TU08_Holemaking Vocab Flashcards
Concentric
Sharing a common center with another object or feature. The cutting tool should have this property with the existing hole in both countersinking and counterboring.
Continuous Chip
A chip that does not break apart and instead continues to fold in on itself. Ductile metals tend to create this type of chip.
Crest
The highest point of a thread. This on a tap determines its major diameter.
Deflection
The unintended movement or deviation of a drill due to the application of mechanical force. This on a drill can cause inaccurate hole location and dimensions.
Discontinuous Chip
A chip that easily fractures from the workpiece into small, separate pieces. Brittle materials tend to create this type of chip.
Ductile
Able to be stretched, drawn, or formed without fracturing, usually drawn out into a thin wire. These metals tend to be soft and produce long, stringy chips.
Fasteners
A device that holds objects together or locates them in relation to one another. These would include screws, bolts, and rivets.
Helix Angle
The angle is formed by the slope of the edge of a flute and a line parallel to the drill centerline. This type of angle affects how a drill evacuates chips, with larger angles better suited for softer materials and smaller angles better suited for harder materials.
Indexable
Having multiple cutting edges that can be rotated into place. For this type of insert, when one cutting edge wears out, an operator can turn the insert to expose a new cutting edge.
Insert
A replaceable cutting bit that has multiple cutting edges. This can be rotated when one edge is excessively worn.
Length-To-Diameter Ratio
L/D ratio. A numerical value comparing the length of a cylindrical tool or workpiece with its diameter. These ratios offer less rigidity.
Mandrel
The rotating shaft on which honing stones or other abrasives are mounted. This is the core of both single-stroke and multi-stroke honing tools.
Oscillates
Moves back and forth repeatedly. Multi-stroke honing tools do this and rotate to create a cross-hatched surface finish.
Pilot
The end of the cutting tool helps guide the cutter straight into a hole. These are smaller than the rest of the tool and concentric with the drilled hole.
Pitch
The distance between a point on an individual thread and the corresponding point on the next thread. This on a tap should be the same as the counterpart of the intended mating fastener.
Shank
A cylindrical part of a tool or device opposite the cutting edges. Theses are shorter and thicker providing more rigid support for cutting tools.
Splines
Teeth added to shafts and interconnecting components that ensure they move together. These fit loosely and provide flexible movement for many devices.
Tolerance
The range of acceptable deviations from the measurements specified in a print. This allows a machined part to differ slightly from its intended dimensions.
Trepanning
A holemaking operation that uses a hollow rotating tool to cut all the way through a workpiece, leaving behind a slug. This can only be used to create through holes but uses less power than conventional drilling.
Walking
The tendency of a drill to move off-center from the intended hole at the beginning of a drilling operation. This is prevented by spot drilling prior to the main drilling operation.
