In todays world of operations management, layouts of manufacturing processes play a key role in achieving and maintaining long term goals. These layouts need to be well thought out and carefully planned for they can effect the cost or producing goods and delivering services for many years into the future. Layouts are dependent on the technology utilized and product type manufactured. There are four typical layouts: process layout, product layout, fixed position layout and combination layout.
A combination layout is a layout that shares properties of two or more layouts.Such as a group technology layout that shares characteristics of a process layout and a product layout. Theyre similar in that the cells are designed to perform a specific set of processes, and it is similar to product layout in that the cells are dedicated to a limited range of products.
Each layout usually involves compromise and balancing of the process variables and its always debatable whether the perfect layout actually exists. The purpose of layout planning is: to maximize the efficiency and profitability of a manufacturing operation to allow consistency and quality in products to be produced to allow flexibility and ease of adaptation for machinery and production personnel to products as required by the market(Anonymous 2). Some characteristics of a good layout would be minimum material movement, workstations close together, easily adjustable to changing conditions and one plant floor so that everyone can see whats going on.
To define and explain, a product layout is a product-orientated layout that is appropriate for producing one standardized product in typically large volumes. Each unit being produced requires the same sequence of operations from beginning till end. During times when product demand is high enough and sustainable over a long period of time, it is usually cost effective to rearrange resources from a process layout to a product layout. In certain cases the equipment layouts are arranged so that the product in manufactured in a sequential and continuous arrangement. A good example would be an assembly line. Assembly lines can vary widely either they can be virtually 100 percent parts assembly by workers or by a transfer line where all the work being done is by machine.
An assembly line is a special case of a product layout. In a general sense, the term assembly line refers to a progressive assembly linked by some type of material handling device (Davis, Aquilano, and Chase 257). The assumption being made is that some form of pacing is present and that allowable processing time is equivalent for all workstations. There are different types of assembly lines such as material handling devices (belt or roller conveyor), line configuration (U-shape, straight, or branching) and workstation characteristics where workers may sit, stand, walk with the line, or ride the line. An important factor not to be over looked is the human factor. Early assembly lines moved at a predetermined pace that means that the line moved ahead regardless of whether or not the work was completed. Under this structure, workers who fell behind had to rush and complete their assigned tasks, with the result often being faulty workmanship.
In recent years this structure has changed instead of having machine-paced lines we now have worker-paced machine lines. The operator now continues to work on a product until the work assigned is satisfactorily completed at a station. The quality of the products being completed is significantly higher than the products being completed on the machine-paced lines. There is also a method being used called assembly line balancing where you assign all of the tasks required to a series of workstations so that the time required to do the work at each station does not exceed the cycle time and the idle time.
Also used and commonly seen is group technology a form of the combination layout. A group technology layout brings together dissimilar machines into work centers (or cells) to work on products that have similar shapes and processing requirements (Davis, Aquilano, Chase 254). Group technology (GT) as a manufacturing philosophy plays a major role in design standardization, manufacturing cell layouts, process planning, purchasing, and manufacturing technology design. One of the most significant ways to use GT is to facilitate significant reductions in design time and effort. A group technology (or cellular) layout allocates dissimilar machines into cells to work on products that have similar weights, shapes, and processing requirements. You can see group technology being used in metal fabricating, computer chip manufacture, and assembly work.
Because group technology is similar to a process layout many companies may shift to a GT layout. When developing a GT cellular layout there are three steps that need to be followed: the first, grouping parts into families that follow a common sequence of steps. This means developing a classification and coding system that is designed for rapid retrieval of all design data pertaining to the manufacturing of the product. This is often a major expense with companies. The second identifying dominant flow patterns of parts-families as a basis for location or relocation of processes. Thirdly physically grouping machines and processes into cells. Often there are parts that can not be grouped or associated with any family in which they are placed in a remainder cell.
In practice most layouts are combination layouts with product and process layouts being combined. There are also many other issues that need to be addressed such as the available space in the existing buildings, input, output and storage areas. Also noted the in process storage areas, proximity to utilities, arrangement to maximize shared resources, the consistent manufacture of quality and cost effective products. Layout can affect both employee relationships and customer satisfaction. A layout can help or hinder employee relationships with one another with subsequent effects on employee motivation and performance. For example the decision to adopt a process layout which often groups workers according to skills may not be compatible with an operation requiring some persons of all skills to produce a variety of different products.
For process and product layouts, the design begins with a statement of the goals and facility. Preliminary layouts are then designed to meet these goals. After initial designs have been developed, improved designs are sought through numerical analysis and discussion with the users. The development of a layout should involve everyone that it is effecting. Computer based models can be used for preliminary estimations to create some preliminary layouts using CAD or similar drawing software. The layouts then can be analyzed against the goals of the facility and improvement made if necessary.
In summary while there are a lot of tools for good layout planning and each layout are dependent on the type of products and external variables impacting on the manufacturing process. A skilled layout planner working with manufacturing staff and management should work through objectives and options to determine the optimal solution for a given facility.