Contaminants machines, effect

Water contamination is a constant threat. The sources of water are many—atmospheric condensation, steam leaks, oil coolers, and reservoir leaks. Rusting of machine parts and the effects of rust particles in the oil system are the major results of water in oil. In addition, water forms an emulsion and, combined with other impurities, such as wear metal and rust particles, acts as a catalyst to promote oil oxidation. 

Quantifying the effect of surface roughness or morphology is difficult, however. Surface preparations that provide different degrees of surface roughness also usually produce surfaces that have different oxide thicknesses and mechanical properties, different compositions, or different contaminant levels. The problem of separation of these variables was circumvented in a recent study [52] by using a modified microtome as a micro milling machine to produce repeatable, well-characterized micron-sized patterns on clad 2024-T3 aluminum adherends. Fig. 2 shows the sawtooth profile created by this process. 

Selection and care of the hydraulic fluid for a machine will have an important effect on how it performs and on the life of the hydraulic components. During the design of equipment that requires fluid power, many factors are considered in selecting the type of system to be used-hydraulic, pneumatic, or a combination of the two. Some of the factors required are speed and accuracy of operation, surrounding atmospheric conditions, economic conditions, availability of replacement fluid, required pressure level, operating temperature range, contamination possibilities, cost of transmission lines, limitations of the equipment, lubricity, safety to the operators, and expected service life of the equipment. 

The slushing material finds its most useful application on big machinery requiring protection of large areas during storage or during intervals of idleness in machine shops. The effect of dust and dirt contamination should therefore be considered an important factor in assessing the quality of these materials. 

Extensive process simulation (broth fill) results for BFS effectively demonstrate that high levels of sterility confidence can be obtained with a properly configured and validated machine. However, in order to maintain high levels of sterility assurance, it is important that levels of microbial contamination are controlled within the filling environment. 

All these effects are accomplished with no physical contact between the laser and the workpiece. The laser beam has only to focus on the area in which it is to work. Thus laser may easily work areas accessible only with difficulty by conventional tooling and no drill chips are left behind to contaminate or scratch the material. The material removed in laser machining operations frequently is in the form of fine dust that is removed from the area by a suction system. 

Surface Finishes. Of almost equal importance are surface finishes and surface coatings. For instance, E-coating (or electrophoretic painting) is an effective contaminant-containment for many machined metal surfaces such as aluminum and magnesium surfaces, and for magnets. Other surface treatments applied in past and current IBM disk drives are listed in Table A1. 

Routes of air-borne contamination into BFS containers were investigated during a study using Sulfur hexafluoride (SFs) tracer gas. During this experiment, the tracer gas was released at a known concentration into a clean room that housed an aseptic BFS machine. Levels of the tracer gas were then measured within subsequently filled BFS units. The study concluded that the container was effectively protected by the localized air shower. Although not necessarily representative of deposition of microbial contaminants, there also was conclusive evidence of some room air within the BFS containers. The control of environmental contamination within the clean room is therefore important. 

Frequency and size of broth fills must be clearly defined. Size of fill is usually based upon the statistical probability of detecting an acceptably low incidence of microbial contamination. Tables have been published to this effect,but the BPS operator must decide both the size and frequency of broth fills based upon their specific facility, routine product batch sizes, and operation. For high-speed BPS machines, filling routine product batches in excess of 100,000 units, relatively large broth fill batches, in comparison with traditional aseptic filling lines, are both feasible and appropriate. 

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