CNC Turning operations at ALNO Product Services
Turning specific operations include:
Turning | Tapered turning | Spherical generation | Hard turning | Facing | Parting
Grooving | Boring | Drilling | Knurling | Threading
Turning
The general process of turning involves rotating a part or
piece of material around an axis while a single point cutting tool is moved
parallel to the axis of rotation. This turning can be done on either an
external or internal surface of the part. The starting material is known as the
raw material or a workpiece is generated by other processes such as casting
forging extrusion or drawing
Tapered turning
Tapered turning produces a cylindrical shape that gradually
decreases in diameter from one end to the other. This can be achieved through
one of the following:
a) from the compound slide
b) from taper turning attachment
c) using a hydraulic copy attachment
d) using a C.N.C. lathe
e) using a form tool
f) by the offsetting of the tailstock - this method more
suited for shallow tapers.
Spherical generation
Spherical generation produces a spherical finished surface
by turning a form around a fixed axis of revolution. Methods include one of the
following:
a) using hydraulic copy attachment
b) C.N.C. computerized numerically controlled lathe
c) using a forming tool, a rough and ready method
d) using bed jig need drawing to explain.
Hard Turning
Hard turning is a type of turning done on materials with a
HRc Hardness greater than 45. It is typically performed after the workpiece is
heat treated
The process is intended to replace or limit traditional
grinding operations. Hard turning, when applied for purely stock removal
purposes, competes favorably with rough grinding.
However, when it is applied for finishing where form and
dimension are critical, grinding is superior. Grinding produces higher
dimensional accuracy of roundness and cylindricity. In addition, polished
surface finishes of Rz=0.3-0.8z cannot be achieved with hard turning alone.
Hard turning is appropriate for parts requiring a roundness
accuracy of 0.5-12 micrometers, and/or surface roughness of Rz 0.8–7.0 micrometers.
It is used for gears, injection pump components, and hydraulic components,
among other applications.
Facing
Facing in the context of turning work 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 a datum from
which dimensions can be taken from.
Parting
This process, also called parting off or cutoff, is used to
create deep grooves which will remove a completed or part-complete component
from its parent stock.
Grooving
Grooving is like parting, except that grooves are cut to a
specific depth 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.
Boring
Enlarging or smoothing an existing hole the machining of
internal cylindrical forms generated by one of the following:
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.
Boring is suitable for castings that are too 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.
Drilling
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 process can be done by separately available
drilling machines.
Knurling
The cutting of a serrated pattern onto the surface of a part
to use as a hand grip or as a visual enhancement using a special purpose
knurling tool.
Reaming
The sizing operation that removes a small amount of metal
from a hole already drilled. It is done for making internal holes with
repeatable accuracy diameters to a specific size.
Threading
Both standard and non-standard screw threads can be turned
on a lathe using an appropriate cutting tool. Either externally, or within a
bore.
Tapping of threaded nuts and holes can be:
a) created using hand taps and tailstock center
b) created using a tapping device with a slipping clutch to
reduce risk of breakage of the tap.
threading operations include
a) All types of external and internal thread forms using a
single point tool also taper threads, double start threads, multi start
threads, worms as used in worm wheel reduction boxes, leadscrew with single or
multi-start threads.
b) by the use of threading boxes fitted with 4 form tools, up to 2" diameter threads but it is possible to find larger boxes than this.
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