Types of Production Systems

Three types of production system can be identified certain features of which influence the actions of production managers.

• small batch and unit production
• Large batch and mass production
• Continuous process production

Woodward compared the affect of these on the span of control of the first line supervisor and levels in the management hierarchy. She drew conclusions on how different approaches to operational systems design affect management control over work done. The importance of information is paramount.

A few points to note are:

• Products can be divided into those a customer regards as single items or multi-component assemblies. Few companies produce single item products n.b. packaging is a product in itself. Subcontractors may produce single components for someone else to assemble (note bulk chemicals also).
• Most production in engineering, electronics, furniture etc is concerned with assemblies of manufactured internally or 'bought in' components . "Make or buy" decisions are important and considerable cost information is required .

Production system are often split between the part that produces components and the part that assembles them and certain basic organisation structures can be identified in a production plant:

• FUNCTIONAL
  - production facilities grouped by function e.g. all furniture drilling machines together, all sanding and finishing machines together. Orders are routed through the functional departments where each operation is performed. The benefits of 'collective expertise' are obtained but the operators are 'task specialists'. This can result in motivational and attitudinal problems. Functional organisation is flexible but needs much close control and information on the progress of 'batches' between shops.

• LINE
  - materials flows through the manufacturing facilities are uni-directional and any product flowing along the line usually requires all the facilities on the line. With computer control of materials movements far more flexibility vis a vis exactly what components go into each product as it passes down the line can be built in. This is a feature of the modern computer controlled car assembly line where so long as the car is a Micra different versions (E, L, GLS, Turbo etc) will sit side by side on the line.

  This type of approach needs a well trained, flexible workforce with supervisors and workers on the shop-floor possessing up-to-the-minute information. When the product type is changed - complex resetting is necessary.

• CONTINUOUS PROCESS
  - is a special form of line organisation that is - plant dominated. The operation of the system is defined almost completely when the plant is designed (chemical plant, nuclear power station etc) Constant control of the process is needed for efficient control operations e.g. to adjust temperatures.

• GROUP ORGANISATION
  - is similar to LINE except that a group or cell of facilities processes a range of items with similar facility requirements. All items (not physically similar necessarily) produced by the group won't need all the facilities. Different facilities within the group will be working on different items. again material flows should be uni-directional as possible and immediate information on work flows and priorities is needed by the supervisors and workers.

These modes of production have substantial implications in terms of ability to control stocks, supplier-customer relationships and the sophistication of purchasing systems.

Comparing Physical Organisations

Manual assembly of products for stock in high volumes is usually line organisation because of use of semi-skilled staff, size of work-in-progress inventories, training time and the efficiency of the work design. However unit assembly by small group or individual is more likely to be MtO or jobbing work. Component manufacture (medium volume) is usually batch or functionally organised because of the need for machine stations and the inflexibility of machine cycle times. Low utilisation of facilities is a problem. The flexibility of functional organisation has a cost of high work-in-progress inventories to stabilise uneven workflow. Line organisations (inflexible) have efficient throughput rates with low inventories. The use of computers to minimise the inefficiencies of each is therefore obvious.

Example: Functional Organisation.

An order requires 10 operations with a total batch work content time of 20 hours only . However work in progress queues may involve 2 days waiting at each work centre. Thus an order would take 3 weeks (10 opertations * 2 days) to have only 20 hours work done on it.

Throughput Efficiency = 20 hours ----> 3 weeks

Thus a typical functional organisation will have a T.E. of 10-20% rarely higher.

Problems in MtO and MfS

Control-ables

1. capacity (output rate)
2. Finished stock levels (inventory investment)
3. Customer delivery times.

The OPS Mgr needs data on these to manipulate efficiency to the best

Examples

• Poor quality control at Jaguar Cars in the 70's led to considerable employee alienation. The company's high quality standards now and emphasis on employee excellence (participation and training) are reaping dividends.

• A restaurant chain decides to re-design its franchise outlets so that only a limited range menu is offered (for fast, efficient service). Any change in eating habits or in the cost structure of the menu will render the design partial

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