The RFQ contains only a few details:
Automotive connector. Pull-out force ≥80 N. Need a quotation for the tester.
At first glance, this looks sufficient to start selecting a load cell or machine capacity. It is not. The missing detail is the interface being tested.
A connector assembly may contain a wire, crimped terminal, contact retention feature, plastic housing, secondary lock, seal and mating connector. Pulling at different points in that assembly produces different mechanical tests. A wire separating from a crimped terminal is not the same failure as a terminal leaving the connector housing, even if both events occur at exactly the same force.
Before selecting a fixture or testing machine, the laboratory needs to establish what is supposed to move, what must remain fixed and which interface the reported force is intended to represent.
Before Selecting a Tester, Define the Interface
“Connector pull test” is convenient language for an RFQ, but it is not a complete test definition.
Several measurements are commonly described using similar terminology:
| Interface under load | Typical test question | Main concern |
|---|---|---|
| Contact vs. housing | Can the housing retain the contact? | Contact retention |
| Wire vs. terminal | Can the crimp retain the conductor? | Crimp quality |
| Plug vs. receptacle | How much force is required to disconnect them? | Mating system |
| Cable vs. complete connector | Can the assembly resist an external pull? | Strain relief / assembly integrity |
The first two are especially easy to confuse because the wire may be used to introduce the tensile load in both cases.
Consider a harness consisting of a wire, crimped terminal and connector housing. The machine reaches 72 N and something separates.
If the conductor pulls out of the crimp barrel, the wire-to-terminal connection has failed. If the terminal remains attached to the wire but exits the housing, the contact-retention system has been loaded instead.
The force value alone does not tell you which occurred.
Contact retention is usually the closest match to what engineers mean when they describe a terminal or contact “pulling out” of a connector.
The contact is already installed in the housing, where a lance, insert, secondary lock or another retention feature keeps it in its intended position. The test applies an axial load intended to challenge that retention system.
Relevant methods include EIA-364-29E for contact retention in electrical connectors and IEC 60512-15-1 Test 15a for contact retention in the insert.
On the bench, the setup may look simple: hold the housing and pull the contact. In practice, the housing must be supported without blocking the extraction path, the applied load should follow the intended contact axis, and the wire or contact must remain secure in the moving fixture.
Supporting the connector incorrectly can change what the machine measures.
Crimp tensile testing asks a different question. Here, the interface of interest is the mechanical connection between the conductor and the crimped terminal or contact. EIA-364-08C is one example of a method used to evaluate tensile strength of a crimped contact-to-conductor joint.
This distinction matters during troubleshooting.
Suppose an operator reports that a “terminal pull test” failed at 68 N. Before changing the crimping process, inspect the specimen. A weak crimp can allow the conductor to leave the terminal, but a correctly crimped terminal can also leave the housing if the retention system is weak. The wire may even slip in the test grip before either interface fails.
Only the first event is actually a crimp failure.
Mating and unmating force should also remain separate from retention testing.
When a plug and receptacle are separated, the measured force can reflect contact friction, seals, latching features, housing geometry and other parts of the complete mating system. Connector specifications may therefore list mating force, unmating force, contact insertion force, contact removal force, contact retention and crimp tensile strength as separate requirements.
A force value should always be read together with the property and method used to obtain it.
Which Standard Actually Applies?
There is no single connector pull-out standard that covers every force measurement described above.
For contact retention, EIA-364-29E and IEC 60512-15-1 Test 15a are relevant examples. For the tensile strength of a crimped contact-to-conductor joint, EIA-364-08C addresses a different mechanical interface.
Other connector properties, including mating, unmating and contact insertion or removal, need to be evaluated against the applicable method and product specification.
This is also why there is no universal answer to the question:
“What is a good connector pull-out force?”
A miniature signal connector, an automotive sealed connector and a high-current power connector may operate in very different force ranges. Even within the same connector family, different contacts or retention designs can carry different requirements.
The test method defines how the load is applied. The applicable product specification, connector drawing or customer requirement generally provides the acceptance criteria that matter for that product.
Testing purpose matters as well. A procedure intended for qualification may not automatically be suitable for inspecting every production connector, particularly when the test damages or permanently alters the specimen.
Before configuring the equipment, determine whether the test is being used for design verification, supplier qualification, production audit, troubleshooting or routine process control.
The Fixture Is Part of the Measurement
Because connector pull-out results are reported as force, attention naturally goes to the load cell. Yet the load cell only measures the force transmitted to it. It cannot determine whether the connector was loaded correctly.
That depends heavily on the fixture.
Supporting the connector housing
Holding the housing securely does not mean clamping it as tightly as possible.
Connector bodies may contain thin walls, flexible latches, seals, secondary locks and narrow cavity features. If the fixture reacts against one of these areas, the support can deform the housing before the intended retention system reaches its normal load.
A fixture can therefore be well aligned and still produce a poor test if it supports the wrong part of the housing.
For one connector, a broad structural shoulder may provide a suitable reaction surface. Another may need a machined nest around the body. Small or irregular connectors may require a dedicated plate or custom insert.
Whatever the design, the contact needs a clear extraction path.
Supporting the housing and obstructing the contact are two very different things.
Holding the wire or contact
The moving side presents a different set of problems.
Insufficient gripping force can allow the wire to slide. Excessive pressure can flatten insulation, damage strands or create a premature failure close to the jaws.
Short wire leads make the problem more difficult because there may be little usable length between the housing and the grip.
Where permitted by the applicable test method, a dedicated terminal or contact fixture may be more appropriate than gripping the wire itself. The goal is to transmit the intended tensile load without introducing a competing failure mechanism.
Alignment deserves the same attention.
A connector may appear straight while the contact axis is still offset from the machine axis. Once the crosshead moves, that offset can introduce bending, housing rotation or contact with the cavity wall.
The machine may still produce a clean-looking curve.
The load path is nevertheless different.
Why Two 85 N Results May Not Describe the Same Behavior
Maximum force is often the value used for acceptance, so it naturally receives most of the attention in a connector pull-out report.
During troubleshooting, the force-displacement curve can provide additional information.
Imagine two contacts that both reach approximately 85 N.
The first trace rises steadily and then drops sharply when the contact releases. The second reaches a similar maximum but shows noticeably more displacement and a gradual change in load before separation.
Reporting only 85 N makes the specimens look almost identical.
The curves suggest that their mechanical behavior before the peak was different.
That difference does not diagnose the cause by itself. Depending on the connector design, it could be normal. It could also point toward progressive movement of the retention feature, wire slip, housing movement or fixture interference.
When a curve looks unusual, inspect what happened before the peak. Check whether the wire moved in the grip, whether the housing rotated, whether the contact shifted visibly or whether part of the fixture entered the extraction path.
A Low Result Does Not Automatically Mean a Weak Connector
Suppose a laboratory obtains five results:
81 N, 82 N, 81 N, 82 N and 81 N.
The scatter is small, but that alone does not prove the test setup is correct. If every connector is mounted at the same wrong angle, the laboratory can repeatedly reproduce the same unintended loading condition.
Now consider two laboratories testing nominally identical connectors. Lab A reports 118 N. Lab B reports 91 N.
Calibration is one possibility, but it should not be the first assumption.
Start with the specimens. Did the contact leave the housing in both tests, or did one wire separate from its terminal? Is there visible housing damage?
Then examine the grips. Look for wire movement, jaw damage or differences in the available free wire length.
Next, compare the housing support, pull direction, cavity position and extraction path. A small difference in fixture geometry can change how the load enters a compact connector.
Only after the mechanical setup has been compared does it make sense to investigate differences in test speed, machine configuration or force measurement.
Single Contact or a 24-Position Connector?
A single-position connector may only need to be centered once. Multi-position housings introduce another problem: repeatable access to individual cavities.
Consider a 24-position automotive connector. The laboratory may need data from cavity 1, cavity 8, cavity 15 and cavity 24. Each position sits at a different location relative to the connector body.
If the housing is manually repositioned for every contact, the fixture needs to do more than hold the specimen. It also needs to help the operator bring each required cavity back onto the pull axis consistently.
The importance of this depends on test volume.
A development lab running a handful of samples may accept a manually adjustable fixture. A supplier checking hundreds of contacts per shift will care much more about positioning time, loading consistency and operator-to-operator variation.
Fixed nests, adjustable fixtures or indexed positioning concepts can be considered depending on connector geometry and throughput.
Adding frame capacity does not solve a positioning problem.
“Our Contacts Are Below 200 N. What Test System Do We Need?”
Once the test interface and specimen geometry are known, equipment selection becomes much easier.
Suppose the expected retention force is approximately 80–150 N. Asking whether the laboratory needs a 500 N, 1 kN or 5 kN machine starts with the wrong parameter if the actual measurement range has not been considered.
Begin with the expected specimen force and choose an appropriate load cell with suitable measurement performance and margin for the application.
Then evaluate the mechanical setup.
Can the housing be supported without deformation or interference? Is there enough wire to grip? Will the contact remain on the pull axis? How much travel is required? What test speed does the applicable method specify? Does the customer need maximum force only, or the complete force-displacement curve?
Frame capacity comes into the decision after those requirements are understood.
Where the RS-8010A Fits in a Connector Pull Test Setup
For lower-force connector, terminal and wire-assembly applications, the ITM-LAB RS-8010A Servo Control Universal Testing Machine can serve as the base platform for a configured pull-test system.
The RS-8010A covers force capacities from 50 N to 5 kN. For connector work, however, the useful configuration is determined by the actual force range rather than simply choosing the highest available capacity.
A typical system may combine the RS-8010A with an appropriately selected load cell, connector housing fixture, wire/contact grip and test software.
Fixture geometry remains application-specific. An automotive sealed connector, miniature signal connector, PCB header and battery connector can all require different support arrangements even when their expected peak forces are similar.
For an application producing approximately 100 N, the first question should therefore not be whether a 5 kN frame is large enough. The more useful questions concern the load-cell range, connector geometry, fixture, alignment and required result.
A Realistic RFQ: What Information Is Still Missing?
Consider the following inquiry:
Customer: Automotive harness supplier
Connector: 12-position sealed housing
Wire: 0.5 mm²
Requirement: >80 N
Output: Maximum force
Volume: 200 contacts/day
There is enough information here to understand the general application, but not enough to finalize the test system.
Does the 80 N requirement refer to contact retention or crimp tensile strength?
If it is retention, will every cavity be tested or only selected positions? Is the test a pull-to-extraction procedure, a specified proof load or another loading sequence? Is the housing supplied loose or as part of a finished harness? How much free wire is available for gripping?
The test volume also matters. At 200 contacts per day, specimen loading and cavity positioning may affect productivity more than the duration of the tensile movement itself.
A few additional details can therefore change the fixture concept without changing the stated 80 N requirement at all.
What to Send Before Requesting a Connector Pull Test System
A useful RFQ does not need to be complicated. It needs to define the specimen and test clearly.
Connector Type: ______
What Is Being Pulled: Contact / Wire / Plug / Cable Assembly
Test Standard: ______
Product Specification: ______
Minimum Required Force: ______ N
Expected Actual Force: ______ N
Wire Size: ______ mm² / AWG
Connector Dimensions: ______
Number of Cavities: ______
Cavities to Be Tested: ______
Available Wire Length: ______
Pull Direction: ______
Required Results: Maximum Force / Force-Displacement Curve / Displacement / Other
Test Volume: ______ specimens/day
Connector Drawing Available: Yes / No
Physical Samples Available: Yes / No
With this information, load-cell range, fixture concept, specimen handling and machine configuration can be evaluated around the actual connector rather than around a generic force value.
Connector Pull-Out Test Equipment Selection Roadmap
FAQ
What is connector pull-out force?
Connector pull-out force describes a tensile force associated with separating part of a connector assembly, but the term needs to be tied to a specific interface.
It may refer to a contact leaving a housing, a conductor leaving a crimped terminal, two connector halves being separated or a cable being pulled from a complete assembly. The test should identify what is moving and what is being restrained.
What is the difference between contact retention and crimp pull force?
Contact retention evaluates how effectively the connector housing or retaining system keeps the contact in position. Crimp pull testing evaluates the mechanical connection between the conductor and the crimped terminal or contact.
If the terminal remains attached to the wire but exits the housing, that is not the same failure as a conductor pulling out of the crimp.
What standard is used for connector contact retention?
EIA-364-29E and IEC 60512-15-1 Test 15a are examples of methods addressing contact retention. The applicable product specification, connector drawing or customer requirement should also be checked for the required test condition and acceptance criteria.
For crimp tensile testing, a different method such as EIA-364-08C may apply.
What fixture is needed for a connector pull test?
The fixture depends on connector geometry and the interface being evaluated. A contact-retention setup generally needs housing support that leaves the extraction path clear, together with a suitable way to load the wire or contact.
Multi-position connectors may also require repeatable positioning so that individual cavities can be aligned with the pull axis.
What load cell should be used for connector pull-out testing?
Select the load cell around the expected actual test force rather than the maximum capacity of the test frame.
If normal connector forces are around 100 N, the measurement configuration should be evaluated around that working range while maintaining appropriate capacity margin and satisfying the required measurement performance.
Final Thoughts
A connector pull test may end with a single value in newtons, but that number only becomes useful when the mechanical event behind it is understood.
Contact retention, crimp failure, wire slip and fixture interference can produce very different engineering conclusions. Define the interface and applicable method first, then establish the expected force range, load path, fixture and measurement requirements.
The machine measures force. The fixture defines the load path.
Need to Configure a Connector Pull-Out Test?
Send ITM-LAB your connector drawing or sample, the interface being tested, applicable standard or product specification, expected force range, wire size, cavity information, test volume and required results.
ITM-LAB can then evaluate the appropriate load cell, housing fixture, wire/contact grip and universal testing machine configuration for the application.
