Glass molding is a proprietary process whereby Nalux has the capability to actually mold glass just as you would mold plastic. The process is able to accurately mold micro structures into the glass so that the glass molding process is capable of making optics such as microlenses, diffractive optics, and waveguides which can be fabricated in large production quantities.
The glass molding process is simple in concept but complicated in practice. In order to perform the glass molding process, a mold for the glass optics must be fabricated. The mold is usually just a top half and a bottom half. To start the process, a glass slug is placed in the bottom half of the mold. Then, the operator places the top half of the mold onto the bottom half of the mold with the glass slug in between. The mold is then placed on the glass molding press. The glass molding press is a heated bottom platen and a heated top platen. The top platen applies slowly increasing pressure to the top half of the mold as it also heats the top half while the bottom platen heats the bottom half of the mold. After a few minutes of the glass molding process, the mold has heated up enough to melt the glass slug inside. The glass slug then flows under the pressure being applied and fills the mold cavity. Temperatures of the glass molding process can be anywhere between 400 degrees and 800 degrees Farenheit depending upon the type of glass being molded. After a cool down period which often lasts for about 10 minutes, the glass molding process is over and has produced a fully formed glass optic and the process is prepared to be repeated as many times as needed.
There are several advantages to the glass molding process over other glass optic fabrication processes. The first advantage is a short cycle time. Glass molding allows parts to be molded on average once every 30 minutes using a single mold. If multiple molds are made, then the glass molding process becomes much faster and a cycle time of 10 minutes per part is achievable. This cycle time can translate into shorter lead times for the glass optics produced by the glass molding process.
A second advantage of the glass molding process is the fine detail that can be obtained in the optics produced. The molds are made using either e-beam lithography, focused ion beam, diamond turning or milling, or mask lithography and plasma etching. All of these methods can make very accurate molds for the process and some of them can achieve sub micron feature sizes. Additionally, the glass molding process allows the glass to flow easily into the narrow features of the mold so that high fidelity is achievable with the glass molding process.
A third advantage is that the short cycle time and the relatively simple molds translate into a relatively inexpensive cost for optics produced using this process. Short cycle times mean less machine cost per part for the glass molding process. Relatively simple molds (when compared with plastic injection molding) mean lower tooling costs for the glass molding process. All of this means that the glass molding process is well suited for situations where more than a few glass optics are needed in short lead times at competitive prices.
Nalux is an expert at the glass molding process. Give us a call and see how we can help you in your next project.