What are process industries?

The manufacturing sector is broadly defined in two categories: discrete parts manufacturing and process industries.  The ISIC (international standard industrial classification) codes 31-37 correspond mostly to process industries whereas codes 38-39 correspond primarily to discrete parts manufacturing industry.

Examples of process industries are food, beverages, tobacco, textiles, apparel, leather goods, fur products, wood and wood products, cork products, paper and paper products, printing, publishing, materials such as chemicals, coal, rubber, petroleum, plastic – and products made from these materials –  pharmaceuticals, ceramics, and basic metals such as steel and aluminum.

Examples of discrete parts manufacturing are fabricated metal products, machinery, equipment such as aircrafts, cameras, automobiles, computers, office equipment, and televisions, jewelry, musical instruments, sporting goods, toys and a host of other consumer products.  The manufacture of discrete items often involves assembly from many different discrete parts, some of which are made by process industries.

The primary production processes in process industries are either continuous, or occur on a batch of materials that are indistinguishable.  For example, a company making spaghetti sauce may make these in batches that equal the size of the kettle used, or produce it in a continuous process where the sauce flows in an uninterrupted flow after being processed.  Either way, there is no concept of a unit of spaghetti sauce while it is being worked upon.  Another example of continuous processing is the manufacture of pig iron in integrated steel mills.  The blast furnaces are never shut down and produce a continuous stream of molten metal. 

It should be noted that at the end of the production process, many items made by process industries are in fact sold in discrete units – e.g., spaghetti sauce is sold in different sized cans/jars and steel may be sold in different sized steel bars.  In contrast, discrete parts manufacturing involves transformation processes on discrete units of incoming raw materials, e.g., printed circuit boards and crankshafts.  The term continuous processing in discrete parts manufacturing means 100% dedicated equipment with no breaks for changeovers.  However, the transformation processes apply to discrete units of raw materials.

How do IE’s think about production processes?

Production processes can be divided into four categories:  elemental processes, compound processes, coordinative and business processes, and managerial processes.  Elemental processes are the most basic activities whereas compound processes are combinations of several elemental processes.  For example, in food industry, examples of elemental process are washing of fruits and vegetables, sizing and peeling. 

Similarly, in an integrated steel mill, compound processes include cooking of pig iron to produce steel (this involves addition of alloying metals and passing of purifying gases while applying heat and pressure at the same time), and hot/cold rolling to make coil (this involves passing the metal bar repeatedly under rollers while applying pressure at the sides to turn the bar into a steel coil).  In most instances, the responsibility for managing elemental and compound processes rests on the shoulders of appropriate chemical, metallurgical, electrical and mechanical engineers.

Industrial engineers are more likely to support and provide leadership in coordinative and managerial processes.  Some common coordinative processes are as follows;