This article takes a deeper look at micromachining tungsten. We explore the advantages of working with this material for micro applications, the challenges in manufacturability, and new technologies that allow for the production of extremely small tungsten parts.
First off, what is tungsten?
Tungsten is a rare metal with some very unique properties. This material has the highest melting temperature of all metals 3,422°C (6,191.6°F), and thus is commonly used in high temperature applications. These applications include light bulb filaments, electrodes and more. Tungsten is extremely dense, with a density about twice that of steel. It’s furthermore incredibly hard, thus resistant to damage and wear. Consequently, it is also relatively brittle and prone to fracture under heavy stresses. Due to it’s high density and material properties, Tungsten is radiopaque under X-ray. This combined with its corrosion resistance and biocompatibility makes it a useful material for medical device applications.
What are methods for micromachining tungsten?
Historically, micromachining tungsten was challenging due to its hardness and brittle nature. However, advances in various emerging manufacturing technologies have allowed for the machining of incredibly small parts and features. Two of these technologies that are paving the way are outlined in more detail below.
Micro Electron Discharge Machining (EDM)
Micro Electron Discharge Machining (EDM) involves using sparks delivered by electrode to selectively remove material from the tungsten workpiece. This technique is ideal for micromachining tungsten because it applies only a small amount of force, thus preventing cracking or chipping.
Femtosecond Laser is another emerging technology that uses high intensity, extremely short laser pulses to vaporize intricate material geometries. Because these pulses are so short, this process minimizes heat affected zones as it vaporizes material, allowing for excellent edge quality. Thus, this method is extremely precise and can produce tiny parts with sub-micron accuracy. Femtosecond laser is especially well suited for micromachining tungsten as it minimizes both the force and heat applied to the material, thereby reducing cracking.
Why is tungsten is popular for micro medical devices?
Tungsten is a popular material for medical devices for a variety of reasons. One of the primary reasons is its high density, which makes it an ideal material for radiopaque markers or shielding. Thus, micro tungsten parts are often used for medical imaging in surgical or implantable devices.
Another reason tungsten is commonly found in medical devices is due to its biocompatibility. Tungsten is considered inert and does not adversely react with the human body, and hence is ideal for use in implantable medical devices. Because if tungsten’s unique characteristics, it is often alloyed with other materials such as platinum or titanium to leverage these properties as design features.
Advances in micromachining tungsten allow for more minimally invasive medical devices.
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