Product shape

Metal injection mol ding (MIM) holds great promise for producing complex shapes in large quantities. Spray forming, a single-step gas atomization and deposition process, produces near-net shape products. In this process droplets of molten metal are coUected and soHdifted onto a substrate. Potential appHcations include tool steel end mills, superalloy tubes, and aerospace turbine disks (6,7). 

Shaped products used for adsorbent purposes are generally less sophisticated and therefore less expensive than catalytic products. In 1985, it was reported that 10,000 t/yr of activated alumina adsorbents were produced in the United States. North American producers of Bayer process-based activated aluminas include Alcoa, La Roche (formerly Kaiser Chemicals), Discovery, and Alcan. Gel-based activated aluminas are produced by La Roche, Vista, and several of the major catalyst manufacturers. In Europe, principal sources of supply are Rhc ne-Poulenc and Condea. 

Refractories may be preformed, ie, shaped, or formed and installed on-site, ie, specialties. Iimovations in placement and vessel constmction has led to a greater emphasis on specialty refractory products. Castables, gunning mixes, and plastic and ramming mixes are used either for repair or for complete new constmction of what is known as monolithic linings. The tendency to use monolithics instead of constmctions using shaped products has been steadily increasing. As of the mid-1990s, monolithic installations are as common as conventional shaped product constmction. 

Production capacity was almost equally spHt between powdered and nonpowdered activated carbon products. Powdered activated carbon, a less expensive form used in Hquid-phase appHcations, is generally used once and then disposed of. In some cases, however, granular and shaped products are regenerated and reused (35). In 1990 production capacity for granular and shaped products was spHt with about two-thirds for Hquid-phase and one-third for gas-phase appHcations (37). 

The activated carbon materials are produced by either thermal or chemical activation as granular, powdered, or shaped products. In addition to the form of the activated carbon, the final product can differ in both particle size and pore structure. The properties of the activated carbon will determine the type of application for which the carbon will be used. 

Designing products is usually performed based on experience since most products only require a practical approach (Fig. 1-4). Experience is also used in producing new and complex shaped products usually with the required analytical evaluation that involves stress-strain characteristics of the plastic materials. Testing of prototypes and/or preliminary production products to meet performance requirements is a very viable approach used by many. 

Complex design BM has started to full fill its rather unlimited capability in producing complex shaped products. The reason is due to designers becoming familiar with the behavior of BM processes and their exceptional design capabilities and few limitations (Chapter 8). 

This interplay of the many variables is extremely complex and involves a matrix of the many variables. As an example in the molding simulation TMconcept system programmed Molding Cost Optimization (MCO) of Plastics Computer Inc., Dallas, TX, there are well over 300 variables. It is not reasonable to expect a person using manual methods to calculate these complex interactions even if molding only a modest shaped product without omissions or errors. Computerized process simulation is a practical tool to monitor the influence of design alternatives on the processability of the product and to select molding conditions that ensure the required product quality (3). 

There is a view that muffins originated in Wales. They were originally a sour dough flat bread. They seem to have disappeared from British life, except in a nursery rhyme. Presumably the original product had a short shelf life. The sort of product now sold as an English muffin has overcome some of these problems. The modem product is a disc shaped product about 7-10 cm in diameter and 2 cm high. 

Note 1 The polymerization or modification reaction and the transformation of the resulting polymer into a shaped product is accomplished in the same processing equipment. 

Lacourse, N. L., Altieri, P. A. (1991). Biodegradable Paekaging Material and the Method of Preparation Thereof, U.S. Patent 4,863,655 (1989) Biodegradable Shaped Products and the Method of Preparation Thereof, U.S. Patent 5,043,196. 

Consider the vacuum forming of a polymer sheet into a conical mold as shown in Figure 7.84. We want to derive an expression for the thickness distribution of the final, conical-shaped product. The sheet has an initial uniform thickness of ho and is isothermal. It is assumed that the polymer is incompressible, and it deforms as an elastic solid (rather than a viscous liquid as in previous analyses) the free bubble is uniform in thickness and has a spherical shape the free bubble remains isothermal, but the sheet solidifies upon confacf wifh fhe mold wall fhere is no slip on fhe walls, and fhe bubble fhickness is very small compared fo ifs size. The presenf analysis holds for fhermoforming processes when fhe free bubble is less than hemispherical, since beyond this point the thickness cannot be assumed as constant. 

Solubility and viscosity explains the basic physicochemical nature and the functional behavior of proteins in aqueous solutions. Proteins contribute to the adhesive or cohesive properties of film matrices by the binding of their polypeptides to other components such as starch granules to yield shaped products that, for example, are necessary for trapping gases in breadmaking. 

Industry estimates indicate that up to 5% of the total resin production finds its way into prototype or mill shape plastic products. By mill shapes is meant those primary uniform configuration subject to established cross-sectional and length tolerances. While this estimate is necessarily conjectural, the best available information indicates that this range is accurate. Modem Plastics magazine estimated mill shape production for 1968 in acrylics, cellulose, nylon, acetal, polycarbonate, high density polyethylene, polypropylene, poly(vinyl chloride), and copolymers to approach 336.4 million pounds. Total United States resin production for 1968 slightly exceeded 16 billion pounds. 

Much of the mill shape production is converted in house by the processors themselves— such as in the case of polyethelene film for... 

This equipment is particularly suited to crushing of soft, friable materials to cube-shaped products with small proportions of fines. For fibrous materials, the screen is provided with cutting edges. Some data are in Table 12.7(c). A list of materials that are handled in hammer mills is in Table 12.5(a), and other products are referred to in Table 12.10. 

Polypropylene (PP) bottles have the advantage that they are inherently hot-fillable (at 85°C) and retortable to 120°C. The bottles are normally extrusion blow-moulded, and can also be made with multi-layering to include barriers against oxygen permeability. This technology is commonly used for sauce bottles and juice products. Since most of the bottles are of an oval shape, product contraction resulting in volume reduction is countered by allowing die bottle to become more oval under the effects of vacuum. 

Die for Extruding a Square Extrudate (a) Explain why a die with a square cross section cannot produce an extruded product with a square cross section, (b) What cross section should the die have to produce a square-shaped product ... 

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