Hoowaki in MICROmanufacturing: Friction lowered by altering microtopography

Originally published in MICROmanufacturing, "Tech News", June 2011.

By Susan Woods

Original article found here:
www.micromanufacturing.com/past_editions/pdf/MayJune2011.pdf (pdf)

A low-cost, scalable technology that uses micromachining to produce complex structures on the surfaces of stamping dies and plastic and glass molds can change the properties of the parts being produced, according to its developer, Hoowaki LLC, Pendleton, S.C. The company designs and fabricates molding tools, usually made of tool steel, that have a defined surface microtopography.

“By molding microstructures into a part surface, we can engineer the surface friction, heat-transfer coefficient, water repellency or other properties of the component,” said William King, Hoowaki’s CTO. “All of these [properties] are in demand for energy applications, from hydraulic equipment to air conditioners to batteries.”

In the case of batteries, for example, their performance depends on the total surface area of the electrodes, as well as the electrode spacing and configuration, all of which reportedly can be controlled with Hoowaki’s micromanufacturing technology. 

The company’s microstructured metal surfaces merge the scalability of conventional microfabrication processes with the flexibility of industrial applications, materials and process requirements, said King, who declined to discuss cuss details on how the micro-surfaces are produced.

 

Surface microtopography impacts the way liquids interact with the surface of the metal. “You can make a surface hydrophilic or hydrophobic with the microstructures,” King said, who is also a professor at the College of Engineering, University of Illinois, Urbana-Champaign. In automotive or aerospace applications, for example, he continued, “you can change the water repellency ... to keep water or ice away from certain parts of the vehicle, or in air conditioners to stop ice from forming on the condenser.”

Other methods that compare to Hoowaki’s microstructure technology, such as laser-based micromachining, microdrilling and micromilling, are more expensive because they are serial processes, said King. Conventional micro-fabrication technologies can create many microstructures in parallel, but only on a few select materials, such as silicon. They are not scalable to materials such as metals, polymers or composites. 

Hoowaki’s micromanufacturing technology reduces tooling costs by 83 to 98 percent compared to other technologies, according to King.