Z94.12.5 Metal Machining

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TAILSTOCK. The movable part on the other end of the lathe away from the headstock. It includes the center which is used to hold the workpieces between centers.

TANG. The flattened end of a taper shank of a rotating tool. It is intended to fit into the driving slot in the socket of the machine arbor.

TAPPING. The production of screw threads in a hole.

TAPS. The cutting tool for tapping operations.

TAYLOR'S TOOL LIFE EQUATION. A mathematical model developed by F. W. Taylor in 1907 relating the life of the tool to the cutting speed.

THREAD MANUFACTURING. Several methods and machines are used to produce external threads, such as turning, rolling, and milling.

THROW-AWAY-INSERTS. (See INSERTS.)

TOLERANCE. The total amount by which a specific dimension is permitted to vary. The tolerance is the difference between the maximum and minimum limits.

TOOL AND CUTTER GRINDER. A grinding machine used mainly to sharpen worn tools and cutters.

TOOL-CHIP INTERFACE. The contact surface between the chip and the tool face (on the rake face) during a cutting operation.

TOOL GEOMETRY. The dimensional characteristics of the cutting edge such as the cutting edge angles, nose radius, chamfer,.etc.

TOOLING. All the equipment used for fixturing workpieces and holding the tools and cutters in metal cutting operations; e.g. chucks, holders, face plates, jigs.

TOOL LIFE. The period of time, usually given in minutes, during which the tool performs its function before it is worn-out and needs to be resharpened or replaced.

TOOLMAKER'S MICROSCOPE. An optical microscope with adjustable vernier table used mainly to study the cutting edges of tools and cutters.

TOOL MATERIALS. The materials from which tools and cutters are made such as high speed steel, carbides, ceramics.

TOOLROOM LATHE. Precision engine lathe built to closer tolerances for machining of parts with high degree of accuracy.

TOOL WEAR. The progression of deterioration of the cutting edge of the tool leading to tool failure.

TRANSFER MACHINE. Highly automated machines for large volume production of a very small variety of parts (sometime called Detroit lines).

TRANSITION FIT. A fit between mating parts having limits of size so prescribed as to partially or wholly overlap, so that either a clearance or interference may result in assembly.

TREPANNING. A drilling operation to produce large holes using a thin, cylindrical cutter and maintaining a core from the drilled hole.

TRIBOLOGY. The subjects of friction, wear, and lubrication as applied to surface structure of component parts.

TRUEING. In grinding, the term applied to the methods of remaking the wheel into a true circle usually by dressing.

TUNGSTEN CARBIDE (WC). The most commonly used non-ferrous carbide material for cutting tools. They are usually made in the form of throw-away inserts.

TURNING. The production of a curvilinear surface when the cutting tool moves in a direction parallel to the axis of rotation of the workpiece. Turning is usually done on turning machines: engine lathe, turret lathe, screw machine, etc.

TURRET LATHES. Lathes which carry out multiple cutting operations, such as turning, boring, drilling, thread cutting, and facing. Various cutting tools, usually up to six (because of the hexagonal turret) are installed on the turret which is located usually on the other end of the machine away from the headstock.

TWIST DRILL. The most commonly used drilling tool, usually with two cutting edges and two flutes.

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