molex TM2000 User Manual
Industrial Crimp Quality Handbook
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Revision: C Revision Date: 12-23-09
INDUSTRIAL CRIMP QUALITY
HANDBOOK
Order No. 64016-0065
Industrial Crimp Quality Handbook
1 Introduction to Crimp Technology
2 Purpose and Scope
3 Definitions and Terms
4 Associated Materials
5 Terminal Description
5.1. Features of Solderless Terminals
5.2. Barrel Serration/Dimples
5.3. Barrel Styles
5.4. Splices
6 Procedures
6.1. Preparing the Wire
6.2. Setup and Operation of a Press
6.3. Setup and Operation of a Hand Crimp Tool
6.4. Setup and Operation of a Air Powered Crimp Tool
6.5. Crimping Dies
7 Quality Crimps
7.1. Visual Inspection of OPEN BARREL Crimps
7.2. Visual Inspection of CLOSED BARREL Crimp
8 Importance of Proper Crimping
8.1. Conditions
8.2. Testing
8.3. Final Tensile Value
8.4. Electrical Resistance
8.5. Crimp joints
9 Miscellaneous
Table of Contents
SECTION
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Industrial Crimp Quality Handbook
SECTION 1
INTRODUCTION TO CRIMP TECHNOLOGY
Developed to replace the need to solder terminations, crimping technology provides a high quality connection
between a terminal and a wire at a relatively low applied cost. The methods for applying crimp terminations depend
on the application, volume, and range from hand-held devices to fully automated systems.
The application methods include a basic hand tool, a press and die set, a stripper crimper, or a fully automatic wire
processing system. However, no matter what method is used, the setup of each tool is critical for achieving a
quality crimp.
Today, many OEM companies are using Statistical Process Control (SPC) to continuously improve their crimp
terminations. Crimp termination is a complex process and to ensure consistent quality it is necessary to understand
the variability and inter-relational interactions that the technology involves.
Without a thorough understanding of the crimping process, and all the factors that can affect it, the result may not
meet expectations. The three key elements in the crimping process are the terminal, the wire, and the tooling.
Terminal
For most applications, it is not economically practical for connector manufacturers to design a terminal to accept
one wire size, one wire stranding, and one insulation diameter (UL type) as well as Mil Specification. Most
terminals accommodate many wire sizes, stranding, and a range of insulation diameters, and the terminals are
designed to meet acceptable levels over this entire range.
Wire
The wire stranding and insulation type can vary widely within one wire size. For example, there is more than 18%
more material in an 18 AWG by 19-strand wire than an 18 AWG by 16-strand wire. The insulation diameter of an
18 AWG wire can range from 1.78mm (.070") to over 4.57mm (.180"). Wire strands can be copper, tinned, over
coated, or top coated. Wire insulation materials, thickness, and durometers vary from application to application.
Tooling
What type of tooling does the application require? Does the application require hand stripping of the wire or does
the volume dictate an automatic wire-stripping machine? Does the application and volume require hand tools,
press and die, or fully automatic wire process machines? Crimping with a manual hand tool, semi-automatic press
and die, or fully automatic wire processor, all involve different levels of variability. The terminal, wire, and type of
application tooling all affect the quality of the completed terminations.
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Industrial Crimp Quality Handbook
SECTION 2
PURPOSE AND SCOPE
Purpose
This handbook provides general guidelines and procedures for understanding and achieving acceptable crimp
terminations. A glossary in Section 3 lists common terms and definitions. Section 4 lists the tools that are
necessary to take accurate measurements and evaluate the crimp's acceptability.
For open barrel only, the tooling setup is critical in determining the quality of the finished crimp. The attributes that
need to be considered include crimp height, conductor brush, bell mouth, cut-off tab and strip length and insulation
position. Variability in one or more of these attributes can reduce the measured pull force. It can be difficult to
establish acceptable variability limits because the attributes all interact with one another.
For example, a track adjustment for bell mouth also will change the cut-off tab length and the insulation wire
position while strip length and wire locations affect the conductor brush and insulation position. Adjusting the
insulation crimp height may result in a slight change to the conductor crimp height measurement. It may be
necessary for the setup person to make multiple adjustments to establishing an optimal setup.
The order in which a setup is done may help reduce the number of repetitions required for an optimum setup.
This handbook is structured so that parts, or all, of its contents can be used as a procedural guide for ISO
requirements.
Scope
This handbook is intended for Molex customers who are crimping Molex open and closed barrel crimp
terminals and are using Molex tooling.
The handbook's contents may slightly differ from other connector manufacturers' or individual company guidelines
and procedures.
This handbook provides a basic overview of what to look for in an acceptable crimp. It is not intended to replace
individual product and/or tooling specifications.
Individual terminals or applications may have special requirements. Tooling limitations also may not permit an
attribute to be adjusted to meet optimum requirements.
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Industrial Crimp Quality Handbook
CONDUCTOR
BARREL
BRUSH
SECTION 3
DEFINITIONS AND TERMS
AWG
Acronym for American Wire Gauge. It is the most
popular of many systems for designating single,
round, solid, non-steel wire diameter in United
States of America. Stranded wires are designated
based on comparison of their total cross-sectional
area of the conductor part only (their current carrying
capacity) and cross-sectional area of a
corresponding solid wire.
Barrel
It is the back end portion of a terminal or contact. It
is crimped to the conductor, insulation, or both.
When designed to receive the conductor, it is called
the conductor barrel. When designed to support or
grip the insulation, it is called the insulation barrel.
Bell Mouth
This is the undisturbed portion of the conductor
barrel nearest the insulation crimp. It is the result
from the actual crimping, which acts as a funnel for
the wires and reduces the possibility of a sharp edge
on the barrel cutting or nicking the wires.
Bend Test
One way to test the insulation crimp is by bending
the wire several times and then evaluating the
movement of the insulation and wire strands. As a
rule, the insulation crimp should withstand the wire
being bent 60 to 90 degrees in any direction, several
times. Use care when working with small wire sizes
so the wire at the back of the insulation crimp does
not shear.
Butt Splice
It is a device to join two conductors, end-to-end,
rather than overlapping.
Chamfer
An angle on the inside edge of the barrel entrance of
a terminal that permits easier insertion of the wires
into the barrel.
Circular Mil (CM)
A unit of area used to indicate wire size. It is the
computed total cross sectional area of conductors.
One circular mil equals cross-sectional area of a
wire one mil (0.001 inches) in diameter.
CMA – acronym for Circular Mil Area
CMA
Acronym for Circular Mil Area
Contact Area
It is the area in contact between two conductors, or a
conductor and a connector permitting the flow of
electricity.
Conductor Brush
The conductor
brush is made up
of the wire strands
that extend past
the conductor
barrel on the
contact side of the terminal. This helps ensure that
mechanical compression occurs over the full length
of the conductor crimp. The conductor brush should
not extend into the contact area.
Conductor Crimp
This is the metallurgical compression of a terminal
around the wire's conductor. This connection
creates a common electrical path with low
resistance and high current carrying capabilities.
Conductor Crimp Height (Open Barrel Crimps)
The conductor crimp height is measured from the
top surface of the formed crimp to the bottom radial
surface. Do not include the extrusion points in this
measurement. Measuring crimp height is a quick,
non-destructive way to help ensure the correct
metallurgical compression of a terminal around the
wire's conductor and is an excellent attribute for
process control. The crimp height specification is
typically set as a balance between electrical and
mechanical performance over the complete range of
wire stranding and coatings, and terminal materials
and plating. Although it is possible to optimize a
crimp height to individual wire stranding and
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Industrial Crimp Quality Handbook
CUT-OFF TAB
LENGTH
CARRIER STRIP
terminal plating, one crimp height specification is
normally created.
*Consult individual terminal specification
requirements.
Crimp
It is the act of physically compressing (forming) a
connector or contact barrel around a cable in order
to make an electrical connection. On a crimped
terminal, a second crimp is often added to the
insulation area for added strain relief.
CSA
Canadian Standards Association is an independent
Canadian testing laboratory similar to UL
(Underwriters Laboratories Inc.).
Cut-off Tab Length
This material protrudes outside the end of the
terminal after the terminal is separated from the
carrier strip. As a rule, the cut-off tab should be
flush or .254mm (.010”) protruding outside the
housing sleeve. A cut-off tab, which is too long,
may expose a terminal outside the housing or it may
fail electrical spacing requirements. In most
situations, a tool is set-up to provide a cut-off tab
that is flush to one material thickness.
Dielectric Test
A test that uses the application of a voltage higher
than the rated voltage for a specific time for the
purpose of determining the adequacy against
breakdown of insulation materials and spacing under
normal conditions. This test is used to ensure the
crimping procedure did not puncture or destroy the
insulation material on the terminal.
Extrusions (Flash)
These small flares form on the bottom wire barrel
resulting from the clearance between the punch
and anvil tooling. If the anvil is worn or if the
terminal is over-crimped an excessive extrusion
results. An uneven extrusion may also result if the
punch and anvil being misaligned.
Ferrule
A short tube used to mate solderless connectors to
shielded or coaxial cable. It is used as an insulation
grip sleeve on solderless terminals.
Flash
It is an abnormal protrusion on the wire barrel,
(either insulation material or metal), which indicates
that the crimping tool is either misaligned or worn
and thus should not be used.
Funnel Entry
It is a crimped terminal or splice barrel, which opens
to facilitate quick and easy wire insertion.
Gas Tight Seal
A contact system that utilizes soft metals at high
contact pressures so that upon mating, metal is
upset and the resultant joint prevents contaminant
gases from entering the contact area.
Gauge
A method of measurement, often using “go” and “nogo” pins or shapes to determine if an attribute is
within tolerance.
Harness
A group of wires or cables joined to form a circuit
network for electronic or electrical equipment. A
harness is usually an assembly of cables cut to the
proper length, terminated, and tied together prior to
being assembled in a piece of equipment.
Insulation Crimp (Strain Relief)
It is a crimp encompassing both the wire and
insulation. This helps to prevent the conductor
from being exposed due to the insulation receding
and offers additional resistance to vibration.
Insulation Crimp Height
Molex does not specify insulation crimp heights
because of the wide variety of insulation thickness,
material, and hardness. Most terminals are
designed to accommodate multiple wire ranges.
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Industrial Crimp Quality Handbook
Within the terminal’s range, an insulation grip may
not completely surround the wire or fully surround
the diameter of the wire. This condition will still
provide an acceptable insulation crimp for most
applications.
A large insulation grip should firmly grip at least
88% of the wire.
A smaller insulation grip should firmly grip at
least 50% of the wire and firmly hold the top of
the wire.
To evaluate the insulation section, cut the wire flush
with the back of the terminal. Once the optimum
setting for the application is determined, it is
important to document the insulation crimp height.
Then, as part of the setup procedure, the operator
can check the insulation crimp height.
Locator
A device for positioning terminals, splices, or
contacts in crimping dies.
MCM (or kcmil)
Unit of area, based on Circular Mil, equal to one
thousand circular mils. Usually used instead of
AWG above wire sizes greater than 4/0 AWG.
Mega (mega, M)
Prefix denoting one million, e.g., one megavolt =
one million volts.
Micro (micro, )
Prefix denoting one millionth, e.g., one microvolt =
one millionth of a volt.
Mil Spec
Military Specification. A specification used for
qualification of products for acceptability as required
for U.S. Government applications (usually for a
military branch), e.g. Mil-T-7928 covers terminals,
lugs, splices, conductors, crimp style.
Mechanical Strength
To insure how strong the connection is or how much
the wire and terminal must be squeezed to get a gas
tight seal. It’s important to crimp the wires tight
enough to keep them from slipping out of the
connector, but not so tight as to crush the wires in
the terminal, causing them to break off. The
connection is weakened if the wires are cut or
nicked.
Nest
The portion of a crimping die, which supports or
reshapes the barrel during crimping.
PSI, psi
(Pound-Force per Square Inch) Non-SI unit of
pressure. Used mainly to denote pressure of air or
other gas, e.g. 75 psi.
Pound-Force (lbf)
Unit of force, 1lbf is approximately equal to force
exerted on a mass of 1 lb by gravitational force of
Earth at its surface, or a force exerted by that mass
(stationary) on a support (i.e. if mass of 1 lb is
hanged on a wire, it exert a force of ca. 1 lbf
(directed down) on that wire).
Pull Force Testing
Pull force testing is a quick, destructive method to
evaluate the mechanical properties of a crimp
termination.
Pull force testing results out
of allowed range are good
indicators of problems in the
process. Cut or nicked
strands in the stripping
operation, lack of bell mouth
or conductor brush, or
incorrect crimp height or
tooling will reduce pull force.
Wire properties and
stranding, and terminal
design (material thickness
and serration design), also can increase, or
decrease the value of the results of a pull force test.
If results of a pull force tests are within an allowed
range, it assures that proper crimp force has been
applied during crimping. It is crucial as, when
making a crimp, enough force must be applied to
break down the layer of non-conductive oxides that
may build up on the stripped conductor and the tinplating on the inside of the terminal grip. This is
necessary to provide a good metal-to-metal contact.
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Industrial Crimp Quality Handbook
PUNCHES
WIRE
ANVILS
TERMINAL
STRIP
LENGTH
If this does not occur, resistance can increase.
Over-crimping a crimp termination will reduce the
circular area of the conductor and increase
resistance.
Serrations
It is the saw-toothed grooves on the surface of a
terminal, which ensures firm gripping of the
conductor. Also provides additional contact area.
Solderless
This means without solder – in our case, denoting
the use of a crimping tool.
Splice
A device used to join two or more conductors
together.
Strip Length
The strip length is determined by measuring the
exposed conductor strands after the insulation is
removed. The strip length determines the
conductor brush length when the insulation position
is centered.
*Consult individual terminal specification
requirements
Tab
Flat rectangular male connection tabs on electrical
components; various sizes to fit female quick
disconnects.
Tensile Test
This is a pull test to determine the mechanical
strength of the crimped wire. They are specific
minimum values set for each wire size. See Section
8.
Terminal
A device designed to terminate a conductor that is to
be affixed to a wire or cable to establish an electrical
connection. It is a synonym for contact. There are
two main types, which include the open barrel and
the closed barrel. Parts of the terminal are:
Insulation barrel Where the wire’s insulation will be
crimped or supported so that it is
firmly gripped.
Wire barrel Where the bare wire will be
crimped.
Contact area Where the terminal will be attached
to the mating part.
Terminal Position
The terminal position is set by the alignment of the
terminal to the forming punch and anvils, and the
carrier-strip cut-off tooling. The tool set-up
determines conductor, cut-off tab length, and
terminal extrusions.
UL
Underwriters’ Laboratories, Inc., founded in 1894,
is chartered as a not-for-profit organization under
the laws of Delaware, to establish, maintain, and
operate laboratories for the investigation of
materials, devices, products, equipment,
construction methods, and systems with respect to
hazards affecting life and property.
Voltage Drop Test
A test of the voltage developed across a component
or conductor being a result of electric current flow in
the component or conductor and its non-zero
electrical resistance. It is the test of the electrical
integrity of the crimp.
Wire
They are a group of conductors that has a low
resistance to current flow, together with any
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Industrial Crimp Quality Handbook
WIRE STOP
WIRES
associated insulation. There are two kinds: a solid
wire, which is one single strand of material, or
stranded group of wire, which is a bundle of wires
twisted together to act as one.
Wire Size
Wires have varying sizes or gauges that carry
different amounts of electrical current with each wire
used for a separate purpose. The size (in AWG) is
called out with a number, such as 8 or 10, followed
by the letters AWG, which stand for American Wire
Gauge.
Wire Stop
It is a stop at the end of a terminal wire barrel. It
prevents wire from passing completely through the
barrel so the wire will not interfere with the function
of the contact.
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