How to Achieve the Most Delicate Finish
Consider the lens on a fighter pilot’s helmet. No blemishes. No distortions. It has to hold the heads-up display projected on its surface so it’s crisp and clean. That lens is as close to perfect as possible and tailor-made for the pilot.
The craftsmanship to create the tool to mold these lenses is very labor intensive. It requires several steps to get the final finish.
A mold like this, while in production, presents several specific challenges for the molder. Care needs to be taken to minimize rejects, especially for deep parts with little or no draft. Often these tools require longer cycle times to minimize quality issues.
Maintenance on this tool is critical, both while the mold is in the use and when the tool is pulled and sent to the shop.
Nothing touches the surface!
Cleaning means special procedures. Be sure hands do not to touch the surface. In just a matter of hours fingerprint acids show up as rust or oxidation on the mirrored surface.
Cleaning wipes and shop rags should never be used. They can scratch the surface or leave particulates on the surface.
As the tool cools, a thin film of condensation will form unless you quickly add a barrier to protect the surface.
Pointers for cleaning and protecting the tool surface
First, use a spray cleaner you can use to thoroughly flush the surface. The cleaner you choose should quickly “flash off” (evaporate) on a cool mold. If residue remains on the tool, use a cleaner that stays on the mold longer and removes residue before it evaporates. Be sure these special cleaners state they leave no residue of their own once they evaporate.
Then immediately apply a rust preventive. Remember, oxidation can start within just hours on these delicate surfaces. A short-term rust preventive displaces moisture and neutralizes acids in the air.
Be sure to select a rust preventive that will “flash off” when the mold is first put back into production. Then you don’t need to remove the rust preventive and and/or touch the surface to clean the tool before you start molding.