User Manual

2
OK Industries Inc. Tel [phone] Fax [phone] www.okindustries.com
Wire Size Min. number Min. strip
AWG Dia. Dia. of turns force
inches mm (Bare Wire) lbs. gms
16 .051 1.30 4 15 6800
18 .0403 1.00 4 15 6800
20 .032 0.80 5 8 3600
22 .0253 0.65 5 8 3600
24 .0201 0.50 6 7 3200
26 .0159 0.40 7 6 2700
28 .0126 0.32 7 5 2200
30 .0100 0.25 7 3.3 1500
*Conforms to MIL-STD-1130B
Wire Wrapping Overview
As the electronics industry has advanced in technology, the need for a faster, more
reliable and inexpensive method of making electrical connections has become a
necessity. In years past, it was sufficient to solder most connections since there was
ample room between terminals and relatively few connections by today’s
standards. However, today’s electronic equipment is far more complex, leading to
many more terminals. The task is compounded by the reduction in equipment size.
The end result is far more terminals - in much less space. To solve this problem, the
industry has had to adapt to a completely different type of connection. The
solderless connection by wire wrapping technique is now a standard method of
making connections to terminals in high density electronic equipment.
The Technology of Wire Wrapping
A wire wrapped connection is made by coiling the wire around the sharp corners of a terminal under mechanical tension. This
method of connection was developed by Bell Telephone Laboratories, Western Electric Company.
By bending the wire around the sharp
corner of the terminal, the oxide layer
on both wire and terminal is crushed or
sheared, and a clean, oxide-free metal-
to-metal contact is obtained.
High Pressure Contact
Terminals Suitable for Wire
Wrapped Connections
Triple Connection
Types of Wrapping Tools
● Pneumatic tools are preferred for
production work.
● Where compressor air is not available,
electric tools are recommended.
● Battery or hand operated tools are
used for service and repair work.
Easy Removal
● A distinct advantage of wire wrapping
is the ease with which a wire may be
removed from a terminal to correct
errors or modify wiring. An unwrap
tool is slipped over the terminal,
engaging the first turn of the
connection. Rotating the tool, the
connection is removed in seconds,
without damage to the terminal.
Wire
● Solid wire is used for wire wrapped
connections. Copper is the most
commonly used wire. Minimum
elongation of 15% is required for 24
through 32 AWG; 20% for larger wire.
Quality Assurance
● Our bits are subjected to a series of
“Qualification Tests”. These consist of
wrapping groups of wire on various
types of test terminals. The wrapped
wires are then subjected to a “Strip”
test to determine adequate tightness.
“Unwrap” tests are also performed to
ensure against an “Overtight” wrap.
● A “Regular” bit wraps the bare wire around
the terminal. A “Modified” bit wraps a
portion of insulation around the terminal in
addition to the bare wire. This greatly
increases the ability to withstand vibration.
Strength of Connection
● The strength of a wire wrapped connection
is considerably in excess of that of a
soldered one. It is less easily stripped from
the terminal and is less subject to breakage.
Gas Tight Contact Areas
● The contact areas of a wire wrapped
connection remain gas tight when exposed
to temperature changes, corrosive
atmospheres, humidity and vibration.
Metal-To-Metal Contact Types of Wrap
Regular Modified
“Strip” Force Chart*