Crimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comCrimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comGeometry and Associated Tolerances
Terminals are designed to perform to specification only when the final crimp form is within a narrow range of
dimensions. Controlling critical crimp dimensions is influenced by many factors including:
? Wire size and material variation
? Terminal size and material variation
? Equipment condition
The final quality and consistency of a crimp can never be any better than the
quality and consistency of the tooling that is used. If other variations could
be eliminated, tooling can and should be able to produce crimp forms that
are well within specified tolerances. In addition, variation from one tooling
set to another should be held to a minimum. Crimp tooling features that are
well controlled and exhibit excellent consistency from tooling set to tooling
set can result in shorter setup time as well as more consistent production re-
sults.
Some critical crimp characteristics are directly defined by the tooling form
and are obvious. These include:
Cross Section Defining Crimp Width,
Crimp Height, and Flash
? Crimp width
? Crimp length
Other critical crimp characteristics can be related to several tooling form fea-
tures and/or other system factors. These may
be less obvious and include:
? Flash
? Roll, twist, and side-to-side bend
? Up/down bend
? Crimp symmetry
? Bellmouth
The following discussion focuses on two characteristics, crimp width and flash, as examples of how tooling can
affect crimp form. Similar arguments can be applied to the others.
Crimp Width
Crimp width is a good example of a feature that should be consistent and in control between different
crimpers of the same part number. The reason for this is quite straightforward. For a given terminal and wire
combination, it is necessary to achieve an area index, AI, which is determined by the terminal designer for op-
timal mechanical and electrical performance. Crimp height, CH, and crimp width, CW, directly affect achieving
proper AI. Area index, AI(as a percentage), is defined as:
where At is the total area of the wire and barrel after crimping. A and A are, respectively, the initial cross-
W B
sectional areas of the wire and barrel before crimping.Crimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comCrimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comGeometry and Associated Tolerances
Terminals are designed to perform to specification only when the final crimp form is within a narrow range of
dimensions. Controlling critical crimp dimensions is influenced by many factors including:
? Wire size and material variation
? Terminal size and material variation
? Equipment condition
The final quality and consistency of a crimp can never be any better than the
quality and consistency of the tooling that is used. If other variations could
be eliminated, tooling can and should be able to produce crimp forms that
are well within specified tolerances. In addition, variation from one tooling
set to another should be held to a minimum. Crimp tooling features that are
well controlled and exhibit excellent consistency from tooling set to tooling
set can result in shorter setup time as well as more consistent production re-
sults.
Some critical crimp characteristics are directly defined by the tooling form
and are obvious. These include:
Cross Section Defining Crimp Width,
Crimp Height, and Flash
? Crimp width
? Crimp length
Other critical crimp characteristics can be related to several tooling form fea-
tures and/or other system factors. These may
be less obvious and include:
? Flash
? Roll, twist, and side-to-side bend
? Up/down bend
? Crimp symmetry
? Bellmouth
The following discussion focuses on two characteristics, crimp width and flash, as examples of how tooling can
affect crimp form. Similar arguments can be applied to the others.
Crimp Width
Crimp width is a good example of a feature that should be consistent and in control between different
crimpers of the same part number. The reason for this is quite straightforward. For a given terminal and wire
combination, it is necessary to achieve an area index, AI, which is determined by the terminal designer for op-
timal mechanical and electrical performance. Crimp height, CH, and crimp width, CW, directly affect achieving
proper AI. Area index, AI(as a percentage), is defined as:
where At is the total area of the wire and barrel after crimping. A and A are, respectively, the initial cross-
W B
sectional areas of the wire and barrel before crimping.A typical design point for AI is 80%. In order to maintain
Cross Sections Showing Min-
(a)
the same AI, the crimp height, CH, needs to change in-
imum (a) and Maximum (b)
Area Index perTerminal
versely to the change of crimp width, CW, in approxi-
Specification?aVariation of
mately the same proportion. Thus, if the CW increases
? 3.5%
+2%, the CH needs to change approximately -2% in order
to achieve the same AI design point. At first glance that
may not seem significant, but in reality it can be very
significant. Using another general industry design rule of
(b)
the ratio of CH to CW of approximately 65%, a typical
set of dimensions used as an example may be: CW = 0.110 in, CH = 0.068 in
Therefore, varying the CW by 2% would result in a CH variation of 2%, or 0.0014 in.
At a CH tolerance of ? 0.002 in, 35% of the total CH tolerance would be used by a
2% variation in CW. Thus, the importance of crimp width control is obvious when
tooling is changed during a production run.
Flash
Most crimp terminations have a requirement to limit flash. Flash is defined as the material which protrudes to the
sides of the terminal down and along the anvil. Flash is normal in the crimping process but excessive flash is very
undesirable. Controlling flash requires a balance of several geometric factors. Other factors influencing flash are
related to surface finish and friction, which will be discussed later in this paper.
A dominant factor in controlling flash is controlling the clearance between the crimper and anvil during the crimp
process. Defining the ideal clearance could in itself be a simple matter were it not for two facts:
? In order to minimize terminals? sticking in the crimper, the sides
of the crimper are tapered. Thus the clearance between the
anvil and crimper varies throughout the stroke.
? Crimper and anvil sets are typically designed to terminate two
to four wire sizes. This creates multiple crimp heights. Since the
sides of the crimper are tapered to minimize terminal sticking,
the maximum clearance permitted without creating flash must
be assigned to the maximum crimp height specified for the
tooling set. In addition, a minimal clearance must be maintained
for the smallest crimp height specified by the tooling set to
Crimper-to-Anvil Clearance = X +Y
prohibit contact between the anvil and crimper.
at the Final Crimp Height
Crimper to anvil clearance is thus a combination of crimp width, crimper leg taper,
anvil width, and crimp height. The critical design point is at the largest crimp
height. This contribution to the gap is directly dependent on dimensional control.
The following is offered as an example:
Nominal condition: CH = 0.073 in, CW = 0.110 in
Crimper leg taper = 3.0 degree
Anvil Width = 0.109 in
Nominal anvil to crimper total clearance = 0.005 in
The clearance can grow rapidly with small changes to
(a)
Significant flash can be generated
the nominal dimensions:
with excessive anvil to crimper
clearance, as shown by nominal
CH remains unchanged = 0.073 in
design condition (a) and +0.003 in
Increase in crimp width, CW, = 0.0008 in
over nominal condition (b)
Increase in crimper leg taper = 0.8 degree
Decrease in anvil width = 0.0008 in
The total increase in total clearance is this case = (b)
0.0026 in
This more than a 50% increase in the nominal design
clearance, which can result in unacceptable flash (see right).
Dimensional control is clearly critical.Crimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comCrimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comGeometry and Associated Tolerances
Terminals are designed to perform to specification only when the final crimp form is within a narrow range of
dimensions. Controlling critical crimp dimensions is influenced by many factors including:
? Wire size and material variation
? Terminal size and material variation
? Equipment condition
The final quality and consistency of a crimp can never be any better than the
quality and consistency of the tooling that is used. If other variations could
be eliminated, tooling can and should be able to produce crimp forms that
are well within specified tolerances. In addition, variation from one tooling
set to another should be held to a minimum. Crimp tooling features that are
well controlled and exhibit excellent consistency from tooling set to tooling
set can result in shorter setup time as well as more consistent production re-
sults.
Some critical crimp characteristics are directly defined by the tooling form
and are obvious. These include:
Cross Section Defining Crimp Width,
Crimp Height, and Flash
? Crimp width
? Crimp length
Other critical crimp characteristics can be related to several tooling form fea-
tures and/or other system factors. These may
be less obvious and include:
? Flash
? Roll, twist, and side-to-side bend
? Up/down bend
? Crimp symmetry
? Bellmouth
The following discussion focuses on two characteristics, crimp width and flash, as examples of how tooling can
affect crimp form. Similar arguments can be applied to the others.
Crimp Width
Crimp width is a good example of a feature that should be consistent and in control between different
crimpers of the same part number. The reason for this is quite straightforward. For a given terminal and wire
combination, it is necessary to achieve an area index, AI, which is determined by the terminal designer for op-
timal mechanical and electrical performance. Crimp height, CH, and crimp width, CW, directly affect achieving
proper AI. Area index, AI(as a percentage), is defined as:
where At is the total area of the wire and barrel after crimping. A and A are, respectively, the initial cross-
W B
sectional areas of the wire and barrel before crimping.Crimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comCrimp Tooling ?
Where Form Meets Function
Quality, cost, and throughput are key attributes for any production process. The
crimp termination process is no exception. Many variables contribute to the results.
Crimp tooling, defined here as crimpers and anvils, is one of those variables.
This paper will focus on defining key characteristics of crimp tooling and the effects
those characteristics may have on the production process.
Introduction
Quality, cost, and throughput are associated with specific measurements and linked to process variables. Crimp
height, pull test values, leads per hour, and crimp symmetry are some of the measures used to monitor production
termination processes.
Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and
operator skill.
Crimp tooling is a significant contributor to the overall crimp termination process. The condition of crimp tooling is
constantly monitored in production by various means. These means are often indirect measures. Crimp Quality
Monitors and crimp cross sections are methodologies that infer the condition of the crimp tooling. Visual inspec-
tion of the crimp tooling can be used
to check for gross failures such as tool breakage or tooling deformation which occurred as a result of a machine
crash. Continuous monitoring of production will help determine when
the process needs to be adjusted and the replacement of crimp tooling can be one of the adjustments that is
made.
Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High qual-
ity crimp tooling can produce high quality crimps with less in-process variation over a greater number of termina-
tions.
It is difficult to distinguish critical tooling attributes with visual inspection only. Some attributes cannot be in-
spected even by running crimp samples. This paper will present the reader with information that identifies key
crimp tooling attributes and the effect of those attributes on the crimping process.
Key Crimp Tooling Characteristics
There are four major categories of key characteristics for crimp tooling. These are:
? Geometry and associated tolerances
? Materials
? Surface condition
? Surface treatment
Each of these categories contributes to the overall performance of the production termination process.
tooling.te.comGeometry and Associated Tolerances
Terminals are designed to perform to specification only when the final crimp form is within a narrow range of
dimensions. Controlling critical crimp dimensions is influenced by many factors including:
? Wire size and material variation
? Terminal size and material variation
? Equipment condition
The final quality and consistency of a crimp can never be any better than the
quality and consistency of the tooling that is used. If other variations could
be eliminated, tooling can and should be able to produce crimp forms that
are well within specified tolerances. In addition, variation from one tooling
set to another should be held to a minimum. Crimp tooling features that are
well controlled and exhibit excellent consistency from tooling set to tooling
set can result in shorter setup time as well as more consistent production re-
sults.
Some critical crimp characteristics are directly defined by the tooling form
and are obvious. These include:
Cross Section Defining Crimp Width,
Crimp Height, and Flash
? Crimp width
? Crimp length
Other critical crimp characteristics can be related to several tooling form fea-
tures and/or other system factors. These may
be less obvious and include:
? Flash
? Roll, twist, and side-to-side bend
? Up/down bend
? Crimp symmetry
? Bellmouth
The following discussion focuses on two characteristics, crimp width and flash, as examples of how tooling can
affect crimp form. Similar arguments can be applied to the others.
Crimp Width
Crimp width is a good example of a feature that should be consistent and in control between different
crimpers of the same part number. The reason for this is quite straightforward. For a given terminal and wire
combination, it is necessary to achieve an area index, AI, which is determined by the terminal designer for op-
timal mechanical and electrical performance. Crimp height, CH, and crimp width, CW, directly affect achieving
proper AI. Area index, AI(as a percentage), is defined as:
where At is the total area of the wire and barrel after crimping. A and A are, respectively, the initial cross-
W B
sectional areas of the wire and barrel before crimping.A typical design point for AI is 80%. In order to maintain
Cross Sections Showing Min-
(a)
the same AI, the crimp height, CH, needs to change in-
imum (a) and Maximum (b)
Area Index perTerminal
versely to the change of crimp width, CW, in approxi-
Specification?aVariation of
mately the same proportion. Thus, if the CW increases
? 3.5%
+2%, the CH needs to change approximately -2% in order
to achieve the same AI design point. At first glance that
may not seem significant, but in reality it can be very
significant. Using another general industry design rule of
(b)
the ratio of CH to CW of approximately 65%, a typical
set of dimensions used as an example may be: CW = 0.110 in, CH = 0.068 in
Therefore, varying the CW by 2% would result in a CH variation of 2%, or 0.0014 in.
At a CH tolerance of ? 0.002 in, 35% of the total CH tolerance would be used by a
2% variation in CW. Thus, the importance of crimp width control is obvious when
tooling is changed during a production run.
Flash
Most crimp terminations have a requirement to limit flash. Flash is defined as the material which protrudes to the
sides of the terminal down and along the anvil. Flash is normal in the crimping process but excessive flash is very
undesirable. Controlling flash requires a balance of several geometric factors. Other factors influencing flash are
related to surface finish and friction, which will be discussed later in this paper.
A dominant factor in controlling flash is controlling the clearance between the crimper and anvil during the crimp
process. Defining the ideal clearance could in itself be a simple matter were it not for two facts:
? In order to minimize terminals? sticking in the crimper, the sides
of the crimper are tapered. Thus the clearance between the
anvil and crimper varies throughout the stroke.
? Crimper and anvil sets are typically designed to terminate two
to four wire sizes. This creates multiple crimp heights. Since the
sides of the crimper are tapered to minimize terminal sticking,
the maximum clearance permitted without creating flash must
be assigned to the maximum crimp height specified for the
tooling set. In addition, a minimal clearance must be maintained
for the smallest crimp height specified by the tooling set to
Crimper-to-Anvil Clearance = X +Y
prohibit contact between the anvil and crimper.
at the Final Crimp Height
Crimper to anvil clearance is thus a combination of crimp width, crimper leg taper,
anvil width, and crimp height. The critical design point is at the largest crimp
height. This contribution to the gap is directly dependent on dimensional control.
The following is offered as an example:
Nominal condition: CH = 0.073 in, CW = 0.110 in
Crimper leg taper = 3.0 degree
Anvil Width = 0.109 in
Nominal anvil to crimper total clearance = 0.005 in
The clearance can grow rapidly with small changes to
(a)
Significant flash can be generated
the nominal dimensions:
with excessive anvil to crimper
clearance, as shown by nominal
CH remains unchanged = 0.073 in
design condition (a) and +0.003 in
Increase in crimp width, CW, = 0.0008 in
over nominal condition (b)
Increase in crimper leg taper = 0.8 degree
Decrease in anvil width = 0.0008 in
The total increase in total clearance is this case = (b)
0.0026 in
This more than a 50% increase in the nominal design
clearance, which can result in unacceptable flash (see right).
Dimensional control is clearly critical.