Manufacturing process effect

One of the goals of successful process development is to design and introduce a smooth-running manufacturing process. Effective laboratory effort prior to scale-up, e.g., pilot plant trials, will pay off by establishing a manufacturing process... 

Mechanical Properties and Structural Performance. As a result of the manufacturing process, some cellular plastics have an elongated cell shape and thus exhibit anisotropy in mechanical, thermal, and expansion properties (35,36). Efforts are underway to develop manufacturing techniques that reduce such anisotropy and its effects. In general, higher strengths occur for the paraHel-to-rise direction than in the perpendicular-to-rise orientation. Properties of these materials show variabiUty due to specimen form and position in the bulk material and to uncertainty in the axes with respect to direction of foam rise. Expanded and molded bead products exhibit Httie anisotropy. 

When adininistered orally, digoxin bioavailabihty ranges from 40 to 90% depending on the manufacturing process. Peak plasma levels occur within 3 h after oral adininistration peak effects occur 2 h later. The dmg is elkninated primarily through the kidney (114). 

The temperature at which decarboxylation occurs is of particular interest in manufacturing processes based on polymerisation in the molten state where reaction temperatures may be near the point at which decomposition of the diacid occurs. Decarboxylation temperatures are tabulated in Table 2 along with molar heats of combustion. The diacids become more heat stable at carbon number four with even-numbered acids always more stable. Thermal decomposition is strongly influenced by trace constituents, surface effects, and other environmental factors actual stabiUties in reaction systems may therefore be lower. 

The Toxic Substances Control Act (TSCA) was enacted in 1976 to identify and control toxic chemical ha2ards to human health and the environment. One of the main provisions of TSCA was to estabUsh and maintain an inventory of all chemicals in commerce in the United States for the purpose of regulating any of the chemicals that might pose an unreasonable risk to human health or the environment. An initial inventory of chemicals was estabhshed by requiring companies to report to the United States Environmental Protection Agency (USEPA) all substances that were imported, manufactured, processed, distributed, or disposed of in the United States. Over 50,000 chemical substances were reported. PoUowing this initial inventory, introduction of all new chemical substances requires a Premanufacturing Notification (PMN) process. To be included in the PMN are the identity of the new chemical, the estimated first year and maximum production volume, manufacture and process information, a description of proposed use, potential release to the environment, possible human exposure to the new substance, and any health or environmental test data available at the time of submission. In the 10 years that TSCA has been in effect, the USEPA has received over 10,000 PMNs and up to 10% of the submissions each year are for dyes (382)... 

The egg products are finally processed and spray-dried. Sometimes Hquid egg whites are concentrated before spray-drying by ultrafiltration (qv) or reverse osmosis procedures. Table 5 presents the effect of egg quaUty on the different egg product manufacturing processes. 

More important than either creep or fatigue in current car design is the effect of environmerit (Chapter 23). An appreciable part of the cost of a new car is contributed by the manufacturing processes designed to prevent rusting and these processes only partly work - it is body-rust that ultimately kills a car, since the mechanical parts (engine, etc.) can be replaced quite easily, as often as you like. 

Improperly set tolerances and uncontrolled variation are one of the greatest causes of defects, scrap, rework, warranty returns, increased product development cycle time, work flow disruption and the need for inspection (Gerth and Hancock, 1995). If manufacturing processes did not exhibit variation, quality problems would not arise, therefore reducing the effects of variability at the design stage, in a cost-effective way, improves product quality (Bergman, 1992 Kehoe, 1996). 

The combination of the cost model and the optimization method will then give an augmented model from which the allocation of the component tolerances are optimized for competitive results. Optimization methods have also been extended to include procedures that select the most cost-effective manufacturing process for each component tolerance in the assembly stack (Chase and Parkinson, 1991). 

Theoretically, the effects of the manufacturing process on the material property distribution can be determined, shown here for the case when Normal distribution applies. For an additive case of a residual stress, it follows that from the algebra of random variables (Carter, 1997) ... 

Kluger, P. 1964 Evaluation of the Effects of Manufacturing Processes on Structural Design Reliability. In Proceedings 10th National Symposium on Reliability and Quality Control, IEEE, Washington, 538-544. 

Substitution means the replacement of a hazardous material or process with an alternative which reduces or eliminates the hazard. Process designers, line managers, and plant technical staff should continually ask if less hazardous alternatives can be effectively substituted for all hazardous materials used in a manufacturing process. Examples of substitution in two categories are discussed—reaction chemistry and solvent usage. There are many other areas where opportunities for substitution of less hazardous materials can be found, for example, materials of construction, heat transfer media, insulation, and shipping containers. 

We all hear that composite materials are very expensive, but you have seen in Chapter 1 that, one, material cost is coming down, and, two, composite structures can be less expensive to manufacture than metal structures. An effective structure can be created with an even more-expensive raw material than metals by using less-expensive manufacturing processes. The bottom line is that the initial cost of the structure can in some cases be lower for a composite material than for a metal. Generally, the life-cycle cost of a composite structure is lower than that of a metal structure. 

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