – Masonry dams are built using either stone masonry or brick masonry. Cement mortar is used to join the masonry blocks. Gravity dam, arch dam etc. are examples of masonry dams. Fig 1: Nagarjuna Sagar Masonry Dam, India
What are the basic materials used for dam construction?
Dam Basics – The purpose of a dam is to impound (store) water, wastewater or liquid borne materials for any of several reasons, such as flood control, human water supply, irrigation, livestock water supply, energy generation, containment of mine tailings, recreation, or pollution control.
Many dams fulfill a combination of the above functions. Manmade dams may be classified according to the type of construction material used, the methods used in construction, the slope or cross-section of the dam, the way the dam resists the forces of the water pressure behind it, the means used for controlling seepage and, occasionally, according to the purpose of the dam.
The materials used for construction of dams include earth, rock, tailings from mining or milling, concrete, masonry, steel, timber, miscellaneous materials (such as plastic or rubber) and any combination of these materials.
What determines the design of dams?
4.1 General comments –
- The design of dams is a specialized and complex task for the following reasons:
- – All dams are different.
- – The consequences of dam failure may be disastrous.
- – The force of water pressure is enormous.
- – The level of acceptable leakage is low; usually it is in the range of liters per second, and often totals less than the losses by reservoir evaporation.
- – The foundation is a key part of the structure and needs careful exploration and improvement.
- – The control of floods is an essential element in dam design and may also be a difficult problem during construction on large rivers.
- – The local seismic risk may modify the design.
- – The impact of reservoirs on the environment demands special study.
– Almost all materials used for dams are local: their characteristics have to be identified and improved upon. Each dam’s design is based upon the optimized utilization of its materials as well as upon the possible construction methods and the available equipment to transport and improve millions of tons of various materials.