Types of Drilling Machines

Drilling machine is the machine which is used to drill holes. Drilling machine plays an important role in work shop. It is placed next to lathe in terms of lathe in a workshop. Drilling machine can basically employed for drilling holes. Other than this it can also perform all the operations performed by a lathe but with little difficulty. Drilling of holes can be done very easily, effectively and at low cost and high speed by drilling operation. All the present day metal cutting drilling machines are originated from bow drills used by Egyptians in the year of 1200 B.C

Drilling machines are of various types depending on size, speed of cut , depth of cut and jobs on which machining operation is being performed. The different types of drilling machines are 1) Portable drilling machine 2) Sensitive drilling machine a) Bench mounting b) Floor mounting 3) Upright drilling machine a) Round column section b) Box column section 4) Radial drilling machine a) Plain radial drilling machine b) Semi-universal radial drilling machine c) Universal radial drilling machine 5) Multiple drilling machine 6) Gang drilling machine 7) Automatic drilling machine a) Vertical drilling machine b) Deep hole drilling machine

1) Portable drilling machine Portable drilling machines are those which can be used very easily and can drill holes anywhere in the workshop. This type of drilling machine is used for drilling holes on the objects which cannot be moved. Portable drilling machines are operated either by hand power or by engaging a separate motor. All the parts of this drilling machine are small and compact. The motor used here is of universal type that means it can be given either D.C power or A.C. The depth of holes which can be obtained by a portable drilling machine are of range 12mm to 18mm. The width of hole which is obtained through the portable driller is very small in size. High speeds are employed and small drill bits are used. In some cases these drilling machines may also work on pneumatic power. 2) Sensitive drilling machine These drilling machines are used in general for drilling small holes at high speeds on light jobs. The base of machine is either mounted on a bench (or) on a floor. Various parts of sensitive drilling machine are a. Vertical column b. Horizontal table c. Motor supporting head d. Drilling mechanism e. Vertical spindle In a sensitive drilling machine all the feed should be given through hand as there is no special provision for automatic feed. The holes are drilled by hand only. This has many advantages. Hand feed helps the operator to feel (or) sense the progress of drill if there arises any jam (or) block the drill can be easily released thus preventing drill from wreck (or) breakage. Sensitive drilling machine can be used for drilling small holes using high speeds by hand feed. The diameters obtained through a sensitive drilling machine are of range 1.5 to 15.5 mm. even smaller holes ranging as small as 0.35mm can be easily obtained by super sensitive drilling machines. The speeds employed for this operation may be as high as 20,000 rpm. 3) Upright drilling machine Upright drilling machine looks similar in construction when compared with sensitive drilling machine. This machine also has a vertical column mounted over a base. But the construction is more robust. It contains a power feed mechanism and also have a excellent table for work loading. Much number of spindle speeds and feeds are possible through upright drilling machine. This machine is most suitable for machining medium size jobs. Upright drilling machines are basically of two types. a. Round column section b. Pillar drilling machine 4) Radial drilling machine

Radial drilling machine can be used to drill pieces of medium to large size. Radial drilling machine has a larger circular base over which a heavy round column is mounted. A radial arm which is allowed to move freely over the length of column is placed. Drill head mechanism is mounted over this arm. This drill head mechanism is free to move throughout the length of the arm. Not only these two but the radial arm can swung 3600. So due to these three features radial drilling machine can drill large jobs also. If the job is small it can be mounted over the table and if the job is large it can be drilled by keeping it on the floor. There are three types of radial drilling machines a. Plain drilling machine b. Semi universal drilling machine c. Universal drilling machine a. Plain drilling machine In this machine provisions are made for a. Horizontal movement of drill head b. Vertical adjustment arm c. Horizontal movement of drill head along the arm d. Circular movement of horizontal arm about vertical column. b. Semi-universal drilling machine In these machines along the all the functions of plain drilling machine drill head can swing along the horizontal plane perpendicular to the arm. Due to this motion holes can be drilled on the work piece many angles other than normal drilling. c. Universal drilling machine In addition to all the features in semi-universal drilling machine the arm on which drill head is mounted can be rotated horizontal axes, this property enables machine to drill a hole at any angle 5) Gang drilling machine In this type number of single spindle drilling machine columns is paced side by side but having a common bas, and common work table. This type of machine is called gang drilling machine. In some cases any adjustments cannot be done as they are fixed permanently but most of machines were able to change the feed and speed of each spindle and even the spindle can be moved. This type of drilling machines is used for production work. These have the flexibility of changing tools also. 6) Multiple spindle drilling machine In this machine number of spindles is connected to a single motor and is driven. This drilling machine is highly used for production work. In these machines feeding motion is generally obtained by lifting up the table. The job can be even securely done by moving the drill head down. The spindles are constructed in such a way that the center distance between each spindle can be adjusted. The spindle is generally mounted with a drill bit. The main disadvantage is speed cannot be controlled for a single spindle. All the spindles are generally connected to the main drive by using universal joint to facilitate adjustment of center distance between spindles. 7) Automatic drilling machines In this method the whole process is automatic starting from loading of work till the unloading of finished product is done without any manual requirement. This machine is most commonly used for production purposes. Other than drilling other operations like shaping, milling, honing, tapping can also be performed. 8) Deep hole drilling machines

This type of drilling machines is basically used for drilling deep holes. This type of machine is generally employed in drilling gun barrels, crank shafts, long shafts etc. In general these machines used at high speed and low feeds. The cutting fluids is strictly employed to cool the edges of tool and to remove the chips from the place of cut. The long job is naturally supported by many supports to prevent any deflection in the work. Rotation of work and drill is done to obtain accuracy. These machines may be horizontal (or) vertical and are employed in such a way that the tool is made to reciprocate from the point of cut to outside the body this helps in removal of the chips

Source: India Study Channel