Abstract: Metal wear has been identified as the major study of machine breakdown in oil palm mills. This results to serious economic loss owing to such mills operating at a greatly reduced installed capacity. This was the findings from a research visit made to one of the major oil palm mills in Nigeria, Rison Palm Oil Mill, Ubima, located in the eastern part of the country. It was found that the greatest wear and breakdown in the mill occurs in the press screw unit. Measurements on the flight thickness were taken at one week intervals covering a period of six months and the resultant wear curves are discussed. A general review of press screws and the Twin Press Screws in particular-commonly employed in Oil Palm Mills, their operational principles as well as descriptions are highlighted. The wear curves show that the first and the second flights wear most, with initial rapid wear within the first week of operation. Flight 1 witnessed the most wear, followed by flight 2. Flights 4 and 5 suffered minimal wear. Smooth operation with minimal wear was recorded for the next five months after the initial rapid wear of flights 1 and 2, followed by a final stage of rapid wear. For continuous operation, the screw was found to give an average service life of twenty-two weeks. Cast manganese steel is suggested for the screw materials.