Custom Flat Coil Springs
Flat metal spiral springs designed for controlled energy storage, rotary output, and long cycle life.
What Is a Flat Coil Spring
Flat coil springs, also known as flat spiral springs, are made from flat metal strip wound into a spiral to store and release mechanical energy through rotation.
Unlike compression or extension springs that work along a linear axis, flat coil springs operate through rotational movement. The flat strip material winds tighter or releases during use, storing or delivering torque rather than linear force.
This rotary energy storage makes them ideal for applications requiring return-to-position mechanisms, constant force output, or compact energy storage in limited radial space.
The flat strip geometry allows multiple turns in a compact diameter, providing higher energy density than round wire springs in rotational applications while maintaining consistent torque delivery throughout the working range.
Need help determining if flat coil springs fit your application?
Discuss Your RequirementsFlat Coil Springs vs Other Spring Types
Understanding the mechanical differences helps you select the right spring configuration for your application's force requirements and space constraints.
Flat Coil vs Compression
Flat coil delivers rotational torque; compression provides linear axial force along spring length.
Flat coil occupies minimal radial space; compression requires axial clearance proportional to stroke.
Flat coil stores energy through winding; compression through axial compression of coils.
Flat Coil vs Extension
Flat coil produces rotary torque; extension generates linear pull force between attachment points.
Flat coil fits compact circular footprint; extension needs linear mounting distance plus travel clearance.
Flat coil winds tighter under load; extension stretches between hooks as coils separate.
Flat Coil vs Torsion
Both deliver rotational torque, but flat coil provides more turns in same diameter through flat strip geometry.
Flat coil achieves higher energy density in radial plane; torsion requires more diameter for equivalent torque.
Flat coil winds/unwinds spiral; torsion stores energy through twist of round wire coils.
Still evaluating which spring type best suits your mechanical requirements?
Get Technical ComparisonCommon Types of Flat Coil Springs
All share the fundamental flat spiral structure, but each variant is optimized for specific torque delivery, rotation range, and mounting requirements.
Power Springs
Pre-wound flat spiral springs enclosed in housings, delivering constant torque for retraction mechanisms and motor drives. Used in cord reels, counterbalances, and automatic return systems.
Clock Springs
Precision flat coil springs designed for timekeeping mechanisms, providing regulated energy release over extended rotation. Requires tight tolerance on strip thickness and torque consistency.
Mainsprings (Main Springs)
Heavy-duty flat spiral springs for high-energy applications, storing significant rotational power. Common in mechanical watches, wind-up toys, and industrial drive systems requiring sustained torque output.
Constant Force Springs
Flat strip springs that provide nearly linear force throughout extension range. Ideal for counterbalancing, tensioning applications, and systems requiring consistent pull force regardless of displacement.
Need guidance on which flat coil spring configuration matches your torque requirements?
Request Application ReviewDesign Parameters & Custom Options
Flat coil spring performance is determined by material properties, geometric dimensions, and manufacturing precision. These parameters directly control torque output, rotation angle, and cycle life.
Share your torque and rotation specifications for custom parameter recommendations
Submit Design RequirementsTypical Applications
Flat coil springs enable specific mechanical functions across industries, from automated return mechanisms to precision energy storage systems.
Rotary Energy Storage
Wind-up motors, mechanical watches, and toys use flat coil springs to store manual winding energy for gradual release through geared mechanisms.
Automatic Return Mechanisms
Cord reels, tape measures, and retractable cables rely on pre-loaded flat coil springs to automatically retract extensions without external power.
Tensioning and Balancing
Constant force springs provide consistent tension for belt drives, document feeders, and counterbalance systems requiring uniform force regardless of position.
Compact Drive Systems
Small mechanisms in medical devices, automotive components, and consumer electronics use flat coil springs where radial space is limited but rotational power is needed.
Describe your application and we'll identify the optimal flat coil spring configuration
Discuss Your ApplicationManufacturing Capability
Our production process controls strip geometry, winding precision, and torque consistency from prototype through volume production.
Custom Tooling & Forming
We design winding arbors, mandrels, and fixtures specific to your spring geometry, ensuring repeatable coil formation and consistent inner diameter control across production runs.
Torque Consistency Control
Strip thickness variation, material hardness, and winding tension are monitored to maintain torque output within ±5% of specification at defined rotation angles.
Dimensional Repeatability
Strip width, thickness, and winding diameter are verified against print tolerances using calibrated micrometers and optical comparators to ensure interchangeability.
Prototype to Mass Production
Initial samples validate design parameters; once approved, the same tooling and process controls scale to production volumes without re-engineering or performance drift.
Ready to move from concept to manufactured flat coil springs?
Start Production PlanningQuality & Inspection
Every flat coil spring batch undergoes dimensional verification, performance testing, and material traceability checks before shipment.
Torque Testing
Springs are wound to specified angles and measured on calibrated torque testers. Output must fall within tolerance band across the working range.
Dimensional Inspection
Strip thickness, width, inner/outer diameters verified per drawing. Out-of-spec dimensions affect torque output and fit, so we measure samples from each production batch.
Fatigue / Cycle Testing
For high-cycle applications, sample springs undergo accelerated life testing to validate material selection and stress levels won't cause premature failure.
Incoming Material Control
Strip steel is certified for chemistry and mechanical properties. Material certs are maintained for traceability, critical for aerospace and medical applications.
Need documentation of our quality processes for your project approval?
Request Quality DocumentationFrequently Asked Questions
Common questions about flat coil spring design, manufacturing, and application requirements.
Power springs are pre-wound flat coil springs enclosed in a housing, delivering rotational torque for retraction mechanisms. Constant force springs are flat strips designed to provide nearly linear force throughout their extension range, used for tensioning applications. Both use flat strip material but serve different mechanical functions—power springs for rotary energy storage, constant force springs for linear force delivery.
Cycle life depends on material selection, stress levels, and rotation angle. Springs designed with conservative stress (below 50% of material yield) in corrosion-free environments can achieve 100,000+ cycles. High-stress applications or aggressive environments may require fatigue testing to validate expected life. We recommend sharing your cycle requirements during design so we can select appropriate materials and stress limits.
Yes, stainless steels like 301, 302, and 17-7 PH are commonly used for flat coil springs requiring corrosion resistance. Stainless provides good spring properties after heat treatment but typically has lower strength than carbon spring steel. For medical, food processing, or marine applications, stainless is often necessary despite slightly reduced torque capacity compared to equivalent carbon steel springs.
Strip thickness typically held to ±0.002" (±0.05mm) depending on nominal size. Inner and outer diameter tolerances range from ±0.010" to ±0.030" based on spring size and complexity. Tighter tolerances are achievable but may require secondary operations or special tooling. Torque output tolerance is typically ±5-10% unless otherwise specified and tested.
Yes, we can generate torque-angle curves during prototype sampling. Springs are tested at multiple rotation increments to map actual torque output against design calculations. This data validates spring performance and helps identify any non-linear behavior. For production orders, we provide torque verification at specified working angles rather than full curve mapping unless requested.
Prototype samples typically require 2-3 weeks including tooling fabrication and initial testing. Production lead times range from 3-5 weeks depending on quantity, complexity, and material availability. Rush services available for urgent requirements. We recommend contacting us with your timeline so we can provide accurate scheduling based on current capacity.
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Ask Our Engineering TeamEngineering Support
Share your drawing or performance requirements. Our engineers review flat coil spring designs for feasibility, consistency, and manufacturability.