How does Zamak handle repeated medical sterilization cycles?

How Does Zamak Handle Repeated Medical Sterilization Cycles?

Material Suitability of Zamak for Medical Applications

Zamak, a family of zinc-based die casting alloys like Zamak 3 and Zamak 5, is widely used in non-implantable medical devices and equipment components such as casings, handles, latches, and housings. Its advantages include precise castability, fine surface finish, and high strength-to-weight ratio. However, its compatibility with repeated sterilization cycles depends on the sterilization method used.

Performance Under Common Sterilization Methods

1. Autoclaving (Steam Sterilization at 121–134°C)

• Limitations: Zamak alloys can degrade under repeated high-temperature, high-pressure steam exposure. They are prone to grain boundary oxidation, coating delamination, and potential structural weakening after multiple cycles.

• Result: Not recommended for components exposed to frequent autoclave cycles unless specially coated or isolated from direct steam.

2. Ethylene Oxide (EtO) Sterilization

• Compatibility: Excellent. EtO sterilization occurs at low temperatures (37–63°C), and Zamak components maintain full mechanical and cosmetic properties.

• Use Case: Preferred for reusable or pre-assembled medical tools and devices that incorporate Zamak parts.

3. Hydrogen Peroxide Plasma (e.g., STERRAD®)

• Compatibility: Good. Zamak handles low-temperature plasma sterilization cycles with minimal degradation, especially when protected with a corrosion-resistant finish like nickel plating.

• Consideration: Surface coatings should be validated for hydrogen peroxide exposure.

4. Chemical Disinfection and Wipes

• Compatibility: Excellent with proper coating. Zamak with clear coating, powder coating, or painting resists surface corrosion caused by alcohols, peracetic acid, and quaternary ammonium disinfectants commonly used in clinical settings.

Enhancing Sterilization Resistance

To improve Zamak’s durability in sterilized environments, Neway recommends:

• Protective plating: Nickel or trivalent chrome finishes provide a barrier against moisture and oxidation

• Epoxy powder coating: Seals surfaces and resists chemical or moisture exposure during cleaning

• Surface polishing and tumbling: Removes porosity and improves surface uniformity for better coating adhesion

• CNC machining of sealing surfaces to reduce water retention areas

Summary of Sterilization Compatibility

Neway’s Medical Casting Support

Neway supports medical OEMs with:

• Precision zinc die casting for device components

• Sterilization-resistant surface treatments including plating, powder coating, and painting

• Functional testing and prototyping of sterilizable assemblies

• Full assembly and CNC machining services for sealed housings and connectors