When a ceramic seal face leaks at 10 microinches Ra, it’s a finishing problem. Vacuum chambers, mechanical face seals, and hermetic feedthroughs all depend on surfaces that are flatter and smoother than standard grinding can deliver. That’s where lapping, polishing & surface finishing earn their place in the workflow.

At C-Mac International, we treat finishing as a precision discipline. Our team has more than 100 years of combined experience with tight-tolerance ceramic parts, and we hold both ISO 9001 and AS9100 certifications to back up our work.

Our Lapping, Polishing & Surface Finishing Capabilities

Grinding typically achieves a ceramic surface roughness around Ra 0.4–0.8 µm. When specs call for tighter tolerances, such as in hermetic seals, optical windows, or semiconductor wafer chucks, grinding alone is insufficient. Precision lapping and polishing bridge this gap to deliver precise surface integrity.

Our dedicated finishing cells meet exacting technical specifications through specialized, multi-stage processing. Standard output metrics include:

Surface roughness. Ra down to 0.025 µm (≈1 µin) on polished faces.
Flatness. Held within 1–2 helium light bands across the lapped surface.
Parallelism. Controlled within single-digit microns across opposing faces.
Surface finish. Mirror-grade polish customized for seal rings, plungers, and substrates.

Our equipment set includes single- and double-sided lapping machines, precision polishing stations, and diamond slurry systems matched to the hardness of each material.

Every batch ships with measured Ra values, so your incoming inspection has something concrete to verify against.

Material Compatibility

Technical ceramics exhibit distinct mechanical behaviors during mechanical finishing due to varying grain structures, hardness profiles, and porosity levels. Achieving targeted Ra values requires adjusting slurry chemistry, plate composition, and downforce pressure for each material class.

We routinely lap, polish, and finish a wide range of advanced ceramic formulations:

Alumina. 90%, 96%, and 99.5% purity grades.
Zirconia. MgO-stabilized and Yttria-stabilized (YSZ) grades.
Silicon nitride. High-strength materials engineered for wear resistance and thermal shock.
Tungsten carbide. Specialized cobalt- and nickel-binder formulations.
Steatite. Magnesium silicate tailored for high-frequency electrical insulation.
Cordierite. Low-thermal-expansion compositions suited for high thermal-cycling applications.

The real challenge with ceramics is twofold:

They’re brittle, so aggressive removal rates cause subsurface chipping that ruins seal integrity.
They’re also extremely hard, so undersized abrasives simply burnish the surface without cutting.

We dial in diamond grit size, plate composition, and pressure for each material. These steps result in surfaces clean enough to support downstream metallization, brazing, or direct vacuum sealing without rework.

Why Choose C-Mac for Custom Ceramic Finishing

Engineers and procurement teams require precise tolerances without sacrificing lead times or budget constraints. C-Mac optimizes the supply chain by offering factory-direct engineering expertise and streamlined production scheduling.

Key commercial benefits of our finishing operations include:

24-Hour RFQ response. Rapid quotation turnaround on custom technical drawings.
Accelerated lead times. Quick-turn finishing programs designed for rapid prototyping and critical line replenishment.
Cost efficiency. Up to 25% savings compared to larger tier-1 ceramic manufacturers.
Inventory solutions. Dedicated stocking and consignment programs ensuring stable pricing and lower unit costs.
Direct technical support. A dedicated single point of contact overseeing projects from initial RFQ through final CMM inspection.

We’re a focused operation, not a layered bureaucracy. When you send a print, an engineer reads it. That shortens the back-and-forth most buyers expect from a ceramics quote.

Optimize Your Component Tolerances with C-Mac

Precision surface finishing is the critical factor that determines whether a technical ceramic component maintains hermetic integrity or leaks under operation. By combining rigorous quality controls (ISO 9001 / AS9100) with deep domain expertise, C-Mac delivers verifiable Ra, flatness, and parallelism tailored to your application requirements.

Submit your technical drawings through our secure contact us portal or price quote form to receive a detailed finishing evaluation and pricing quote from an application engineer within 24 hours.