Daruma Pin

Specifications

How to choose Springs

Points to check when selecting, with the values for this product (Daruma Pin).

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

   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 SUS304-WPB (φ12 or less) / SWB (φ14 or more)

   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

Product line centered on seven types for shaft diameters of 6 to 20 mm, with wire diameters of 0.8 to 2.6 mm. Made of SUS304-WPB or hard steel wire, retention is achieved by integral forming of the spring steel wire.

FAQ

Q. What are the applicable shaft diameter and wire diameter ranges for the Daruma Pin?

A. The applicable shaft diameter is 6 to 20 mm, and the wire diameter d is 0.8 to 2.6 mm. The product line is centered on seven types for shaft diameters of 6 to 20 mm.

Q. How should I select the material for the Daruma Pin?

A. The material is SUS304-WPB (φ12 or less) or SWB (φ14 or more).

Q. How does the Daruma Pin prevent detachment?

A. Retention is achieved by integral forming of the spring steel wire.

Q. Is the Daruma Pin RoHS compliant and available for online ordering?

A. Yes, it is RoHS compliant and compatible with online ordering.

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 Open page 136
  Found on: https://www.samini.co.jp/catalog_list/