The process implemented by Varel Europe to manufacture its drill bits within its factory in Ibos (Hautes-Pyrénées, France) is now well established and even though it meets the quality requirements, it is still continuously improved by the company. The drill bits, with diameters ranging between 120 and 660 mm, are produced using an infiltration process. The body of the drill bit is made of tungsten carbide and cutting elements made of synthetic diamond (PDC) are welded to the blades of the body (up to 200 for a drill bit with a diameter of 660 mm). Although the dimensional checks of the drill bits are carried out during the production stage, the positioning of the cutting elements is not measured afterwards. “Before considering the implementationof in-production inspections, we wanted to determine whether accuracy had an impact on the drilling performance”, explains Bruno Cuillier, Product Engineering Director with Varel Europe. To that end, it is necessary to have a numerical model of every drill bit actually produced, in order to compare it to the theoretical design model. The digital file containing the actual positions of the cutting elements can then be used bythe simulation system. The next step will be to determine whether the deviations found in the positions of the cutting elements can affect the performance of the drill bit during the drilling operations.
Eight drill bits scanned and analysed
The first step of this large project, namely the 3D digitisation of the drill bits, was entrusted to Cetim Sud-Ouest.Eight drill bits of different dimensions were scanned with an optical camera system. The collected meshed scatter plots (in STL format) were then processed in order to obtain a colour mapping showing the deviations of the actual dimensions from the theoretical dimensions and obtain 3D models in standard STEP format reproducing the actual shape of every cutting element of the drill bits. Varel Europe will then use these representative 3D models of the produced drill bits to assess how much the accuracy of the positioning of the cutting elements can affect the drilling performance.
