Technical Data and Documents

Technical Data

[Materials] How much is the limit of an operating temperature of spring materials?

Materials	Marks	Temp.℃
Piano wire	SWP	120
Stainless steel wire for spring	SUS304	250
Inconel X-750	NCF-750	450

[Materials] Regarding magnetism of stainless steel.

SUS304 is austenite stainless steel, and is nonmagnetic when the solution treatment( rapid cooling from about 1200C ) is carried out. But when it comes to steel wire for springs, a part will be martensitic by cold work, tinged with magnetism.
Since the magnetic increase by cold work of SUS316 is smaller than SUS304, SUS316 is called nonmagnetic.

[Materials] Are there any easy ways to recognize stainless steel wire and piano wire?

The magnetic strength adhering to magnets is greatly different between stainless steel wire for spring use and piano wire.
In addition, compared to piano wire, the brightness of the surface skin of stainless steel wire is generally rather dull.

[Common springs] How do I recognize the direction of helix on a spring?

As for the direction of coiling, a spring that is coiled clockwise from the end is called right hand coiling. Generally springs are coiled clockwise if there is no special direction on drawings.

[Common springs] Please tell me about heat treatment of springs.

For large-sized springs fabricated by hot forming, we do tempering treatment so that the products have necessary solidity after hardening. Small springs fabricated in room temperatures undergo low temperatures annealing for two reasons. One is to remove residual stress by processing, and the other is to improve the wire properties of piano wire and stainless steel wire.

[Compression spring] Please tell me number of coils and how to count it .

Number of coils can be separated into total coils, active coils, and number of end turns.
Total coils count all coils including end turns. Active coils is the number of coils used to calculate spring constant .
* The product in the photo has 4 active coils and 6 total coils. Active coils = Total coils - Number of both end turns
The number of end turns is usually one each. In this case the number of active coils is two less than total coils.

[Compression spring] What does the end of spring with ground and without ground look like?

The photo on the left is ground one and on the right is not ground.

[Extension spring] Why do extension springs snap at the hook ?

Two types of stress simultaneously generate at the rising bent part of a hook. One of them is bending stress generates because it is pulled. The other is torsional stress as a spring. This stress concentrations is considered as the cause of breakage in many cases.

[Torsion spring] Which size is appropriate for the shaft of the inner coil ?

The inner diameter decreases when a spring is twisted in the coiled direction. For this reason, usually the diameter of the shaft is chosen to be 90% of the inner diameter of the coil.

Technical Documents

Compression spring

Technical Documents

Ends shape

Extension spring

Technical Documents

Ends shape

Torsion spring

Technical Documents