Broken engine’s crankshaft misalignment inspection by using reverse engineering technique

Abstract

The research aims to study the measuring data comparison between the broken crankshaft and the new crankshaft. The broken crankshaft has been investigated whether to measure dimensions or misalignment value. Therefore, the new crankshaft was measured and compared with a broken crankshaft using a 3D laser scanner. The misalignment value has been related to the overlapping value of a broken crankshaft by using a 3D software application.The broken crankshaft has been compared with the new crankshaft in contemporary models. The broken crankshaft was produced and assembled from an automobile manufacturer’s factory. It belonged to a particular Diesel engine that fractured while running in normal driving conditions. The broken crankshaft dimension has been investigated to find out the worn-out and misalignment value. The broken crankshaft inspection was measured using a micrometre and a 3D laser scanner application. Both crankshafts were created as artefact 3D models by the 3D laser scanner of the HandySCAN700 model. The accuracy of the 3D laser scanner will be presented in terms of measuring error. Two crankshafts were combined in concentric mate function. The inspection points were carried out at 4 points of each 90 around the main journal diameter, by following the guidelines of crankshaft inspection on a workshop manual basis. The overlapping value of each main journal will be measured by a 3D compare function at 0, 90, 180 and 270 respectively.The results showed the average diameter of the broken crankshaft’s main journal was less than the limit value. A new crankshaft was judged to be needed to be replaced. Moreover, it showed the lowest diameter of main journal No. 2 was 69.890 mm. It carried a 0.06% excessive worn-out value. The measuring error value of the 3D laser scanner was found and required for user-performed calibration procedures. The highest overlapping value was higher than the standard tolerance, up to 117%. It was located at the main journal No. 3 at 180 and near the fractured point of the broken crankshaft.The study of the broken crankshaft inspection was limited to either under-warranty or over-warranty cases. Most of the technicians in authorised automobile dealerships had no intention of performing the inspection process completely. In addition, they were lack of measuring skills and data records. Moreover, automotive manufacturers cannot support the 3D dimension data because it may affect the business’s confidential data leakage.The workshop manual mentioned the crankshaft inspection as a basic tool. In the case of complex components, automotive manufacturers should consider the utilisation of non-contact measuring tools for inspection reference.A reverse engineering technique was applied to scan the broken crankshaft into a 3D model using 3D laser scanning technology, which is used to reduce the measuring time and measuring value error in the inspection process.