Liquidmetal Technologies Blog

Liquidmetal Blades, Knives, and Other Sharp Things

Posted by Joe Stevick on Mon, Jun 03, 2013 @ 05:53 PM

Because Liquidmetal alloy is hard like a ceramic, stiff like steel, elastic like a plastic, and corrosion resistant like it has been given an expensive coating, a keen area of interest is in blade or blade-like applications. This is not surprising, especially given the nearest-to-net™ shape moldability of our alloy.  In fact, we are currently investigating new applications where precise piercing of metal foils with high repeatability are required.

However, it does beg the question: "how sharp a blade can you mold?" This is a great question asked on our Function & Finish blog post, and one which we thought deserves its own blog post in response.  We hope this blog post will be interesting to you, especially if blades are your business.

First, Liquidmetal alloy has been demonstrated in knife applications in the past, and even won several awards and magazine front-page features as a revolutionary blade material. Scuba gear dive knives were a special area of interest due to the exceptional resistance of Liquidmetal alloy to salt water corrosion.

Liquidmetal Knives                Blade May 2003

These knives in the past were laboriously ground to their final dimensions from cast bars of Liquidmetal alloy, and distributed to a limited number of enthusiasts, who were considerably excited about the material advantages. Unfortunately, these elegantly shaped and custom handled knives which made their way into circulation were so rare and exotic they are now collector’s items.

Untitled

Fast forward to the present…

Liquidmetal Technologies believes it is now positioned to manufacture any moldable geometry with a substantially improved casting technology. Our working design-guide calls for a minimum radius on all corners of 0.2 mm which allows for laminar fluid flow throughout the part and consistent 100% fill factor. Therefore, a blade geometry with a 200 um (0.2 mm) radius on the cutting edge of the blade could be easily molded today in Liquidmetal alloy, followed by a simple grind, etch, or other technique to finish the edge to the customer’s specification.

cast corner radius exampleBut to take this further, let’s assume that an as-molded sharp is required. In this case, it is theoretically possible to generate curvatures well under the 0.2 mm guideline if certain mold geometry conditions are met. The figure to the right shows a cross-section of an as-molded Liquidmetal part with a sharp 90 degree angle where the filled corner radius has been measured to be 5.9 um (0.0059 mm). The inset image shows the same corner magnified at 1000x with the measurement detail.

The final piece of the puzzle is the question: “how sharp is sharp?” To answer that question, let’s compare our 5.9 um radius to the curvature on the edge of a commercial razor blade. The scanning electron microscope image below (borrowed from http://www.bladeforums.com) shows a 3,000x image of a razor edge, measured to have a diameter of about 0.4 um, or about an order of magnitude smaller than our as-cast edge.

Gillette blades

Considering that we have done nothing to sharpen the 90 degree corner on our as-molded Liquidmetal part, we think that this could be something that is interesting to pursue.  Our unoptimized sharp edge is only an order of magnitude lower than a brand-new razor blade.  Our new processes may now finally be ready to support an application that can take advantage of our ability to replicate sharp features. 

If you’d like to explore an opportunity in this area, please contact us here.

Tags: Case Study, Sharp Edges, Knives