Page 44 - MetalForming March 2011
P. 44

  Tooling Technology
Maximize the Life
of Your Nitrogen
Gas Springs
 The life expectancy of a nitrogen gas spring begins with the man- ufacturer. Choose a gas-spring manufacturer whose representatives can offer assistance with design and provide custom nitrogen systems based on the application. Also ask your sup- plier for product-performance guide- lines, including recommended charg- ing pressure, operating temperature and speed, all of which influence gas- spring life expectancy.
When choosing a gas spring, base the decision on multiple criteria: select-
To optimize gas-spring life, it is important to understand the factors that affect their performance. The greatest influences on the life of a nitrogen gas spring
are fitness for the application, proper spring installation and regular gas-spring maintenance.
Metalformers should think about adding nitrogen-gas spring accessories (shown) to the die design to assist with spring operation. Consider piping gas springs together to provide the ability to monitor, control and adjust force from outside the die. Many gas-spring manufacturers offer a wide selection of hoses, fittings, control panels and other equipment to simplify piping operations.
42 MetalForming/March 2011
ing the correct spring for the task it must perform, locating it properly in the die and picking the appropriate mounting method. Once the choice
has been made, be sure to follow the manufacturers’ guidance to ensure optimal performance.
Die Design and Tool Build
Die design plays a critical role in optimizing nitrogen-gas spring life. The recommendations provided here can apply to new die designs as well as to retrofits of existing dies.
Nitrogen gas springs have standard operating specifications. A typical gas spring may be charged to a maximum pressure of 2175 psi (150 bar) with operatingtemperaturesashighas160F. It is imperative that gas springs do not exceed maximum charging and oper- ating-temperature guidelines.
Whenever possible, the actual rod travel of the gas spring should not exceed 90 percent of the gas-spring stroke. This provides a safety factor to avoid die or gas spring damage, and serves as a basic rule for good per- formance. Selecting a rod travel of only 75 to 80 percent helps reduce the pres- sure rise in the cylinder and the amount of heat produced, improving the spring’s overall performance. Although

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