Drill Press Part

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Title: Drill Press Parts

Author(s): Kelly Curran

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Drilling Machines - Feed Rates Calculations    The feed rate for drilling depends upon the hardness of the material, the type of material the drill is made of, and the size of the drill bit. In this information sheet we will concentrate on feed rate factors and calculations for high-speed steel drills. Although some carbon steel drills are still available, most drills used by industry are either high-speed steel or carbide. Carbide drilling will be covered in the carbide unit. The spindle feed rate on drilling machines is given in terms of inches per revolution (IPR). Inches per revolution is the rate at which the tool will advance into the work every revolution of the tool. The feed rate that can be used is determined mainly by the size of the chip that the drill can withstand. As the size of the drill increases, the feed rate of the drill also increases. Drill feed Table 1 gives you the recommended feed rates for general-purpose work using a two-flute drill. Like in any other type of machining, it is better to start with a slower feed rate, then increase the feed rate to the capacity of the machine tool, the setup, and the desired surface finish. Table 1  Recommended Feed Rate for High-Speed Steel Twist Drills Drill Diameter, Inches Feed, Inches per Revolution Drill Diameter, Inches Feed, Inches per Revolution Drill Diameter, Inches Feed, Inches per Revolution 1/16 to 1/8 1/8 to 1/4 .001 to .003 .002 to .006 1/4 to 1/2 1/2 to 1 .004 to .010 .007 to .015 Over 1 .015 to .025 If the recommended feed rate for a 1/2-inch drill is 0.005, the operator sets the machine feed on the drill press to 0.005 feed in inches per revolution. Most drilling machines are set up to feed in inches per revolution. If, however, the feed rate for the machine is set up in feed rate in inches per minute (IPM), the operator needs to multiply the operating R.P.M. of the drill by the feed rate in inches per revolution. Let’s try some feed rate calculations for IPM. Follow along using the recommended feed rate charts in Figure 1. A 0.500-inch high-speed steel (HSS) drill is to be used on a piece of 1018 steel with a brinnel hardness of 200. The closest RPM setting to perform this cut is 800 rpm. Look up the feed rate in inches per revolution (I.P.R.) in the charts and calculate the feed rate in inches per minute. RPM = 800 Feed in inches per revolution (I.P.R.) = 0.004 low side Feed (in. / min.) = RPM x I.P.R. Feed (in. / min.) = 800 x 0.004 Feed = 3.2 in. / min. If we need to calculate the feed rate for a drill that has more than two flutes, adjustments need to be made to the feed rate calculations. Consult the tool manufacturer for information on feed rates.