Applications
Where this spring style fits
Review best-fit uses, assembly constraints and situations where another spring style may be a better choice.
View application guidance →Torsion Springs
Custom Hairpin Springs
An open U- or hairpin-shaped spring for shallow layouts where two arms flex around a curved center rather than around a tightly wound coil body.
- Typical configurations
- 20
- Wire diameter
- 0.3–4 mm
- Outside diameter
- 3.16–55.36 mm
- Free length
- 24.81–194.59 mm
About Custom Hairpin Springs
Hairpin springs fit assemblies that need spring action in a relatively flat, open shape. Depending on the form, the arms may act through bending and limited torsion around the center loop. Because the contact points and arm lengths define the leverage, a simple overall size is not enough to specify the part.
Key Design Characteristics
- Arm length and contact location strongly affect the force at the ends.
- The center bend radius must be large enough for the chosen wire and life target.
- The free gap between arms sets installed preload when the part is squeezed or opened.
- The spring can often be easier to assemble than a coil torsion spring when the mechanism is shallow or open-sided.
What to Specify for a Custom Quote
- Wire diameter and center bend radius or loop geometry
- Free arm spacing and full outline of each leg
- Installed positions and required force at the contact points
- Maximum opening or closing movement
- Material, surface finish, cycles, temperature and quantity
Manufacturing Review
Form consistency is best controlled from a flat drawing or checking fixture that locates the center bend and arm endpoints. Small angular changes at the bend can move the endpoints noticeably.
Common Assembly Roles
- Shallow latch and clip return
- Open-frame biasing parts
- Simple two-arm spring functions without a full helical coil
Product Data
Typical Spring Configurations
Use these data points to compare practical starting dimensions and material options. Final production specifications are confirmed against your drawing and working conditions.
| Model | Wire dia. | OD | ID | Free length | Rate | Material | Coils | Max load |
|---|---|---|---|---|---|---|---|---|
| SW-150-0249-0545-0751 | 1.5 mm | 24.9 mm | 21.9 mm | 54.54 mm | 1.004 | Music Wire (SWP-A) | 3.9 | 8.16 |
| SW-050-0085-1838-0761 | 0.5 mm | 8.46 mm | 7.46 mm | 183.76 mm | 0.222 | 65Mn Spring Steel | 5.5 | 7.3 |
| SW-150-0194-0468-0798 | 1.5 mm | 19.35 mm | 16.35 mm | 46.75 mm | 0.914 | 304 Stainless Steel | 8.4 | 5.36 |
| SW-030-0088-0892-0760 | 0.3 mm | 8.76 mm | 8.16 mm | 89.24 mm | 0.021 | Beryllium Copper (QBe2) | 3.9 | 0.42 |
| SW-080-0103-0370-0788 | 0.8 mm | 10.3 mm | 8.7 mm | 36.97 mm | 0.579 | Carbon Spring Steel Wire (SWC) | 8.1 | 3.55 |
| SW-030-0051-1222-0740 | 0.3 mm | 5.07 mm | 4.47 mm | 122.25 mm | 0.088 | 301 Stainless Steel | 7.3 | 3.02 |
| SW-030-0061-0445-0766 | 0.3 mm | 6.12 mm | 5.52 mm | 44.5 mm | 0.073 | Carbon Spring Steel Wire (SWC) | 5.5 | 0.59 |
| SW-200-0215-0578-0745 | 2 mm | 21.47 mm | 17.47 mm | 57.75 mm | 3.016 | 301 Stainless Steel | 6.2 | 45.12 |
| SW-080-0084-1827-0794 | 0.8 mm | 8.41 mm | 6.81 mm | 182.67 mm | 1.457 | 304 Stainless Steel | 5.5 | 58.77 |
| SW-300-0530-0440-0768 | 3 mm | 52.95 mm | 46.95 mm | 44.03 mm | 1.107 | Oil-Tempered Spring Wire (SWO) | 5.8 | 6.56 |
| SW-080-0189-0610-0721 | 0.8 mm | 18.94 mm | 17.34 mm | 60.96 mm | 0.076 | Beryllium Copper (QBe2) | 5.4 | 0.57 |
| SW-100-0209-1946-0757 | 1 mm | 20.9 mm | 18.9 mm | 194.59 mm | 0.434 | Music Wire (SWP-B) | 2.9 | 15.86 |
| SW-030-0032-0248-0730 | 0.3 mm | 3.16 mm | 2.56 mm | 24.81 mm | 1.359 | Carbon Spring Steel Wire (SWC) | 2.5 | 4.58 |
| SW-150-0184-1713-0743 | 1.5 mm | 18.42 mm | 15.42 mm | 171.27 mm | 1.72 | 60Si2MnA Spring Steel | 6 | 61.03 |
| SW-100-0239-0493-0793 | 1 mm | 23.94 mm | 21.94 mm | 49.33 mm | 0.304 | Music Wire (SWP-B) | 2.7 | 3.84 |
| SW-400-0554-1090-0736 | 4 mm | 55.36 mm | 47.36 mm | 109.04 mm | 6.791 | 304 Stainless Steel | 2.4 | 217.84 |
| SW-200-0434-0433-0791 | 2 mm | 43.42 mm | 39.42 mm | 43.28 mm | 0.239 | Inconel X-750 | 9.3 | 2.82 |
| SW-300-0518-1312-0775 | 3 mm | 51.78 mm | 45.78 mm | 131.18 mm | 0.706 | Music Wire (SWP-B) | 9.8 | 26.06 |
| SW-050-0124-1335-0796 | 0.5 mm | 12.42 mm | 11.42 mm | 133.52 mm | 0.046 | 301 Stainless Steel | 6.9 | 0.73 |
| SW-080-0094-1769-0781 | 0.8 mm | 9.38 mm | 7.78 mm | 176.9 mm | 0.339 | Phosphor Bronze (QSn4-0.3) | 9.8 | 16.02 |
Rate: N/mm; maximum load: N. Dimensions are in millimeters.
Engineering Data
Typical Dimensions & Design Data
Use these data points to compare geometry, material and working parameters when defining your custom spring. Final values are reviewed and confirmed for the actual assembly before production.
| Configuration | Data type | Key parameters | Material / basis |
|---|---|---|---|
| Engineering Data 01 | Engineering Data |
|
Round/flat/profile wire as applicable |
| Engineering Data 02 | Manufacturing Range |
|
Carbon / stainless / alloy spring materials |
| Engineering Data 03 | Design Input |
|
Per application |
| Typical Configuration 04Data point | Typical Configuration |
|
Hard drawn bright wire |
| Engineering Data 05 | Manufacturing Range |
|
SS / carbon / spring / alloy / brass / bronze etc. |
Design note: dimensions, force / torque, material, tolerances, fatigue life and compliance are finalized against your drawing and operating conditions during quotation.
Next Design Decisions
Next Steps for Your Spring Design
Once the spring style is selected, confirm how it works in the assembly, which material suits the environment, how it will be manufactured and which dimensions and performance points should be controlled on the drawing.
Materials
Choose the material for the environment
Spring wire needs enough strength for the required deflection and enough formability for the center bend. Stainless wire is common where exposed handling or corrosion is expected.
Compare spring materials →Manufacturing
Plan prototype and production
Review forming, heat treatment, secondary operations, inspection and the path from first samples to repeat production.
View manufacturing capabilities →Engineering Data
Open matching engineering guides
Matching material and wire-diameter pages provide additional design data for material and size selection.
Open Spring Engineering Guide →Material Direction
Common Material Families to Review
The links below are selection guides, not a claim that every grade is suitable for every size or load.
Related Spring Design Guides
Review the design and measurement requirements for this spring family.
Engineering Support
Spring Engineering Guides
Use these guides to compare material, wire diameter and standard requirements before finalizing the product drawing.
Material data
304 Stainless Steel Torsion Springs Engineering Data
3 matching hairpin springs data rows are included in the category.
Material data
Carbon Spring Steel Wire (SWC) Torsion Springs Engineering Data
3 matching hairpin springs data rows are included in the category.
Material data
301 Stainless Steel Torsion Springs Engineering Data
3 matching hairpin springs data rows are included in the category.
Wire diameter
0.3 mm Torsion Springs Engineering Data
4 matching hairpin springs data rows are included in the category.
Wire diameter
0.8 mm Torsion Springs Engineering Data
4 matching hairpin springs data rows are included in the category.
Wire diameter
2 mm Torsion Springs Engineering Data
2 matching hairpin springs data rows are included in the category.
Compare Designs
Related Spring Products
Use these alternatives when the available space, connection style, travel or force direction changes.
Torsion Springs
Straight-Leg Torsion Springs
A torsion spring with simple straight arms for hinges, levers and pivots where both contact points can be defined directly from the coil axis.
Torsion Springs
Single-Leg Torsion Springs
A compact torsion-spring arrangement with one main working arm and the opposite end retained close to the coil for one-sided rotary return.
Wire Forms
Wire-Formed Components
Custom 2D and 3D wire parts formed to a drawing when the component needs to locate, retain, connect, guide or support another part rather than behave like a conventional coil spring.
Product Questions
Hairpin Springs FAQ
Is a hairpin spring the same as a torsion spring?
It can perform a similar return function, but its open geometry and load path are different from a tightly coiled torsion spring. The design should be based on the actual arm movement.
What dimension most affects the force at the arm tip?
Arm length is especially important because it sets the leverage from the active bend region to the contact point.
RFQ
Send the Working Requirement
A drawing is ideal. If you do not have one yet, provide the dimensions, load or torque, travel, environment and expected quantity that matter in the assembly.
CustomSprings Engineering Catalog
Request This Spring
Send your dimensions, quantity and drawing for engineering review.