This thesis was submitted to the School of Graduate Studies in partial fulfillment of the requirements for the Degree Master of Applied Science. / <p>Accuracy and surface finishes play an important role in modem industry. However, the deformability of ductile materials induces challenges in achieving high accuracy and surface finish. Undesired projections of material produced during metal cutting, known as burrs, significantly reduces the accuracy of the parts and affect both the assembly process and product quality. Around 30% of total production costs are used for deburring processes. This thesis presents one modem and promising method in reducing burr size through the use of ultrasonic assistance. With ultrasonic assistance, high frequency vibrations are added in the feed direction during cutting. In particular, ultrasonic assisted drilling of 1100-0 aluminum using high speed steel standard twist drills was investigated.</p> <p>Two simulation studies were conducted. Firstly, a finite element model of orthogonal cutting with and without ultrasonic assistance was developed. The results predicted that ultrasonic assistance should produce smaller burrs for the simulated operating conditions. Secondly, a drilling exit burr model was created based on a circular plate deflection model. Unfortunately this simulation failed to predict the experimentally observed burr sizes and thus the model requires further development.</p><p>To provide the ultrasonic vibration a preloaded workpiece holder and a drive circuit were designed and implemented for use with a commercial piezoelectric actuator. This equipment was cost effective (costing about 400 CAN$) and functional.</p><p>The effects of ultrasonic assistance under different vibration and cutting conditions were investigated experimentally. The experimental results demonstrated that, for certain combinations of vibration frequency and amplitude, burr size reduction can be achieved. Under these conditions the ultrasonic impact actions become significant, causing chip segmentation and smaller burrs. The results also show that ultrasonic assisted drilling allows a higher spindle speed and feed to be used without increasing burr size. However, ultrasonic assistance has a negative impact on tool life. Compared with conventional drilling, chipping of the chisel edge and greater wear of the cutting lips was observed after drilling 10 holes. This situation may be improved in the future if drills with suitable coating are used in place of the standard high speed steel drills.</p> / Thesis / Master of Engineering (ME)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18892 |
| Date | 03 1900 |
| Creators | Shuet Fung, Simon Chang |
| Contributors | Elbestawi, M., Bone, Gary M., Mechanical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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