Understanding the Role of Polishing Wheels in Glass Edging

After rough grinding, polishing wheels remove fine scratches and produce a transparent, glossy edge. The correct wheel choice depends on your machine’s design, spindle speed, coolant type, and desired finish.

Key Parameters of Polishing Wheels

• Abrasive type: Ceramic, diamond, or resin-bonded silicon carbide.

• Grit size: From 240# (semi-polish) to 2000# (mirror finish).

• Concentration: Diamond concentration (25%, 50%, 75%) affects cutting speed and wheel life.

• Bond hardness: Soft bonds release dull grit faster; hard bonds last longer but require more pressure.

Wheel Selection for Straight Line Single-Edgers

Sequence of Polishing Stations

A typical straight line machine has 8–12 spindles. The last 4–5 are dedicated to polishing. Recommended sequence:

• Station 1 (after grinding): 240# resin-bond diamond wheel – removes grinding marks.

• Station 2: 600# resin-bond – begins gloss.

• Station 3: 1200# resin-bond – high gloss.

• Station 4: 2000# or felt wheel with cerium oxide paste – mirror finish.

Wheel Dimensions and Bore

Most straight line machines accept 150 mm diameter wheels with a 50 mm bore. Confirm the thickness (15–20 mm) and the spacer design. Do not mix brands without testing concentricity.

Wheel Selection for Double-Edged Machines

Higher Speed Requires Different Bonding

Double edgers run at higher spindle speeds (3000–4500 RPM vs. 2000–2800 RPM for single edgers). Use polishing wheels with a harder resin bond to prevent the wheel from glazing or disintegrating. For 1200# and finer, a polyimide bond offers excellent heat resistance.

Pressure and Coolant Flow Adjustments

Because both edges are processed simultaneously, the polishing wheels on a double edger must have consistent performance left and right. Match the wheel batch number and run them in for 30 minutes before production. Use water-soluble coolant at 5–8% concentration for best lubricity.

Special Cases – Beveling and Arc Machines

Beveling Machine Polishing Wheels

Bevel edgers require wheels that maintain an angle profile. Use formed (profiled) resin-bond wheels that exactly match the bevel angle. Do not try to use flat wheels on a bevel machine – you will destroy the edge geometry.

Arc and CNC Edging Centers

These use small-diameter (100–125 mm) polishing wheels mounted on a rotating spindle. Choose flexible wheels with a soft bond to follow the curve without chattering. Conical or bullet-shaped wheels work best for tight radii.

Troubleshooting Poor Polish Related to Wheel Selection

• Haze or white edge: Polish grit is too coarse (try 1500# instead of 800#) or coolant concentration is low.

• Burn marks: Wheel is too hard or spindle speed too high. Switch to a softer bond or reduce RPM by 10%.

• Uneven polish across edge: Wheels are not aligned to the glass centerline. Also check for worn spindle bearings.