What are the typical quality requirements for gas springs

Below is a summary to which tests gas springs can be requested to perform to.  Take care, it is not a statement that they withstand to those conditions, but it shows a typical request.

the cost for a temperature & cycle test is around 500 euros.
The salt spray test is not an inhouse test, although we do stand behind the 72 hours salt spray resistance.

These are the specifications to which gas springs have been tested:

• Cycle testing up to and in excess of 30,000 cycles
• Temperature testing from -40 degrees centigrade to + 100 degrees centigrade
• Salt spray testing which for standard steel parts goes up to 72 hours

 

1)      temperature

The GAS SPRING shall operate while and after exposed to temperatures over the range of -40 °C to + 70 °C.

 

Verification by similarity (test) when possible.

The manufacturer should have several temperature test reports.

Please also provide the data sheet of the seal (to check the temperature range).

 

2)      humidity

The GAS SPRING shall operate while exposed to the diurnal cycle for the B3 climatic category in

accordance with STANAG 4370, AECTP 200 Leaflet 2311/2.

Verification shall be conducted in accordance with STANAG 4370, AECTP 300 Method 306,

aggravated cycle 3, severity B.

Severity : several 24h cycles between 30C and 60C at 95%RH.

 

Verification by similarity (test) when possible.

The manufacturer should have performed this kind of humidity tests.

Test data on similar gas spring with the same base, coating materials, and equivalent coating

thickness may be used to meet this requirement.

 

3)      Salt fog

The GAS SPRING shall withstand exposure to salt fog atmosphere.

Verification shall be conducted for 192 hours (eight alternating 24-hour periods of salt fog exposure

and drying conditions) in accordance with STANAG 4370, AECTP 300 Method 309.}

Severity : temperature of 35 C with 5% salt concentration.

 

Verification by similarity (test) when possible.

Similarity by test on similar gas springs. The manufacturer should have performed such corrosion

tests.

Data sheet of the epoxy coating.

Test data on similar gas spring with the same base, coating materials, and equivalent coating

thickness may be used to meet this requirement.

 

4)      Forbidden and Hazardous substances

The manufacturer shall provide

Material Safety Data Sheet (see example of MSDS attached to this email).

Declaration of conformity RoHS

Declaration of conformity REACH with a list of hazardous substances (see MSDS)

 

5)      Dissimilar metals

Materials shall be selected to withstand the effect of corrosion.

For parts of the GAS SPRING in direct contact with air, assembly of dissimilar metals, when

unavoidable, shall be chosen to limit the galvanic couple below 0.25 V.

Dissimilar metals are defined and classified in MIL-STD-889.}

Verification based on the list of metallic materials of the main components of the gas spring.

For instance, interface between the extremities of the gas springs and its end fittings, between the

end fittings and the antenna housing.

Statement regarding dissimilar metals needed from gas springs manufacturer.

 

6)      Screws and nuts

Screws and nuts shall be made of A4 stainless steel and selected according to ISO 3506 and ISO 724.}

Verification by analysis.

Statement regarding used screws and nuts needed from gas springs manufacturer

 

7)      Service Life

The GAS SPRING shall meet the requirements of this document in the service environment or if it is

kept in storage for up to 20 years.}

Verification by similarity (test) when possible.

Lifetime (operating and storage)

Statement regarding service life needed from gas springs manufacturer.

 

8)      Endurance

The GAS SPRING shall operate during and at the conclusion of 10,000 cycles of operation.}

Verification by similarity (test) when possible.

The manufacturer should have performed such endurance tests.

Statement regarding endurance needed from gas springs manufacturer.

 

9)      Safety - Objective

Safety requirements shall be taken into account in the design of the GAS SPRING to insure safety for

personnel, for all phases of its life cycle. The GAS SPRING shall be provided with any markings, devices

• or systems required to ensure the safety of personnel appointed to its handling, its deployment and

withdrawal, its operation or its maintenance.}

Verification by analysis. Statement needed for gas spring manufacturer.

Certificate of Conformity (CoC), needed from supplier gas springs.

Safety marking confirmation needed from gas spring supplier.

as a general note:

We supply a considerable amount of gas springs to the construction industry with such customers as JCB , Caterpillar and Terex. Our springs are mounted on doors, windows, engine and access covers and are subject to temperature, humidity and at times extreme conditions for which these vehicles operate in.

 

life cycle statement or lifetime of a gas spring:

In ideal fitting circumstances, at room temperature and a maximum of three cycles per minute our Gas Springs have a permitted maximum force loss of 10% after 50,000 cycles. In some instances, our customers have successfully tested our Gas Springs to over 200,000 cycles.

 

However, it should be noted that in real-life applications the life expectancy of a gas spring is extremely difficult to predict and can vary considerably due to a number of factors.

 

These factors include the type of environment the spring is to be used in, for how long and in what manner the spring has been stored prior to use, whether the spring is subject to temperature change or temperature cycling, whether the application is subject to vibration, the usage frequency, the type of end fittings used and whether the spring is subject to lateral movement to name a few examples.

 

We always recommend the customer tests the spring on their application to gain an understanding of what the lifecycle will be for them. From our latest internal testing we have seen a lifecycle of 100,000 cycles after rigorous testing.