SPRING 2024

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THE DISTRIBUTOR’S LINK
LAURENCE CLAUS HOW FASTENERS ARE MADE - PART 2: HOT HEADING AND SCREW MACHINING from page 84
parts provided the operator or machine can hold the blank
steady during the forming process. Usually, the first blow
forms the head shape, and the second blow creates any
required head markings.
¤ High Speed Header – Cold headers can
be specially transformed to warm or hot headers by
introducing a source of heat and, sometimes, providing
cooling of the tool space and parts so that they do not
overheat (see Figures 3 and 4). Other machines start out
as warm or hot headers and are designed and built to
accommodate introducing heat and cooling the tool space
from the day they are built.
FIGURE 2: STACK OF HOT FORMED HEX BOLTS
Although there are primary and secondary forming
processes that might extrude the pre-threaded blank
diameter, these tend to be exceptions. If the blank diameter
must be closer tolerance than what the straight bar offers,
it must either be turned down or extruded. Most of the time
it is turned down in a secondary machining operation.
The warm and hot heading equipment can take
several different forms:
¤ Press – Vertical Presses are often used to warm
and hot head parts. This option is a good one for shorter
parts but becomes problematic when parts are too long,
and their length would make it challenging to get them out
of the dies.
¤ Horizontal Upsetter – These resemble a large,
bulky cold header and often can toggle to strike a part
twice. The dies are clamshell in design so that the part
is laid into the die, and it closes around the blank. The
part is struck with a punch and the hot material takes
the desired shape defined by the tooling. This is almost
always just forming the head and can be done on very long
FIGURE 3: HIGH SPEED HOT NUT FORMER
FIGURE 4: NUTS FORMED FROM HIGH SPEED HOT FORMER
CONTINUED ON PAGE 156