1. Job shop production
2. Batch production
3. Mass production
This classification is normally associated with discrete-product manufacture, but it can also serve for plants used in the process industries. For example, some chemicals are produced in batches (batches production); whereas others are produced by continuous-flow processes (mass production).
JOB SHOPS: The distinguishing feature of job production is low volume. The manufacturing lot sizes are small, often one of a kind. Job shop production is commonly used to meet specific customer orders, and there is a great variety in the type of work the plant must do. Therefore, the production equipment must be flexible and general-purpose to allow for this variety of work. Also, the skill level of job shop workers must be relatively high so that they can perform a range of different work assignments. Examples of products manufactured in a job shop include space vehicles, aircraft, machine tools, special tools and equipment, and prototype of future products.
Construction work and shipbuilding are not normally identified with the job shop category, even though the quantities are in the appropriate range. Although these two activities involve the transformation of raw materials into finished products, the work is not performed in a factory.
BATCH PRODUCTION: This category involves the manufacture of medium-sized lots of the same item or product. The lots may be produced only once, or they may be produced at regular intervals. Purpose of batch production is often to satisfy continues customer demand for an item. However, the plant is capable of a production rate that exceeds the demand rate. Therefore, the shop produces to build up an inventory of the item. Then it changes over to other orders. When the stock of the first item becomes depleted, production is repeated to build up the inventory again.
The manufacturing equipment used in batch production is general-purpose but designed for higher rates of production. For example, turret lathes capable of holding several cutting tools are used rather than engine lathes. The machine tools used in batch manufacture are often combined with specially designed jigs and fixtures, which increase the output rate. Examples of items made in batch-type shops include industrial equipment, furniture, textbooks, and component parts for many assembled consumer products (household appliances, lawn movers, etc.) Batch production plants include machine shops, casting foundries, plastic molding
factories, and press-working shops. Some types of chemical plants are also in this general category.
It has been estimated that perhaps as much as 75% of all parts manufacturing is in lot sizes of 50 pieces or less. Hence, batch production and job shop production constitute an important portion of total manufacturing activity.
MASS PRODUCTION: This is the continuous specialized manufacture of identical products. Mass production is characterized by very high production rates, equipment that is completely dedicated to the manufacture of a particular product, and very high demand rates for the product. Not only is the equipment dedicated to one product, but the entire plant is often designed for the exclusive purpose of producing the particular product. The equipment is special-purpose rather than general-purpose. The investment in machines and specialized tooling is high. In a sense, the production skill has been transferred from the operator to the machine. Consequently, the skill level of labor in mass production plants tends to be lower than in a batch plant or job shop. Two category of mass production can be distinguished:
1. Quantity production
2. Flow production
Quantity production involves the mass production of single parts on fairly standard machine tools such as punch presses, injection molding machines, and automatic screw machines. These standard machines have been adapted to the production of the particular part by means of special tools –die sets, molds, and form cutting tools, respectively – designed for the part in question. The production equipment is devoted full time to satisfy a very large demand rate for the item. In mass production, the demand rate and the production include components for assembled products that have high demand rates (automobiles, some household appliances, light bulbs, etc.), hardware items (such as screws, nuts, and nails), and many plastic molding products.
Flow production is the other category of mass production. The term suggests the physical flow of the product in oil refineries , continuous chemical process plants, and food processing while these are examples of flow production, the term also applies to the manufacture of either complex single parts ( such as automotive engine blocks) or assembled products. In these cases, the items are made to “flow” through a sequence of operation by material handling devices (conveyors, moving belts, transfer devices, etc.) Example of flow production include automated transfer machines for the production of complex discrete parts and manual assembly lines of the assembly of complex products.
Source: Computer Integrated Manufacturing (Book) NISTE Ministry of Education Government of Pakistan