Basic Types of Drilling Machines

Basic Types of Drilling Machines
Drilling machines or drill presses are one of the most common machines found in the machine shop. A drill press is a machine that turns and advances a rotary tool into a workpiece. The drill press is used primarily for drilling holes, but when used with the proper tooling, it can be used for a number of machining operations. The most common machining operations performed on a drill press are drilling, reaming, tapping, counterboring, countersinking, and spotfacing.
There are many different types or configurations of drilling machines, but most drilling machines will fall into four broad categories: upright sensitive, upright, radial, and special purpose.
UPRIGHT SENSITIVE DRILL PRESS

Figure 1 Upright sensitive drill press

The upright sensitive drill press (Figure 1) is a light-duty type of drilling machine that normally incorporates a belt drive spindle head. This machine is generally used for moderate-to-light duty work. The upright sensitive drill press gets its name due to the fact that the machine can only be hand fed. Hand feeding the tool into the workpiece allows the operator to "feel" the cutting action of the tool. The sensitive drill press is manufactured in a floor style or a bench style.

UPRIGHT DRILL PRESSThe upright drill press (Figure 2) is a heavy duty type of drilling machine normally incorporating a geared drive spindle head. This type of drilling machine is used on large hole-producing operations that typically involve larger or heavier parts. The upright drill press allows the operator to hand feed or power feed the tool into the workpiece. The power feed mechanism automatically advances the tool into the workpiece. Some types of upright drill presses are also manufactured with automatic table-raising mechanisms.

Figure 2  Upright drill press

RADIAL ARM DRILL PRESSThe radial arm drill press (Figure 3) is the hole-producing work horse of the machine shop. The  press is commonly refered to as a radial drill press. The radial arm drill press allows the operator to position the spindle directly over the workpiece rather than move the workpiece to the tool. The design of the radial drill press gives it a great deal of versatility, especially on parts too large to position easily. Radial drills offer power feed on the spindle, as well as an automatic mechanism to raise or lower the radial arm. The wheel head, which is located on the radial arm, can also be traversed along the arm, giving the machine added ease of use as well as versatility. Radial arm drill presses can be equipped with a trunion table or tilting table. This gives the operator the ability to drill intersecting or angular holes in one setup.

Figure 3 Radial arm drill press

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SPECIAL PURPOSE DRILL MACHINESThere are a number of types of special purpose drilling machines. The purposes of these types of drilling machines vary. Special purpose drilling machines include machines capable of drilling 20 holes at once or drilling holes as small as 0.01 of an inch.
Gang Drilling Machines

Figure 4 Gang drill press

The gang style drilling machine (Figure 4) or gang drill press has several work heads positioned over a single table. This type of drill press is used when successive operations are to be done. For instance, the first head may be used to spot drill. The second head may be used to tap drill. The third head may be used, along with a tapping head, to tap the hole. The fourth head may be used to chamfer.

Multiple Spindle Drilling Machine

The multiple spindle drilling machine is commonly refered to as a multispindle drill press. This special purpose drill press has many spindles connected to one main work head (Figure 5).All of the spindles are fed into the  workpiece at the same time. This type of drilling machine is especially useful when you have a large number of parts with many holes located close together.

Figure 5 Multispindle drill press

Micro-Drill Press

The micro drill press is an extremely accurate, high spindle speed drill press. The micro drill press is typically very small (Figure 6) and is only capable of handling very small parts. Many micro drill presses are manufactured as bench top models. They are equipped with chucks capable of holding very small drilling tools.

Figure 6 Micro drill press

Turret Type Drilling Machine

Turret drilling machines are equipped with several drilling heads mounted on a turret (Figure 6). Each turret head can be equipped with a different type of cutting tool. The turret allows the needed tool to be quickly indexed into position. Modern turret type drilling machines are computer-controlled so that the table can be quickly and accurately positioned.

Figure 6 CNC Turret type drilling machine

DRILLING MACHINES: FEATURES, FUNCTIONS AND FUTURE

DRILLING MACHINES: FEATURES, FUNCTIONS AND FUTURE

According to Riccardo Azzoni, president of Atlantic Machinery, "The greatest assets a boring machine can have are: user-friendliness, accuracy, ease of setup and affordability." Most of the other industry experts interviewed by WOOD & WOOD PRODUCTS shared similar opinions.

Peter Zurcher, national sales manager at Grass America said, "boring machines should be easy to operate with added safety features built in and easy and simple to maintain." He added that he also values straightforward changeovers in boring machines.

A.C. Brown, field service manager for Medalist Industries, added "quick, repeatable setup for a wide range of parts is an important feature of boring machines." Other priorities Brown noted include: "the capacity to bore at varying hole depths in the same setup without the use of costly fixturing; the capacity to bore mirror imaged parts within one setup; and being able to do away with U-joint type spindles and drive trains."

"Quick setups, accuracy and speed," are the most significant features noted Richard (Tim) Byrnes, president of Richard T. Byrnes Co. Gary Wells, president of Tritec Assoc., said accuracy is the greatest concern. "Precision is the overriding consideration," he said, "followed by versatility."

Roger Stiles, president of Roger Stiles & Assoc., maintained the difference between set-up time and run time is the top priority of boring machines.

Another function of a boring machine is its increased computer capabilities. "The level of computer technology applied to our machines enhances the flexibility, a key element in just-in-time production," said Walter Favruzzo, general manager at Stefani Group America. Ken Amidon, technical sales representative at Stiles Machinery, said, "The biggest thing in point-to-point machines, beside a computer, is programmable selectable spindles," which allow the operator to "put a hole anywhere." Even with a 32mm system there can be an oddball hole, he added, but an operator can put one in a hard-to-reach spot.

Multifunctionality

Some manufacturers and distributors notice a demand for versatility resulting in an increase of multi-function machines. Warren Wade, president of Tekna said that in the future "the gap between boring and true routing machines will slowly close. Point-to-point CNC boring equipment will be capable of doing more sophisticated routing procedures."

Stiles said he sees a trend in machines combining routing, boring, and edgebanding on one machine.

Machining centers: multi-function

equipment vs. dedicated machines

Some experts hold that as the boring operation becomes more computer controlled, machining centers will evolve. The boring machine is "changing rapidly into a machining center, capable of performing multi-task operations such as drilling, routing, grooving and hardware insertion," said Favruzzo. Likewise, Rolf Zollinger, machines and systems sales manager for Koch Ltd., said that more CNC adaptability will increase the machine's flexibility in the future. He added that the equipment will become "more multi-purpose, more universal, more like machining