- supermarket bar-code scanners
- bio-metric security systems
- medical devices
- document scanners
- clean room particle counters
- telecommunication products
- LED lighting
- PC peripherals, such as webcams
- smart phone
Most common types of optical thermoplastics
The most common optical molding plastics are:
- Cyclic-olefin polymers & co-polymers
The polymer manufacturers provide data related to their mechanical and optical properties. Optical designers should study how these materials behave under a wide range of conditions so that they can arrive at appropriate solutions.
The optical plastic injection molding process
There are two main components to the process:
- the mold
- the injection molding machine
There three main aspects of the mold used to manufacture polymer optics:
1. the cavity specs
2. the optical inserts
3. the housing that holds the cavities and inserts
As noted above, one key advantage of using polymer optics is the ability to marry optical and mechanical features into one platform.
During the molding process, all thermoplastics shrink as they cool. Generally speaking, the shrinkage is around a half percent. It is critical that the shrinkage be factored in when determining the final dimensions of the mold.
The molding machine
The optical injection-molding machine, aka a press, is comprised of a moving and a fixed platen, a clamping unit and an injection unit. Plastic pellets are introduced into the injection unit where they are melted and and injected into a mold. As the plastic cools and solidifies in the mold, the material conforms to the shape of the insert and cavity details, producing the final optic. After cooling, the mold opens and ejects the finished optic product.
Choice of competent optical molder crucial
Optical designers should only partner with an optical molder who thoroughly comprehends the engineering challenges. Ideally, the molder has been working with the designers from the start.
Designers should visit the plastic injection molding facility as soon as possible in the process to determine its capabilities. After all, the optical parts produced will be no better than the machinery in which they are molded.
To sum up, manufacturing precision polymer optics is a highly-specialized discipline requiring a thorough knowledge of optical design, mold construction techniques, state-of-the-art mold processing capability and optical expertise.