Author: APEX Technical Team Publish Time: 2026-08-28 Origin: Site
A magnetorheological finishing machine should not be selected from nominal aperture alone. A part can fit within an XY envelope and still be impractical to process because of sag, local surface-normal angle, fixture height, workpiece mass, finishing-head access, sensor clearance or metrology limitations. Conversely, a smaller optic can require a larger or differently configured platform when steep concave or convex regions restrict access.
The correct selection process starts with the workpiece, the remaining error and the acceptance method. It then connects the machine architecture, MRF wheel or head, calibrated removal function, dwell-time solution, support strategy and measurement data into one correction workflow.
Provide the surface equation or 3D model, clear aperture, radius or aspheric coefficients, maximum local normal angle, concave/convex regions, edge transitions and any discontinuities. These factors determine orientation, reachability and collision risk.
State total outside dimensions, thickness, mass, datum structure and allowable contact areas. The fixture, adapters and setup sensors consume machine space. Nominal XY envelope is therefore not the same as maximum workpiece size or usable clear aperture.
Identify the substrate, grade, heat treatment, coating or plated layer, remaining thickness and corrosion sensitivity. Compatibility, stable removal and post-process cleaning must be demonstrated for the actual material system.
MRF is normally a corrective finishing process, not a substitute for blank generation or high-stock-removal grinding. Provide initial PV/RMS, texture, subsurface-damage condition where relevant, edge defects, holes or interruptions and the available correction allowance.
A smaller footprint can address higher-spatial-frequency or tighter-curvature regions but may increase path length; a larger footprint may improve throughput but can restrict access and edge control. Wheel or head diameter, fluid state, working gap and process settings must be calibrated together.
Axis count alone does not guarantee a surface result. Evaluate the actual axis ranges, rotary orientation, fixture, wheel geometry, working gap, sensor access and coordinated path. Optional axes must be specified with their project performance and limits.
Define the instrument, data format, aperture, fit, removed terms, filtering, mask and coordinate convention before processing. Large, steep, off-axis or freeform components may require stitched interferometry, CGH or validated scanning methods.
Deterministic removal requires a stable, measured removal function under the selected wheel, fluid and process settings. The plan should define calibration frequency, acceptance of the reference spot or ribbon, traceability to the dwell-time calculation and response to drift.
For large or low-stiffness optics, support points, gravity orientation, clamping, soak time and temperature uniformity can dominate the measured figure. Machining and inspection conditions must be related and documented.
Define batch size, part mix, expected incoming variation, allowable correction cycles, loading and cleaning time, metrology time and uptime assumptions. Polishing time alone is not total process lead time.
Confirm footprint, utilities, fluid handling, environmental requirements, lifting and handling, operator skills, spare parts, training, software scope, remote support and FAT/SAT responsibilities.
Specify the workpiece, evaluated aperture, PV/RMS and texture definitions, measurement instrument and wavelength, fit and removed terms, filtering, uncertainty, repeated measurements, support condition, process cycles and decision rule. Machine-axis accuracy is not a substitute for optical acceptance.
Platform | Published Nominal Scope | Architecture / MRF Tool | Selection Focus |
PKC300-Q | 300 × 300 mm planar processing envelope | X/Y/Z/B/C; standard Ø50 mm wheel | Compact small-aperture platform; steep geometry still requires full access and fixture review. |
PKC500-Q | 500 × 500 mm maximum planar processing envelope | X/Y/Z/A/B/C; standard Ø50 mm, Ø150 mm option | Medium-aperture multi-axis work; balance curvature access, footprint and throughput. |
PKC700-Q | 700 × 700 mm maximum planar processing envelope | X/Y/Z/A/B; optional C; standard Ø150 mm wheel | Medium-to-large optics, support and metrology-assisted setup; project options require definition. |
PKC1200-Q | 1,200 × 1,200 mm nominal XY processing envelope | Gantry X/Y/Z/A/B; standard Ø300 mm head | Large optics; support, gravity, thermal stability, handling and large-area metrology dominate selection. |
Selection boundary The table compares published nominal platform scope. It does not convert the XY envelope into a guaranteed workpiece diameter, clear aperture or optical result. Final configuration and guarantees are established through application review, sample validation, the signed technical agreement and FAT/SAT records.
· 2D drawing and 3D model, nominal surface equation, datum system and evaluated aperture.
· Material, grade, coating or plating, heat treatment, total dimensions, mass and allowable contact areas.
· Initial surface-form and texture data, defects, holes or interrupted regions, and the preceding process.
· Target PV/RMS and texture with instrument, wavelength, fit, removed terms, filtering, mask and uncertainty requirements.
· Batch size, throughput target, allowable correction cycles, required automation and data interfaces.
· Site conditions, utilities, lifting/handling, export destination, end use and requested FAT/SAT plan.
Q: Does a 500 mm platform guarantee a 500 mm clear aperture?
A: No. Nominal planar envelope is one constraint. Geometry, fixture, tool and sensor access, support and metrology determine the usable workpiece and evaluated aperture.
Q: Does deterministic mean one polishing cycle?
A: No. Deterministic means the removal function is characterized and the dwell-time path is calculated from measured error. Additional measurement and correction cycles may be required.
Q: Can surface-form RMS and roughness Ra be compared directly?
A: No. They describe different quantities and spatial scales. Each requires its own instrument, bandwidth, filtering and reporting convention.
Q: Can a published case result be treated as a machine guarantee?
A: No. A case result applies to the cited workpiece, configuration and measurement conditions. Project guarantees must be written into the technical agreement and FAT/SAT plan.
Tell us the material, approximate dimensions, surface geometry, incoming condition and target result. A short, non-sensitive summary is enough to start the equipment discussion.
