Polishing Glass: CEROX™ and OPALINE™

• Introduction
• Morphological Characteristics of the Powders
• Areas of Use
• Influence of Work Conditions on Polishing Effectiveness
• Influence of suspension concentration
• Influence of rotation speed on polishing efficiency
• Influence of applied pressure on the object to be polished
• Influence of suspension temperature

• Introduction

Because of its combined natural hardness and a chemical reaction produced by the glass/cerium oxide interface, cerium oxide has for a long time been the best agent for polishing glass occurring at the glass/cerium oxide interface. This reaction results in the formation of a silicate layer that renders the surface of glass fragile and makes it more sensitive to mechanical erosion.

To better respond to the conditions and specific polishing needs of their customers, Rhodia has perfected two ranges of high performing polishing powder sold under the trade names CEROX™ and OPALINE™.

• CEROX™: for polishing mineral glass, mirrors, TV glass, goggles, optical lenses.
• OPALINE™: for polishing high precision optical parts.

With the support of its applications laboratory, Rhodia Electronics & Catalysis offers powders with morphology and characteristics that are suitable for different applications in the glass industry.

• Morphological Characteristics of the Powders

This influences polishing effectiveness, that is, the amount of glass removed and the quality of the surfaces polished.

The three characteristics of powder morphology are:

• the specific surface, giving an idea of cohesion and grain porosity,
• the degree of exterior sintering, which influences grain hardness,
• the granulometric breakdown, influencing the ability to yield stable suspensions.

All these characteristics are carefully controlled during manufacturing to guarantee perfect performance consistency.

• Areas of Use

Based on your area of application, following are the recommended types of polish suitable and CEROX™ and OPALINE™.

P.U.F.: Polyurethane Foam.

• Influence of Work Conditions on Polishing Effectiveness

Definition of polishing efficiency Polishing efficiency (PE) is defined in terms of the quantity of glass removed per time unit and surface unit of object to be polished.It is expressed by the following formula:

• Influence of suspension concentration

Polishing efficiency improves when the polishing bath concentration is increased. Bath concentration depends mainly on the type of polisher, or pad, used. When pads are changed from polyurethane (PU) or non-woven types to felt or pitch types or hard polyurethane, the suspension concentration should be increased from 50 to 100 g/l, 100 -150 g/l, and 200g/l respectively.

• Influence of rotation speed on polishing efficiency

It is generally observed that polishing efficiency is proportional to speed regardless of the type of polisher and operating conditions used. Therefore, operation at the maximum speed available, while remaining within the values compatible with the type of pad used, is recommended.

• Influence of applied pressure on the object to be polished

This is the pressure applied on the glass to be polished which is not the same as that indicated by the spindle manometer. At medium and high rotating speeds (> 250 rpm), the influence of pressure is very significant up to 0.8 to 1 bar. Beyond that, the efficiency remains constant. When high production rates are required (in the polishing of standard spectacle glass for instance), it becomes necessary to work at high rotation speeds (> 1,000 rpm) and high pressure (> 1 bar).

• Influence of suspension temperature

Under our test conditions, CEROX™ 1650 has optimum polishing efficiency at operating temperatures between 15° to 30° C. For the entire range of our products, optimum results can be achieved between: 20° and 30° C in the case of PU, non-woven, pitch, hard polyurethane-type polishers; 30° and 40° C for felt-type polishers.

• Contacts

If you would like more information about CEROX™ and OPALINE™ powders or would like a sample, please contact:
ec-electronics@eu.rhodia.com