Exploring wear detection method for special drilling parts in liquid media

In special drilling projects conducted under arduous liquid conditions, wear-related failures of hardmetal moving parts can easily trigger accidents. The problem is that no acceptable method is available to detect such wear failures. This work endeavors to propose a novel wear detection method for preventing the hardmetal moving parts from the accidents: (i) designed and optimized an attachment device for a conventional ball-on-disc tester; (ii) used a part-screw downhole motor made of cemented carbide as a typical example to validate the detection method; and (iii) offered solutions to wear issues. The designed device consisted of top cover, sleeve, and working platform. The device strength is inspected through finite element static stress, and its structure is then optimized using the zero-order method. Wear experiments are performed on the screw downhole motor rotor under conditions of air, water, and mud showed that the main wear mechanisms in air is abrasive wear, whereas motors experienced fatigue abrasive and tribo-corrosion wears under water and mud conditions. As a result, the solutions are proposed based on the wear mechanisms to prevent the wear failures. (C) 2016 Elsevier Ltd. All rights reserved.