AbstractsMedical & Health Science

"Experienced dry-press operators have long known that when they slow down their presses, to the proper speed they are able to exert more pressure on a wetter mix with out pressure cracks becoming apparent. When a clay mix is compressed in a dry-press there is a gradation of the pressure exerted, from the rams to the center, causing in some cases a soft centered brick. "Shelly brick", are undersirable [sic] because they do not have uniform physical properties through out. This weakens their structure, due to unequal stresses developed in drying and fireing [sic]. The defective structure of dry-pressed brick has been attributed to many other causes, such as uneven moisture distribution, improper grain size gradation, grain size segregation, occluded air, plasticity of the mix, degree of pressure, and rate of compression. All of these factors have their effect on pressure transmission in one way or another, consequently we attribute the imperfect structure of some dry-pressed ware to inadequate and non-uniform pressure transmission to all parts of the ware. A review of the literature discloses no imformation [sic] or data pertaining to the effect of variation of time of applied pressure on dry-pressed ware. It is, therefore proposed to make a study of the effect of variation of time of applied pressure on pressure transmission in dry-pressing" – Introduction, p. 1-2.