Surface roughness chart

Referring to the surface roughness chart for the manufacturing process to be used, select the appropriate value of A corresponding to the characteristic s design surface roughness. 

Figure 2.7 Surface roughness to process risk chart, s ...

Equations 2-60 and 2-61 are illustrated graphically in Figure 2-21. This chart is called a Moody diagram, and it may be used to find the friction factor, given the Reynolds number and the surface roughness. 

At high Reynolds numbers (Re > 2500), the surface roughness is an important parameter and must be allowed for in the calculations. Friction factor charts [53] include curves relating to various values of the relative roughness, that is the ratio of the mean height of surface roughness to the tube diameter. 

Apart from density and particle size, several other solid properties, including angularity, surface roughness and composition may also signiflcantly affect the quality of fluidization. However, in many cases Geldart s classiflcation chart is still a useful starting point to examine fluidization quality of a speciflc gas-solid system. 

In practice pipes are not smooth and for turbulent flow it is found that/also depends on surface roughness. Friction factor charts for rough pipes are available. ... 

Fig. 3.85 Coordinate chart of shrink percentage of first layer and surface roughness on different iron single crystal face...

We now have to thank Stanton and PanneU, and also Moody for their studies of flow using numerous fluids in pipes of various diameters and surface roughness and for the evolution of a very useful chart (see Fig. 48.6). This chart enables us to calculate the frictional pressure loss in a variety of circular cross-section pipes. The chart plots Re)molds numbers (Re), in terms of two more dimensionless groups a friction factor < ), which represents the resistance to flow per unit area of pipe surface with respect to fluid density and velocity and a roughness factor e/ID, which represents the length or height of surface prelections relative to pipe diameter. 

For turbulent flow, numerous correlations exist for both smooth and rough-walled pipes. A number of charts have been prepared such as those by Moody, and by Stanton and Pannell, in which friction factor is correlated against Reynolds number for differing pipe surface roughness. Itisimportantto note thatthisFanningfrictionfactorhasavalueof one-quarter of the Darcy friction factor. 

Quality issues standard information includes a process capability chart (where relevant), typical surface roughness and detaU, as weU as any information on common process faults. 

Fig. 11. The effect of fiber addition on the specific wear rates of a few polymers (2). The rectangular bar chart indicates specific wear rate (units on the left of the graph) and vertical arrows indicate the coefficient of friction (units on the right of the graph). Test conditions are (i) 440°C steel ball (dia. = 9 mm) sliding on polymer specimen, Normal load = 5 N, y = 0.1 m/s, roughness of polymer surface = 400 nm, 30% humidity (72) (ii) test conditions same as for (i) (72) (iii) test conditions same as for (i) (72) (iv) reciprocating-pin-steel plate apparatus, counterface roughness Eg, = 0.051 ixm, N2 environment, (73) (v)) test conditions same as for (iv) (73) (vi) pin-on-steel (AISI02 quench hardened) disk apparatus, counterface roughness = 0.11 um, p = 0.66 MPa, y = 1 m/s (29) (vii) test conditions same as for (vi) (29) (viii) test conditions same as for (vi) (29). Reprinted from Ref. 2.

In order to read fair off the chart in Fig. 6.1.3, we need, in addition to Rep from Eq. (6.1.6), the wall relative roughness kg/R. The relative roughness is simply an estimate of the absolute roughness of the inside surface of the cyclone walls kg, divided by the inside radius of the cyclone R, expressed in any consistent set of imits. Here, kg is normally taken to be about 0.046 mm or 0.0018 inches for commercial steel pipe. In some apphcations wherein brick or erosion protecting, refractory liners are installed, kg may as high as 3 mm or 0.125 inches. 

Here a polished stylus of 2.5 pm (0.001 inch) radius is run over the substrate surface under a load of 1 g. This generates a signal, in a similar meuiner to a gramophone record stylus, which is proportional to the irregularity of the surface. The roughness value is read from either a meter or a strip chart. 

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