Designers need to understand a wide range of manufacturing processes and techniques to match their knowledge of materials. This topic does not try to encompass all known techniques but outlines and exemplifies the main manufacturing processes and techniques.
It is important to understand how the different processes link together in the manufacture of a product. During manufacture material is usually first shaped crudely and then more precisely into finished parts or components and finally assembled. Some products or components are made by a single process although most require a mixture of processes.
manufacturing technique - A specific manufacturing term, sometimes relating to one material group only.
Different techniques for different materials
casting relates to metals, plastics, food, ceramics and some composites, but not to timber or textiles.
Technique often relates to the viewpoint of the manufacturer and the user.
Craft Production 5.2
Small scale production methods
craft production - A small-scale production process centered on manual skills
one-off production - An individual (often craft-produced) article or a prototype for larger-scale production.
Prior to the Industrial Revolution
most products were manufactured by craft techniques
development of skills
sources of materials and energy
sales and distribution
relationship of craftsman or designer with client or consumer.
Small economies of scale
High value of the product
Area of lower labor costs (relative)
High flexibility in manufacture (specialized individual orders)
May be an option in developing countries when Economic development, infrastructure and market needs are considered,
In developed countries it gives rise to the "master craftsman"
mechanization – A volume production process involving machines controlled by humans
the availability of new sources of power like water and steam power during the Industrial Revolution led to the introduction of mechanization.
assembly-line production – The mass production of a product via a flow line based on the interchangeability of parts, pre-processing of materials, standardization and work division.
What is the relevance of assembly-line production to mechanization in regards to
design of products?
effect on the workforce?
Trade-offs of mechanizing a production process.
quality of product
batch production - Limited volume production (a set number of items to be produced
mass production – The production of large amounts of standardized products on production lines, permitting very high rates of production per worker
Compare batch production and mass production in a mechanized production system based on:
economies of scale.
automation – A volume production process involving machines controlled by computers
The development of computer and information technology in the "technological revolution" led to the introduction of automation
This transformation requires electricity to be reasily available
computer-aided manufacture (CAM) - The use of computers to aid manufacturing
computer numerical control (CNC) – Refers specifically to the computer control of machines for the purpose of manufacturing complex parts in metals and other materials. Machines are controlled by a program commonly called a "G code". Each code is assigned to a particular operation or process. The codes control X,Y,Z movements and feed speeds.
How does CAD, CAM and CNC contribute to an automated production system?
just-in-time (JIT) - A situation where a firm does not allocate space to the storage of components or completed items, but instead orders them (or manufactures them) when required. Large storage areas are not needed and items that are not ordered are not made.
just-incase (JIC) – A situation where a company keeps a small stock of components (or complete items) or ones that take a long time to make, just in case of a rush order.
mass customization -A sophisticated CIM system that manufactures products to individual customer orders. The benefits of economy of scale are gained whether the order is for a single item or for thousands
changing the relationship between the manufacturer and the consumer
The relationship is akin to craft production, where the individual requirements of the consumer dominate
The impact of automation on working conditions
nature and type of employment
health and safety issues
The impact of automation on product quality
Many products require such precision in their manufacture that, without automation, it would not be possible to produce them at an affordable price
For many years, foreign import automobiles had much higher quality control than American automobiles
Economic Considerations 5.5
scale of production
complexity of product
size and weight of product for storage and distribution,
type of advertising and marketing,
costs relating to availability and procurement of materials
Types of Costs
fixed costs - The costs that must be paid out before production starts, for example, machinery. These costs do not change with the level of production.
variable costs – Costs that vary with output, for example, fuel or raw materials .
Return to the list on the previous slide and identify the type of cost for each
Cost based on production process
raw materials and labour costs will be significant for an individually crafted mahogany table, but for an injection-moulded plastic component these costs would be low and the capital cost of machinery high.
Once "break-even" point is reached, profits can be made, because fixed costs have been covered. Variable costs will continue to rise with increased production.
Clean Manufacturing 5.6
The introduction of mass production increased damage to the natural environment.
A historical perspective is important. Environmental considerations were not an issue in the 18th and 19th centuries. Little quantitative data was available, and all governments encouraged the growth of industry
Why clean our manufacturing processes?
promoting positive impacts
ensuring neutral impact or minimizing negative impacts through conserving natural resources
reducing pollution and use of energy,
reducing wastage of energy and resources.
The "end-of-pipe" approach.
The initial response to reducing emission of pollutants is usually adding clean-up technologies to the end of the manufacturing process.
legislation provides an impetus to manufacturers to clean up manufacturing processes.
Strategies for cleaning up manufacturing are mainly reactive
Many companies react to legislation or impending legislation by doing the minimum required. More radical approaches, for example, life cycle analysis, are proactive
more radical approaches require a rethink of the whole system and may result in significant product and/or process modification or radically new technologies.
targets for reducing pollution and waste from industry are agreed internationally, but not all industrial nations agree to the targets
What are the difficulties of stating targets against the background of ever-changing social, political and economic changes?