Nitrogen Gas Spring Selection Guide: Choosing the Right Spring for Your Application

What is a Nitrogen Gas Spring?

Nitrogen gas springs are a safe, durable, cost-effective alternative to traditional mechanical coil springs in many industrial applications. They operate with pressurized nitrogen gas. When the gas is pressurized, the spring stores energy. When the pressure is removed, the stem is pushed up by the expanding gas, and the spring delivers its rated force. A small amount of lubricating oil is also sealed inside the spring housing to keep the piston moving smoothly in both directions.

One gas spring can equal the force of up to 10 mechanical springs with a fraction of the physical footprint. And, unlike their coiled counterparts, fully charged gas springs provide immediate and consistent force over the entire stroke length, with no change in force due to metal fatigue over time.

Ready Technology designs and manufactures nitrogen gas springs that are innovative, tough, and long-lasting. We carry an extensive selection of standard gas springs and also provide custom spring manufacturing services. What’s more, all Ready Design-Tite™ nitrogen gas springs are equipped with a special flexible guiding system that absorbs minor variations from vertical during movement. This reduces wear and tear on the spring and damage due to lateral movement, for a longer spring service life.

Learn more about how to evaluate and select the best nitrogen gas spring for your application.

How to Choose the Right Gas Spring for Your Application

As always, your application tonnage and stroke, including material type and thickness, part geometry, production volume, and press tonnage and style, will help determine the best gas springs to buy. Start by considering which of these general categories fit your application:

Standard Gas Springs: These are ideal for medium-load applications and typical factory production environments

Compact Gas Springs: These are smaller and more cost-effective for smaller applications such as compact press equipment and low-load applications.

Heavy Duty Gas Springs: These are rated for higher loads and adverse operating conditions, including high speeds and/or force requirements or humid or high-temperature environments. They are fabricated from high-strength materials to accommodate these challenges reliably.

Custom Gas Springs: Standard, in-stock gas springs are the fastest way to get your stamping project started. However, Ready Technology can also design and machine custom gas springs for your application with our “Design A Spring” program, special gas springs, especially discontinued or obsolete items. Our engineers use the details of your application as well as the following information to create custom nitrogen gas springs:

READY Technology’s Nitrogen Gas Die Springs

We carry 10 series of Design-Tite nitrogen gas springs for use in metal stamping applications. They are available in a range of stroke lengths, diameters, and force capacities.

• BE Series: Extra compact for use in space-limited die set applications.
• CE Series: Sub-compact for high force stroke lengths in small spaces.
• LE Series: International Organization for Standardization (ISO) Line. This line meets all ISO and VDI piston, housing, and height standards, as well as mounting and charge port specifications.
• SE Series Renault Line: This series conforms to Renault’s mounting, charge port, and body height requirements. All springs in this series provide the same force as the LE-ISO Series, but in a shorter height.
• PE Series Performance Line: This series offers similar forces, body lengths, and stroke lengths to both the LE and SE series die springs, but in a narrower body diameter.
• M Series: A versatile line of semi-compact springs in a range of forces, stroke lengths, and body lengths.
• T Series: A super-compact series that features one third more force than the BE Series in similar-sized, bore-seal housings.
• H Series: Die springs with maximum force capacity that also retain the compact size of a gas spring.
• R Series: Featuring a threaded exterior body for secure installation and convenience.
• Manifold Gas Spring Series: These use multiple gas spring cylinders mounted into a machined manifold plate with cross-drilled gas ways to connect all cylinders and reduce overall height to provide a consistent force throughout the press stroke.
• Controlled Movement Series: Nitrogen gas cylinders with stem controlled movement which can stop at the desired working position with the possibility of deciding when stem withdrawal is to take place by means of an electrical signal, in accordance with the application that is being executed.

Factors to Consider When Selecting a Nitrogen Gas Spring

Ready Technology carries 11 series of pre-engineered, standard nitrogen gas springs in stock and ready to ship. Additional details, measurements, and options for our full selection of nitrogen gas springs are available in our website catalog.

Gas springs are available in many sizes to deliver different amounts of force over different distances. They can also operate at varying speeds depending on their size. It’s important to understand how the factors below impact a spring’s suitability for a specific application.

Force

The amount of force each spring delivers is known as its force in decaNewtons (daN). This is calculated based on several things including material type, thickness, part features (e.g., coining, piercing, bending), and press speed.  The amount of force a spring can produce is related to its gas charge pressure (p) and the dynamic seal diameter (D_seal) of the gas spring.

Force at the end of the stroke, when the stem is fully extended, can be considerably higher than the initial force on contact. For this reason, it’s important to consider how this affects the number and placement of springs in the die. Force can also increase at high temperatures, so be aware of how this may impact stamping operations with different material types or thicknesses, or with different part features.

Stroke and Overall Spring Length

Stroke length is the distance the piston can travel from fully closed to fully open. It may be helpful to think of this as the spring’s range of motion and the maximum amount of movement the spring provides for the application. Ideally, you should specify a spring such that no more than 90% of its rated stroke length is used during normal operations. This is also referred to as maintaining a 10% stroke reserve, which reduces wear and tear on the spring and improves its longevity.

It’s also important to think about stroke length in relation to press speed. Springs with a shorter stroke length can usually run faster. However, as stroke length increases, speed decreases in order to avoid excessive heat due to friction and pressure build up in the spring.

Ready carries 10 series of nitrogen gas springs, and depending on the specifics of each line, stroke lengths can be as short as 6mm or as tall as 300mm. Please note that this range of stroke lengths is not available for each spring in all series.

The amount of vertical space a gas spring takes up is also important. There are always space considerations in a stamping press due to tooling and other factors of the application, and these determine the available clearance for a spring. Spring dimensions include the open length (i.e., the length of the entire spring including the piston and cylinder, and the closed length (i.e., when the piston is fully retracted into the spring housing). As with stroke lengths, a variety of open and closed lengths are available in each spring product line.

Cylinder and Piston Diameters

The outer diameter of both the cylindrical housing, or body, of the spring and the outer diameter of the piston, or stem, are also important in sizing a gas spring. The size of a spring is relevant to the maximum force it can apply, as well as to the amount of space it takes up inside the die. Ready’s gas springs are available in several cylinder diameters, and depending on the specifics of each series, these can be as small as 12mm or as large as 195mm. Not every diameter size is available for all series.

Mounting Pattern and Configuration

Gas springs should be mounted vertically and perpendicular to the die. Flanges are used to securely attach gas springs, and to aid proper positioning and orientation. They are available in several sizes and shapes for mounting flush or proud of the die plate surface. Threaded cylinder bodies are also available to ensure a secure fit and proper orientation.

Gas springs can be used singly (i.e., autonomously) or in interconnected groups that are linked with tubing or connected to a manifold. Control panels that adjust and monitor distribution are available to adjust and control distribution of pressure among the springs.

Operating Conditions

In addition to the characteristics of the spring, it’s critical to assess the typical operating conditions to which it will be exposed. This includes things like:

• Operating temperature
• Press tonnage and speed (in strokes per minute)
• The material being stamped
• Relative humidity and temperature in the facility
• Any potential exposure to corrosive materials coolant or vapors

All of the above can have a negative impact on spring performance and useful life. For example, the internal gas pressure increases with temperature, impacting the spring’s force output at high temperatures. High operating temperatures may reduce the performance of lubrication, which can lead to friction, lateral loading, elevated temperatures, or spring damage. Additionally, high humidity can reduce the integrity of the seal between the piston and cylinder, which can lead to gas leakage or poor spring performance.

High-Performance Nitrogen Gas Die Springs at READY Technology

At Ready, we have many nitrogen gas spring options available and in stock, along with flanges, valves, gauges, manifolds, hoses, and more. As the leading innovator in our industry, we can help you replace existing coil springs or design a new die set with gas springs. We are ISO 9001 certified, and committed to providing the highest quality service, products, and support for all of our customers.

Our engineers are available to discuss your application and help you select the best nitrogen gas spring for your needs and production goals. Review our online catalog to learn more, or contact us today with your questions or request for a quote.