Manufacturing process

Three processes are industrially operated in which aqueous solutions of sodium chloride are electrolyzed for the manufacture of chlorine, sodium hydroxide and hydrogen  

Manufacture using the membrane process is gaining in importance, since new chlorine capacity exclusively utilizes this technology. In Japan sodium chloride electrolysis is exclusively carried out membrane plants. The percentage contributions of the three processes to chlorine production are given in Table 1.7-15 (Europe) and Table 1.7-16 (worldwide). 

We can readily polymerize styrene by a variety of methods including solution, emulsion, suspension, and bulk processes. Historically, bulk polymerization was the first commercial process, but it has now largely been superseded by solution and suspension polymerization. 

The manufacturing process for cationic surfactants can be divided into two parts. The first part is the creation of an alkylated amine. Several processes can achieve this endpoint and are briefly reviewed below. The largest volume process which was developed by Armour starts with tallow triglyceride which is split to yield fatty acid and glycerine. The fatty acid is reacted with ammonia and converted to fatty nitrile under high pressure and temperature conditions 

Alternate routes to amine derivatives have been developed in the intervening years. The production of dimethylamines can be accomplished by the routes shown in eqs 6.1.4-6.1.7. [8]. Both routes involve the reaction of an alkyl halide with dimethylamine. The first route is the conversion of a fatty alcohol to fatty chloride using phosphorous trichloride. The alkyl chloride is reacted with dimethylamine giving the alkyl dimethylamine [9, 10]  

In the second route an alpha olefin derived from ethylene reacts with hydrogen bromide and a free radical initiator resulting in an alkyl bromide. The alkyl bromide is reacted with dimethylamine providing the desired product [11,12]  

Alcohols and aldehydes are also suitable materials for the creation of an alkyl amine. In addition to the aforementioned formation of alkyl chloride as an intermediate, alcohols can be directly converted to amines under hydrogenation conditions in the presence of ammonia while aldehydes are prereacted to form imine followed by hydrogenation [13]. Selectivity of the primary amine with these techniques is difficult and this process is more typically utilized for the preparation of tertiary amines where the reaction can be driven to completion. In certain cases, alcohols and aldehydes provide structural elements which are not attainable from natural sources. An example is the formation of a hydrogenated tallow 2-ethyl hexyl amine. The amine is prepared as shown below in eqn 6.1.8 using a hydrogenated tallow amine reacted with 2-ethyl hexanal [14, 15]  

The intermediate imine is hydrogenated giving the secondary amine. Formation of tertiary is suppressed due to the steric hindrance of the branched chained substituent. The 

A cross-linked polyolefin foam sheet is produced by two methods using chemical cross-linking and by two methods of radiation cross-linking. The two well-established manufacturing processes for polyolefin foams using radiation cross-linking are the Sekisui process and Toray process. The differences between these two manufacturing methods are mainly in the expansion step, which is almost always done separately. However, the 

Flow diagram of the manufacturing process for polyolefin foams using radiation cross-linking. 

Comparison of Radiation and Chemical Cross-Linking Processes for Producing Polyolefin Foams 

Item Radiation Cross-Linking Chemical Cross-Linking 

Cost Decreases with production volume Relatively constant 

In this very broad field, very little that is specific can be said. Usually it is the intent of the manufacturer to select reaction vessels from alloys that will be resistant to reactants and products in the process. If this is not feasible, other means must be used for protection, one of which could be the use of inhibitors. 

It is usually desirable to select alloys that are resistant to the acid to be stored. When this is not possible, it is necessary to protect the metal (usually mild steel) by means of a suitable inhibitor. 

In most cases, the prepreg tapes then have to be cut into specific shapes as required by the component s design (i.e. its geometry and ply sequence) 

For obtaining a low -weight, high-bending-stiffness structure, sandwich constructions are a conunon choice for composite components. To make a sandwich, low-density materials are inserted as sandwich cores between two faces of the structural material itself (so in this case between two stacks of prepreg plies). Commonly used core materials are plastic foams (for example, made from PVC, PS, or PET) and balsa wood. Examples of core materials for more sophisticated, structured sandwich cores are honeycombs (made from aluminium, or resin-impregnated paper sheets), or fibre-reinforced foams. 

When preparing sandwich cores for part manufacture, particular care should be taken to ensure that only material free of contamination is used during 

Therefore, when using such core materials for sandwich constructions in part manufacture, suitable procedures for cut-out preparation, cleaning, wrapping, storage and transport, as well as for humidity control (measurements, plus drying prior to lay-up), must be implemented. 

An appropriately designed mould is crucial for accurately controlling the process and, thus, for obtaining a qualitatively acceptable composite structure. Some of the most important criteria to be taken into account are as follows  

You should learn and digest the very new and different characteristics of composite materials as actually used in structures as compared to what you are familiar with in metal structures. You must know the reasons why composite materials are used. 

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. 

You should become acquainted with the various manufacturing processes for composite structures. That large body of processes for 

This chapter will give general information about hydroforming and isostatic pressing and more detailed information about autofrettage process (Section 11.1) and waterjet cutting technology (Section 11.2). 

Hydroforming Hydroforming is one of the new technologies in the manufacturing processes that has become popular in recent years due to the increasing demands for lightweight parts in various fields, such as bicycle, automotive, aircraft, and aerospace industries [ 1 ]. In hydroforming process, workpieces are uniformly plastically formed (stretched) in every direction under hydrostatic pressure up to 6000 bar (mostly up to 2500-3000 bar) of a fluid (water or oil) in a controlled manner. The final shape of the hydroformed piece results from the contact with the process fluid from one side and with a male or female die from the other side. 

Industrial High Pressure Apfdications Processes, Equipment and St ety, First Edition. Edited by Rudolf E ers. 2012 Wiley VCH Verlag GmbH Co. KGaA. Published 2012 by Wiley-VCH Verlag GmbH Co. KGaA. 

Isostatic Pressing Pressure applied to a liquid or a gas acts uniformly in every direction at every contacting surface. This basic principle, first postulated by Blaise Pascal, 1623-1662, is commonly called isostatic pressing and is widely utilized for compacting powder or densifying porous materials. 

Depending on the compressibility and the porosity of the material, the dimensions are reduced proportionally to the applied pressure, but the shape of the product remains unchanged. 

Chemical fibers are produced according to three different methods wet spinning, dry spinning, and melt spinning. 

These spinning methods have the following principles in common. 

A major difference between spinning methods is in how the raw material (pellets or powder) is liquefied. 

In wet as well as dry spinning, the raw material is liquefied into the spinning compound using a solvent. These methods are called solution spinning. As the technical process for these methods is relatively complex, they are used only if the polymer cannot be melted by heating but decomposes instead. For melt spinning, the pellets are simply melted to produce the spinning compound. 

Furthermore, the spinning methods differ essentially in terms of how the filaments pressed through the nozzles solidify. In melt spinning (Fig. 2.20), the spinning compound is spun into a cold-air quench duct. Because in this process no solvents are released, the recycling of by-products is not necessary. Polyamide and polyester are produced according to this method. 

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Changes in the consumer needs which are manifested by the appearance of new types of products, new manufacturing processes and new uses for products, each requiring specific qualities. 

Simple service of control devices, easy automation of the control process allows for extensive application in part manufacturing processes. 

Repeatability. This refers to two aspects of inspection similarity between objects that are inspected and possibility of maintaining constant inspection conditions (settings) for all the inspections performed. Obviously, interpretation of data in repeatable conditions is significantly simplified. Usually, inspection during or after manufacturing process will be repeatable. Another example of repeatable inspection is inspection of heat exchangers in power nuclear plants, inspection of aircrafts as these are well standardised. However, a large part of the NDT inspection done is not repeatable. 

Neural network classifiers. The neural network or other statistical classifiers impose strong requirements on the data and the inspection, however, when these are fulfilled then good fully automatic classification systems can be developed within a short period of time. This is for example the case if the inspection is a part of a manufacturing process, where the inspected pieces and the possible defect mechanisms are well known and the whole NDT inspection is done in repeatable conditions. In such cases it is possible to collect (or manufacture) as set of defect pieces, which can be used to obtain a training set. There are some commercially available tools (like ICEPAK [Chan, et al., 1988]) which can construct classifiers without any a-priori information, based only on the training sets of data. One has, however, always to remember about the limitations of this technique, otherwise serious misclassifications may go unnoticed. 

In general, radioscopic X-ray inspection systems are used in the serial examination of industrial workpieces since they enable a flexible adjustment of the beam direction and of the inspection perspective as well as on-line viewing of the radioscopic image. In the past few years this economic and reliable method has become prevalent in weld inspection during the manufacturing process of pipes. The configuration of such radioscopic systems is schematically represented in fig. 1. 

In many applications, it is necessary to learn about the surface characteristics of a wire, and it is also important to measure them during tlie manufacturing process. 

Therefore, it is important for judging the performance and the safety of the product to understand the size of the defect and the position by the ultrasonic method quantitatively. And, the reliability of the product improves further by feeding back this ultrasonic wave information to the manufacturing process. 

And, the reliability of the product improves further by feeding back accurate ultrasonic wave information obtained here to the manufacturing process. 

Non-Desfructive testing can be apph ed widely in all industrial organisations during construction and after construction to determine, in first case, whether flaws have been introduced due to manufacturing process or in the second case, whether flaws have developed dtie to service conditions. NDT is therefore used to inspect... 

An important application of the HMT is the test for ferrous inclusions in high pressure turbine disks made from a non-magnetic metal alloy. On principle, such ferrous inclusions can be introduced during the manufacturing process and, if present, they can be the origin of cracks in these most critical parts. Therefore such tests are stringent necessary. 

Figure C2.11.1. A flow chart summarizing tire ceramic design and manufacturing process.

When collecting a sample, for instance, only a small portion of the available material is taken, increasing the likelihood that small-scale inhomogeneities in the sample will affect the repeatability of the analysis. Individual pennies, for example, are expected to show variation from several sources, including the manufacturing process, and the loss of small amounts of metal or the addition of dirt during circulation. These variations are sources of indeterminate error associated with the sampling process. 

Gases used in the manufacture of semiconductor materials fall into three principal areas the inert gases, used to shield the manufacturing processes and prevent impurities from entering the source gases, used to supply the molecules and atoms that stay behind and contribute to the final product, and the reactive gases, used to modify the electronic materials without actually contributing atoms or molecules. 

DNQ—novolac resist chemistry has proved to have remarkable dexibiUty and extendibiUty. First introduced for printing appHcations, DNQ—novolac resists have been available since the eady 1960s in formulations intended for electronics appHcations. At present, most semiconductor manufacturing processes employ this resist chemistry. Careful contemporary research and engineering support the continuing refinement of this family of materials. 

An extremely important safety issue with respect to ah. wood product manufacturing processes is personal worker safety. Ah of the processes use much moving machinery, usuahy including many saws or knives. Workers must continuahy remember the inherent dangers these machines involve as weh as other possible dangerous situations which could result from malfunctions or other errors. In addition, most processes are more or less dusty and noisy. Most employers require use of safety glasses and many require hearing protection, safety shoes, and hardhats as weh as other kinds of protection needed for Specific jobs. 

In 1957 Standard Oil of Ohio (Sohio) discovered bismuth molybdate catalysts capable of producing high yields of acrolein at high propylene conversions (>90%) and at low pressures (12). Over the next 30 years much industrial and academic research and development was devoted to improving these catalysts, which are used in the production processes for acrolein, acryUc acid, and acrylonitrile. AH commercial acrolein manufacturing processes known today are based on propylene oxidation and use bismuth molybdate based catalysts. 

Manufacturing processes have been improved by use of on-line computer control and statistical process control leading to more uniform final products. Production methods now include inverse (water-in-oil) suspension polymerization, inverse emulsion polymerization, and continuous aqueous solution polymerization on moving belts. Conventional azo, peroxy, redox, and gamma-ray initiators are used in batch and continuous processes. Recent patents describe processes for preparing transparent and stable microlatexes by inverse microemulsion polymerization. New methods have also been described for reducing residual acrylamide monomer in finished products. 

Acrylate and methacrylate polymerizations are accompanied by the Hberation of a considerable amount of heat and a substantial decrease in volume. Both of these factors strongly influence most manufacturing processes. Excess heat must be dissipated to avoid uncontrolled exothermic polymerizations. In general, the percentage of shrinkage decreases as the size of the alcohol substituent increases on a molar basis, the shrinkage is relatively constant (77). 

In all manufacturing processes, grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of an elastomer. Ungrafted styrene—acrylonitrile copolymer is formed during graft polymerization and/or added afterward. 

In addition to graft copolymer attached to the mbber particle surface, the formation of styrene—acrylonitrile copolymer occluded within the mbber particle may occur. The mechanism and extent of occluded polymer formation depends on the manufacturing process. The factors affecting occlusion formation in bulk (77) and emulsion processes (78) have been described. The use of block copolymers of styrene and butadiene in bulk systems can control particle size and give rise to unusual particle morphologies (eg, coil, rod, capsule, cellular) (77). 

Additional information on elastomer and SAN microstmcture is provided by C-nmr analysis (100). Rubber particle composition may be inferred from glass-transition data provided by thermal or mechanochemical analysis. Rubber particle morphology as obtained by transmission or scanning electron microscopy (101) is indicative of the ABS manufacturing process (77). (See Figs. 1 and 2.)... 

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