Quality Crimp Handbook
QUALITY CRIMPING
HANDBOOK
Order No. 63800-0029
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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Page 1 of 24
Quality Crimp Handbook
Table of Contents
SECTION
1
Introduction
2
Purpose
3
Scope
4
Definitions
5
Associated Materials
6
Procedure
7
Measurement
8
Process Control
9
Trouble Shooting
10
Wire Gauge Chart
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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Page 2 of 24
Quality Crimp 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 and 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). 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, semiautomatic 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.
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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Quality Crimp Handbook
SECTION 2
PURPOSE
This handbook provides general guidelines and procedures for understanding and achieving acceptable crimp
terminations. A glossary in Section 4 lists common terms and definitions. Section 4 lists the tools that are
necessary to take accurate measurements and evaluate the crimp's acceptability.
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, and 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 before establishing an optimal setup.
The order the setup is done may help reduce the number of repetitions required for an optimum setup.
Section 6 has a flowchart for a process setup while Section 8 is a trouble-shooting guide for common
problems. Using Statistical Process Control (SPC) during the crimping process can help minimize the Parts
per Million (PPM) reject levels. Section 7 provides a general explanation of the benefits of using SPC.
This handbook is structured so that parts, or all, of its contents can be used as a procedural guide for ISO
requirements.
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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Quality Crimp Handbook
SECTION 3
SCOPE
This handbook is intended for Molex customers who are crimping Molex open barrel crimp terminals
and are using Molex tooling, primarily in semiautomatic or automatic wire processing termination methods.
The handbook's contents may slightly differ from other connector manufacturers' guidelines or individual
company 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.
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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Quality Crimp Handbook
BEND UP
SECTION 4
BRUSH
BELL
MOUTH
CONDUCTOR
CRIMP
ROLLING
SEAM
INSULATION
CRIMP
TWISTING
STRIP
LENGTH
BEND
DOWN
CUT-OFF
TAB
TERMINAL CROSS
SECTION VIEW
EXTRUSIONS
CRIMP
HEIGHT
EXTRUSION
EXTRUSION
Figure 4-1
DEFINITIONS
Anatomy of a Crimp Termination (Figure 4-1)
Bell Mouth (Flare)
The flare that is formed on the edge of the
conductor crimp acts as a funnel for the wire
strands. This funnel reduces the possibility that a
sharp edge on the conductor crimp will cut or nick
the wire strands. As a general guideline, the
conductor bell mouth needs to be approximately 1
to 2 times the thickness of the terminal material. *
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.
Conductor Brush
The conductor brush is made up of the wire strands
that extend past the conductor crimp on the contact
side of the terminal. This helps ensure that
mechanical compression occurs over the full length
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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
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, (See Figure 4-1). 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 terminal plating,
one crimp height specification is normally created.
*Consult individual terminal specification requirements
Cut-off Tab Length
This material protrudes outside the insulation crimp
after the terminal is separated from the carrier strip. As
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Quality Crimp Handbook
a rule, the cut-off tab is approximately 1.0 to 1.5
times terminal material thickness. * A cut-off tab
that is too long may expose a terminal outside the
housing or it may fail electrical spacing
requirements. In most situations, a tool is setup to
provide a cut-off tab that is flush to one material
thickness.
Extrusions (Flash)
These small flares form on the bottom of the
conductor crimp resulting from the clearance
between the punch and anvil tooling. If the anvil is
worn or the terminal is over-crimped, excessive
extrusion is the results. An uneven extrusion may
also result if the punch and anvil alignment is not
correct, if the feed adjustment is off, or if there is
insufficient/excessive terminal drag.
Insulation Crimp (Strain Relief)
This is the part of the terminal that provides wire
support for insertion into the housing. It also allows
the terminal to withstand shock and vibration. The
terminal needs to hold the wire as firmly as possible
without cutting through to the conductor strands.
The acceptability of an insulation crimp is subjective
and depends on the application. A bend test is
recommended to determine whether the strain relief
is acceptable for each particular application.
is important to document the insulation crimp height.
Then, as part of the setup procedure, the operator can
check the crimp height.
Insulation Position
This is the location of the insulation in relation to the
transition area between the conductor and insulation
crimps. Equal amounts of the conductor strands and
insulation needs to be visible in the transition area. The
insulation position ensures that the insulation is crimped
along the full length of the insulation crimp, and that no
insulation is crimped under the conductor crimp. The
insulation position is set by the wire stop and strip length
for bench applications. For automatic wire processing
applications, the insulation position is set by the in/out
press adjustment.
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.
Figure 4-2
Insulation Crimp Height
*Consult individual terminal specification requirements
Process
Example Control Chart
Thousandths
31.5
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.
Within the terminal’s range, the strain relief 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.
Sample
30.5
Contol Limit
Control Limit
Upper Specification
29.5
Lower Specification
28.5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Measurements
1. A large strain relief should firmly grip at least
88% of the wire.
2. A smaller strain relief should firmly grip at least
50% of the wire and firmly hold the top of the
wire.
To evaluate the insulation crimp section, cut the wire
flush with the back of the terminal. Once the
optimum setting for the application is determined, it
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
Figure 4-3
The combination of people, equipment, tooling,
materials, methods, and procedures needed to produce
a crimp termination. Process Control is used to track
attributes over time to aid in the detection of change to
the process. Detecting a process change when it
happens helps prevent many thousands of bad crimps.
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Quality Crimp Handbook
Pull Force Testing
Shut Height
This is the distance (at bottom dead center on a press)
from the tooling mounting base plate to the tooling
connection point on the ram of the press.
Terminal Position
Figure 4-4
PUNCHES
Pull force testing is a quick, destructive way to
evaluate the mechanical properties of a crimp
termination. When making a crimp, enough
pressure must be applied to break down the oxides
that may build up on the stripped conductor and the
tin-plating on the inside of the terminal grip. This is
necessary to provide a good metal-to-metal contact.
If this does not occur, resistance can increase.
Over-crimping a crimp termination will reduce the
circular area of the conductor and increase
resistance.
Pull force testing is also a good indicator 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 pull
force levels.
WIRE
TERMINALS
ANVILS
Figure 4-6
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 bell mouth, cut-off tab length, and terminal
extrusions
PRESS BASE PLATE
RAM
SHUT HEIGHT
GAUGE
Figure 4-5
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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Quality Crimp Handbook
Ruler (Pocket Scale)
SECTION 5
ASSOCIATED MATERIALS
Caliper
This is used to estimate the five-piece measurement of
bell mouth, cut-off tab, conductor brush, wire position,
and strip length. The recommended maximum
resolution is 0.50mm (.020”).
A gauge, consisting of two opposing blades. It used
for measuring linear dimensional attributes.
Pull Tester (Reference Figure 5)
A device used to determine the mechanical strength of a
crimp termination. Most pull testing is done with a
device that clamps the wire, pulls at a set speed, and
measures force by means of a load cell. A pull tester
also can be as simple as hanging fixed weights on the
wire for a minimum of one minute.
Eye Loop
This is a magnification
tool, normally 10 times
power or greater, which
is used in the aid visual
evaluation of a crimp
termination.
Toolmaker’s Microscope
Crimp Micrometer
This is a micrometer specifically designed to
measure crimp height. The measurement is taken in
the center of the crimp so the conductor bell mouth
does not influence it. It has a thin blade that supports
the top of the crimp while a pointed section
determines the bottom radial surface.
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
This is used for close visual evaluation and statistical
measurement of bell mouth, cut-off tab, conductor
brush, wire position and strip length.
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Quality Crimp Handbook
SECTION 6
11.
PROCEDURES
Tool Setup (Reference Procedures Flow Chart)
1. Check that tooling is clean and not worn. If
necessary, clean and replace worn tooling.
2. Disconnect power to the press and remove
guarding devices.
3. Install the appropriate tooling into the press.
4. Load terminals into the tooling so that the first
terminal is located over the anvil.
5. Manually cycle the press to help ensure a complete
cycle can be made without interference. If it
cannot, remove tooling and check press shut
height. Go to procedure 3.
6. Check that the tooling is aligned. Check the
impression on the bottom of the crimp that was
made by the anvil tooling. Check that the extrusions
and crimp form are centered. If not, align tooling
and go to procedure 5.
7. Check that the terminal feed locates the next
terminal over the center of the anvil tooling. If not,
adjust terminal feed and feed finger and go to
procedure 5.
8. Re-install all safety devices that were removed
during the set-up. (Follow all safety
requirements listed in individual press and/or
tooling manuals.)
9. Crimp sample terminals under power.
10. Evaluate cut-off tab length and conductor bell
mouth. If adjustment is necessary, disconnect
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
power to the press and remove guarding. Adjust track
position. Manually cycle the press and check the feed
finger for feed location, go to procedure 7.
Evaluate conductor brush. If adjustment is necessary,
disconnect power to the press and remove guarding.
Adjust wire stop for bench applications or press position
on automatic wire processing equipment. Go to
procedure 8.
Evaluate insulation position. If necessary, adjust strip
length, crimp new samples, and go to procedure 11.
Loosen insulation crimp height.
Crimp sample terminals.
Measure conductor crimp height and compare to
specification. If necessary, disconnect power and
remove guarding. Adjust conductor crimp height, install
guards, connect power, and go to procedure 14.
Perform a pull force test. Refer to troubleshooting
(Section 9) if this test fails.
Adjust insulation crimp.
Crimp sample terminals.
Evaluate insulation crimp. If necessary, disconnect
power and remove guarding. Adjust insulation crimp
height, install guards, connect power, and go to
procedure 18.
Measure crimp height and compare to specification. If
necessary, disconnect power and remove guarding.
Adjust conductor crimp height, install guards, connect
power, and go to procedure 18.
Document measurements.
Please Work Safely At All Times.
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Quality Crimp Handbook
PROCEDURES FLOW CHART
Start
A
Evaluate tooling
to ensure it is
clean and not
worn
No
Wire
processi
Replace
tooling / clean
Ye
Disconnect power and
remove necessary guards
Adjust press
position
Install tooling into
the press
Set shut height
of the press
Load terminals
into tooling
Remove tooling
from the press
Adjust terminal feed
and/or feed finger
Bench
Evaluate
insulation
position
Adjust
wire stop
B
A
Good
Not
Good
Crimp
samples
No
Adjust conductor
crimp height
Align
tooling
Conductor
crimp height
OK?
No
No
Disconnect power and
remove necessary
guarding
Ye
Pull
Force test
Ye
Install safety guarding
and connect power
Manually cycle
the press
Crimp
samples
Adjust track
position
Not
Good
Disconnect power and
remove necessary
guarding
Install safety guarding
and connect power
Pas
Adjust
insulation
Adjust insulation
crimp height
Crimp
samples
Not
Pas
Trouble shooting
(See Section 9)
Install safety guarding
and connect power
Disconnect power and
remove necessary
guarding
No
Insulation
OK?
Adjust conductor
crimp height
Ye
End
Order No: TM-638000029
Revision: C
Adjust
strip length
Install safety guarding
and connect power
Terminal feed
OK? Terminal
centered over
anvil?
Evaluate cut-off
tab and
bell mouth
Crimp
samples
Good
Loosen insulation
crimp
Ye
No
Evaluate
conductor
brush
Good
B
Ye
Tooling
aligned?
Not
Good
Disconnect power and
remove necessary
guards
Manually cycle
the press
Complete
cycle?
Bench press
or wire
processing
Release Date: 09-04-03
Revision Date: 10-20-09
Ye
Conductor
crimp
OK?
No
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Disconnect power and
remove necessary
guarding
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Quality Crimp Handbook
bottom wire due to the effects of the terminal
serrations.
SECTION 7
MEASUREMENT
Wire Chart
Pull Force Testing
1. Cut wire length approximately 152.00mm (6.00”)
long.
2. Strip one end to 13.00mm (.500”), or long enough
so no wire insulation is under the insulation grip, or
loosen the insulation crimp so it has no grip on the
insulation of the wire.
3. Terminate the appropriate terminal to the wire to
the nominal crimp height.
4. Visually inspect the termination for bell mouth, wire
brush and cut strands.
5. Set pull tester to 25.4.00mm per minute (1.00" per
minute). For most applications, a higher rate will
not have a significant impact on the data. The
slower rate prevents a sudden application of force
or jerking that snaps strands. Verify higher pull
rates with data taken at 1.00” per minute.
6. If necessary, knot the un-terminated end of the wire
(If insulation slips on wire).
7. Regardless of pull tester type, both wire and
terminated end must be securely clamped. (Note:
Clamp terminal contact interface, do not clamp
conductor crimp)
8. Activate pull test.
9. Record pull force readings. A minimum of five pull
force measurements should be done to confirm
each set-up. A minimum of 25 readings should be
taken for capability.
10. Compare lowest reading to minimum pull force
specification.
Note: High variability and lower CpK's are common
for double wire applications. The variability is due
to more variation in conductor brush, conductor bell
mouth and fewer strands of one wire being in
contact with the serrations on the terminal barrel. A
double crimp application is considered no better
than the smallest wire crimped. Higher pull force
readings can be seen if both wires are gripped and
pulled exactly together. Pulling each wire
individually will result in a much lower pull force
reading. If both wires are of the same size, the top
wire will normally result in a lower reading than the
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
Note: Pull force has only a minimum specification. For CpK
calculations, the average reading is assumed nominal and
the upper specification limit is set so CP and CpK are
equal. High pull force readings that increase the standard
deviation can lower CpK even if the mean and lowest
reading are increased.
Test Values for Pull Force Test
UL486A
Size of Conductor
Pullout Force*
AWG
mm2
Lb.
N
30
0.05
1.5
6.7
28
0.08
2
8.9
26
0.13
3
13.4
24
0.20
5
22.3
22
0.324
8
35.6
20
0.519
13
57.9
18
0.823
20
89.0
16
1.31
30
133.5
14
2.08
50
222.6
12
3.31
70
311.5
10
5.261
80
356.0
8
8.367
90
400.5
*Consult individual specifications
Crimp Height Testing
1. Complete tool set-up procedure.
2. Crimp a minimum of five samples.
3. Place the flat blade of the crimp micrometer across the
center of the dual radii of the conductor crimp. Do not
take the measurement near the conductor bell mouth.
4. Rotate the micrometer dial until the point contacts the
bottom radial surface. If using a caliper, be certain not
to measure the extrusion points of the crimp.
5. Record crimp height readings. A minimum of five crimp
height readings is necessary to confirm each set-up. A
minimum of 25 readings is necessary to determine
capability.
6. Check crimp height every 250 to 500 parts throughout
the run.
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Quality Crimp Handbook
Note: Crimp height is usually control charted
because it is a quick, nondestructive measurement
and is critical for the termination's electrical and
mechanical reliability. There are three primary
purposes for control charting. One, the number of
setup samples is normally small, and its statistical
value is limited. Two, since special cause/effects
on a process are irregular and unpredictable; it is
necessary to have a means of catching changes in
the process as soon as they occur. This prevents
having to scrap thousands of terminations after the
run is over. Three and this is most important, the
data is necessary to assess and improve the crimp
process.
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
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Quality Crimping Handbook
Figure 7-1
PULL TESTING
Figure 7-2
CRIMP MICROMETER
Order No 63800-0029
Revision: A
Release Date: 09-04-03
Revision Date: 09-04-03
Figure 7-3
CALIPER
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Quality Crimp Handbook
SECTION 8
CRIMP PROCESS CONTROL
The crimp process is the interaction of a terminal, wire,
tooling, personnel, methods and procedures, and
environmental attributes. When this process is
controlled, it will produce a quality termination. Quality
control is an important part of quality crimping. It
should not take excessive setup or inspection time to
do, and it can save a harness manufacturer thousands
of dollars in potential rework or re-manufacturing.
Variability is the slight change that occurs from crimp to
crimp. There are two types of variability, common or
special. Common causes of variation affect the
process uniformly and are the result of many small
sources. Common variability is inherent tolerances
within a reel of wire or terminals. Common variability
also is created by the natural tolerances of the stripping
and crimping machines.
Reducing variability at the common level typically has
to come from changes to the wire, terminal, and tooling
manufacturer.
Special causes of variation occur irregularly and
unpredictably. Without checks throughout a run, having
a tool become loose after the first hundred crimps or a
jam resulting from a damaged tool may be undetected
until thousands of crimps are made.
Process Capability
Before putting a new crimping tool in production, Molex
recommends that each customer do a capability study,
using the specific wire that will be used in its process.
A capability study, which is based on the assumption of
a normal distribution (bell-type curve), estimates the
probability of a measurement being outside of
specification.
CpK
0.67
1
1.33
1.67
2
Capability
+/- Sigma % Yield
2
95.45
3
99.73
4
99.99
5
99.99+
6
99.99++
PPM*
45,500
2,699
63
0.57
0
* PPM - Parts per million potential defects.
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
A 25 piece minimum sample needs to be taken from
the crimping process. Calculate the average and
standard deviation for each specification. A capability
index is defined by the formula below. Cp may range in
value from zero to infinity, with a larger value indicating
a more capable process. A value greater than 1.33 is
considered acceptable for most applications. Cp is
calculated with the following formula.
___Tolerance___
6*Standard Deviation
The CpK index indicates whether the process will
produce units within the tolerance limits. CpK has a
value equal to Cp if the process is centered on the
mean of specification; if CpK is negative, the process
mean is outside the specification limits; if CpK is
between 0 and 1 then some of the 6 sigma spread falls
outside the tolerance limits. If CpK is larger than one,
the 6-sigma spread is completely within the tolerance
limits. CpK is calculated with the lesser of the following
formulas:
__(USL - Mean)__
3*Standard Deviation
__ (Mean - LSL)__
3*Standard Deviation
USL = Upper Specification Limit, LSL = Lower
Specification Limit
Six sigma is a goal of many companies because it
represents virtually zero defects. The ability of a
company to achieve a six-sigma level depends on the
amount of common variability in its process. For
example, hand stripping the wire produces more
variability than a stripping machine; crimping hand tools
produce more variability than a press and die set, and
bench terminations produce more variability than a
wire-processing machine.
A part of the variability in crimping will result from the
type of instruments that are used to measure the parts
and the operator's ability to repeat the measurement. A
crimp micrometer will measure more accurately than a
dial caliper. An automatic pull force system will
measure better than a hook type scale. It is important
that the measurement gauge has enough resolution.
Two operators may measure the same part differently,
or the same operator may measure the part differently
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Quality Crimp Handbook
when using two types of gauges. Molex recommends a
gauge capability study to identify what part of the
variability is coming from measurement error. Microterminals crimped to small wire sizes need a tight crimp
height range to maintain pull force. The variability from
measurement error can keep CpKs low.
The capability of the crimping tools needs to be reconfirmed if the production data is significantly different
from the capability study.
on the chart before making a crimp height adjustment.
If data is recorded after each adjustment, the process is
likely to assume control and provide little data for
improving the process. The operator needs to make as
many notes as possible on the chart. The only truly
effective and economically sensible way to manage a
manufacturing process is to understand, monitor and
reduce sources of variability that are inherent to the
process itself. Every minute required for setup or
adjustments is unproductive.
Production
What does this sample chart tell us?
Before the tool is ready for production, the level of
capability needs to be established. Many harness
manufacturers run only a few hundred or few thousand
wires at one time. In this case, it is not practical or
economical to run a twenty-five-piece capability with
every set-up.
Visual Inspection
It needs to be standard operating procedure for the
operator to manually fan each bundle of crimped wires
and visually check bell mouth, conductor brush,
insulation position, cut-off tab length, and insulation
crimp.
Control Charting
Crimp height is typically control charted because it is a
quick nondestructive measurement and is critical for the
termination's electrical and mechanical reliability.
There are three primary purposes for control charting.
One, the number of setup samples is usually small, with
limited statistical value. Two, since special cause
effects on a process are irregular and unpredictable; it
is necessary to be able to catch changes in the process
as soon as they occur. This prevents thousands of
terminations from being scrapped after the run is over.
Three, and most important, this data is necessary to
assess and improve the crimp process.
Once the tooling process is setup and the wire size
does not change, keep one control chart for wire color
changes, wire length changes, terminal material
changes, or setup adjustments. Record the data point
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
X and R Chart
Control limit for sample of 5 = Avg
(Avg of 5readings) + .577 x Avg (Ranges)
It indicates that a process shift occurred between
measurement 12 and 13. This type of shift could occur
due to a change in wire, a change in terminal lots, a
jam in the machine that damaged the tooling, a change
in operators, or an adjustment to the insulation crimp.
Since the measurements are still within specification,
would you stop production to adjust crimp height?
A shift in the process due to a change in material may
warrant a crimp height adjustment. A shift after a jam
would not indicate an adjustment, but a close
evaluation of the tooling. A shift in the process
between operators would not indicate an adjustment,
but an evaluation of measurement capability. The
purpose of a control chart is to identify what caused the
shift in process to determine if an adjustment to the
process is needed.
UNCONTROLLED COPY
Page 16 of 24
Quality Crimp Handbook
SECTION 9
TROUBLE SHOOTING
Wire Preparation
Symptom
Irregular insulation cut
(Figure 9-1)
Cut or nicked strands
(Figure 9-2)
Irregular conductor cut-pulled strands
(Figure 9-3)
Wire length variability too high
(Figure 9-4)
Wrong strip length (Figure 9-4)
Cause
Worn tooling
Wire cut depth too shallow
Damaged tooling
Cut depth too deep
Conductor not on wire center
Worn tooling
Wire cut depth too shallow
Wire drive rollers/belts worn
Insulation durometer too hard
Wire straightener too loose or tight
Incorrect setup
Figure 9-1
IRREGULAR INSULATION CUT
Figure 9-3
PULLED STRANDS
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
Solution
Replace tooling
Adjust cut depth
Replace tooling
Adjust cut depth
Contact wire supplier
Replace tooling
Adjust cut depth
Replace belts/rollers
Increase drive pressure
Adjust wire straightener
Re-setup tooling
Figure 9-2
CUT STRANDS
Figure 9-4
WIRE LENGTH VARIABILITY OR WRONG STRIP LENGTH
UNCONTROLLED COPY
Page 17 of 24
Quality Crimp Handbook
Bell Mouth and Cut-off Tab Length
Symptom
Low pull force
(Figure 9-6 and 9-7)
Cut or nicked strands
(Figure 9-8)
Long cut-off tab (Figure 9-9)
Figure 9-5
OPTIMAL CRIMP
Cause
Excessive bell mouth, no cut-off tab
Excessive bell mouth, cut-off tab alright
No bell mouth and/or excessive cut-off tab
Good bell mouth and excessive cut-off tab
Figure 9-6
EXCESSIVE BELL MOUTH
Figure 9-8
NO BELL MOUTH EXCESSIVE CUT-OFF TAB
Order No: TM-638000029
Revision: C
Solution
Adjust track position for small cut-off tab
Check for worn or incorrect punch tooling and replace
Adjust track position
Check for camber in terminal strip
Check for worn cut-off and replace if necessary
Check for worn punch tooling, replace, and re-adjust track
Release Date: 09-04-03
Revision Date: 10-20-09
Figure 9-7
EXCESSIVE BELL MOUTH
NO CUT-OFF TAB
Figure 9-9
EXCESSIVE CUT-OFF TAB GOOD BELL MOUTH
UNCONTROLLED COPY
Page 18 of 24
Quality Crimp Handbook
Conductor Brush and Insulation Position
Symptom
Insulation under conductor crimp, good
conductor brush (Figure 9-10)
Insulation under conductor crimp, long
conductor brush length (Figure 9-11)
Cause
Solution
Strip length too short
Check specification, adjust strip length longer
Bench - Wire stop position incorrect
Wire Processing – Press position incorrect
Adjust wire stop to center of transition area
Adjust press position away from wire
Check specification, adjust strip length longer
Re-adjust wire stop position for bench applications OR
re-adjust press position for wire processing applications
Check specification, adjust strip length shorter
Re-adjust wire stop position for bench applications OR
re-adjust press position for wire processing applications
Insulation under conductor crimp,
short or no conductor brush (Figure 9-12)
Insulation edge centered in transition area,
conductor brush too long (Figure 9-13)
Strip length too short
Strip length too long
Irregular wire cut-off or strands pulled
from insulation bundle
Insulation edge centered in transition area,
conductor brush too short (Figure 9-14)
Strip length too short
Insulation edge under insulation crimp,
good or long conductor brush (Figure 9-15)
Strip length too long
Insulation edge under insulation crimp,
short or no conductor brush (Figure 9-16)
Bench - Wire stop position incorrect
Wire processing - Press position incorrect
Verify operators wire placement ability
Figure 9-10
INSULATION UNDER CONDUCTOR
CRIMP, GOOD CONDUCTOR BRUSH
Figure 9-12
INSULATION UNDER CONDUCTOR CRIMP,
SHORT OR NO CONDUCTOR BRUSH
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
Check specification, adjust strip length longer
Re-adjust wire stop position for bench applications OR
re-adjust press position for wire processing applications
Check specification, adjust strip length shorter
Re-adjust wire stop position for bench applications OR
re-adjust press position for wire processing applications
Adjust wire stop to center of transition area
Adjust press position away from wire
Operate training, reduce crimping rate
Figure 9-11
INSULATION UNDER CONDUCTOR CRIMP,
CONDUCTOR BRUSH TOO LONG
Figure 9-13
CONDUCTOR BRUSH TOO LONG
Figure 9-15
INSULATION UNDER INSULATION CRIMP,
CONDUCTOR BRUSH TOO LONG
Check for worn stripping tooling
Figure 9-14
CONDUCTOR BRUSH TOO SHORT
Figure 9-16
INSULATION UNDER INSULATION CRIMP,
CONDUCTOR BRUSH TOO SHORT
UNCONTROLLED COPY
Page 19 of 24
Quality Crimp Handbook
Insulation Crimp
Symptom
Cause
Solution
Terminal surrounds less than 88% of a large
diameter wire (Figure 9-21)
Terminal contacts less than 50% of a small
diameter wire (Figure 9-22)
Insulation crimp barrels cut through insulation
into conductor strands (Figure 9-23)
Insulation not firmly gripping insulation,
fails bend test (Figure 9-24)
Crimp too loose, not enough
terminal insulation barrel
Tighten insulation crimp height
Evaluate terminal
Too much terminal insulation barrel
Evaluate terminal
Crimp too tight
Adjust insulation crimp height*
Crimp too loose
Adjust insulation crimp height tighter
* Inexpensive hand tools provide no adjustment for the insulation crimp. A hand tool is intended for low volume
applications. Although you are not able to adjust the insulation crimp on a hand tool, an insulation crimp, which
pierces the insulation, may still be considered acceptable for many applications. This criterion only applies to hand
tools due to their low speed crimp cycle. If the insulation crimp pierces the insulation, the wire strands tend to move
aside without damage.
Figure 9-17
PREFFERRED
INSULATION CRIMP
Figure 9-18
PREFFERRED
INSULATION CRIMP
Figure 9-20
ACCEPTABLE INSULATION CRIMP
Figure 9-22
MARGINAL INSULATION CRIMP
Order No: TM-638000029
Revision: C
Figure 9-21
MARGINAL INSULATION CRIMP
Figure 9-23
MARGINAL INSULATION CRIMP
Release Date: 09-04-03
Revision Date: 10-20-09
Figure 9-19
ACCEPTABLE
INSULATION CRIMP
Figure 9-24
MARGINAL INSULATION CRIMP
UNCONTROLLED COPY
Page 20 of 24
Quality Crimp Handbook
Crimp Height
Symptom
Crimp height off target
(Figure 9-26)
Crimp height variability too high
(Figure 9-27)
Cause
Changed wire type vendor or stranding
Changed insulation color or durometer
Changed crimp tooling
Changed crimp press (shut height)
Changed press type (manufacturer)
Changed terminal reel (lot code)
Changed tooling set-up
Damaged or worn tooling
Wire variability
Terminal variability
Damaged, loose or worn tooling
Measurement error
Terminal spring-back too great, over crimping
Cut or missing wire strands
Solution
Adjust tooling back to target
Inspect incoming product
Tooling replacement or tightening
Gauge capability analysis
Crimp height adjustment
Stripping process adjustment
Figure 9-25
OPTIMAL CRIMP HEIGHT CHART
Figure 9-26
CRIMP HEIGHT OFF TARGET
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
Figure 9-27
CRIMP HEIGHT VARIABILITY TOO HIGH
UNCONTROLLED COPY
Page 21 of 24
Quality Crimp Handbook
Pull Force
Symptom
Wire breaks before conductor
crimp - low pull force
(Figure 9-29)
Wire pulls out of conductor
grip - low pull force
(Figure 9-29)
Cause
Cut or nicked strands
Crimp height too low
Small or no bell mouth
Insulation crimp through insulation wall
Crimp height too high
Small or no conductor brush
Conductor bell mouth too big
Gold terminal application
Terminal material thickness too small
Light serrations on terminal
Solution
Check the stripping process
Adjust crimp height
Adjust tooling track
Raise insulation crimp height
Adjust crimp height
Increase strip length
Adjust tooling track
Evaluate the terminal application
Contact your local sales engineer
Figure 9-28
OPTIMAL PULL FORCE CHART
Figure 9-29
LOW PULL FORCE CHART
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
UNCONTROLLED COPY
Page 22 of 24
Quality Crimp Handbook
SECTION 10
Wire Gauge Chart
AWG
8
8
8
8
8
8
10
10
10
10
12
12
12
12
12
14
14
14
14
14
16
16
16
16
16
16
18
18
18
18
18
18
20
20
20
20
20
20
22
22
Wire Area
Sq. mm Sq. inch
8.302
.01287
7.820
.01212
7.955
.01233
8.605
.01334
8.513
.01319
8.424
.01306
5.261
.00816
4.740
.00735
5.006
.00776
5.320
.00825
3.308
.00513
3.632
.00563
3.085
.00478
3.294
.00511
3.3118
.00514
2.082
.00323
2.270
.00352
1.941
.00301
2.078
.00322
2.112
.00327
1.308
.00203
1.433
.00222
1.229
.00191
1.317
.00204
1.307
.00203
1.330
.00206
.823
.00128
.897
.00139
.811
.00126
.963
.00149
.825
.00128
.823
.00128
.519
.00080
.563
.00087
.507
.00079
.616
.00096
.523
.00081
.519
.00081
.324
.00050
.355
.00055
Order No: TM-638000029
Revision: C
Stranding
No.
Dia.
1
.1280
19 .0285
49 .0179
133 .0113
168 .0100
665 .0020
1
.1019
37 .0159
49 .0142
105 .0100
1
.080
7
.0320
19 .0179
65 .0100
165 .0063
1
.0641
7
.0253
19 .0142
41 .0100
105 .0063
1
.0508
7
.0201
19 .0113
26 .0100
65 .0063
105 .0050
1
.0403
7
.0159
16 .0100
19 .0100
41 .0063
65 .0050
1
.0320
7
.0126
10 .0100
19 .0080
26 .0063
41 .0050
1
.0253
7
.0100
Release Date: 09-04-03
Revision Date: 10-20-09
Wire Diameter
mm
In.
3.25
.128
3.68
.145
3.73
.147
3.73
.147
3.73
.147
3.73
.147
2.59
.102
2.92
.115
2.95
.116
2.95
.116
2.05
.081
2.44
.096
2.36
.093
2.41
.095
2.41
.095
1.63
.064
1.85
.073
1.85
.073
1.85
.073
1.85
.073
1.30
.051
1.52
.060
1.47
.058
1.50
.059
1.50
.059
1.47
.058
1.02
.040
1.22
.048
1.19
.047
1.24
.049
1.19
.047
1.19
.047
.81
.032
.97
.038
.89
.035
.94
.037
.91
.036
.91
.036
.64
.025
.76
.030
Circular
Mills
16384
15433
15700
16983
16800
16625
10384
9354
9880
10500
6529
7168
6088
6500
6549
4109
4481
3831
4100
4167
2581
2828
2426
2600
2580
2625
1624
1770
1600
1900
1627
1625
1024
1111
1000
1216
1032
1025
640
700
UNCONTROLLED COPY
Wire Break
N
Lbs.
2175.00 489.0
2048.72 460.6
2084.21 468.6
2254.49 506.9
2230.22 501.4
2206.99 496.2
1378.44 309.9
1241.75 279.2
1311.63 294.9
1393.89 313.4
866.69 194.8
951.56 213.9
808.16 181.7
862.88 194.0
869.37 195.5
545.45 122.6
594.81 133.7
508.59 114.3
544.28 122.4
553.24 124.4
342.58
77.0
375.43
84.4
322.07
72.4
345.15
77.6
342.48
77.0
348.47
78.3
215.60
48.5
234.93
52.8
212.40
47.8
252.23
56.7
216.03
48.6
215.72
48.5
135.94
30.6
147.53
33.2
132.75
29.8
161.43
36.3
136.99
30.8
136.07
30.6
84.97
19.1
92.93
20.9
Page 23 of 24
Quality Crimp Handbook
AWG
22
22
24
24
24
24
24
26
26
26
26
28
28
28
30
30
30
32
32
32
Wire Area
Sq. mm Sq. inch
.382
.00059
.329
.00051
.205
.00032
.227
.00035
.201
.00031
.241
.00037
.200
.00031
.128
.00020
.141
.00022
.127
.00020
.154
.00024
.080
.00012
.089
.00014
.093
.00014
.051
.00008
.057
.00009
.060
.00009
.032
.00005
.034
.00005
.039
.00006
Americas Headquarters
Lisle, Illinois 60532 U.S.A.
1-800-78MOLEX
amerinfo@molex.com
Stranding
No.
Dia.
19 .0063
26 .0050
1
.0201
7
.0080
10 .0063
19 .0050
41 .0031
1
.0159
7
.0063
10 .0050
19 .0040
1
.0126
7
.0050
19 .0031
1
.0100
7
.0040
19 .0025
1
.0080
7
.0031
19 .0020
Far East North Headquarters
Yamato, Kanagawa, Japan
81-462-65-2324
feninfo@molex.com
Wire Diameter
mm
In.
.79
.031
.76
.030
.61
.024
.58
.023
.61
.024
.58
.023
.58
.023
.40
.016
.53
.021
.51
.020
.48
.019
.32
.013
.38
.015
.41
.016
.25
.010
.30
.012
.30
.012
.20
.008
.20
.008
.23
.009
Far East South Headquarters
Jurong, Singapore
65-6-268-6868
fesinfo@molex.com
Circular
Mills
754
650
404
448
397
475
394
253
278
250
304
159
175
183
100
112
118
64
67
76
Wire Break
N
Lbs.
100.11
22.5
86.29
19.4
53.63
12.1
59.47
13.4
52.69
11.8
63.06
14.2
52.31
11.8
33.56
7.5
36.88
8.3
33.19
7.5
40.36
9.1
21.08
4.7
23.23
5.2
24.24
5.4
13.28
3.0
14.87
3.3
15.64
3.5
8.50
1.9
8.93
2.0
10.09
2.3
European Headquarters
Munich, Germany
49-89-413092-0
eurinfo@molex.com
Corporate Headquarters
2222 Wellington Ct.
Lisle, IL 60532 U.S.A.
630-969-4550
Fax: 630-969-1352
Visit our Web site at http://www.molex.com
Order No: TM-638000029
Revision: C
Release Date: 09-04-03
Revision Date: 10-20-09
UNCONTROLLED COPY
Page 24 of 24