In medical device manufacturing, material performance defines both patient safety and device reliability.Whether reinforcing catheters, forming guidewires, or shaping implantable coils, wire selection is one of the most critical engineering decisions. The standard most often relied upon in these applications is ASTM A313, which governs cold-drawn stainless steel spring wire. How did a spring wire specification become so heavily relied upon by the medical device industry?

For decades, Zapp has specialized in supplying precision-drawn stainless steel wire that fully complies with ASTM A313 requirements, while also meeting the enhanced cleanliness and performance standards expected in the medical industry.

Why ASTM A313 Matters in Medical Device Design

Originally developed for spring wire, ASTM A313 has become a critical benchmark for medical device engineering. Its strict requirements for tensile strength, temper control, and corrosion resistance ensure that wire products meet the demanding performance needs of life-saving technologies. In practice, its influence can be seen in:

• Catheter reinforcement braids that deliver torque control and pushability
• Micro coils used in occlusion devices, embolization platforms, and delivery systems
• Guidewires that balance high tensile strength with precise flexibility
• Biopsy needles that must remain sharp, strong, and resistant to fracture
• Suture wire designed for strength, flexibility, corrosion resistance, and consistency

In these applications, wire is more than a structural material, it directly dictates navigation, handling, and patient outcomes. Zapp medical wire provides tailored solutions within the ASTM A313 framework, ensuring consistency from development, through PPAP, to eventual full production.

The Role of Tensile Strength

ASTM A313 defines tensile strength as a function of wire diameter and temper. This gives design engineers predictable performance across a range of wire sizes and hardness levels.

Typical tensile strength values for medical-use wire:

Zapp medical wire offers a full spectrum of tempers, giving device OEMS the ability to fine flexibility and fatigue resistance.

Alloys in ASTM A313 for Medical Devices

ASTM A313 covers multiple stainless alloys, but medical applications typically rely on austenitic stainless steels for their corrosion resistance and biocompatibility. Common alloys include:

304V – The industry standard for guidewires, braids, and coils. Vacuum arc remelted (VAR) for superior cleanliness and fatigue strength.

316LVM – Low-carbon, vacuum-remelted. Favored for implantable coils and stents requiring biocompatibility and enhanced corrosion resistance.

302/304 – Cost-effective options where biocompatibility and high tensile strength are needed. 

17-7 PH – A precipitation-hardenable grade ideal for spring like behavior in device support structures.

While ASTM A313 does not mandate VAR or ESR processes, Zapp routinely provides these enhanced variants to meet medical wire fatigue life and cleanliness requirements. For implant grade wire, complementary standards such as ASTM F138 are also applied.

Other Key Implant-Grade Medical Wire Standards

ASTM Standards

• ASTM F138 – Implant Grade 18Cr-14Ni-2.5Mo Stainless Steel Bar and Wire
  • Applies to: 316LVM stainless steel (vacuum re-melted for purity)
  • Common in: Orthopedic implants, surgical instruments, and cardiovascular devices
• ASTM F139 – Implant Grade 18Cr-14Ni-2.5Mo Stainless Steel Sheet and Strip
  • Applies to: 316L stainless sheet/strip for implant use
• ASTM F2181 – Tensile Testing of Wire Used in Surgical Implants
  • Applies broadly to all implant-grade wires, providing mechanical test methodology
• ASTM F2063 – Implant-Grade Nitinol Alloy for Surgical Implants
  • Applies to: Nickel-Titanium (NiTi) shape-memory alloys
  • Used in: Stents, guidewires, orthodontic archwires
• ASTM F90 – Cobalt-20Chromium-15Tungsten-10Nickel Alloy for Surgical Implants
  • Applies to: CoCrWNi alloys
  • Used in: Cardiovascular devices, orthopedic fixation
• ASTM F1058 – Wrought Cobalt-28Chromium-6Molybdenum Alloy
  • Applies to: CoCrMo alloys
  • Used in: Hip stems, dental implants
• ASTM F562 – Cobalt-Nickel-Chromium-Molybdenum Alloy (MP35N)
  • Applies to: MP35N wire
  • Used in: Cardiovascular leads, pacing wires, and stents

Engineering Considerations for Device Performance

When sourcing wire under ASTM A313, device designers must account for key properties that directly influence function:

Tensile Strength – Determines pushability, torque response, and fatigue resistance.

Temper – Affects shape memory, braid density, and stiffness.

Diameter Tolerance – Controls catheter profile and assembly fit.

Surface Finish – Impacts lubricity, cleanliness, and adhesion with polymers.

The Zapp Group can also provide wire, rod, strip and profiles forms. Depending on the dimension, the material can be straightened, cut to length and centerless ground, optimized for smoothness, and repeatable performance in complex processes or assemblies.

Real-World Applications

Catheter Reinforcement – Spring temper 304V wire, typically 0.001–0.003 inches in diameter (0.0254-0.0762mm), forms braids that provide kink resistance and torque transmission in neurovascular, cardiac, and peripheral catheters.

Guidewires – Cores and outer coils are produced from spring temper 304V, often combined with coatings or radiopaque markers for enhanced visualization.

Implantable Coils – Annealed or quarter-hard 316LVM wire delivers fatigue resistance and biocompatibility, supporting long-term implant safety.

Each of these use cases demonstrates how ASTM A313 compliance, combined with Zapp medical wire's precision manufacturing, enables device engineers to meet demanding requirements.

Conclusion

For engineers and sourcing teams in the medical device industry, ASTM A313 provides the essential foundation for designing wire-based components. When paired with enhanced melting practices, precision finishing, and proven supplier expertise, this standard ensures that devices meet both performance and regulatory expectations.

By partnering with Zapp, medical device OEMs gain not only material compliance but also the assurance of consistency, reliability, and support throughout product development. Whether designing next generation guidewires, catheter systems, biopsy needles, or implantable coils, choosing ASTM A313 compliant wire from a trusted medical wire supplier sets the stage for successful device innovation.