Superior performance
Co-Ni Alloy Product (SPRON)®

Creating Time - Optimizing Time - Enriching Time
Seiko Instruments Inc. (SII), founded in 1937 as a member of the Seiko Group specializing in themanufacture of watches, has leveraged its core competency in high precision watches
to create a wide range of new products and technologies.
Over the years SII has developed high-precision processed parts and machine toolsthat pride themselves on their sub-micron processing capability,
quartz crystals that came about as a result of our quartz watch R&D,
and electronic components such as micro batteries.
Optimizing our extensive experience and expertise, we have since diversified
into such new fields as compact, lightweight, exceedingly quiet thermal printers,and inkjet printheads, a key component in wide format inkjet printers for corporate use.
SII, in the years to come, will maintain an uncompromised dedication
to its time-honored technologies and innovations of craftsmanship, miniaturization, and efficiency
that meet the needs of our changing society and enrich the lives of those around us.

Genealogy of Seiko Group
1947 Wako Co., Ltd.
2001 Seiko Watch Corporation
1881 K. HattoriHattori Seiko Co., Ltd.

Seiko Corporation

2006 Seiko NPC Corporation1975 Nippon Precision
Circuits Inc.

1998 Seiko Time Systems Inc.
1892 Seikosha

2022 Seiko Group Corporation

Seiko Holdings Corporation

Seikosha Co., Ltd.

2021 Seiko Time Creation Inc.

1996 Seiko Clock Inc.
1996 Seiko Precision Inc.
2013 Seiko Solutions Inc.

1937 Daini Seikosha Co., Ltd.

Seiko Instruments &Electronics Ltd.

2004

Seiko Instruments Inc.

CONTENTS
Superior performance Co-Ni Alloy Product (SPRON)®����������������������������������������������������������������������� 3
SPRON510�������������������������������������������������������������������������������������������������������������������������������������������� 4
SPRON100�������������������������������������������������������������������������������������������������������������������������������������������� 8
Glossary / Environmental Policy���������������������������������������������������������������������������������������������������������� 9
Product Introduction��������������������������������������������������������������������������������������������������������������������������� 10

Superior performance Co-Ni Alloy Product ()®

It all started with the precision spring.
With its evolution came the Co-Ni alloy productthat is paving the way of the future.

Power spring inmechanical watches■ History of SPRONThe Grand Seiko isequipped with the SPRONThe Sendai Precision Materials Laboratory – the predecessor of the Sendai Unit where
production of SPRON is based – began collaborating in 1953 with the Institute ofMaterials Research, Tohoku University to develop the spring that serves as a powersource for mechanical watches. In 1956, we succeeded in developing SPRON 100, astrain age-hardening type, high-elastic and high-corrosion-resistant alloy that leverages
the work-hardening properties of the cobalt base.
In 1957, Sendai Precision Materials Laboratory began producing watch springs as awatch spring manufacturing company. Combining the material’s properties with theprecision processing technology allowed SPRON to be used in a wide range of highprecision springs and as spring material in medical instruments.
Later, growing needs for enhancements in super-miniaturization technology and highperformance spring material led to the development of SPRON 510, featuring material
strength and corrosion resistance surpassing that of SPRON 100.
Originating as a part with a dimension of only a few millimeters, the SPRON 510 is
now used for precision spring material in fields related to semiconductors, dental, medical, and others.
The SPRON also serves as a part of the power spring in the Grand Seiko and othermechanical watches under the Seiko brand.

■ The origin of the name “SPRON”
The name SPRON is coined from “SPRING + MICRON.” As the name implies, our precision springs boast outstanding material properties and are machined to a precisionfinish controlled to the micron level.
* SPRON is a registered trademark of Seiko Instruments Inc.

3

SPRON510■ SPRON510
In 1956, the superior performance Co-Ni alloy product (SPRON) was developed as springmaterial in “Grand Seiko”, the high grade mechanical watch, through collaboration with theInstitute of Materials Research, Tohoku University.
SPRON510 is corrosion resistant and significantly excellent at every aspect of mechanicalcharacteristics below.

[Feature of SPRON]
Hardness(Hv)

SPRON510(with cold processing and age treatment)
SUS 304-WPB
ASTM B574 Ni-based alloy

650
600
550
500

Elongation

35(%)

71600

1001800(MPa)

600
700

10800

1CorrosionResistanceHCl 10%TensileStrength2000450

9000

Fatigue limit(MPa)(mg/cm2·H)[Mechanical and physical characteristics]
Tensile strength

Stiffness

Up to 2940MPa
Up to 5684MPa(Up to 300kg/mm2) (Up to 580kg/mm2)

Elongation Hardness

3%Density

Hv. to 800 8.5 to 8.7 g/cm3

Young's modulus

Modulus ofrigidity

216 to 225GPa
83.3GPa(22 to 23×103kg/mm2) (8.5×103kg/mm2)

Linear expansion
coefficient(20 to 50°C)

Intensity ofElectrical
Poisson’s
magnetization
resistivity
ratio(5k0e)

12 to 13×10-6/°C

98 to100µΩ-cm00.33<Measured a wire drawing material with cold processing and age treatment>4

■ Chemical components
Other■ Relationship between mechanicalcharacteristics and heat treatment temperature
Relationship between heat treatment temperatureand mechanical strength of SPRON 510

Mo(Molybdenum)

Elongation (%)
60

Tensile strength (MPa)3500

Co(Cobalt)
Cr(Chromium)

Chemicalcomposition

Tensilestrength

3000
Hardness(Hv)

50

HardnessElongation

2500
40800
2000

30600
1500
400

Ni(Nickel)

20020100010500

000100

200

300

400

500

600

700

800

9000.01000 1100

Heat treatment temperature (°C)* The above graph shows the tensile strength, hardness, and elongation when a materialwith 90% processing rate of wire-drawing is heat-processed at each temperature fortwo hours.

■ Five advantages of SPRON
1. No Corrosion
Results of corrosion tests in 48% hydrogen bromide (HBr) and 36% hydrochloric acid (HCl) show that SPRON
510’s corrosion resistance is superior to that of the corrosion-resistant metal materials shown below.
Corrosion resistance of SPRON510 and other Metals
Immersion: 36%HCl (hydrochloric acid)

Immersion: 48%HBr (Hydrogen bromide)
Weight loss ratio
0.0%

SPRON 510Ni-based heatresistant alloy

2.0%

ASTM B574
Ni-based alloy
Co-Cr-based
corrosionresistant alloy

4.0%
6.0%

SUS316L

8.0%

Weight loss ratio
0.0%

SPRON 510

10.0%

Ni-based heatresistant alloy

20.0%

ASTM B574
Ni-based alloy
Co-Cr-based
corrosionresistant alloy

30.0%
40.0%
50.0%

SUS316L

60.0%
10.0%

70.0%

12.0%

80.0%
90.0%

100%

9Hr

18Hr

[Measurement conditions]

36Hr

72Hr (Ave)

100.0%

9Hr

18Hr

36Hr

72Hr (Ave)■ Test piece: φ20mm, Mass 0.2 to 0.3g

■ Immersion: 48%HBr (60°C) / 36%HCl (60°C)

5

SPRON510
2. Strong
The fatigue limit of SPRON510 (processing rate when rolled: 73%, age treatment: 525°C) is 900MPa.
S-N Curve
Stress σ (MPa)S-N curve of SPRON510 with processing rate of 73%

2,000

SPRON510 thickness: 0.135mm(processing rate: 73%, age treatment: 525°C×2h)

1,800

SPRON510 thickness: 0.135mm(processing rate: 73%)

1,600
1,400

Fatigue Test

1,200

[Measurement conditions]

1,000■ JIS Z 2273-1978

800■ Stress ratio R=0.1600*T he graph shows that the fatigue limit is900MPa when age treatment is performed
at 525°C.

4002000
1,000

10,000100,000

1,000,000

10,000,000

100,000,000

Cycle number to failure (N)

3. Elastic
Fatigue due to both statistical and dynamic loads is very small, achieving large spring load by a fine spring.
Relaxation rate after 1,000,000 times of tensile spring tests of SPRON510 is one-fifth or one-sixth as much as thatof piano wire.
Relaxation and Number of repetition due to tensile spring test
BeforeDuringAfter

Relaxation

BeforeDuringAfter

Relaxation

8%

SPRON510

8%

SWP-A
SPRON510SUS304-WPB
SWP-A

6%

SUS304-WPB

6%

τ=430N/mm2
τ=430N/mm

2

τ=630N/mm

2

τ=630N/mm2
Repeated Stress×N (τ×N)∆Stress∆amplitude
200N/mm2
Stress amplitude(2.2Hz) 2200N/mm(2.2Hz)[Measurement conditions]
Repeated Stress×N (τ×N)■ Wire diameter: φ0.3mm ■ Center diameter: φ3mm
■ Number of coils: 33-35 ■ Free length: 16.0mm

4%
4%
2%
2%
0%
1,000
0%
1,000

10,0001,000,000

10,000,000of repetitions 1,000,000(N)
10,000 Number100,000

100,000

10,000,000

Number of repetitions (N)Relaxation and Stress due to tensile spring test
BeforeDuringAfter

Relaxation

BeforeDuringAfter

Relaxation

SPRON510

8%

SWP-A
SPRON510
SUS304-WPB
SWP-A

8%6%

SUS304-WPB

6%∆∆Relaxation (%)∆
Stressτ∆
Relaxation (%)

Stressτ[Measurement conditions]■ Wire diameter: φ0.3mm ■ Center diameter: φ3mm
■ Number of coils: 35 ■ Free length: 16.5mm

4%4%

G=7.4kg/mm2×103

G=8.3kg/mm2×103

G=7.4kg/mm2×103

G=8.3kg/mm2×103

2%
2%
0%
50
0%
50

G=8.5kg/mm2×103
G=8.5kg/mm2×103
70

90110

130150170

7090 Stressτ
110(kg/mm130)

150

170

2Stressτ (kg/mm2)64. No Magnetization

SPRON is suitable for parts in measurement/analysis equipment that will not welcome magnetism.

Magnetic characteristic (permeability)
Magnetic permeability (μ)

attracted to magnet

1.020

1.000

SPRON510
SUS304
SUS316

not attracted to magnet

020

4060

* Magnetic permeability (μ)
Ability of a material to support the formation of a magnetic
field within itself.
Generally, a material with μ<1.02 is regarded as non-magnetic.

80

Cold reduction (%)

5. Heat resistant (both hot and cold)
SPRON 510 has excellent characteristics in both high and low temperature ranges.
Low-/high-temperature characteristics
SPRON510 low temperature tensile testing
Relationship between tensile strength andelongation at low temperature

SPRON 510 high temperature tensile testing
Relationship between tensile strength andelongation at high temperature

Elongation (%)

Tensile strength (MPa)
2500

100

Elongation (%)

Tensile strength (MPa)
2500

10090
2000

80

90
2000

80

70
1500

6070
1500

60

50
40

1000

50401000

3020500

3020500

100−2000−150−100−50050Temperature (°C)

1000200

400

60080001000

Temperature (°C)

Tensile strength Annealed material 1050°C (0.5mm thick)Tensile strength Cold working ratio 73% (0.135mm thick)Elongation Annealed material 1050°C (0.5mm thick)Elongation Cold working ratio 73% (0.135mm thick)Tensile strength Annealed material 1050°C×24h
Tensile strength Cold working ratio 85%
Elongation Annealed material 1050°C×24h
Elongation Cold working ratio 85%■ Applications
Evaluated highly for its corrosion resistance and durable quality, SPRON is used for key devises in various field likevalves, dental wire, pressure sensor, mass flow controller, and various kinds of fine spring.

• Metal diaphragm and pipe inpressure sensor• Corrosion-resistant fi ne parts• Fine parts for medical use• Several kinds of fi ne spring(coil, torsion, plate)Pressure sensor, mass flow
control device, diaphragm→S trength, corrosion

resistance, durability

Fine springs→E lasticity,durability, corrosion
resistance

SII supplies SPRON as custom-made machined products, featuring its strong characteristics. Mirror surface polishing andfine cutting is possible with SPRON.
7SPRON100
Overview

Applications

SPRON 100 is a strain age-hardening type Co-Ni alloythat makes the most of the work-hardening propertiesof cobalt-based alloys. High mechanical strength andcorrosion resistance combined with excellent precision
processing technologies make it ideal for precision
devices, medical precision parts, and precision screws,
as well as mechanical watches.

- Precision springs(coils, torsion springs, flat springs, disc springs)- Springs for measuring instruments- Cable guides for driving robot devices- Medical precision parts- Wires for medical devices

Characteristics[Mechanical and physical characteristics]
Tensile strength

Elongation

Hardness

DensityYoung’s modulus

Modulus of rigidity

Linear expansion
coefficient(20 to 50°C)

Electrical resistivity

Up to 2156 MPa(Up to 220 kg/mm2)

3%

Hv. to600

8.3 to 8.6 g/cm3

206 to 216 GPa(21 to 22×103 kg/mm2)

80.4 GPa(8.2×103 kg/mm2)

12 to 13×10−6 /°C

98 to 100 μΩ-cm<Measured a wire drawing material with cold processing and age treatment>

Chemical components

Relationship between mechanical characteristics and heat treatment temperatureRelationship between heat treatment temperatureand mechanical strength of SPRON 100

Other

Tensile strength (MPa)
2500

Cr

Elongation (%)
60

502000(Chromium)Fe(Iron)Chemicalcomposition

Hardness(Hv)
700

Co(Cobalt)

40
1500

600
500

Tensilestrength
HardnessElongation

30
1000
20400
300
200

Ni(Nickel)

500

10100
000

100

200

300

400 500

600

700

800

0900 1000 1100

Heat treatment temperature (°C)* The above graph shows the tensile strength, hardness, and elongation when amaterial with 90% processing rate of wire-drawing is heat-processed at eachtemperature for two hours.

S-N curve
Stress σ (MPa)S-N curve of SPRON 100 with processing rate of 74%

2,000

SPRON100 thickness: 0.130mm(processing rate: 74%, age treatment: 525°C×2h)

1,800

SPRON 100 thickness: 0.130mm(processing rate: 74%)

1,600
1,400
1,200

Fatigue Test

1,000

[Measurement conditions]800■ JIS Z 2273-1978

600■ Stress ratio R=0.1400*T he graph shows that the fatigue limit is
800MPa when age treatment is performed
at 525°C.

200
01,00010,000100,000

1,000,000

Cycle number to failure (N)810,000,000

100,000,000Glossary / Environmental Policy
GlossaryTermUnit

Description

As rolling

Roll drawing has completed.

S-N curves

Graph showing the results of bending fatigue test. (Stress and repetition counts are logarithmically
expressed in the vertical and horizontal axes, respectively.)StressMPa

Degree of cold deformation processing, such as wire drawing and rolling. Also known as cold working ratio.
The working ratio is the quotient of the sectional area divided by the difference between the sectional areasof the material before and after working, expressed in percentage (%).

Rate of work
Vickers hardness

Hv.

Strength
Cycle number to fallure
Stiffness
Electrical resistivity
Intensity of magnetization

The quotient of the force applied for the indent divided by the surface area of the indent which wasproduced on the test piece by an indenter (diamond square cone of which angle of opposite faces is 136°).
Mechanical strength such as tensile strength and hardness

N

Number of repetitions for fatigue test.

MPa (kg/mm2)

Maximum stress value in transverse testμΩ-cmElectrical resistance ratio specific to a substanceG

Magnetic flux density in a 5 KOe magnetic field

Aging treatment
Coefficient of linear
Expansion

Stress value in fatigue test.

Heat processing to improve mechanical characteristics by applying a specified temperature
1/K (1/°C)

The rate of length change in accordance with the temperature change

Durability

Fatigue characteristics (characteristics resistant against repeated loads)

Corrosion resistance

Durability against corrosive gases and solvent

Heat resistanceResistance to degredation of characteristics, such as mechanical strength, in a high temperatureenvironment

Young’s modulus

GPa (kg/mm2)

Proportional constant existing between vertical stress and vertical strain

Elasticity

Young’s modulus and modulus of rigidity

Heat treatment

Heat application and cooling of metallic materials in appropriate conditions to gain desired characteristics

Non-magnetic material
Tensile strength

Property of barely being influenced, if at all, by magnetism
MPa (kg/mm2)

Maximum stress value for tensile test

Modulus of relaxation

Relaxation degree due to repeated loading by tensile coil spring model

Poisson’s ratio

The ratio of the lateral contraction strain to the longitudinal extension strain when a material is stretchedelastically uniaxially.

Modulus of rigidity
Cold working

GPa (kg/mm2)

Proportional constant between stress and shear strain when shear force is applied
Deformation processing performed at normal temperature* The above glossary was created based on terms appearing in the SII catalogues and does not certify the contents and products.

Environmental Policy
The Seiko Group recognizes that the preservation of the global environment is one of the most important issues in the world today. We will
constantly strive to help realize a sustainable society that will benefit everyone.
1. We are committed to a wide range of environmentally responsible activities, and we will continue to make unceasing efforts toimprove our environmental performance, thereby providing increased value for all our stakeholders.
2. We not only comply with all relevant laws and regulations, but also go far beyond legal compliance in our efforts to reduce
environmental risks and prevent pollution.
3. Being acutely aware of the part we have to play in mitigating climate change, we are working hard to reduce greenhouse gas
emissions.
4. Because we recognize the limits of our precious natural resources, we are increasing our efforts to reuse and recycle every resourcepossible.
5. We are also working to preserve biodiversity, recognizing that our business activities inevitably affect surrounding ecosystems, andthat we also benefit from the health and diversity of those systems.
6. We rigorously ensure proper management of all chemical substances used in production as well as any that are contained in ourfinished products.
7. We consider the environment throughout the entire life cycle of our products. We are proud that our products and services actively
contribute to environmental conservation.
8. Environmental responsibility starts as a management imperative, but to effectively carry out that mission requires the understanding
and cooperation of every employee throughout our Group. With that in mind, we are working to raise everyone’s environmental
awareness so that all of us can work together to protect and nurture our natural environment.
9. Transparency is another part of our social responsibility. We are therefore promoting active disclosure of material information about
our environmental activities and promoting increased communication with local, regional, and global stakeholders.
10. In order to derive maximum benefits from these policies, we establish clear environmental targets and strategies to attain them.
Then we steadily improve our efforts by constantly re-examining both our targets and our progress towards achieving them.

9

Product Introduction

B

M

10

IATF

M

B

11

Micro-Energy Division who manufactures the products described inthis catalog holds the ISO 9001 quality management system
certificate, and the ISO 14001 environmental management systems
certificate.

www.sii-me.com
SearchElectronic Components Sales Head Office
1-8, Nakase, Mihamaku, Chiba-shi, Chiba 261-8507, Japan
Telephone:+81-43-211-1735 Facsimile:+81-43-211-8034

Asia

Seiko Instruments Trading (H.K.) Ltd.

7/F, Ying Tung Industrial Building,
802 Lai Chi Kok Road, Kowloon, Hong Kong
Telephone: +852- 2494-5111
Facsimile: +852- 2424-0901

Seiko Instruments Taiwan Inc.
2F., No. 143, Changchun Rd.,
Taipei, Taiwan R.O.C.
Telephone: +886-2-2563-5001
Facsimile: +886-2-2563-5580

Seiko Instruments (Shanghai) Inc.
Room 2701, 27th Floor,
Shanghai Plaza,
138 Mid Huaihai Rd.,
Shanghai 200021, China
Telephone: +86-21-6375-6611
Facsimile: +86-21-6375-6727

Seiko Instruments (Shanghai) Inc.
Shenzhen Branch

Room 2215, Office Tower, Shun Hing
Square Di Wang Commercial Centre,
5002 Shen Nan Dong Road, Shenzhen,
518008, China
Telephone: +86-755-8246-2680
Facsimile: +86-755-8246-5140

EuropeSeiko Instruments GmbH
Siemensstrasse 9
D-63263 Neu Isenburg, Germany
Telephone: +49-6102-297-0
Facsimile: +49-6102-297-50100
Email:info@seiko-instruments.de
http://www.seiko-instruments.de

North/Central/South America

Seiko Instruments U.S.A., Inc.

21221 S. Western Ave., Suite 250,
Torrance, CA 90501, U.S.A.
Telephone: +1-310-517-7802
Facsimile: +1-310-517-7792
Email:info@seikoinstruments.com
http://www.sii-me.com

Contact us(Specifications are subject to change without notice.)

Released in February 2023
Copyright©2023 Seiko Instruments Inc. All Right Reserved.

No.SPC3019EJ-03P2311