Process
Thixomolding is a semi-solid (Thixotropic) molding process for magnesium somewhat analogous to plastic injection molding.
Magnesium chips are fed at ambient temperature into a heated barrel and propelled forward by a rotating screw.
The combined heat from resistance type heater bands and the shearing force provided by the rotating screw create a slurry of spheroidal solid particles within a molten matrix.
This slurry is forced into a pre-heated mold to produce high precision, ultra-thin wall net or near net shaped parts.
The process combines the benefits of die casting and plastic injection molding.
Applications
Automotive
Magnesium is used in many components in vehicles to reduce weight and improve fuel economy. Structural components such as brackets and mounts are typical as well as cosmetic trim pieces that can be finished to meet a wide range of appearance specifications.
Aerospace
The strength-to-weight-ratio of magnesium alloys makes it a great choice for use in aerospace applications.
Electronics
Magnesium, with its strength and natural EMI Sheilding properties, is a great material for electronics enclosures as well as frames for electronic components in laptops & tablets.
LED Lighting
Heat Sinks can be designed using thixomolded magnesium that reduce weight in lighting assemblies as well as disipate heat.
Medical
Magnesium can be used in medical devices as well as in temporary implants. Alloys are available with bioabsorbable properties. See NanoMag for more information.
Advantages
Energy Consumption
The equipment used to process magnesium only melts a few pound of material at a time. By comparison die casting typically melts hundreds of pounds at a time in a large crucible. The energy required for thixomolding is a fraction of the energy required for standard die casting. This makes Thixomolding more environmentally friendly.
Safety
In the Thixomolding Process, Magnesium is entirely enclosed in the processing equipment. This significantly reduces the risk of exposure to people and surrounding equipment.
Tool Life
The nature of semi solid processing magnesium is much gentler on tools/molds. Lower temperatures and better flow characteristics reduce the average wear and tear. We have tools with over 500,000 shots still in operation today, with very little maintenance required.
Dimensional Capability
Thixomolding provides improved dimensional stability and repeatability over conventional die casting. NADCA Precision Tolerances are easily obtained in most applications. Precise control of operating variables maximizes process consistency and quality.
Environment
Magnesium is one of the most common and abundant elements on Earth. It is 100% Recyclable. Thixomolding further reduces the impact on the environment by improving material yield over standard die casting. This is due to lower oxidation, evaporation, and less material required to produce parts.
Microstructure
Thixomolding provides an improved globular structure with minimal porosity and shrinkage. Typical Die Casting microstructures are composed mainly of dendritic forms with higher percentages of porosity and shrinkage voids.