Drilling machines Flashcards
Is essential in any metalworking shop. Consists of a spindle and a work table.
Drilling machine or Drill press
May be defined as the operation of producing a hole by removing metal from a solid mass using a cutting tool called sa twist drill.
Drilling
The operation of truing and enlarging a hole by means of a single-point cutting tool, which is held in a boring bar.
Boring
The operation of sizing and producing a smooth, round hole from a previously drilled or bores hole with the use of a cutting tool having several cutting edges.
Reaming
The operation of producing a tapered or cone-shaped enlargement to the end of a hole.
Countersinking
The operation of enlarging the top of a previously drilled hole to a given depth to provide a square shoulder for the head of a bolt or cap screw.
Counterboring
The operation of smoothing and squaring the surface around a hole to provide a seat for the head of a cap screw or a nut.
Spot-facing
The operation of cutting internal threads in a hole with a cutting tool called a tap. Special machine or gun taps are used with a tapping attachment when this operation is performed by power in a machine.
Tapping
The simplest type of drilling machine is the ________. This type of machine has only a hand feed mechanism which enables the operator to “feel” how the drill is cutting and to control the downfeed.
Bench-type sensitive drill press
Similar to the sentitive-type drill except that it is larger and heavier.
Standard Upright Drilling Machine
Sometimes called a radial-arm drill, has been developed primarily for the handling of larger workpieces than is possible on upright machines.
Radial drilling machine
Consists of several individual columns, drilling heads, and spindles mounted on a single base and utilizing a common table. Various numbers of spindles may be used, but four or six are common
Gang-drilling machine
May incorporate 20 or more spindles on a single head driven by a drilling machine spindle. This type of automated drilling is used, for example, by the automotive industry for the drilling of engine blocks.
Multi-spindle Drilling machine
Three main parts of a drill
shank, body, point
Types of drill shanks
straight, tapered
Are held in a drill chuck
Straight-shank drills
Fit into the internal taper of the drill press spindle.
Tapered-shank drills
The portion of the drill between the shank and the point.
Body
Are two or more helical grooves cut around the body of the drill. They form cutting edges, admit cutting fluid, and allow the chips to escape from the hole.
Flutes
The thin partition in the center of the drill that extends the full length of the flutes. This part forms the chisel edge at the cutting end of the drill. Gradually increases in thickness toward the shank to give the drill strength.
Web
The narrow, raised section on the body of the drill. It is immediately next to the flutes and extends along the entire length of the flutes. Its purpose is to provide a full size to the drill body and cutting edges.
Margin
The undercut portion of the body between the margin and the flutes, it is made smaller to reduce friction between the drill and the hole during the drilling operation.
Body clearance
Speed of a twist drill is generally referred to as _____. It is the distance that a point on the circumference of a drill will travel in 1min.
Cutting speed, surface speed, or peripheral speed.
RPM Formula (N)
V x 12/ piD
The distance that a drill advances into the work for each revolution. (fr)
Feed
Machining Time Formula (Tm)
L + A/Fr x N or L + A/Fm OR L/Fr x N or L/Fm
Metal Removal Rate Formula (MRR)
Pi/4 x D^2 x Fr x N or pi/4 x D^2 x Fm
Can be used to estimate the horsepower, Hp needed to perform a cut
MRR (Metal removal Rate)
Horsepower Formula (hp)
MRR x HPs
