Case Study: How GMN Hybrid Ceramic Bearings Improved the Performance of an Optical Grinder

An ophthalmic equipment manufacturer was designing a new machine to cut the lens prescription into the blank material. They were having issues with bearing noise and total system runout creating out of tolerance surface finish. GMN engineers stepped in and helped optimize the spindle assembly and bearing configuration to remove the bearing noise and produce sub-micron surface finishes.

Optical Grinders for Lens Equipment

Optical grinders are specialized machines used for precision grinding and shaping of optical components, such as lenses and prisms. They are essential in the production of high-quality optical elements used in various applications, including cameras, microscopes, and other optical instruments.

In this particular case, our OEM’s optical grinder made lenses to the required prescription. Lens blanks were put in, and the machine’s cutting spindle cut out the curvatures for the prescription. It was important to this company to make the spindle that did the cutting themselves instead of buying a spindle from a spindle manufacturer.

The Challenge

Initially, our OEM’s machine was experiencing excessive tool chatter, or vibration, that was resulting in rough surface finish. But because they were making the lenses to required prescriptions, the spindle’s accuracy had to be extremely tight, down to the sub-micron level; it essentially couldn’t have any axial movement.

In order for the project to be successful and go into production, they needed a solution with precision at the forefront.

How GMN Helped

Since their first indication of an issue in their new design testing was bearing noise, they initially reached out to GMN Bearing USA engineers for help with a bearing failure analysis. Upon further inspection and discussions, we found out that the bearings they were using were also not reaching the desired surface finish requirement.

Our engineering team quickly got to work helping redesign the spindle to optimize the bearing arrangement and preload strategy.

We recommended using sealed ceramic bearings for better contamination protection and doing a spring-preloaded “double big O” arrangement, with the front pair in tandem facing the direction of the axial load to provide rigidity against the cutting, and the back pair tandem facing the opposite direction to help with radial rigidity and provide the system preload.

Doing a spring preload allowed the customer to optimize the preload to minimize tool chatter and bring the surface finish down, while the use of ceramic bearings supported the tighter rigidity and high speeds required for their machine. Using GMN P4+ precision bearings also meant they had P2 runouts, which helped with bringing the surface finish into tolerance.

The Result

With the help of GMN precision bearings, our customer’s optical grinder went into production, and they have been making these machines for almost 10 years now.

Our level of technical expertise allowed us to help them redesign their system in a way that improved the life and quality of their machine, all while ensuring they maintained what was most important to them; the freedom to build their own spindles.

Contact a GMN Engineer

Our in-house technical experts and engineers understand that when it comes to trusting your bearing supplier, it’s the small details that matter, especially in the world of industrial manufacturing.

Contact us to learn more about our bearing analysis services and our unique system design approach for OEM applications!