Exit burrs are formed on the end of hole and have some undesirable characters leading to assembly quality problem. Deburring is one of the practical procedures used to solve this problem. Nevertheless, this step is a time consuming and causes high operation cost. This work studied the experimental investigations in drilling forging brass using a special tungsten carbide drilling tools. The exit burr height and workpiece diameter were measured at various spindle speeds and feed rates based on 2k plus center point experimental design and investigated by analysis of variance (ANOVA). The results of ANOVA indicated that spindle speed and feed rate on exit burr height and workpiece diameter were statistically significant at the level of significance of 0.05.

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 uncoatedtungsten 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%.

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In the drilling of forging materials, exit burrs are produced on the end of hole and had some undesirable characters leading to assembly quality problem. Deburring is one of the practical techniques used to solve this problem. However, this technique is a time consuming and causes high operation cost. Hence this work presented an experimental study in drilling forging brass using special tungsten carbide drilling tools. The exit burr size was evaluated at various spindle speeds and lot size. Effect of spindle speed on exit burr height was investigated using analysis of variance (ANOVA). The results of ANOVA indicated that the spindle speed of 415 rpm gave lowest exit burr height and produced higher quantity and quality of products.