Comparative study of process of internal thread with cutting and forming tap in austempered ductile iron - an approach of physical quantities

Abstract

This study aims to compare the performance of cutting taps and forming taps in the process of internal threading in austempered ductile iron (ADI), in view of the physical quantities involved. A large majority of the parts used in the industry has internal threads to be used as fastening element and transmission of movement. However many of these parts are made of relatively hard machining material, as is the case of ADI. Achieving stability and reliability in the process is of paramount importance when dealing with internal threading, as it can compromise the entire previous process flow, should it fail. A survey of the state of the art showed the need to characterize and measure the phenomena related to process variables as well as the physical characteristics of the tool and of the workpiece so as to provide the best possible way to its applicability. The study points to a theoretical superiority of the process of threading by rolling, rather than by the similar process of cutting in ADI. This statement is based on the best characteristics of these tools for this process, such as higher torque strength, for example. In contrast it revealed the criticality of this application due to the high hardness and abrasion characteristics of ADI, besides the need for a good fixation and stability of the entire machine tool. However there is a need to develop tests that enable the visualization of parameters studied and characterization of the best process, in view of the large number of variables involved.