Silicone Insulated Wire- Medical Grade Silicone Applications

Silicone insulated wire and cable is an excellent choice for medical cable applications. Besides being extremely flexible, silicone rubber can withstand autoclave and other forms of sterilization. Properties that make silicone suitable for medical applications include: Low thermal conductivity, low chemical reactivity, low toxicity and thermal stability (consistency of properties over a wide temperature range of 100°C to 250°C). Abrasion resistance is a concern when considering silicone insulation or jacket. Formulas for higher tear strength are available to increase resistance to abrasion.

Applications suitable for silicone cables include:

• Arthroscopic
• Surgical Robotics
• Electrosurgical
• Implantable
• Ophthalmic
• Foot Switch
• Patient Monitoring

What makes a material medical grade? Materials are tested for bio-compatibility and are categorized to be used for medical applications. Medical grade materials are generally grouped into three categories: non implantable, short term implantable and long-term implantable. Materials approved as USP Class V and VI can be considered medical grade, most medical grade silicone is at least Class VI certified.

Uses for medical grade silicone cables include:

• Tubing/Lumen
• Drains
• Feeding tubes
• Catheters
• Implants for long and short term use
• Sensors

Co-extruded and multi-layer silicone cables can be used for high voltage applications such as X-Ray and MRI equipment which require electrical noise suppression and limited power loss . Co-extrusion involves extruding a semi-conductive silicone layer around the conductor to remove air thus reducing corona. Extruding both semi-conductive layer and jacket simultaneously insures no air or particles are caught between the layers. Benefits for co-extruded silicone include corona, moisture & ozone resistance, lightweight and flexible cable design and radiation resistance to name a few.

When working with your custom cable manufacturer, it is crucial to provided them as much information as possible about the application, the environment, sterilization and bio-compatibility requirements. The more information you can provide to your silicone cable manufacturer will help in determining if silicone is right for your application and to offer you material choices that will enhance your product's performance.

Silicone Wire- Popular Applications of Silicone Insulated Wire and Cable

Silicone insulated wire is a popular choice for a variety of industries due to its operating temperature range, extreme flexibility, and voltage properties. Silicone wire and cable compounds are available in special grades and formulas are available for specific requirements such as, medical grade/implantable, low smoke/halogen-free, increased resistance to abrasion , flame retardant and more.

Silicone wire advantages include:

• Service temperatures from –50 to +200 °C
• Special grades are available for use in a temperature range from –90 to +300 °C
• Excellent aging resistance, even under extreme conditions
• High resistance to many different chemical substances
• Outstanding electrical properties
• Extreme flexibility

Aerospace

Aerospace and space applications often require low smoke halogen-free wire and cable. Silicone insulated cable can be manufactured with low smoke halogen-free grades. Low smoke halogen-free silicone cables offer several advantages over conventional cable products:

• Silicone does not emit any corrosive gases.
• Flame resistance - Ensures reduced flame propagation.
• Halogen-free cables generate little smoke, ensuring clear visibility during fires.

Commonly used Mil-Specs for silicone wire, is the MIL-W-16878

• MIL-W-16878/7 Wire, Silicone Insulated, 200°C, 600 Volts.
• MIL-W-16878/8 Wire, Silicone Insulated, 200°C, 1000 Volts.
• MIL-W-16878/29 Wire, Silicone Insulated, 150°C, 600 Volts.
• MIL-W-16878/30 Wire, Silicone Insulated, 150°C, 1000 Volts.
• MIL-W-16878/31 Wire, Silicone Insulated, 150°C, 1000 Volts, Glass Braid, Abrasion Resistant.
• MIL-W-16878/32 Wire, Silicone Insulated, 200°C, 1000 Volts, Glass Braid, Abrasion Resistant.

Other Mil-Specs using silicone insulated wires with FEP Jacket include MIL-DTL-8777, MS25471 and MS27110.

Medical Applications

Medical device manufactures use silicone insulated wire and cable because can be used in an autoclave, its chemical resistance and ultra flexible nature. Silicone is widely used in applications that include medical robotics, implantable, sensors and handheld devices just to name a few. Silicone wire is also manufactured for medical tubing and is typically used in applications such as catheters, drains, feeding tubes, and peristaltic pumps. Manufacturers considering silicone for these types of applications can choose from special grades that meet stringent health agency requirements.

Automation and Ribbon Cables

Typical ribbon cables are not designed for repetitive flexing. These cables are generally made of PVC which is brittle and not resistant to harsh chemicals. For applications in the automation and robotics industries a cable designed specifically for hi flex applications is needed. Silicone ribbon cables can withstand millions of flex cycles and can be extruded or bonded from as little as two conductors to over twenty and can be manufactured up to 40AWG. Applications such as multi-axis motion systems, robotic equipment, linear motor stages and packaging equipment all require flexible flat cable designed to achieve reliable performance. Silicone ribbon cables are also used in static installations where a flexible cable is required.

Automotive

temperatures, tight spaces, and contact with fluid and chemicals. This type of environment is perfect for silicone wire and cables. Silicone insulated wire is normally used in the automotive industry for ignition, battery and spark plug wire. Custom silicone cables can be manufactured to improve the engine's performance. High performance options for ignition wires can include EMI suppression, Kevlar strength members, fiberglass braid, nickel alloy conductors.

There are many applications suited for silicone wire and cable. This article only named a few. If you would like to discuss your application or have questions, please contact Calmont. Feel free to leave a comment or share this article. To find out more about silicone insulation visit our silicone page or our Insulation and jacket materials page.