Flow line manufacturing is used to manufacture high volumes of products with high production rates and low costs. Separate dedicated flow line is created for each product. Dedicated machines are used to manufacture the products at high production rates. These machines are generally expensive. A large volume of the products must be produced in order to justify the cost of such expensive machines. Flow line manufacturing is most suitable to manufacture high volumes of products continuously. Flow line manufacturing is used in such industries where raw materials are fed at one end and finished products are produced continuously at the other end. Thus flow line manufacturing is utilized in mass production industries. Flow line manufacturing is shown in figure 1. Flow line layout is also called a product layout.
Figure 1: Flow line manufacturing
Advantages of flow line manufacturing are as per the following.
1. Smooth and logical flow of materials
Smooth and logical flow of materials are achieved in flow line manufacturing because dedicated machines are used to manufacture the products at high production rates and separate dedicated flow line is created to manufacture each product.
2. Simplified production planning and control
Manufacturing operations are simple in flow line manufacturing which simplify production planning and control. Scheduling jobs, controlling materials and performing machines operations become very simple in flow line manufacturing.
3. Reduced material handling cost
Material/parts are moved within small areas during manufacturing process. Machines are ready to accept a job during various stages of manufacturing, almost no need to store and protect materials between two machines. Status & location of materials are easy to track and control. Thus cost of moving, storing, protecting and controlling materials becomes low in flow line manufacturing which ultimately reduces material handling cost.
4. Shorter production lead time
Waiting time is minimal for each part during manufacturing process in flow lines and flow of materials is uninterrupted. This causes shorter production lead time and high production rates in flow line manufacturing.
5. Small amount of work in progress inventory
Amount of work in progress inventory is small in flow line manufacturing because of shorter production lead time.
Disadvantages of flow line manufacturing are as per the following.
1. Lack of flexibility
Major drawback of flow line manufacturing is lack of flexibility to manufacture products for which they are not designed. This drawback is inherently present in flow line manufacturing because dedicated machines are setup to execute limited operations and they are not allowed to be reconfigured. Flow line manufacturing is not suitable in such cases where variety of products to be manufactured changes frequently.
2. High investment in machines and equipments
Similar machines are not grouped together in flow line manufacturing. High investment in machines and equipments is required and capacity of machines is not fully utilized because of duplication of machinery inherently present in flow line manufacturing.
3. Lack of specialization in supervision
Manufacturing processes are executed in one line and different types of machine are installed in one line. In job shop manufacturing, a supervisor is supposed to have the specialized knowledge about his/her departmental activities, machines and processes. But in flow line manufacturing, a supervisor is supposed to have detailed knowledge of all the machines, processes and activities causing lack of specialization in supervision.
4. Work stoppage because of breakdown
If one machine in the flow line fails then other machines in that flow line stops functioning and thus manufacturing process will be stopped.