Experimental and Numerical Study of Multi Hole Extrusion Process

The main objective of the present work is the study the experimental and numerical study of multi hole extrusion process for making circular rods. The pure lead is used as extrude material for extrusion. The die consists of 5 holes with 5mm diameter. For prediction work, process has simulated using a Finite Element Method (FEM) code metal forming software DEFORM-3D®. All the experimental work and simulation are done at ambient conditions. The maximum load and maximum ram displacement are calculated for circular rods during the experimental work. From the results, it is noted that the behavior of load vs displacement is almost same for both experimental and numerical study of multi hole extrusion process. This study becomes illustration the behavior of the other tough materials by which one can understand the extrusion behavior of nonferrous materials.

Effect of Helical Drill Points on Delamination in Drilling Carbon Fiber Reinforced Plastics (CFRP)

A study of helical drill points for drilling carbon fiber reinforced plastics (CFRP) is presented. A helical drill point has an “S” contour with a radiused crown chisel that reduces the thrust force and make the drills self-centering. The S-shape chisel edge has a lower negative rake angle than a conventional chisel edge, and therefore may cut rather than extrude material. Experiments of drilling CFRP with helical drill points and conventional drill points were conducted. The results indicate that the helical drill points can reduce delamination significantly as compared to the conventional drill points under same cutting condition. Otherwise, delamination size decreases with increasing the cutting speed and increases with increasing the feed

Craters Produced on Metals by Single Ion Impacts

summaryThe surface is a major perturbation on displacement cascades resulting from ion impacts. Ion impacts on dense materials result in nanometer sized craters on materials with densities greater than 7.3 g/cm3. Although stable when the irradiation is interrupted, single ion impacts can modify or annihilate existing craters. Single ion impacts can extrude material from the specimen. Flow from the melt zone of cascades is responsible for the observed changes.

Rheological Properties of Two Unvulcanized Rubber Compounds as Determined on an Extrusion and a Rotational Viscometer

The viscometer manufactured by A. Macklow-Smith Ltd., which operates at constant rate of extrusion, is a capillary instrument designed for the determination of flow properties of plastics. The instrument has been used for examining the rheological characteristics of rubber compounds and it has been possible to derive the shear stresses required to extrude material at various shear rates between 2 and 1050 sec−1. The general method of operation of the instrument for this purpose is discussed including the determination of preheat time before extrusion and the aspect of incipient vulcanization in the viscometer during extrusion. The effects of various lengths and diameters of dies on rheological parameters and entrance effects are discussed. An important aspect of the work is the observation of a piston height effect in the extruder barrel. Two different compounded polymers have been examined and in one case, the extrusion pressure was found to decrease with piston height whilst in the other highly elastic material, it was found that as the piston descended, the extrusion pressure increased to an equilibrium value. The importance of this effect in obtaining consistent shear stress data is discussed. Results of the work have been expressed in terms of apparent viscosity and also in terms of the parameters which describe a power law relating shear stress and shear rate within the capillary die. Rheological data have been obtained at various temperatures within the range of processing temperatures of the compounds. The effects on rheological properties of mastication and relaxation time after mastication have been examined. Results have been compared with figures obtained on conventional laboratory viscometers such as the Mooney Plastometer and the Wallace Rapid Plastimeter. A biconical, rotational viscometer has also been used at the lower range of shear rates and the results are compared with those obtained from the extrusion viscometer.