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Technology

Technology is the systematic knowledge of the industrial arts. Industrial engineers have been applying technology to the workplace for over two centuries. Manufacturing systems analysed by method and time studies have been improved by the division of labour, automation and robotics. Large productivity improvements have been achieved by applying technology to manufacturing processes. From the mechanisation of flour production to the robotic assembly of vehicles, process costs have been reduced. The application of technology to the motor industry has resulted in vast increases in productivity.

Method study is concerned with the dissection of a complex operation into it’s single constituent parts, which are then systematically analysed. The method study engineer synthesises the complete operation using components which optimise factors such as symmetry and the rhythm of movement.

The time study engineer measures the time taken to carry out an operation. The analysis is carried out in a systematic manner and it makes this form of study suitable only for simple and repetitive tasks. Often, time study exposes inefficient operations and these can then be analysed using method study.

It was the use of both method and time studies that led to the wide-scale use of the division of labour and the creation of the assembly line concept. Workers grouped on lines achieve productivity levels many times greater than single operatives making the entire product.

Automation has also produced large productivity increases by replacing men with machines. In highly automated manufacturing plants, the operator controls and supervises the process. The main power olders in future societies will not be capitalists or socialists, but people who possess expert technological skills. In this way, power will be passed to the techno-structure.

Automation

Automation in the manufacturing industries covers a whole range of electrical and mechanical equipment. In the field of automatic assembly, devices are used for automatic feeding and insertion. In addition, work transfer is by conveyor or rotating table. The type of system used for the assembly of a product is dependent upon many factors. The local cost of labour affects the economic justification of using automation to replace that labour. The frequency of design changes and the number of product styles dictate how flexible the equipment needs to be. The market life of the product influences the amortisation period of the capital investment. Finally, the annual product volume determines the required cycle time.

In addition to the above economic considerations, another reason for employing automatic assembly may be one of necessity. In certain areas, where labour is scarce, the use of automatic assembly is imperative. Certain operations may be hazardous or they must take place in dangerous working conditions. For example, the handling of toxic chemicals or working in extreme temperature conditions may exclude the use of manual workers. A further reason may be associated with the scheduling of the assembly operations: better control over production can be achieved with automation and product quality will be more consistent.

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The assembly operation consists of the two basic activities of handling and insertion.  If a product is to be assembled automatically then thought has to be given to the economics of these activities. The automatic feeding of simple parts is usually carried out using a vibratory bowl feeder. Components in bulk random orientation are placed into the feeder and the parts are presented to the workhead in an ordered manner. Difficult parts may be fed by special feeders, hoppers or by magazines. The insertion process is defined as being the action where one part is assembled to another part, or group of parts. High speed operations, where the same parts are inserted for long periods of time, are normally effected by standard pick-and place units. Difficult operations, involving the assembly of a number of different parts with different operations may require assembly robots.  The flexibility of the robot is created by using computer programs to control the robot arm movements. The difference between a robot and a pick-and-place is that the path of the robot arm is not restricted by mechanical means, whereas pick-and-place units rely upon mechanical stops to determine the path they follow.

Division of labour

The division of labour is the process whereby one complex operation is broken down into a number of simpler tasks. These single tasks are carried out using a series of people, each doing one task. In this manner, a complex task performed by one worker is replaced by a number of workers operating in series. This allows operations to be carried out simultaneously, instead of the single operator having to complete one task before commencing another, different task. Unskilled workers can then be used to carry out these simple operations and they soon become efficient at the particular task.

Assembly systems

An assembly method can be classified into one of six types, and most systems may contain a number of different methods.

The traditional form of assembly is manual and, for high volume production, the workers are arranged on an assembly line. Other forms of manual assembly include a single worker assembling a complete product and groups of workers assembling a portion of the product.

When the range of products is more limited, a manual assisted method can be used, whereby workers are assisted by mechanical devices, such as parts feeders. The feeders present the parts to the assemblyworker in an ordered manner.  The assembly time is reduced by eliminating the time taken to separate the parts from bulk random orientation.

The third form of assembly uses automatic indexing assembly machines.  A rotary or in-line machine has a number of workstations with automatic feeders which supply components to workheads for assembly of the part to the fixture, or part-built assembly. The workstations are 'special-purpose' and are dedicated to the assembly of one product only. Production volumes need to be high for the economic justification of these machines. Component quality must also be high to avoid excessive workstation downtime, caused by jamming, etc.

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The efficiency of an automatic free-flow assembly machine is less dependent on parts quality. The transfer of work pieces between each workstation is non-synchronous. Small buffer stocks are held between each workstation and the other workstations still operate even if one is stopped because of a fault, e.g. a defective part jammed in the escapement mechanism.

The programmable automatic assembly machine has a non-synchronous transfer line with a series of programmable or robotic workstations to assemble components. Parts are presented to the workheads by automatic feeders or, in the case of difficult components, magazines may be used. The workheads can execute one or a number of operations. Flexibility is acheived by using different programs for each product to be assembled.

The final type of assembly system is robotic assembly and it is used for the assembly of products manufactured in low production volumes. This method can also be used when there is large product variety. Work transfer is not by conveyor, as all the assembly operations are carried out by a single robot.  Transfer of the completed sub-assembly onto the next operation may also be done by the same robot.

The direct labour content in assembly is reduced in the progression from manual assembly to robotic assembly. However, the complexity of the equipment increases as workers are replaced by machines.  Indirect labour also increases for the maintenance and computer control of the equipment.

Economic aspects

The application of technology to manufacturing is used to increase productivity and the selection of a system for the economic assembly of a product depends upon a number of factors. The final selection must take into account the following:

- Market life of product - influences the decision of the company on investing in capital equipment. Products with short market lives are usually assembled manually.

- Variations in demand - Automatic assembly machines are designed to operate with fixed cycle times. Low demand leads to increasing stock levels or the machine has to be stopped. Both of these actions are expensive. Flexibility to assemble different types of products is needed if there are large demand variations. This flexibility can only be provided by manual assembly or programmable machines.

- Parts quality- Automatic assembly machines are intolerant of defective parts and they can cause a station to breakdown. Whilst inter-station buffers will reduce the effect on efficiency, manual assembly is necessary for products that use low quality parts.

- Number of products - to be assembled by a system determines how flexible it needs to be. Different products manufactured in high volumes can be assembled using programmable workheads. Smaller volumes require manual assembly.

- Major design changes - Products subject to frequent design changes need flexible assembly systems, in a similar way to systems used to assemble a variety of products.