Cold finishing is the term generally used to
distinguish products that have been subject to cold processing from
the as rolled original section.
Cold finishing comprises the following classifications:
(a) Cold Die Drawing (b) Cold Turning (c) Cold Grinding
Cold drawing has been used for a great many years to improve the
as-rolled condition of hot rolled bars, rounds, squares, hexagons,
flats, and a variety of sections termed "special shapes."
Other processes such as cold drawing and grinding, cold turning
and polishing, and cold grinding and polishing are used to refine
the as rolled condition of hot rolled bars, but by far the largest
demand is confined to cold drawn bars.
Various practices are employed to obtain the maximum effects of
cold drawing, but generally speaking, standard practice would average
as follows:
Rounds up to 3"
Hexagons up to 3 7/8"
Squares up to 4'
Flats up to 12"
Cold drawing is by far the outstanding method yet developed that
will improve, at minimum costs, the surface imperfections, lack of
true cross section, straightness and many other defects constant
in hot rolled products. The advantages of cold drawing are not confined
to the above mentioned improvements as it-is the only operation besides
heat treatment that produces a marked effect on the physical properties
of the as-rolled original section . Of course, different results
are obtained in physical properties due to the varying sizes and
analysis.
The reduction in the as-rolled original section varies with different
analyses and the required physical properties. Generally speaking,
the original hot rolled section is reduced about 1/16th" of an inch
plus the average rolling tolerance of the original section.
Cold drawing radically reduces the necessity of extra machining
and straightening operations and eliminated considerable heat treating.
Cold drawing has a very decided influence on another important property
of steel-machinability. Comparative tests on the same material, machined
in both the as rolled and cold drawn condition, show that from 15%
to 20% greater production is obtained in machining cold drawn bard
in automatic screw machines. The problem os machinability is very
complex as it is made up of varying factors which cannot always be
evaluated or stated in absolute terms.
Cold Drawn Bars also supplied in the Ground and Polished state where
maximum uniformity and close tolerance to size in the overall dimension
is essential. This class of material is usually supplied in Rounds
1 1/8" and smaller.
Cold Turning plays a very important part in Cold Finished Steels.
While this process does not produce any marked change in the physical
properties of the original section, it does have a distinctive effect
on the surface. The principle results of cold turned bars are:
(1) uniformity of section, (2) improved size tolerance and (3) bright,
smooth finish.
Cold grinding has the same effect on the original section as cold
turning. This process further improves the qualities of the cold
turned bar to a greater degree from the standpoint of
(1) uniformity of section, (2) improved size tolerance and (3) bright,
smooth finish.
Cold grinding is essential where maximum uniformity in the overall
dimension is a requisite.
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