Some investigations into development of nozzle and suction system for air blast shot peening machine

Shot peening is an important surface enhancement process, which helps in assuring satisfactory fatigue life and reliability of the automotive, aerospace and marine components. One of the most important factors affecting shot peening performance is the type of shot peening machine. This paper presents an innovative design of a laboratory-based air blast shot peening machine. This machine has a vertical nozzle suction system to take the advantage of gravity feed as well as the feed created by suction of the pressurized air. Special attention was paid to the design of the nozzle and the mixing chamber so as to obtain adequate suction of shots. The performance of the machine was evaluated by carrying out various shot peening tests on AISI 1045 steel specimens. The tests included microscopic examination of coverage with ×10 magnification lens, fatigue and wear resistance. The wear resistance of the peened AISI 1045 material increased by 3.5 times the unpeened one. The fatigue tests showed improvement in fatigue life of the workpiece up to about four times. Besides, there was an increase in yield and torsional strength of the workpiece by about 1.5 times.