Turning
Turning
is another of the basic machining processes. Turning produces solids of revolution which can be tightly toleranced because of the specialised nature of the operation. Turning is performed on a machine called a lathe in which the tool is stationary and the part is rotated. The figure below illustrates an engine lathe. Lathes are designed solely for turning operations, so that precise control of the cutting results in tight tolerances. The work piece is mounted on the chuck which rotates relative to the stationary tool.
Turning operations
Turning specific operations include:
Longitudinal Turning
This operation is one of the most basic machining processes.
That is, the part is rotated while a single point cutting tool is moved parallel to the axis of rotation. Turning can be done on the external surface of the part
as well as internally (boring).
Tapered turning
from the compound slide or from taper turning attachment.
Facing
is part of the turning process. It involves moving the cutting tool at right angles to the axis of rotation of the rotating workpiece. This can be performed by the operation of the cross-slide, if one is fitted, as distinct from the longitudinal feed (turning). It is frequently the first operation performed in the production of the workpiece, and often the last- hence the phrase "ending up".
Parting
This process is used to create deep grooves which will remove a completed or part-complete component from its parent stock
.
Grooving
is like parting, except that grooves are cut to a specific depth by a form tool instead of severing a completed/part-complete component from the stock. Grooving can be performed on internal and external surfaces, as well as on the face of the part (face grooving or trepanning).
Non-specific operations include:
i.e. the machining of internal cylindrical forms (generating) a) by mounting workpiece to the spindle via a chuck or faceplate b) by mounting workpiece onto the cross slide and placing cutting tool into the chuck. This work is suitable for castings that are to awkward to mount in the face plate. On long bed lathes large workpiece can be bolted to a fixture on the bed and a shaft passed between two lugs on the workpiece and these lugs can be bored out to size. A limited application but one that is available to the skilled turner/machinist
is used to remove material from the inside of a workpiece. This process utilizes standard drill bits held stationary in the tail stock or tool turret of the lathe.
The cutting of a serrated pattern onto the surface of a part to use as a hand grip using a special purpose knurling tool
both standard and non-standard screw threads can be turned on a lathe using an appropriate cutting tool. (Usually having a 60, or 55° nose angle) Either externally, or within a bore. Generally referred to as single-point threading.
: