Drilling Operation and Methods

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ting Cut Tool ions icat ppl A
By Geor ge S r, Jr. C chneide MfgE

Cutting Tool Applications

Upcoming Chapters Metal Removal Cutting-Tool Materials Metal Removal Methods Machinability of Metals Single Point Machining Turning Tools and Operations Turning Methods and Machines Grooving and Threading Shaping and Planing Hole Making Processes Drills and Drilling Operations Drilling Methods and Machines Boring Operations and Machines Reaming and Tapping Multi Point Machining Milling Cutters and Operations Milling Methods and Machines Broaches and Broaching Saws and Sawing Abrasive Processes Grinding Wheels and Operations Grinding Methods and Machines Lapping and Honing

Chapter 9 Drilling Methods & Machines
9.1 Introduction
One of the most important and essential tools in any metalworking shop is the drilling machine or drill press. Although the drilling machine is used primarily for drilling holes, it is often used for reaming, boring, tapping, counterboring, countersinking, and spotfacing. All drilling machines operate on the same basic principle. The spindle turns the cutting tool, which is advanced either by hand or automatically into a workpiece that is mounted on the table or held in a drill press vise. Successful operation of any drilling machine requires a good knowledge of the machine, proper set-up of the work, correct speed and feed, and proper use of cutting fluids applied to the cutting tool and work.

9.2 Types of Drill Presses
Many types and sizes of drilling machines are used in manufacturing. They range in size from a simple bench mounted sensitive drill press to the large multiple-spindle machines able to drive many drills at the same time. Figure 9.1 shows a schematic diagram of a standard vertical drill press as well as a schematic diagram of a turret-drilling machine. Described below are these and other types of drill presses such as sensitive and radial drills.

Fixed head (power head)

Spindle

Column

Column

Adjustable head

George Schneider, Jr. CMfgE
Professor Emeritus Engineering Technology Lawrence Technological University Former Chairman Detroit Chapter ONE Society of Manufacturing Engineers Former President International Excutive Board Society of Carbide & Tool Engineers Lawrence Tech. Univ.: http://www.ltu.edu Prentice Hall: http://www.prenhall.com Spindle Chuck

Hand wheel

Turret

Table Table

Base (a) (b)

Base

FIGURE 9.1: Schematic illustration of (a) vertical drill press, (b) CNC turret drilling machine. Chapter 9/Tooling & Production 1

www.toolingandproduction.com

Chap. 9: Drilling Methods & Machines
9.2.1 Simple Drill Press
A simple drill press (Fig.9.2) may be floor mounted as shown, or have a shorter main post and be mounted on a bench. The motions of this machine are very simple. The table on a floor model can be raised or lowered and rotated around the machine column. The spindle rotates and can be raised and lowered, with a stroke of 4 to 8 inches. Stops can be set to limit and regulate the depth. castings, weldments, or forgings, radial drills are ideal. The length of the arm along which the spindle housing rides specifies their size. This arm can be from 3 to 12 feet long. The column that holds the arm may be from 10 to 30 inches in diameter. A radial drill is shown in Figure 9.4. For very large work, the arm may be rotated 180 degrees and work placed on the shop floor. Speeds and feeds are dialed in by the machine operator and are the same as for other drill presses. Drilling is either hand or power feed.

9.2.2 Sensitive Drill Press
The name ‘sensitive’ is used to indicate that the feed is hand operated and that the spindle and drilling head are counterbalanced so that the operator can ‘feel’ the pressure needed for efficient cutting. A table mounted sensitive drill press is shown in Figure 9.3. The drill press has the same motions as the previous one plus a telescoping screw for raising and lowering the table and a sliding ‘drill...
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