Surface Defects
In practice the quality determination of component parts often involves the
identification and subsequent quantification of characteristic defects, that
pertain to the particular manufacturing process employed. In consequence
it is often possible to associate specific products, materials and manufacturing
processes, with particular types of observable surface defect. For example,
injection moulded components may tend to exhibit undesired sink or tooling
marks, and/or incomplete or additional topological features, whose form,
position and orientation, directly relate to both component and tool design.
Similarly, cutting, grinding and polishing operations may produce characteristic
surface markings, including an altered texture and excessive burrs due to
tool wear or the inclusion of foreign abrasive materials. Other characteristic
defects include a distinctive wrinkled aspect to sheet metal components,
and defective solder joints, which exhibit a predictable abnormal surface
appearance and shape. Further examples are the excessive splatter and surface
discoloration observed during welding and laser machining, and various surface
imperfections upon semi-conductor wafers, and in the glaze of ceramic tableware,
both of which result in the distribution of characteristic observable surface
traits.
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