Drilling

Question 1

The web

Answer 1

Forms a small hole for the drill to seat into. chips are not cut here in the normal sense. the metal can be said to deform instead.

Question 2

The lips

Answer 2

Form chips which are removed by the screw action of the helical flutes.

Question 3

Lands or margins

Answer 3

Guide the drill by rubbing against the walls of the hole.

Question 4

Counterboring

Answer 4

provides a stepped hole, in which a larger diameter follows a smaller diameter partially into the hole.

Question 5

Countersinking

Answer 5

similar to counterboring, except that the step in the hole is cone-shaped for flat head screws and bolts.

Question 6

Reaming

Answer 6

used to slightly enlarge a hole; provide better tolerance on diameter, and improve surface finish.

Question 7

Centering

Answer 7

drills a starting hole to accurately establish its location.

Question 8

Spot facing

Answer 8

similar to milling and used to provide a flat machined surface on the workpiece in a localised area.

Question 9

Tapping

Answer 9

performed by a tap to create an internal screw thread on an existing hole.

Question 10

Gang-drilling machines

Answer 10

independent columns, each with different drilling operation, work piece slid from one column to next.

Question 11

Turret-type, upright drilling machines

Answer 11

used when numerous drilling operation are required in rapid succession, turret rotates needed tool into position for each operation.

Question 12

Radial drilling machines

Answer 12

used on large workpieces, spindle mounts on radial arm, allowing drilling operations anywhere along the arm length.

Question 13

Multiple-spindle drilling machines

Answer 13

Single powerhead operates multiple spindles enabling multiple holes at one time, each hole can be unique.

Question 14

Pecking

Answer 14

Drill repetitively goes in and out of the hole. the interrupted drilling is used to keep chips from building up when drilling deep holes.