Batch production is one of manufacturing methods where limited quantity of each type of product is authorized for manufacture at a time. It is characterized by the manufacture of a limited number of products produced at periodic intervals and stocked in warehouses as finished goods awaiting sales. Typical examples of such batch production are process industries such as pharmaceuticals, paints, chemicals, medium and heavy engineering industry engaged in the manufacture of electric motors, switch gear, heave motor vehicles, internal combustion engines; manufacturer of readymade garments etc.
Characteristics of Batch Production
- Short Runs: Short production runs and frequent changes of setup also characterize batch production. The equipment and the assembly setup is used for a limited number of parts or assemblies and is then changes to make a different product. The production is generally made to stock. In project production, each project has a definite beginning and a definite end.
- Skilled labor in specific trades: The labor force is expected to possess skill in one specific manufacturing process: turning, milling, drilling, welding, grinding, hobbling, fitting etc. The operator may perform simpler machine setups but the separate machine tool setter performs those involving complex operations. Requirement of resources for a project production is not uniform. Generally resource requirement (men, materials, money etc) in the beginning of the project is low, which builds up fast with the progress of project as more and more resources are absorbed, then it levels off until there is gradual cutback as the project approaches completion.
- Supervisor to possess knowledge of a specific process: The supervisors have considerable knowledge of a specific process. Supervisor in the grinding section for example, may not expert in turning and drilling work but is expected to possess knowledge of different types of grinding operations. Similarly, a supervisor in the gear shop is expected to have sound knowledge in working of different types of gear cutting machines.
- Limited span of control: The amount of supervision required in batch production is lower than that of jobbing production. The ration of direct workmen to supervisors is more or less a function of batch size. The smaller the batch, the lower is ration of direct workers to supervisors, and vice-versa. This is because smaller lots require each supervisor to spend a great deal of his time in allocating new work, giving instructions, follow up on the shop floor for proper movement of materials, identifying delays and interruptions and arranging, in consultation with planning, work load in his section to keep his men busy. In project production layout is fixed. Where the output of a project is a product, such products are generally characterized by immobility during transformation. Operations on such products are carried out in fixed position assembly type of layout, which can be observed in production of ships, locomotive, aircraft, construction of roads/ buildings etc.
- General-purpose machines and process type of layout: Plant and equipment is procured and arranged to obtain maximum flexibility. General-purpose machines and handling equipment capable of performing variety of operations with minimum setup times are installed in lieu of variety of products. The machines are arranged to give process layout by function. Similar machines capable of doing similar types of operations are grouped together and kept at one place. Presses, for example, are put together and kept at one place; gear-cutting machines are located at the fourth place and so on. Each group of machines is usually designated as a work center or a section or a shop.
- Manual materials handling: Materials handling in batch production as compared to jobbing production is small. Individual components and parts are placed in trolleys or trays and are transported as unit loads. Materials handling may be mechanized by deploying power driven trucks.
- Manufacturing cycle time affected due to queues: The manufacturing cycle time is smaller than jobbing production but is much more than mass and flow production. The batches of work tend to queue up at different machines due to differing cycle times, batch sizes and sequence of operations.
- Large work-in-progress: Work in progress is large due to varying work content of different components, imbalance in manufacturing times, formation of queues between the machines.
- Flexibility of production schedules: Disruptions due to machine breakdowns or absenteeism do not seriously affect production as job can be shifted to another machine or another operator. In project production, cost of overruns is high. Often delays take place in the completion of the projects. Such delays are generally very expensive due to escalation in the cost of factors of production and incident of penalties.
- Need to have production planning and control: Functions of production planning and control in batch production unit are more complex than those in jobbing production or mass production:
- Materials control and tools control functions are important. Some kind of replenishment system needs to be used to ensure routine replenishment.
- Detailed operational layouts and route sheets are prepared for each part of the product.
- Loading and scheduling needs to be detailed and more sophisticated since every machine requires to be individually scheduled.
- Progressing function is very important to collect information on progress of work. A separate progress card to be maintained to record progress of each component.
- Expediting is generally necessary since quite often jobs, due to imbalances in work contents, tend to lag behind.
In batch production because of large number of activities, involvement of different agencies and strict precedence requirements, scheduling and control assumes great importance. Some network planning techniques like PERT and CPM have been found useful to overcome the problems.