General Engineering Applications

In addition to their use in specialised applications as discussed in earlier chapters, a variety of plastics are used in many general engineering applications such as gears, bearings and so on, some of which are listed in Table 8.1. 

As shown in Table 8.1 plastics are used in gears, bearings, bushes, cogs, cams, sprockets, gaskets, valve seals, pump impellers, piston rings, pipes and hoses, compressors, valves, pumps, wear pads and O-rings. 

Pump impellers PEEK, 30% carbon fibre reinforced 

ABS Acrylonitrile-butadiene-styrene HOPE High-density polyethylene LDPE Low-density polyethylene MoS Molybdenum disulfide PA Polyamide(s) PAI Polyamide-imide PBT Polybutylene terephthalate PEEK Polyether ether ketone PEI Polyether imide PET Polyethylene terephthalate PI Polyimide PMMA Polymethylmethacrylate POM Polyoxymethylene PP Polypropylene PPS Polyphenylenesulfide PSU Polysulfone PTEE Polytetrafluoroethylene PU Polyurethane PVDE Polyvinylidine fluoride UHMWPE Ultra-high molecular weight polyethylene UV Ultraviolet XPE Crosslinked polyethylene Source Author s own files  

Gears are a particularly critical application of plastics and, as such, are considered in more detail in the flowing sections. 

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There exists, however, as demonstrated by numerous experiments [7], a lower value for Recr that is approximately at 2000. Below this value the flow remains laminar even in the presence of very strong disturbances. If the Reynolds number is greater than 10,000, the flow is considered to be fully turbulent. In the 2300 to 10,000 region, the flow is often described as transition flow. It is possible to shift these values by minimizing the disturbances in the inlet flow, but for general engineering application the numbers cited are representative. 

Tough-pitch copper, of 99.85% purity, is used in chemical and general engineering applications where the highest conductivity is not... 

Part of the N S Group, one of the world s major suppliers of automotive components, PREMIER VANDERBILT LTD is a market leader in the manufacture of plain bearings for automotive and general engineering applications. 

Phosphorus deoxidised arsenical copper, of 99.2% purity with 0.3% to 0.5% arsenic, is widely used for copper tube and general engineering applications where brazing and welding are required. 

The selection criteria in this data set are based on their common usage for general engineering applications. Certain sectors like aerospace and the... 

Unfortunately, the LCPs are often too expensive for general engineering applications. On the other hand, there are considerable supplies of engeneering plastics in the form of post-consumer scraps, which are a low cost source of raw materials for polymer blends. However, unlike LCPs, the molecules of common thermoplastics relax during melt processing therefore a good molecular orientation is almost impossible. 

The opportunities for improving the heat resistance of NBR vulcanisates through the use of improved polymers and optimised compounds have been described in Sections 4.6 and 6.3. The progress in this field has been sufficient to ensure that NBR will retain many automotive and general engineering applications in which improved heat resistance is necessary. 

This type of collector has found wide application in general engineering and very high collection efficiencies are possible, but at the expense of considerable power requirements. General-purpose collectors at pressure drops across the collector of 150 mm will have collection efficiencies of 98 per cent at 10 pm and above. Units with pressure drops of 800 mm and efficiencies of more than 99 per cent on sub-micron particles are available. 

It will be noted that the materials covered by the BS specifications fall into several distinct groups, sometimes with apparently small differences within the group. Characteristics which could influence the selection of the most appropriate material for a specific application are tabulated in Table 4.1 for wrought products, but some elaboration is desirable since the successful utilisation of aluminium begins with the selection of alloy. Additionally, mention should be made of materials not covered by the BS General Engineering series. 

No general conclusions on the relations among these parameters can be drawn for the scarcity of better information. Experiments should be designed to measure the tribological properties of TFL for engineering applications. 

Consequently, exergy analysis can likely assist in efforts to optimize the design of CTES systems and their components, and to identify appropriate applications and optimal configurations for CTES in general engineering systems. 

In engineering applications we routinely incorporate inorganic fillers, such as glass fibers and mineral particles, into nylons. In general, fillers perform three functions they reduce the cost of the product, they increase its stiffness, and they reduce shrinkage and warpage in molded products. 

A general limitation of rotational instruments is that the high shear rates typical of most engineering applications cannot be achieved because, at the high speeds needed, secondary flow occurs and compromises the measurements. 

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