QTM AND LAYOUT
Plant layout primarily deals with the allocation of the total floor, rather cubic area among various production and service departments along with their specified stationing inside the plant area. The space for each work station is required for equipment, tools, loading and unloading work on machines, temporary material storage, benches, hoods, files, maintenance, clearance, operator work area etc. Moreover, space is also required for the movement of material handling equipment, aisles between the machines, inspection spots, safety spots, space for inspection, lubrication, repair and maintenance of machines etc.
Quantitative Techniques in Management (QTM):
QTM can be applied to layout problems. Some of the commonly used techniques for this purpose are: LP: Linear Programming, Transportation Problem, Assignment Technique, Dynamic Programming, Waiting Line Theory and Simulation. The computer based layout is the most applicable in QTM.
Two types of computer software are available: Construction Programs and Improvement Programs.
ADLEP and CORELAP are REL-based computer programs to aid construction of a layout. (ADLEP: Automated Layout Design Program, CORELAP: Computerized Relationship Layout Planning). CRAFT: Computerized Relative Allocation of Facilities Planning minimizes a linear function of the movements amongst departments and thus is an improvement program. It uses flow of material matrix and cost/unit moved/unit distance and space requirement data.
A general inference by technical experts reveal that overall plant areas are generally about 150 to 200 sq. feet per employee for light manufacturing operations, 500 sq. feet for medium manufacturing and as high as 1,000 sq. feet for process industries. This estimate is just a guideline. In fact, the modern production systems with their varied and unique characteristics require separate independent solutions to these problems.
The area is to be allocated considering the needs of future expansion, and required flexibility. The area allocation is closely related to the type of material flow. 3-D is used to allocate area. Area is earmarked for point-of-use and storage. There is also area left for aisles. The provision is made for column spacing.
Models of Plant Layout
Three things have to be assembled before commencing productionâ€”the men, the machines and the materials. When these three are brought together, we create some kind of arrangement or layout.
It is inevitable to prepare the blue prints and models of the plant layout be fore the actual laying function begins. The location of the machines, equipment and plant facilities is the result of trial and error method backed up by varied considerations. They are arranged and rearranged until the most desirable setting is done. Templates or models represent the actual space requirements for each machine or service department along with their sequential relations, easy access to the same scale as the floor plan of the area in which they are to be installed. It is a good visual aid which helps in solving certain constraints in the layout before they arise. The popular methods of plant layout models are as under:
1. Square layout
2. Template layout or two-dimensional layout.
3. Model layout or three-dimensional layout
Square layout is a preliminary layout of the plant. It indicates the total square feet floor area and its allocation among various work stations and the plant facilities on the basis of some appropriate scale. It simply indicates the location of work station, plant facility and the flow patterns of the materials. Such floor charts are more helpful in arranging and rearranging the machines in terms of their impact on material handling. It is nothing but the blue print of the plant layout. It is very simple to prepare and easy to understand. Duplicate copies can be made very easily. The disadvantage with this layout is it does not provide any visual aid, besides the height considerations of the layout are not taken into consideration. The complex layout may distort the simplicity of its reading. However, it is the basis for the templates and model layouts.
This is the most common method of presenting the plant layout. They are two-dimensional and consider the height of the floor area. Generally, cardboard, hardboard, colored papers, tapes etc. are used in presenting the building, walls, work stations, plant facilities etc. A template is generally prepared to a suitable scale and they are characterized by their transparency. The advantages of this type of layout are as under:
1. Compared to square layout, the height of the layout is also taken into consideration and provides a visual aid in understanding the layout
2. Its reading and interpretation is easy.
3. It is possible to produce duplicate copies thereof.
4. It is cheaper as compared to model layout..
It has the following disadvantage:
1. It does consider height, but it is hard to visualize the impact of the overhead equipment on the plant and the process
2. Compared to model layout, its interpretation is difficult for non-technical personnel.
This model is also known as the three-dimensional (3D) model. The models of the plant and equipment with their appropriate scale are used in preparing the model layout. The models are obtained from the commercial suppliers. Sometimes the vendors also supply the scale models. Generally, models layouts are prepared to the same scale as template layout. They are most expensive and are generally not used unless it is warranted by the complexities involved in the plant layout.
They are advantageous as under:
1. It is easy to explain to the management.
2. It provides a visual aid in understanding the layout by non-technical personnel.
3. It is easy to shift the models for the study of the operational management.
4. It facilitates the study and checking of overhead structures.
5. Different photographic situations can be developed for the purpose of comparing various alternative arrangements.
It suffers from the following disadvantages:
1. It is costlier as compared to other forms of layout presentations.
2. Like blue prints, it cannot be folded and its movement for spot reference becomes difficult.
3. As they are large in size, it requires more storage area.