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The Theory and Application of Precision Hand Crimping Tools
As featured in the March/April 2001 issue of
Wiring Harness News
By John D. Butler, PE
Courtesy of
APPLITEK TECHNOLOGIES CORP
Providence, RI
About the Author:
John D. Butler has accumulated over twenty years of experience in the electrical
wire processing industry. John is the inventor of over twenty U.S. and Foreign patents
and has authored several technical publications related to the wire processing industry.
John serves as the Director of Engineering for Applitek Technologies Corporation.
Applitek is a leading supplier of crimp related products and services including: terminal
attaching machines, terminal applicators, crimp cross-sectioning equipment, special
machines, tooling, and terminal design consultation.
Applitek is a North American distributor of WEZAG Hand Crimping Tools.
The following is the eighth in a series of articles presented in Wiring Harness News
pertaining to "crimp technology" by the author (refer to the Bibliography for a
complete listing).
Abstract:
Hand crimping tools are widely used in many industries and for various uses. These
uses include: "in-field" service tools, small production requirements, prototyping
terminal or connector designs, developing crimp specifications, repair tools for the
wire harness production environment, and for use in environments that present restrictions
to crimp equipment size, weight, and maneuverability such as those presented with wire
harness assembly boards. Hand crimping tools can be either "manually-driven" or
"power-driven".
There are several features that a precision hand crimping tool should incorporate.
Specifically, the tool should guaranty that a specific crimp height has been achieved.
It should provide for precision alignment of the opposed crimping forms. Where
applicable, the tool itself should provide for a means of accurately locating, supporting,
and holding the terminal or connector in place during crimping as opposed to the operator
holding the components. The tool should be designed such that the manual force required
falls within acceptable human factor guidelines. The shape, weight and required human
intervention of the tool should conform to good ergonomic practice. Ideally, the tool should
be designed as to be affordable. In the following article, the author provides an in-depth
discussion of some hand tool history, basic mechanism theory, ergonomics, and desirable
hand crimping tool characteristics and features. A variety of hand crimping tool designs are discussed including both flawed designs as well as those designs exhibiting good
engineering practice.
Preface:
Terminal or connector attaching equipment can be divided into three general categories:
(1) Hand Crimping Tools, (2) Bench/Semi-automatic Equipment, and (3) Automatic
Equipment. Not all applications can utilize equipment from all three categories. There are
some applications that can only be performed with hand tools and conversely there are
some that can only be practically done by a "semi" or "fully" automated process. The
following is a brief discussion of the three categories:
Generally speaking, Hand Crimping Tools are hand held devices, either "manually-driven", such as the one shown in FIG.(1), or "power driven" via electricity, pneumatics, or
hydraulics. "Manually-driven" almost always refers to those devices that are two-handled
and squeez-ed by the hand just like the hand motion required when using pliers.
"Power-driven" refer to devices that eliminate the closing and opening (i.e. squeezing)
motion of the hand. They are still manually actuated but the actuation is typically of
relatively lower forces via a trigger or button which initiates the particular power medium
used to take over (i.e. electricity, pneumatics, or hydraulics). Hand crimping tools are widely
used in many industries and for various uses. These uses include: "in-field" service tools,
small production requirements, prototyping terminal or connector designs, developing crimp
specifications, repair tools for the wire harness production environment, and for use in
environments that present restrictions to crimp equipment size, weight, and maneuverability
such as those presented with wire harness assembly boards.
The terminals or connectors to be crimped are generally "loose" piece however there
are some hand crimping tools that are designed with tracks and feed mechanisms to
facilitate processing of reeled "continuous strip" terminals or connectors. Most hand
crimp tools are designed to be used by one hand while the other hand is required to hold
and position the wire end to be crimped hence, a "two-handed" operation.
The second category, Bench/Semi-automatic Equipment, generally refers to bench or
table-top mounted equipment. Except for manual foot-lever (kick) or hand-lever presses,
most are power driven via electricity, pneumatics, or hydraulics. The "semi" designation
refers to the requirement of an operator to manually present the wire end to the terminating
press or mechanism. Typical equipment would include a terminating press and terminating
applicator and stripper crimpers. The terminals or connectors to be crimped are generally
automatically fed from a reel in "continuous strip" form. However, there are many types of
equipment in this category that handle "loose" piece terminals or connectors. When
outfitted with crimp monitors, the equipment can continuously monitor the quality of crimp
produced. Most equipment in this category are designed such that the equipment cycle is
foot pedal actuated or actuated by a wire sensor with one hand being requir-ed to position
the wire end to be crimped hence, a "one-handed" operation.
The third category, Automatic Equipment, generally comprises fully automated wire
processing "turn-key" systems. The wire is automatically fed in continuous length
from a reel or barrel, automatically measured for accurate length, automatically cut to a
pre-determined length, end stripped, terminated, and ejected and collected. The terminals
are generally automatically fed in "continuous strip" form from a reel, although there are
many machines that handle "loose" piece terminals and associated "loose" piece
components such as seals and housing blocks. Many "state-of-the-art" automated
machines are PC controlled with the operator having the ability to change terminating press
settings such as the crimp height right from the computer screen. When, outfitted with
crimp monitors, the equipment can continuously monitor the quality of crimp produced.
Most fully automatic equipment in this category are designed such that the equipment cycle
is virtually "hands free" hence, a "no hands" operation.
Hand crimp tools for electrical related purposes have been used since the early
1900's well before the invention and implementation of either "semi" or "fully"
automated equipment. Over this period of time, hundreds of patents have been awarded
for hand crimping tool innovations. Consequently today, hand crimping tools come in
various shapes and configurations, as shown in FIG.(2), and vary widely in quality,
performance, and cost. Given the variety of choice, the significant number of flawed designs
available, the lack of knowledge of crimp quality criteria, and the fact that hand crimping tool
global sales (number of units sold) continue to out number either of the other two categories
each year, there exists a need for more published technical information available to the
purchaser and user of hand crimping tools for evaluation and comparison sake. Therefore,
the focus of this article is on detailing the theory behind several design characteristics and
features both flawed designs as well as those designs exhibiting good engineering
practice will be discussed.
Before we begin our discussion however, the following premise and explanation must
be stated for it serves as the basis of the arguments to be presented:
"The major goal of any crimping method is to attach a terminal or connector to
the wire in such a manner as to ensure a quality connection while simultaneously
maintaining the integrity of the component(s) attached. The method must provide
for a means of achieving repeatable good quality crimps within accepted statistical
limits and practice."
In other words, independent of whether a hand crimping tool is used, or a bench terminating
press, or the most sophisticated fully automated wire processing machine ever devised by
mankind, given the same terminal applied to the same gage wire with the same crimp form
shape, and given correct crimp specifications, the resultant crimps should be equal in
quality. Further, the premise states that the equipment used must be designed such that the
correct crimp is achieved each and every time.
Copyright 2001 by John D. Butler. All rights reserved. This article or parts within may be
reprinted for private use only, without alteration, and providing credit is given to
the source.
For more information about WEZAG Hand Crimping Tools, including reprints of this
article, contact APPLITEK TECHNOLOGIES CORP., 160 Georgia Avenue, Providence,
RI 02905; Phone: (401) 467-0007; FAX: (401) 467-5525; E-MAIL: applitek@tiac.net
Visit Applitek at http://www.applitek-usa.com
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