Sheet thicknesses

The resistance to corrosion of some alloy sheet is improved by cladding the sheet with a thin layer of aluminum or aluminum alloy that is anodic to the base alloy. These anodic layers are typically 5—10% of the sheet thickness. Under corrosive conditions, the cladding provides electrochemical protection to the core at cut edges, abrasions, and fastener holes by corroding preferentially. Aircraft skin sheet is an example of such a clad product. 

The theory has beea exteaded to evaluate sheet breakup (19). This model (19) assumes that the fastest growing wave detaches at the leading edge ia the form of a ribboa with a width of a half-waveleagth. The ribboa ioimediately coatracts iato multiple ligaments, which subsequeatly reshape themselves iato spherical droplets. The characteristic dimension of the ligament, Dy is as foUows, where / is the sheet thickness at the breakup locatioa. 

Calendering operations are done routinely, and warm roUs (40—90°C) are recommended for optimum sheet smoothness. A process aid, such as low molecular weight polyethylene wax, is often used. Sheet thicknesses of 0.5—1.3 mm (20—50 mils) can normally be produced. 

For moderate general process requirements at gauge pressures less than 2058 kPa (300 Ibf in ) and less than 177°C (350°F), tube-sheet holes without grooves are standard. For all other sei vices with expanded tubes at least two grooves in each tube hole are common. The number of grooves is sometimes changed to one or three in proportion to tube-sheet thickness. 

The burden must have a definite sohdification temperature to assure proper pickup from the feed pan. This limitation can be overcome by side feeding through an auxiliary rotating spreader roll. Apphcation hmits are further extended by special feed devices for burdens having oxidation-sensitive and/or supercoohng characteristics. The standard double-drum model turns downward, with adjustable roll spacing to control sheet thickness. The newer twin-drum model (Fig. ll-55b) turns upward and, though subject to variable cake thickness, handles viscous and indefinite solidification-temperature-point burden materials well. 

It is now easy to calculate the force on the narrow structure. If the pillar has a width w = 10 m where it passes through the ice sheet (thickness f = 2 m), it presents a section of roughly 20 m on which ice presses. The maximum stress the ice can take is 6 MPa, so the maximum force it can exert on the structure is... 

The finite size effects in the contact between a spherical lens of polyurethane and a soft flat sheet of crosslinked polyfdimethyl siloxane) (PDMS) has been addressed by Falsafi et al. [37]. They showed that for deformations corresponding to contact diameters larger than the sheet thickness, the compliance of the system was affected by the glass substrate supporting the soft sheet. In order to minimize the finite size effects in the adhesion measurement of small elastomeric lenses, Falsafi et al. [38] and Deruelle et al. [39] used relatively thick elastic sheets to support their samples. 

Mimmum gasket width Mnumum tube sheet thickness... 

Blech-konne, /. tin can. -kasten, m. tin box sheet-iron box. -lack, m. tinplate varnish sheet-metal varnish, -messing, n. sheet brass, -rohr, n. sheet-iron tube tin tube, -schmied, m. tinner, -stfirke, /. plate (or sheet) thickness, -taiel, /. sheet iron, iron plate. -trichter, m. tin (plate) funnel, -trommel, /. tin (plate) drum, -ware, /. sheet-metal ware, ( i ually) tinware. 

Products are affected dimensionally by the difference between their forming temperature and their product-use temperature. Thus, a plastic s coefficient of thermal expansion and contraction has a significant effect on service conditions. The thermoforming pressure, time, and temperature variations that can exist will affect the final dimensions. Of these factors, evenness in heating throughout the sheet thickness before forming is usually the most important control. Type of heater has a direct effect on obtaining uniform heat... 

The speed of closure to the form is a function of machine condition and sheet thickness, with the thicker sheets being more difficult to move rapidly. The designer should indicate this to the sheet former when form stability at elevated temperatures is critical and the process must be tailored to improve this condition. One should also select a material which is intrinsically more stable and easily formed to minimize the possibility of unmolding. These factors must be considered in conjunction with the design of the product to minimize sheet stretching differentials in the part. 

The cycle time is controlled by the heating and cooling rates, which in turn depend on the following factors the temperature of the heaters and the cooling medium, the initial temperature of the sheet, the effective heat transfer coefficient, the sheet thickness, and thermal properties of the sheet. 

Detonation velocity of sheets containing 15% natural rubber is given in Figs 8 9 as functions of sheet thickness and density. These data are taken from Kegier Schaii (Ref 45, p 499), who show that the decrease in D produced by stretching the sheet is due to a decrease in sheet density... 

The calendering process can be described by means of a combined drag and pressure flow. The rotating rolls of a calender drag the mbber through the calender nip. The clearance as well as viscoelastic properties determine the sheet thickness. 

In operation the tube sheets are subjected to the differential pressure between shell and tube sides. The design of tube sheets as pressure-vessel components is covered by BS 5500 and is discussed in Chapter 13. Design formulae for calculating tube sheet thicknesses are also given in the TEMA standards. 

To allow sufficient thickness to seal the tubes the tube sheet thickness should not be less than the tube outside diameter, up to about 25 mm diameter. Recommended minimum plate thicknesses are given in the standards. 

Choose 20 mm o.d., 16 mm i.d 4.88-m-long tubes ( in. x 16 ft), cupro-nickel. Allowing for tube-sheet thickness, take... 

Arai and Hashimoto[2611 studied disintegration of a thin liquid sheet in a co-flowing air stream. For a constant sheet thickness, an empirical correlation was derived for the sheet breakup length as ... 

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