Value and quality

Citation

Weston, J. (2004), "Value and quality", Industrial Robot, Vol. 31 No. 1. https://doi.org/10.1108/ir.2004.04931aaa.002

Value and quality

Value and quality

John Westonis a Principal Consultant at Manufacturing Support Group, TWI Ltd, Granta Park, Great Abington, Cambridge CB1 6AL, UK. Tel: +44 (0)1223 891162; Local Fax: +44 (0)1223 890669; E-mail: john.weston@twi.co.uk; Web site: www.twi.co.uk

Keywords: Joining materials, Quality control, Risk assesment, Asset valuation

Almost everything contains joints, and the organisation, where the author works, provides support to industry both with its knowledge of joining technologies and the engineering of the joint itself. The issues of value and quality frequently arise during contact with industry.

Financially, the operations involved in making the joint are usually only a small part of the total product cost. Even when welding content is high, as in a ship, the process cost can be relatively low (<10 per cent for the ship). That said, the value added by the process is significant because without the joint(s) there would be no product. Furthermore, if the joint is inadequate the product will fail (e.g. if they leak the ship may sink). As yet accountants do not have a mechanism for considering this disparity between cost and value, with the result that the justification of joining equipment (robotics) can be difficult. The author believes that this incongruity will be confronted.

Studies that are looking at the way value can be added to a product or service to increase profitability will probably lead this attack. The thinking is as follows: the builder of a bus is actually associated with the business of moving people. Today, he will simply sell to a bus company. However, if he could help in move people more reliably, perhaps he can increase his margins and profit. He might do this by changing his function to cover the supply of clean, serviced and fuelled buses. Leasing schemes, offered by some robot suppliers, show a move in this direction; however, they are but a small step in what the author believes will be a major shift in the way that we acquire and operate equipment used in joining.

The other problem, which plagues robot system suppliers, is the quality issue. Few manufacturers have a good understanding of quality in terms of welded joints. They have a fair understanding of nuts and bolts because if the hole is too small or the thread incorrect, the system will NOT function and therefore they MUST obtain these relationships right. Because these relationships are a must-get-right, the whole process from design to assembly focuses on meeting the required tolerances. This is not the case for welded joints, where many a poor weld will perform the required basic function. While the ship might have leaked, it would have stayed together as an entity and with a good pump probably went to sea. Furthermore, a skilled welder can join almost anything – and is frequently required to do so. Because they can do this the design and production chain have seldom considered all the aspects influencing joint quality.

Too often the “drawing” has:

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  an arrow, “weld here”, with no size or length or quality requirement!

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  welds must be leak tight, but to what degree and for how long (and is there a structural strength requirement) are not specified;

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  welders (operators) must be “coded”, but there is no mention of the qualification that is expected;

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  hundred per cent inspection is required, but no thought given to the relevance of that request nor to the type of inspection to be undertaken.

One cannot overemphasise the importance of knowing:

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  What is required of the joint (e.g. shape, mechanical and chemical properties) in terms of end use conditions.

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  What additionally needs to be done, for example upstream, to obtain the required joint shape and fit-up.

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  How to determine that the quality of the finished joint is as required.

A good understanding of value and quality has led to robotic welding, which can produce high quality at high rates. Even better understanding of the problems outlined earlier will lead to greater use of automation in joining cutting processes.