Costing assemblies

The anodes most suitable for burying in soil are cylindrical anodes of high-silicon iron of 1 to 80 kg and with diameters from 30 to 110 mm and lengths from 250 to 1500 mm. The anodes are slightly conical and have at the thicker end for the current lead an iron connector cast into the anode material, to which the cable connection is joined by brazing or wedging. This anode connection is usually sealed with cast resin and forms the anode head (see Fig. 7-2). Ninety percent of premature anode failures occur at the anode head, i.e., at the cable connection to the anode [29], Since installation and assembly costs are the main components of the total cost of an... 

Before setting about the task of developing such a model, the product development process requires definition along with an indication of its key stages, this is so the appropriate tools and techniques can be applied (Booker et al., 1997). In the approach presented here in Figure 5.11, the product development phases are activities generally defined in the automotive industry (Clark and Fujimoto, 1991). QFD Phase 1 is used to understand and quantify the importance of customer needs and requirements, and to support the definition of product and process requirements. The FMEA process is used to explore any potential failure modes, their likely Occurrence, Severity and Detectability. DFA/DFM techniques are used to minimize part count, facilitate ease of assembly and project component manufacturing and assembly costs, and are primarily aimed at cost reduction. 

Often, the manufacturing processes involved for composite structures fabrication are greatly simplified as compared to those for metal structures. Reduced part count results in a much lower assembly cost and overall reduction in the factory labor hours. 

Reactors Assembled cost is 5/lb. Dished bottoms, open tops, height equal to diameter, bottom surface equals 1.5 times the surface of a flat plate of the same diameter. Tanks of over 1500 gal capacity are of 1/4" plate, smaller ones of 3/16" plate. Freeboard equals volume of the dished head. 

Outserts are large machined metal plates with holes and other anchorages onto which a plastic is locally overmoulded to ensure specific functions. The metal plate brings high rigidity and the plastic ensures insulation, frictional properties, damping... This technique cuts the assembly costs of numerous small plastic parts. 

The simplest assembly and joining methods. In-mould assembly can significantly reduce or eliminate assembly costs. 

Figure 8.10 covers gas-fired turbine and cylinder-type engines, and Fig. 8.11 covers steam turbine drivers. Motor drivers and gear assembly cost is also shown in Fig. 8.10. Having a required compressor BHP, the driver cost of choice may be read from one of these two figures. The gear assembly cost is applicable to any of the drivers given in Figs. 8.10 and 8.11.

Instrumental in saving "down stream" assembly costs"(2)... 

The creation of molded circuit boards which reduce "down stream" assembly costs. 

Cost estimates for each system at each of the four production levels are the sum of materials, manufacturing, and assembly costs, as well as a manufacturer s markup and a 10% cost contingency (as is standard automotive cost estimation practice). As might be expected, cost of the finished system decreases with increasing production volume. 

An alternative is to have the tray fabricated with all nuts welded to the tray pieces. This alternative saves both assembly costs and installation time, and the savings easily pay for the added fabrication costs (128, 274). It is estimated (274) that a loose-bolted tray takes 15 percent more time to install than one which has no loose bolting. Often, a loose-bolted tray assembly requires two assemblers (one to screw the bolt and the other to hold the nut), while only one assembler is required when the nuts are welded. Despite the cost and time disadvantages, loose-bolting is almost always preferred to welded nuts, because it enables easy removal of corroded or worn parts in the fiitme. Welded nuts are only justified in clean, noncorrosive services, and when installation time is critical. Sometimes, loose bolting is specified between the tray floor pieces, and welded nuts are specified for the downcomer and tray inlet areas (274). 

The total assembly cost of a product is related to both the product design and the assembly system used for its production. Assembly costs can be reduced to a minimum by designing the product so that it can be assembled economically by the most appropriate assembly system. Assembly systems can be classified info fhree cafegories ... 

The early history of assembly process development is closely related to the history of the development of mass production methods. Thus, the pioneers of mass production are also considered the pioneers of modern assembly. Their ideas and concepts significantly improved the manual and automated assembly methods employed in large-volume production. In the past decade, efforts have been directed at reducing assembly costs by the application of flexible automation and modem techniques. 

The suitability of a product design for assembly influences its assembly cost and quality. Generally, product engineers attempt to reduce the assembly process cost based on plans drawn by designers. The recent trend has been toward product assemblability from the early design phase in order to respond to the need for reduction in time and production costs. 

Correlation of assemblahUity evaluation indexes to assembly cost... 

The Boothroyd-Dewhurst method aims primarily at reducing assembly costs by means of an integrated construction system. Other measures, such as product structuring, sorting, the construction of subassemblies and the differential construction technique are not considered. The evaluation of the suitability of the assembly system requires that the product be a constructed one. This means that assembly suitability is taken into consideration only very late in the construction process. The Boothroyd-Dewhurst DFA method is also available for PCs. 

In addition to the assembly cost reductions through DFA, there are reductions in part costs that are more significant. Other benefits of DFA include improved reliability and reduction in inventory and production control costs. Consequently, DFA should be applied regardless of the assembly cost and product volume. 

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