PrintAfter a webinar, I was asked by an engineer if a micro molder is able to mold, or overmold, glass optical components into a larger structure, simultaneously, withstanding wide temperature ranges. The temperature range this engineer specified ranged from -40° to 105° Celsius. In the wide majority of cases, this answer is a crystal clear yes, Accumold can do this. There are a few exceptions and notes.
What materials are required when overmolding glass?
When overmolding glass, a broad spectrum of materials will perform well, molding over glass from a temperature standpoint is of little concern to a skilled micro molder. The glass optical component can withstand much higher temperatures than the plastic used. Temperature shouldn’t be the primary concern for an engineer.
The material’s CTE is completely different however. Most plastics and resins will expand significantly more than glass. If you’re trying to get a hermetic seal over a wide temperature range, that could present a significant challenge because the plastic is going to expand away from glass. A micro mold DfMM team would need to work alongside an engineer to achieve this goal and determine what’s possible.
Why is overmolded plastic over glass important?
The automotive industry is often concerned about components maintaining geometric integrity despite wide temperature fluctuations. Ensuring these critical components operate in extreme temperatures is necessary for part survival.
Datacom could be an industry concerned about wide operational temperatures. Commercial electronics might see high-temperature swings as well, especially during the assembly process. Engineers aren’t always concerned with end-use, but the manufacturing process, preventing reflow issues.
Overmolding glass optical components into a larger structure, are often used in medical cases as well. But those sit on a skin. Because they are non-invasive cases, so hermetic seals aren’t typically necessary.
Best practices when overmolding glass optical components
Outside of soft durometer materials, most plastics and resins are going to be workable when overmolding around glass optics. The most important feature that is to be considered isn’t temperature but retention features. An engineer may choose a retention feature such as a lip, tab, or ring to hold the glass component in place. It’s surprising how many times simple features like this are overlooked.
The other challenge in overmolding glass optics into larger plastic structures is part handling. Some glass filters, for example, can be extremely small and placing without breaking can be a challenge. We also work with engineers to anticipate and correct these issues in advance. In the micro mold process, you’ll notice most issues can be prevented by looping in your micro molder’s DfMM team as early as possible.