Abstract
Burr is an undesirable phenomenon occurring in drilling operation which is one of the essential operations in the machining industry since it is directly influencing the operating costs. Exit burr height (EBH) values as the function of drilling time during drilling the specific holes of the forging brass workpieces used for producing the water-valve components with the uncoated- tungsten carbide (WC) and the AlCrN coated-WC drills were discussed. The data sets of drilling time, corresponding to EBH values at the appropriate criterion were used to develop the tool life models in terms of cutting speed and feed rate using Taylor’s equation. Monte Carlo simulation was adopted to study the uncertainty of cutting speed and feed rate on tool life predictions for sensitivity analysis. The results showed that drilling with a low feed rate decreased the averages of EBH. The predicted tool life values of the AlCrN coated-WC drills were higher than those of the uncoated-WC ones based on the results of tool life predictions. The appropriate operating condition of the cutting speed of 60 m/min and the feed rate of 0.2 mm/rev was recommended for manufacturers in the drilling of the forging brass workpieces using the AlCrN coated-WC drills. Moreover, the predicted tool life values for the uncoated-WC and the AlCrN coated-WC drills were about 600 and 800 min, respectively. This indicated that the AlCrN coated-WC drill increased tool life by 30%.
Highlights
Tool life is very important in the machining industry to improve the quality of a cutting tool as well as a machine component
Exit burr height (EBH) increased rapidly with increasing drilling time within the range of approximately 200–500 min when drilling at a feed rate of 0.25 mm/rev by keeping the cutting speed constant at 50 m/min
The averages EBH increased very slightly with increasing time within the range of approximately 70–650 min when drilling at a feed rate of 0.15 mm/rev by keeping the cutting speed constant at 50 m/min and increasing very rapidly after 650 min
Summary
Tool life is very important in the machining industry to improve the quality of a cutting tool as well as a machine component. The reliability of the tool affects quality of the machined parts and productivity. It is one of the important five criteria (tool life, material remove rate, cutting forces, surface finish and chip shape) used for studying the material and cutting tool behaviours during machining [1]. The tool life model can be effectively used to predict tool wear and length of cutting time that the tool can be operated before changing a new tool. Tool life criteria used in the cutting operations can be observed from failure of the tool, occurrences of maximum width of the flank wear, the depth and width of crater wear, sound of the tool, type of chip, degradation of machined surface [2]
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