There are multiple finishing options that are available to Liquidmetal® parts.
Upon ejection from the mold, Liquidmetal parts are attached to a tree that must be removed. The tree includes the sprue, runner, and gate as excess features. The simplest means of removing this material is to use a water-jet system where the tree is clamped into a fixture and quickly cut, leaving only the parts with a non-cosmetic quality surface where the gate was removed. In some cases, this surface quality may be sufficient for the application; however, if not, the surface will need to be processed further.
At the Manufacturing Center of Excellence in Rancho Santa Margarita, Liquidmetal Technologies operates a CNC machining center. Liquidmetal alloys are a very hard and strong material; draft angles are required on all surfaces to ensure that the mold can eject the part without causing damage to either the part or the mold. Holes with tolerances in the ±0.008mm (±0.0003”) range can be machined along with grinding operations performed on surfaces and outer diameters that can hold the same tolerance. In some cases, parts will be molded as close to tolerance as possible and cleaned up with minimal stock removal from the part in a secondary operation.
Most customers chose to utilize the as-molded finish of Liquidmetal parts. This allows us to do a minimal amount of post processing on the surface, and leaves the customer with a finish that matches the surface roughness of the mold. If a polished mold is specified, it is typical to see Liquidmetal parts come out of the tool with a surface roughness of 0.025-0.050µm (1-2µin). The best corrosion resistance also occurs with an as-molded product. In some cases, customers may determine that a blasted finish is optimal for aesthetic reasons. A variety of blasting media can be used for this, including Zirconia, Alumina, Silica, etc. This can be discussed further with Liquidmetal engineers.
Other options for part finishes include painting and even PVD (physical vapor deposition).