In 1984, Robert Hayes from Harvard University and Steven Wheelwright from Stanford University, joined forces to write a book called Restoring our Competitive Edge¹. In it they identified 5 different production technologies.
More than 30 years later these definitions still hold true, indeed the passage of time has shown that these technology classifications are evergreen.
Table 1 below shows the differences between the 5 production technologies in detail and draws heavily from Hayes and Wheelwright¹.
Here is a summary of each production technology;
Projects are rarely viewed as a production technology although they often have all the hallmarks of production operations. For example, maintenance activities on airplanes or army vehicles must be organised so that leadtimes are minimised and resource utilisation is optimised. This work is controlled using project methodologies and success is determined by the rate of project completion.
Commercial printers or machine shops often look disorganised because of the sheer number of customised activities. Like projects however, they use specialised labour and if those resources are forced to multitask with high levels of work in progress, then this causes inefficiency and a reduction in throughput.
Batch flow line
Batch flow lines, including tools and specialised fittings, are characterised by many workstations with materials and tasks changing with each product type. The natural tendency in these businesses is to increase the batch sizes, and therefore work in progress (WIP) within the batch flow line. This gives the impression of increased resource utilisation however, it actually reduces capacity of the entire facility and reduces customer delivery performance.
Paced assembly line
This production technology is probably the best known. Car manufacturing, think Toyota, and computer manufacturing, think Dell, have been the birth place and proving ground of improvement methodologies such as Lean and Six Sigma. These methodologies must be modified if they are applied within other production technologies.
Process flow line
Process flow lines are our speciality and include food & beverage, liquids, sheet goods, mining, solid & fluid packaging operations. This production technology is on the highest end of the scale with respect to technical and asset complexity.
Table 1: Detailed comparison of the 5 production technologies
|Project||Job Shop||Batch flow line||Paced assembly line||Process flow line|
Product & production characteristics
|Customised products requiring a variety of resources.||Small batches of large number of different products. Many of which require a different set or sequence of processing steps.||Relatively stable line of products each is produced in periodic batches. Most follow same flow pattern.||Work stations laid out in the sequence needed to produce a group of highly similar products. Product passes thru series of steps at a controlled rate.||Production over a predetermined sequence of steps, but processing is almost totally automated and material flow is continuous rather than discrete.|
|Examples||Buildings, aircraft maintenance, new factories, prototypes of products||Commercial printing, machine shops, custom-designed PCB’s.||Speciality chemicals, speciality hose fittings, hydraulic equipment, heavy equipment, tools, electronic devices, metal castings.||Automobiles, computers, watches, toys.||Food & beverage, liquids, sheet goods, mining, solid & fluid packaging operations.|
|Challenges||Estimating, sequencing tasks, pacing||Estimating labour utilisation, fast response, de-bottlenecking||Designing procedures, balancing stages, responding to diverse needs.||Productivity improvement, adjusting staffing levels, rebalancing when needed||Avoiding downtime, timing expansions, cost minimisation|
|Control over work place||Worker||Worker & foreman||Worker, foreman & production supervisor||Process design & management decisions||Equipment & process design|
|Process flow||No pattern||A few dominant flow patterns||One or two single dominant flow patterns||A rigid flow pattern||Clear & inflexible|
|Scheduling||Uncertain, frequent changes||Uncertain, frequent changes||Varies, frequent expediting||Process designed around fixed schedule.||Inflexible, sequence often dictated by technology|
|Type of equipment||General purpose||Mostly general purpose, some specialisation||Varies||Specialised, low & high technology.||Specialised, high technology|
|Capital intensity||Generally very low||Low, as long as equipment utilisation is high||Varies||Varies, moderate capital intensity.||Capital intensive, equipment seldom idle.|
|Definition of capacity||Fuzzy, usually expressed only in monetary terms||Fuzzy, in monetary terms only||Varies||Clear, in terms of output rates||Clear, expressed in physical terms|
|Additions to capacity||Incremental||Incremental over wide range||Varies||Incremental, but requires rebalancing||Some incremental, mostly in chunks.|
|Labour content (value added)||High||Very high||Varies||Low||Very low|
|Worker skill level||High||High||Mixed||Low||Varies|
|Worker training requirements||Very high||High||Moderate||Low||Varies|
|Material requirements||Varies||Difficult to predict||More predictable||Predictable||Very predictable|
|Control over suppliers||Very low||Low||Moderate||High||Very high|
|Vertical integration||None||None||Very little||Some backward, often forward||Often backward & forward|
|Raw material inventories||None||Small||Moderate||Varies, frequent deliveries||Large, continuous deliveries|
|Work in Process (WIP)||Large||Large||Moderate depending on control||Small||Very small|
|Finished goods inventory||None||Small or none||Varies||High||Very high|
|Responsibility for quality control||Direct labour, with management checks||Direct labour||Varies||Primarily QC specialists||Process control specialists|
|Production information requirements||Very high||High||Varies||Moderate||Low|
|Scheduling||Uncertain, frequent changes||Uncertain, frequent changes||Varies, frequent expediting||Process designed around fixed schedule||Inflexible, sequence often dictated by technology and raw materials|
|Staff needs||Coordination mainly||Coordination||Coordination||Process control & coordination||Process control|
|Importance of load forecasting||Little||Little||Moderate||High||High|
|Workforce management tasks||Training, assignment & motivation||Training, assignment, some motivation||Varies||Selection & attendance||Training & supervision|
|Response to business downturns||Layoff||Layoff||Layoff||Build inventory, then layoff||Cut prices, build inventory, then shut down|
¹ – Restoring our Competitive Edge – Competing through manufacturing, by Robert H. Hayes & Steven C. Wheelwright, John Wiley & Sons, 1984.