How Is a Gas Spring Made? The Ten Steps from Cylinder Tube to Finished Strut
A gas spring (gas strut, tailgate strut, lift support) looks simple: a steel cylinder, a piston rod, nitrogen and a little oil. Making it reliably in volume takes about ten operations, and each one decides part of the quality. This article walks through them in the usual order.
What is inside a gas spring
- Cylinder: steel tube, closed at one end.
- Piston rod and piston: the rod is hardened and surface-finished; the piston carries the damping orifice or works with a groove in the cylinder.
- Guide and seal pack: held at the open end of the cylinder.
- Nitrogen and oil: the gas gives the force, the oil lubricates and damps the end of the stroke.
- End fittings: ball sockets, eyes or threads at both ends.
Step by step: from tube to finished spring
- Cut the cylinder tube to length. Roll cutting leaves no chips inside the tube (TD-41860).
- Press the damping groove (only for groove-damped springs). The length, depth and number of grooves set how fast the strut opens (TD-627).
- Roll the ring groove near the open end to locate the guide and seal (TD-42815).
- Close the cylinder bottom. Cold spin closing makes the bottom in one piece with the tube, without a welded cap or plug (TD-31040).
- Clean the cylinder inside before assembly.
- Prepare the piston rod: cut, harden, finish and fix the piston.
- Fill the oil in a measured amount (TD-YL506).
- Press in the guide and seal and fold the tube edge (TD-AT155, TD-724).
- Charge with nitrogen to the specified force.
- Fit the end fittings and set their angle (TD-91528).
- Test force and leak tightness.
Where quality is decided
- The closed bottom must never leak: a one-piece spun bottom has no weld porosity and no plug gap.
- Groove depth must be the same on every cylinder, or the opening speed varies from strut to strut. Servo grooving keeps depth independent of oil temperature.
- Edge folding holds the whole seal pack against the gas pressure for the life of the spring.
- Cleanliness: chips or burrs inside the cylinder damage the seal, which is why chip-free cutting matters.
Planning a line
Most factories start by buying the station that limits their output, usually bottom closing or grooving, and add stations later. Multi-station closing machines can run one size on all stations for volume, or a different size on each station for mixed small lots. See the full gas spring production line for machines and videos of each step.
FAQ
Do all gas springs need a damping groove?
No. Many use only the piston orifice; the groove is used when damping must work in any mounting position or must change along the stroke.
Can we test our cylinders on your machines?
Yes. Send tube OD × wall × length and drawings to sales@tdco.com.tw.