Crush force

The crushing force in a pendulum mill may be obtained as follows. 

Any bubble within a liquid is subject to both the crushing force of the hydrostatic pressure (Pjj) and those due to surface tension effects (2a/Rq). In order that the bubble should remain in equilibrium, the supporting forces due to the pressure of gas (P ) and vapour (P ) in the bubble must equal the crushing forces (Eq. 2.19). 

Compressive strength, or ability of a specimen to resist a crushing force, is measured by crushing a cylindrical specimen (ASTM-D-695) as shown in Figure 14.14. Here a sample of specified dimensions is placed between two heads, one movable and one set. Force is applied to the movable head moving it at a constant rate. The ultimate compression strength is equal to the load that causes failure divided by the minimal cross-sectional area. Since many materials do not fail in compression, strength reflective of specific deformation is often reported. 

Bingham plastic Plastic that does not flow until the external stress exceeds a critical threshold value, coefficient of expansion Change in dimensions per degree of temperature, compression strength Resistance to crushing forces. 

Vertebral resistance to a crushing force was increased by about 10% at all boron dose levels (200-9000 mg B/kg ration) no effect on femurs and tibias. Dietary loadings of 3000 and 9000 mg/kg were reproductively toxic to males and the developing fetus (31)... 

Imperial Chemical Industries Ltd, BelgF 636956(1964) CA 62, 7580-81 (1965) [A Blasting Explosive was prepd by mixing for 15 mins 88 parts granular AN 12 ps of a 50% aq AN soln in a rotary blender equipped with paddles. The resulting mass was spread on sheets and dried at 45° for 14 hrs. The crystal cake was crushed, forced to pass a sieve (BS No 6) and then mixed with 9 parts of fuel oil for each lOOps of sieved material]... 

Figure 7.1 The force exerted by the hot gas counteracts the crushing force of gravity.

Finally the crushing force of the tablets after relaxation gives information on the formed bonds inside the material and the compactibility. Compactibility has been described by Leuenberger [167]. For the future it can be expected that a prediction of compactibility as a result of the process of tablet formation is possible. 

A low crushing force is often caused by the composition of the special formulation. If the formulation itself is not the reason for a low crushing force, compression force can easily be increased. Another possible explanation can be low humidity of the tableted product. 

Finally tablets yam and chipping can occur before the tablets leave the die table of a rotary machine. Usually the lower punches or the tablet scraper of the tableting machine are not properly adjusted. Another reason can be low crushing force. 

There is a whole range of tests based on compression between parallel plates54 and two standards exist to define the rate of application of the crushing force and the geometry of the test apparatus. 

Fig. 4. Relationship between the calculated spreading coefficient WS(B/A) and granule friability ( ), tablet crushing force ( ) and tablet capping index (A) [71]...

Fig. 5.24 depicts some laboratory methods for the determination of the strength of agglomerates and cohesive powders. Often, even in a scientific environment, the transversal crushing force is measured (Fig. 5.24a). This method is quite acceptable for...

This relationship has the benefit of providing a more physical result at zero level, but it suffers from the fact that the density continues to grow in an unbounded fashion with increasing level. We can instead imagine that the bulk density will increase with level or crushing force but that the compressive forces required in order for it to reach a maximum value are not attainable, since the expression is not bounded from above. We can substitute this relationship into the differential equation and then solve for the level as a new function of time ... 

Figure 10.6 Crush force—displacement curves for carbon fabric/epoxy segment specimens at different loading rates.

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