EFFECT OF HOLE DRILLING PROCESSES ON SERVICE LIFE OF BUCKET USED IN BUCKET ELEVATOR

Abstract

ABSTRACT

In this study, effect of the hole drilling processes on the service life of the bucket used in a bucket elevator was investigated as a preliminary study to discover the cheapest process while offering suggestions for a longer service life of the buckets. Three processes of drilling are considered; 1) drilling using drilling machine and screw drill (SD), 2) using an NC machine and screw drill (SNC) and 3) using an NC machine and drill first with screw drill, followed by drilling using end mill (ENC). Fatigue tests at two levels of stress amplitude were conducted using an Instron 8801 Servo-Hydraulic Fatigue Testing Machine to apply cyclic load and record the number of cycles to failure. Comparison of the fatigue life among the three processes was reported. Preliminary results show that the ENC process could provide the highest service life. This was about 1.4 times of that of the SD process. Finally, fracture surfaces were observed to explain the effect of the drilling process on service life of the bucket.

KEYWORDS: Crack Initiation, Surface Roughness, Drill Surface Quality, Life Estimation