Efficiency of mechanical trituration of amalgam. II. Effects of some variables

The performance criterion of success time has been employed to determine the effects of oscillation frequency, amplitude, mercury content and the mass of the capsule charge on the relative efficiency of the trituration process. The effects of frequency and amplitude can be satisfactorily explained in terms of the impact energy of the mix on the capsule endwall; this includes the contribution of the resulting rise in temperature. However, attempts to measure the temperature of the capsule contents during operating revealed experimental difficulties which may lead to erroneous estimates if thermocouples or similar devices are used. The mass of the amalgam mix has a distinct effect on trituration efficiency, and is most apparent at lower mercury contents. The consequence of this is that "double spills" or larger mixes will require less time to reach the same state as their smaller counterparts. At minimal mercury contents there is the distinct danger of overtrituration as a result. Mercury content is relatively more important than mix mass, and suggests that variations in dispensers and preproportioned capsules may have considerable importance in the uniformity of the resulting mix. Amalgamators may be described by a "power number", having the same dimensions as mW/g, being the product (frequency in Hz)3/(amplitude in m)2, which is thus a guide to the maximum power capable of being expended on the trituration process assuming 100 percent efficiency. Success time provides a measure of that efficiency. The use of the success time in studies of "difficult" variables in the trituration process has been indicated, and these will form the basis of future work.