The working principle of a drilling machine is applicable in a different field and on various materials such as wood, metal, rock etc. This has shown the fact that different construction companies make use of a drilling machine. They are made of various types, making them suitable for specific operations.
Today we’ll be looking into the working of drilling machine on metal and wood.
Drilling operation on metals
In this metal operation swarf is carried away from the tip of the drill bit by the fluting of the drill bit. The cutting tip produces more chips which continue the movement of the chips outwards from the hole. Cutting fluid or coolant is sometimes applied to prolong the tool’s life by cooling and lubricating the tip and chip flow.
When using a gun drill coolant may be introduced with the drill shank, it is used mostly while drilling aluminium. The cutting fluid help to ensure smooth and accurate cutting and prevent the metal from grabbing the drill bit while drilling the hole.
When cutting soft metals like brass that can cause grabbing of the drill bit and even causes chatter. 1-2 mm can be ground on the cutting edge to create an obtuse angle of 91 to 93 degree. This prevents chatter and instead cuts the metal. The cutting tool edge pushes away the metal rather than grabbing the metal, creating high friction and hot swarf.
On heavy feeds and comparatively deep holes, oil-hole drills are used in the drill bit. It is designed with a lubricant pump to the drill head through a small hole in the bit and flowing out along the fluting. The arrangement of a conventional drill press can be used in oil-hole drilling. However, it is more common in automatic drilling machinery, because the workpiece rotates rather than the drill bit.
In computer numerical control (CNC) machine tools which are also called peck drilling or interrupted cut drilling. It is used to keep swarf from detrimentally building up when deep holes.
This peck drilling involves plunging the drill partway through the material, which more than five times the diameter of the drill. It then retracts it to the surface, which is repeated until the cutting is completed.
The advance way the process, is called high-speed peck drilling or chip breaking as it only retracts the drilling slightly. Its process is faster but used only in moderately long holes, else the drill bit will overheat. It is also used when drilling stingy material to break the chips.
Another best alternative of the CNC machine is a Magnetic Base Drilling Machine. In this type, the base allows drilling in a horizontal position and even on a ceiling. The cutter should be used in this machine because they drill faster in less speed. The cutter size varies from 12mm to 200mm DIA and from 30mm to 200mm depth of cut. The base drilling machines are widely used in construction, fabrication, marine, and oil & gas industries.
Research has shown that in the oil and gas industry, pneumatic magnetic drilling machines are used to avoid sparks, as well as special tube magnetic drilling machines that can be fixed on pipes of different sizes and even inside.
Drilling in wood
As wood is a softer material than most metals, drilling in wood is considerably easier and faster than drilling in metal. In wood cutting fluid is not need, but the issue in drilling wood is ensuring clean entry and exit holes and preventing burning.
However, burning in wood drilling is one of the unwanted occurrence as it destroys fine woodworking applications. Well, this can be avoided when a sharp bits and appropriate cutting speed. Twist drill bits used in metalworking also work perfect in wood as its tend to chip wood out at the entry and exist of the hole
There are many types of specialized drill bits for boring clean holes in wood. these include, brad-point bits, forstner bits and hole saws.