Cost advantage

The operating cost includes items like fuel and other consumables. Maintenance costs are obviously repairs and periodic reworking of the structure. After the passage of years, nearly the entire aircraft structure has often been replaced part by parti The final category is the salvage value. What is the object worth at the end of its life Consider an aluminum airplane for which some scrap value exists at the end of its useful life. When the structure is no longer suitable to be flown, and there we 

Labor cost in a structure is directly related to part count. If part count can be reduced, then labor costs (and inventory costs) wili decrease. Composite structures are generally composed of many fewer parts than are metal structures. Integral part design and fabrication techniques reduce fastener count and bonding operations. Thus, composite structures can have cost elements that are considerably lower than those for metal structures. 

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. 

Manufacturing efficiency embodies a wide variety of topics far beyond the scope of this book. However, a materials utilization factor will be defined and characterized for composite materials and metals as a 

In contrast, with composite materials, the materials utilization factor is rarely higher than 1.2 to 1.3. That is, only a maximum of 20-30% of the material is wasted with composite structures. Whereas obviously with a materials utilization factor for some metal parts of 15-25, the waste is 1500-2500% Those are not individually typical numbers, but are the worst cases in both situations, i.e., for metals and composite materiais. For metals, there are many, many operations for which the waste factor is very iow. And for composite materials there are also many situations where the waste factor is much lower than 20-30%. The point is that the worst-case situations are totaliy different for these two kinds of materials based on the way objects are inherently created with the two different types of materials. Composite materials are built up until the limits of the desired geometry are reached. At that point, the layup operation simpiy ceases. Composite materials and structures are fabricated in as ciose to the final configuration as possible, i.e., so-calied near-net shape. 

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In 1994 in the U.S., recycled PET, HDPE, LDPE, and PS had a 16—46% cost advantage (4). This cost advantage largely disappeared by 1996. Bureau of Labor Statistics data indicate U.S. plastics prices in mid-1997 are seven percent below those of mid-1995 after being more than ten percent less in 1996... 

Other synthetics with cost advantages and large volume productions are L-carvone [6485-40-17, the primary component in natural spearmint essence D-carvone [2244-16-8], the primary component in natural diU and caraway anethol [4180-23-8], in place of anise and fennel spices and smaller amounts of thymol [89-83-8] replacing thyme and disulfide synthetics for onion and gadic. AH of these synthetics must be labeled as artificial which may limit their use among consumers. 

R—Co alloys 18%, NdFeB 4%, Alnicos 11%, and others 2%. Because of the superior magnetic properties and cost advantage, the market share of NdFeB magnets had increased to 16% by 1990. 

Duplex stainless steels (ca 4% nickel, 23% chrome) have been identified as having potential appHcation to nitric acid service (75). Because they have a lower nickel and higher chromium content than typical austenitic steels, they provide the ductabdity of austenitic SS and the stress—corrosion cracking resistance of ferritic SS. The higher strength and corrosion resistance of duplex steel offer potential cost advantages as a material of constmction for absorption columns (see CORROSION AND CORROSION CONTROL). 

Further information on the different systems including a more detailed discussion of thek costs, advantages, and disadvantages is available (1,39,40). Information on actual experience is also available (32,34—36,41—47). 

Some alkylphenol appHcations can tolerate "as is" reactor products, most significantly in the production of alkylphenol—formaldehyde resins. These resins can tolerate some of the reactant and by-product from the alkylphenol reactor because they undergo purification steps. This resin production route has both capital and operating cost advantages over using purer alkylphenol streams as feedstock. For these savings, the resin producer must operate the process in such a way as to tolerate a more widely varying feedstock and assume the burden of waste disposal of some unreactive materials from the alkylphenol process. 

One more variation to the many methods proposed for sulfur extraction is the fire-flood method. It is a modem version of the Sickian method, by which a portion of the sulfur is burned to melt the remainder. It would be done in situ and is said to offer cost advantages, to work in almost any type of zone formation, and to produce better sweep efficiency than other systems. The recovery stream would be about 20 wt % sulfur as SO2 and 80 wt % elemental sulfur. The method was laboratory-tested in the late 1960s and patents were issued. However, it was not commercially exploited because sulfur prices dropped. 

Vinyltoluene, comprising a mixture of ca 33% para- and 67% y /i7-methylstyrene, has been marketed for ca 45 yr by Dow Chemical Company and also by Cosden. However, the performance properties of the polymers prepared from the para isomer are not only superior to those of the polymer prepared from the typical mixed isomers, but are generally superior to those of polystyrene (60). This advantage, coupled with a raw material cost advantage over styrene, suggests that i ra-methylstyrene may displace significant amounts of styrene, currendy a 3.2 x 10 t/yr domestic market. 

Continuous processes have lower labor costs but have higher failure risk. Batch processes can be started back up in a shorter period of time than can a complex continuous process. Batch processes are easier to take through the regulatory process than are continuous processes. Thus batch processes are often chosen for mammalian ceU culture systems, even though continuous processes can offer significant cost advantages. CeU culture costs constitute only a smaU (10—30%) fraction of the overaU cost of making a product. 

There has been much interest in making chemicals from brine because of the low expense compared to alternative methods. Lithium, for example, had been mostly produced from spodumene ore, but now most is produced from brine. Those now producing from ore are seriously researching brine reserves and contemplating converting to brine sources before the turn of the century. Similady, solar salt has cost advantages over mined rock salt. Potassium chloride produced from brine has more than doubled from 1980 to 1990. 

A hard carbon with high capacity can be made from epoxy novolac resin [12]. The epoxy resins used cost about US 2.50 per pound and give pyrolysis yields between 20 and 30%. However, it is well known that phenolic (or phenol-formaldehyde) resins can be pyrolyzed to give hard carbons with a yield of over 50% [42]. In addition, these resins cost about USSl.OO per pound. Phenolic resins therefore offer significant cost advantages over epoxy resins, so we... 

Clays are also common fillers in plywood resins. Clays have a cost advantage over most of the materials mentioned above, though there are some drawbacks to their use, particularly in terms of consistent quality. All fillers present some problems in this regard, though some are worse than others. 

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