Now showing 1 - 2 of 2
  • Publication
    Impact fatigue fracture of polycrystalline diamond compact (PDC) cutters and the effect of microstructure
    The fatigue behaviour and failure of polycrystalline diamond compact (PDC) cutting tools under cyclic impact loading is investigated. These tools are composed of a polycrystalline diamond layer in-situ bonded onto a tungsten carbide substrate via a high temperature and high pressure sintering route. Their main application is in oil and gas drilling and non-ferrous machining. The tools were subjected to repeated impact loading until catastrophic failure occurred or up to 5000 impacts. Results show typical fatigue fractures, with cracks initiated and intermittently grown with each successive impact. Impact force or stress (S) was varied and the number of impacts (N) to crack initiation, growth and catastrophic failure recorded in order to generate S–N fatigue curves. PDC cutters with a coarser grain microstructure exhibited up to 70% better impact fracture resistance than their fine grain counterparts. Their fatigue endurance limit was also about 10–15% higher. The frequency at which impact loads occurred did tseem to affect the fatigue behaviour.
    Scopus© Citations 45  2026
  • Publication
    Carbon Footprint Analysis of a Polymer Manufacturing Process
    (International Manufacturing Conference, 2011) ;
    This paper describes a carbon footprint (CF) analysis of a manufacturing process based on large scale polymer food tray production using Polyethylene Terephthalate (PET). The methodology utilised, allows for the calculation of the CF, in accordance with PAS (Publically Available Specification) 2050, of a 16.6g recycled PET (rPET) tray, based on a cradle-to-grave life cycle. Using an Irish plastics manufacturer as the experimental basis for the research, primary activity data was measured for in-house processes while secondary data was used for upstream and downstream stages. The CF of a 16.6g rPET tray was found to be 23.42 g CO2e or trays. The raw material inputs and manufacturing processes were found to contribute 45% and 33% of the greenhouse gases emissions (GHGs),respectively. The end-of-life stage was found to contribute 18% of the GHGs, while the secondary packaging and transport stages contributed only 2% each. By manufacturing the tray with 85% recycled content, the CF was found to be 60% lower compared to a benchmark based on only virgin materialutilisation. By increasing the end-of-life recycling rate from 22.5% to 32%, the CF was found to be reduced by 2%. Transport was found to have a minimal effect on CF.