SPRING 2022

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THE DISTRIBUTOR’S LINK
LAURENCE CLAUS HOT FORGING FASTENERS from page 96
FIGURE 3: COMPLETED STRUCTURAL NUTS EMERGING
FROM THE HOT HEADER
The Process
The process can be split into two different categories;
high speed and lower speed. The high speed processes
are pretty close in comparison with cold heading, utilizing
continuous raw material coils, automated feeding, and
high speed equipment. The result is a process producing
high part yields. They may utilize a simple approach of
adding heat with an induction coil to just a selected
portion of the raw material wire prior to the blank being
cut-off (Figure 1) or utilize a more sophisticated approach
of heating the entire raw material wire section just prior
to cut-off and carefully controlling the temperature across
all the die stations (Figure 2). Even though parts now
have the benefit of heat, machine size is still a limiting
factor as heat does not infinitely expand the machine
capabilities and most machines are capable of producing
only marginally larger parts than what can be produced in
cold forming. These processes, however, are well suited
for high volume structural nuts, special high volume
engineered components, and standard titanium fasteners
(Figure 3).
Almost all parts larger than 1 ½” in diameter or very
long in length utilize a lower speed process. In these
instances the blank is prepared from bars cut to discrete
lengths. Each blank is cut to length using a power shear
or a metal cutting band saw. All the blanks needed to fulfill
the order are normally cut and staged prior to forming. The
next step is to get heat into the part where it is needed.
Unlike cold forming, where many geometry changes may
be taking place, when hot forming large parts normally
only a head or other unique feature is formed. This means
that only a selected area of the part (typically one end
only) needs to be heated. This is accomplished with the
operator placing that end of the blank into an induction
coil or a small forge to heat up the area in interest. The
operators will usually time or measure temperature to
establish that the desired temperature has been reached.
Depending on the length and geometry of the part, the
operator will grab the unheated end with their hands or
a set of tongs or crane and quickly transfer the blank to
the forming press. These presses may be set-up vertically
or horizontally. Once introduced to the die, the press is
cycled, striking the part and forming the shape that is in
the die (Figure 4).
FIGURE 4: HOT FORMED PART BEING REMOVED FROM THE DIE
CONTINUED ON PAGE 180