An investigation of the relationship between temperature, forces and tool wear in turning and drilling

Developing a means of predicting tool life has been and continues to be a focus of much research effort. A common experience in attempting to replicate such efforts is an inability to achieve the levels of agreement between theory and practice of the original researcher or to extrapolate the work to different materials or cutting conditions to those originally used. This thesis sets out to examine why most equations or models when replicated do not give good agreements. One reason which was found is that researchers in wear prediction, their predictions are limited because they generally fail to properly identify the nature of wear mechanisms operative in their study. Also they fail to identify or recognise factors having a significant influence on wear such as bar diameter. Also in this research the similarities and differences between the two processes of single point turning and drilling are examined through a series of tests. A literature survey was undertaken in wear and wear prediction. As a result it was found that there was a paucity in information and research in the work of drilling as compared to the turning operation. This was extended to the lack of standards that exist for the drilling operation. One reason for this scarcity in information on drilling is due to the complexity of the drilling and the tool geometry of the drill. In the comparative drilling and turning tests performed in this work, the same tool material; HSS, and similar work material was used in order to eliminate the differences which may occur due to this factor. Results of the tests were evaluated and compared for the two operations and SEM photographs were taken for the chips produced. Specific test results were obtained for the cutting temperatures and forces of the tool. It was found that cutting temperature is influenced by various factors like tool geometry and cutting speed, and the temperature itself influenced the tool wear and wear mechanisms that act on the tool. It was found and proven that bar diameter influences the temperature, a factor not considered previously

Selective laser melting of a high precision turbomachinery application in IN718 alloy

The paper describes the manufacture of an outlet guide vane (OGV) component, in IN718 alloy, used in jet engines by Selective Laser Melting (SLM). The OGV component is a static part in the last stage of the compressor and is characterised as a series of airfoils or vanes secured by two flanged rings. The part tolerances at the leading and trailing edge require a high dimensional precision of +/-0.072 m whilst the profile tolerances are slightly more generous. The current challenge to manufacture a prototype OGV in IN718 alloy from a wrought stock involves a lengthy machining process in a hard-to-machine alloy. The tooling access is greatly restricted between the curved vanes, and the process involves careful fixturing and process management to mitigate residual stress in the component arising from the removal of material.Partial funding of this research by the project of Polish National Agency for Academic Exchange (NAWA, PPI/APM/2018/1/00045/U/001), Poland