Table of Contents:-
- Meaning of Layout Planning
- Meaning of Facility Layout Planning
- Objectives of Facility Layout Planning
- Types of Facility Layout Planning
- Layout Planning and Analysis
Meaning of Layout Planning
Facility layout planning includes decisions regarding the physical allocation of the economic activity centres in a facility. The objective of facility location planning is a more effective workflow at the facility, allowing workers and equipment to be more productive.
The process of preparing a layout is both an art and a science. There is no pre-existing method for preparing it. The final layout will naturally consume many trials, errors, and compromises. To make the final layout as perfect as possible, the layout personnel would do well to proceed step by step in the layout planning process.
These steps are shown in the image given below:
The layout procedure might start with an analysis of the product to be manufactured and the expected volume of its production. An analysis of the product includes a study of the parts to be manufactured and/or bought and the stages at which they should be assembled to obtain the end product. The volume of production is estimated in terms of market and management policies.
Strategic Considerations in Equipment Selection and Plant Layout Design
For a given product, at a stated volume of production, a process most appropriate must be determined. The process that is determined, like any other factor, may not be permanent because it will be influenced by changes in the volume of production, changes in the product and changes in equipment. The process which is decided upon, determines the type of equipment that would be needed to manufacture a given product at a given volume.
The equipment necessities of a company vary with its methods of grouping machines or the type of layout, the primary consideration being an increasing use of machines and not of labour. The equipment, which is selected, determines the number of workers that will be required. The trend nowadays is to replace labour with machines, because that results in increased production, reduced costs, better quality and fewer labour troubles. However, the labour cannot be completely dispensed with; it would always be needed to switch on and switch off the machines, even if the whole plant is mechanized.
At the fourth stage, product and volume have led to a process which dictates the type of equipment which would be acquired and which, in turn, would require operators. However, the operators require the services of indirect labour of material handlers, janitors, maintenance staff, quality control staff and production supervisors. The arrangement of all these facilities and personnel constitutes the plant layout. Once the plant layout is designed, the layout engineer often engages the services of an architect or the construction division of the company to design the system.
Meaning of Facility Layout Planning
Layout refers to the arrangement of facilities. A facility layout refers to the arrangement of machinery, equipment and other industrial facilities such as receiving and shipping departments, tool rooms, maintenance rooms and employee amenities to achieve the smoothest and quickest production at the minimum cost.
According to Keith and Gubellini, “Facility layout deals with the arrangement of the physical facilities and the manpower which are required to manufacture a product or perform a service”.
According to Shubin, “Facility layout is the arrangement and location of production machinery, work centres and auxiliary facilities and activities (Expectation, handling of material storage and shipping) for the purpose of achieving efficiency in manufacturing products or supplying consumer services”.
Objectives of Facility Layout Planning
A good facility layout should have the main objective of minimising the cost of production. The subsidiary objectives to attain this goal are as follows:
1) Optimum utilisation of available floor space.
2) Provision of optimum location of an adequate number of service centres.
3) Minimisation of handling and transportation of materials. This results in the most economical way of dealing with materials.
4) Economic utilisation of employees, equipment and machinery.
5) Minimisation of work-in-progress inventory by reduction in delays and bottlenecks in the production process. This results in the maximisation of inventory turnover.
6) Maximisation of convenience and safety of workers. This results in boosting their morale.
7) Efficient planning and control over the processes of production.
Types of Facility Layout Planning
The various types of facility layout are as follows:
1) Process Layout
Process layout is also called the functional layout or job shop layout. In process layout, machines and services are grouped on a functional basis and operations of the same type are performed in the same area. The processing units are organized by functions into departments on the assumption that specific facilities and skills are available in each department. Similar equipment and operations are grouped.
2) Flexible Manufacturing System (FMS)
A Flexible Manufacturing System is an arrangement of machines, interconnected by a transport system. The transport carriers work to the machine on pallets or other interface units so the work-machine registration is accurate, rapid and automatic.
3) Hybrid or Combined Layout
A combination of process and product layout is known as a combined layout. It is possible to have both types of layout in an efficiently combined form if the products manufactured are somewhat similar and not complex. For example, in a soap manufacturing plant, the machinery manufacturing soap is arranged on the product line principle, but ancillary services, such as heating, the manufacturing of glycerin, the powerhouse, and the water treatment plant are arranged on a functional basis.
4) Product Layout
Product layout involves the arrangement of machines in one line, depending upon the sequence of operations. The raw material enters at one end of the line and individual operations are performed in the pre-fixed sequence and get converted to the final shape.
5) Fixed Position Layout
In this type of layout, the major product being produced is fixed at one location. Equipment, components and labour are moved to that location. All facilities are arranged and brought around one work centre. The movement of men and machines to the product is advisable because the cost of moving time would be less than the cost of moving the product, which is very bulky.
6) Cellular Production/Cellular Manufacturing Layout
Cellular manufacturing is a type of layout where machines are grouped according to the process requirements for a set of similar items that require similar processing. These groups are called cells. After being processed in the cell, the finished products may go on to another cell.
Layout Planning and Analysis
Various techniques are available for planning the layout. For developing a suitable layout type one can use the following models:
Templates are most commonly used while preparing layouts. Templates are two-dimensional or block templates that consist of a thin plate of wood or metal, which serves as a gauge or a guide in mechanical work. A plant layout template is a scaled representation of a physical object within a layout. This object may be a material, machine handling equipment, a worker or even materials. The templates are fixed to a plan drawing and moved around the drawing to explore the various layout possibilities. This process continues until a layout emerges that eliminates unnecessary handling and backtracking of materials and offers flexibility to admit revisions at the least cost. The template method is particularly useful in developing a layout for an existing building or department or when the building’s configuration is already established through other layout techniques.
Advantages of Templates
1) They can be readily interpreted and followed by technical persons
2) They are flexible in use and can be moved on the scaled plan to evaluate various feasible positions for different facilities.
3) They are cheaper as compared to models.
4) They make the layout visual before drawing.
Disadvantages of Templates
1) It is difficult to visualize the impact of the overhead equipment on the plant and the processes.
2) Non-technical person finds it difficult to interpret the clear picture.
A block diagram is a specialized, high-level type of flowchart. Its highly structured form provides a quick overview of significant process steps, key process participants, and the relationships and interfaces involved.
A block diagram is a valuable tool for designing and improving new processes. In both cases, the block diagram provides a quick, high-level view of the work and may rapidly lead to process points of interest. Because of its high-level perspective, it may not offer the level of detail required for more comprehensive planning or analysis.
Optimizing Layout Design through Material Movement Analysis and Block Diagramming
The historical or predicted material movement in the existing or proposed facility must be analyzed to start block diagramming. This info is usually provided with a “froia to chart”, or “load summary chart”.This gives the average number of unit loads transported between departments over time. A unit load can be a single unit, a pallet of material, a bin of material, or a crate of material- however, the material is normally moved from location to location.
The next step in designing the layout is to calculate the composite movements between departments and rank them from most movement to least movement. Composite movement refers to the back-and-forth activity between each pair of departments. Finally, trial layouts are placed on a grid graphically representing the relative distances between departments in uniform blocks. The objective is to assign each department to a block on the grid so that non-adjacent loads are minimised. Non-adjacent is a distance farther than the next block, horizontally, vertically, or diagonally.
The trial layouts are scored based on the number of nonadjacent loads. Ideally, the optimal layout would feature zero non-adjacent loads. In practice, achieving this is rarely possible. The process involves experimenting with various layout configurations to minimize the number of non-adjacent loads, and it continues until an acceptable layout is found.
Operations Sequence Analysis
Operations sequence analysis is used to develop a good scheme for the arrangement of departments graphically and analyse the layout problem. It required an existing or proposed arrangement of departments and a projection of the traffic or flow that will take place between one department and each of the other departments during some period.
Departments are represented by nodes (circles). Inter-departmental flow information is represented by solid lines connecting adjacent departments. Dashed lines represent traffic between nonadjacent departments. The projected volumes are written above the appropriate lines. The departments (circles) are moved to reduce the amount of non-adjacent flow. This proceeds until no further improvement can be found.
Computer Aided Layout Planning (CALP)
This method has three steps. They are:
1) Specification Phase: In the specification phase one has to decide how relevant planning details are to be fed to the computer.
2) Analysis Phase: In the third phase, i.e., the analysis phase, model building and analysis of output are considered. The CALP system should be flexible to date changes and error corrections. With an appropriate computer model major summaries and output reports are generated, which give good documentation to measure the effectiveness of various alternatives.
3) Preparation Phase: In the preparation phase, planning objectives are defined and the information necessary for decision making is identified. This phase specifies the input required for the computer. Structuring of different computer disk files is also defined.
Automated Layout Design Programme (ALDEP)
Here the close relationship between the two departments is used to build up the layout. The computer selects randomly the first facility and locates it. Subsequent facilities are selected based on the closeness relationship factor given in the preference matrix. When no further high relationship facility is found the other facilities are located randomly. The preference matrix provides the relative facility location preferences denoted by letters ranging from A (essential) to F (Undesirable). Various arrangements of facilities can be generated in the same way for further analysis. The effectiveness of each of the layouts is measured by the performance score, which says how well the wanted relationships are fulfilled.
This program requires the inputs:
- Description of building specifying features (aisles etc.) if any.
- Number of layouts to be generated.
- Size of each facility,
- Preference matrix,
The layouts so generated are plotted using a plotter, which gives the layouts with preference scores to help select the best layout. This ALDEP program can also handle layout problems of multi-storey buildings (up to three floors).
This program is more suitable for re-layout problems where one or more than one department can be kept in fixed locations and other departments may be shifted from the present location.
Computerized Relative Allocation of Facilities Technique (CRAFT)
The above difficulty can now be alleviated due to the availability of computer software packages such as the Computerized Relative Allocation of Facilities Technique (CRAFT). The basic technique of optimization in CRAFT is similar to what we did visually; exchanges of positions between different departments. The computer program, therefore, requires input data such as:
- The existing layout and the distances between different locations.
- The floor area requirements of the different departments.
- Load Summary.
In addition to this, the computer program introduces two more aspects:
1) The possibility of the differences in the costs of material handling between two different pairs of departments, expressed as rupees per load per unit distance.
2) CRAFT also takes into account the non-moveability of certain departments in practice. For example, the receiving section may have to be located near the railway tracks if a large volume of raw materials is received by rail. Such positional constraints should also be part of the input data.
The ultimate aim of the CRAFT program is to minimize the material handling costs for the entire plant.
Relationship Diagram/Systematic Layout Planning (SLP)
For situations where quantitative data is complex, using a relationship diagramming technique is more relevant. Richard Muther developed a format for displaying manager preferences for departmental sites, known as Muther’s grid. Muther’s diagram uses letters and codes to represent the proximity of departments to one another. The information from Muther’s diagram can be used to make a relationship diagram to evaluate a current layout or proposed layouts.
Phases of Systematic Layout Planning (SLP)
The SLP technique has remained popular for more than 30 years because of its simple step-by-step approach to facility design.
Phase I: Determination of the Location of the Area where Departments are to be Laid Out
Phase I involves identifying the locations of the departments. For example, this area may be on the north side of a building, on the west side or in a new building adjacent to the existing manufacturing building. This phase is the easiest among the four other phases.
Phase II: Establishing the General Overall Layout
This phase involves determining the flow of materials between departments, examining special adjacency requirements, determining the space required for each department, balancing it with the space available, incorporating practical constraints (e.g., budget, safety), and generating up to five alternate layout plans. The plans are then evaluated based on cost and other non-cost considerations and a layout is selected for departments and general work areas.
Phase III: Establishing Detailed Layout Plans
Establishing Detailed Layout Plans: The relative positions of departments found in Phase II do not provide details about the location and layout of each specific auxiliary equipment, machine, and support services such as restrooms, cleaning rooms, inspection stations, and battery-charging rooms. This detailed layout of departments and support services is done in phase III. The procedures for generating layouts in Phase III are the same as in Phase II, except that Phase II deals with the layout of departments, whereas Phase III deals with the layout of machines and other auxiliary equipment in each department.
Phase IV: Installing the Selected Layout
The detailed layout must be approved by all concerned people affected supervisors, employees and managers. Then the final layout is prepared. The drawings must show every possible detail because they are used to plan the move to the new facility. In phase IV, funds and time are appropriated for the move, and the actual relocation of machinery and services takes place.
The input data required by SLP are classified into five categories. P-Q-R-S-T these stand for.
- Productivity (or Materials or services).
- Quantities (Sales Volumes & inventory).
- Routing (or processes of necessary operations).
- Supporting Services (for people, Processes and information systems).
- Timing (Operating hours, seasons, urgency…)
Quantitative factors are easily analyzed in a closeness rating chart, developed by Richard Muther (1962). named systematic layout planning (SLP). The closeness rating chart is a grid that qualitatively assesses the desired proximity between the departments. For some departments, closeness may be undesirable. The grid of a closeness rating chart resembles the mileage chart on a map, the rating for department A relative to B is the same as the rating for B relative to A Codes denote the desired proximity according to the relative strength of the closeness:
- A – Absolutely necessary,
- E – Very important,
- I – Important,
- O – Ordinary importance,
- U – Unimportant, and
- X – Undesirable.
The codes consider these factors:
- Sharing the same personnel,
- Records, and communication;
- The sequence of workflow, and
- Unsafe or unpleasant conditions.
The closeness rating chart may be used to create a block diagram for an effective layout. The chart may also be used to check the effectiveness of a layout created using another method or computer tool.