Free-Size Extension Spring, Piano Wire

Specifications

How to choose Springs

Points to check when selecting, with the values for this product (Free-Size Extension Spring, Piano Wire).

1. 1. Select the Spring Rate from the Required Force

   The spring rate k is the load required to deflect the spring by 1 mm. Multiply it by the deflection at installation and at operation to confirm that the required force can be obtained. Listed products range widely from 0.007 to 9.91 N/mm, and a margin should be allowed for variation, including the spring rate tolerance (for example, ±10%).

2. 2. Keep Within the Maximum Load and Deflection Limits

   Using the spring beyond its maximum load or maximum deflection causes set (permanent deformation) or breakage. Confirm that the load at the maximum point of the operating stroke is within the maximum load, and for compression springs, that the solid height is not reached.

3. 3. Installation Space, Outside Diameter, and Free Length

   This product: Outer diameter D 3–50 mm

   Check that the outside diameter fits the hole or housing, and that the inside diameter does not interfere with the shaft it passes over (applicable shaft diameter). The free length is the length under no load; the difference from the installed length is the initial deflection. Because the coil diameter changes under load, allow sufficient clearance.

4. 4. Select a Material Suited to the Operating Environment

   This product: Material SWP-A

   Piano wire SWP-A has high strength but is prone to rust, and many versions are supplied with rust-preventive oil treatment. For humid environments or environments subject to washing, stainless steel such as SUS304-WPB is a candidate. For strongly corrosive environments such as seawater, titanium is a candidate.

5. 5. Extension Springs: Initial Tension and Hook Shape

   Close-wound extension springs have initial tension, the load required before the spring begins to extend. For applications requiring movement with a small force, check the initial tension value. Also check that the hook shape, such as reverse loop, 90-degree, or 180-degree, matches how the mating part is engaged.

6. 6. Torsion Springs: Angle and Arm Direction

   For torsion springs, check the torque at the operating angle (torsion spring rate × angle) and the arm length. The winding direction should match the direction of twist, and it is common to use the spring in the direction that winds it up. For free-size products, also specify the bending direction.

This guide was written by AI based on the listed products' documents and specification items.

About Springs and all products

Description

Manufactured from rust-preventive oil-treated piano wire to the specified F dimension. Maximum load and initial tension remain constant regardless of the F dimension.

FAQ

Q. What are the material and surface treatment of the Free-Size Extension Spring, Piano Wire?

A. The material is SWP-A piano wire, and the surface treatment is rust-preventive oil treatment.

Q. What sizes can the Free-Size Extension Spring, Piano Wire be manufactured in?

A. Springs are manufactured to a specified F dimension. Outer diameter D is supported from 3 to 50 mm, and free length L from 10 to 600 mm.

Q. Do the maximum load and initial tension of the Free-Size Extension Spring, Piano Wire change with the F dimension?

A. No, the maximum load and initial tension remain constant regardless of the F dimension.

Written by AI based on the content of the source documents.

Source documents

• Catalog スプリングネット 製品カタログ（ばね類） 178 pages
  Found on: https://www.samini.co.jp/catalog_list/