In precision metal polishing, the goal is to achieve a consistent surface finish with minimal micrometer-scale scratches and controlled material removal. Silicon carbide (SiC) abrasives are sometimes used in the early to mid polishing stages, especially for hard metals, ceramics, and composites. A common comparison arises between F88 (≈88 μm, 90% SiC) and F90 (≈90 μm, 88% SiC). Although the size difference appears marginal, the combination of particle size and purity changes how they interact with the workpiece, influencing control and scratch propensity.
At ZhenAn, with 30 years of experience supplying SiC for precision finishing, we examine which option gives better control and fewer scratches in precision metal polishing and why.
1. Precision Polishing: Surface Quality Goals
Precision polishing aims to:
Reduce Ra (roughness average) to tight tolerances (sub-micrometer for many applications)
Avoid deep or random scratches that become visible or affect functional performance (e.g., sealing surfaces, optical mating parts)
Provide predictable material removal so dimensions stay within spec
Maintain uniformity across complex geometries
Achieving this requires abrasives that cut consistently without introducing uncontrolled fracture or embedding.
2. Particle Size: F88 vs. F90 - Control Implications
F88 (88 μm) - slightly smaller than F90.
F90 (90 μm) - slightly larger.
In polishing:
Smaller particles (F88) → lower single-impact depth, finer cut marks, easier to transition to next finer grit without compounding scratches.
Larger particles (F90) → deeper individual cut marks, more material removed per pass, but higher risk of sporadic deeper scratches if particle distribution is uneven.
Control: F88 gives better micro-surface control due to smaller engagement area and reduced depth per cut.
3. Purity: 90% SiC vs. 88% SiC - Scratch Propensity
F88 (90% SiC) - higher SiC content, fewer impurity particles (silica, free carbon).
F90 (88% SiC) - lower SiC content, more impurities.
Impurities act like hard but irregular "rogue" particles:
They can cause random deeper scratches because they may fracture unpredictably or have different hardness/shape.
Higher purity (F88) → more uniform fracture, consistent cutting edges, fewer rogue scratches.
Lower purity (F90) → higher likelihood of inconsistent scratch pattern and embedded contaminant particles.
Scratch reduction: F88 (90% SiC) is clearly better due to higher purity and uniform cutting action.
4. Combined Comparison for Precision Metal Polishing
|
Factor |
F88 (88 μm, 90% SiC) |
F90 (90 μm, 88% SiC) |
|---|---|---|
|
Particle Size |
Smaller → finer cut marks |
Larger → deeper cut marks |
|
SiC Purity |
Higher → more uniform cutting, fewer rogue particles |
Lower → more impurities, irregular scratch risk |
|
Material Removal Control |
Better (predictable, shallow cuts) |
Lower (some sporadic deeper cuts) |
|
Scratch Risk |
Lower (fewer random deep scratches) |
Higher (impurities + larger size) |
|
Surface Finish Consistency |
Higher |
Lower |
|
Suitability for Precision Metals |
Excellent (especially for tight Ra targets) |
Acceptable for less critical surfaces |
Conclusion: F88 (88 μm, 90% SiC) provides better control and less scratching in precision metal polishing because it combines smaller particle size with higher purity, yielding finer, more uniform cuts and fewer rogue abrasive effects.
5. Practical Selection Guidelines
Tight Ra/Surface Finish Spec → Choose F88 for finer marks and better uniformity.
Critical Scratch Avoidance (e.g., aerospace, medical, optical components) → Higher purity essential → F88 wins.
Material Hardness → For very hard metals, smaller, purer grit cuts more controllably without micro-chipping.
Progressive Polishing Sequence → Start with coarser only if necessary; move quickly to F88 for precision stage.
Cost Consideration → F88 may cost slightly more per kg, but reduces rework and improves yield in precision work.
6. Industry Example
A manufacturer of aerospace hydraulic valve bodies switched from F90 (90 μm, 88% SiC) to F88 (88 μm, 90% SiC) for final polishing of aluminum alloy surfaces:
Reduced random deep scratches by ~60%
Achieved Ra target consistently without extra lapping steps
Improved surface reflectivity and coating adhesion
Lowered rejection rate in final inspection
7. Why Choose ZhenAn for Precision Polishing SiC
30 years of experience producing tightly sized, high-purity SiC for precision finishing
Exact control of particle size (F88, F90, and finer) and SiC content (88%–99%)
ISO & SGS certified for batch-to-batch consistency
Custom abrasive papers, slurries, or compounds for progressive polishing sequences
Global supply ensuring reliable delivery to precision manufacturing industries
Conclusion
For precision metal polishing, F88 (88 μm, 90% SiC) outperforms F90 (90 μm, 88% SiC) in both control and scratch minimization. Its smaller particle size produces finer cut marks, and its higher SiC purity ensures uniform cutting action with fewer rogue particles that cause random deep scratches. This leads to more consistent surface finish, higher yield, and better dimensional control - critical in aerospace, medical, and high-end industrial applications.
For expert advice on SiC grit and purity selection for your precision polishing process, contact our specialists at:
FAQ
Q1: Does a 2 μm difference in grit size really matter in polishing?
A: Yes - in precision polishing, even small differences affect cut depth and scratch distribution, especially on hard metals.
Q2: Can lower purity SiC be used if cost is critical?
A: It can, but expect more random scratches and less consistent finish; may require extra lapping steps.
Q3: Is F88 suitable for final mirror polishing?
A: F88 is typically a medium-fine stage; for mirror finish you'd move to F120+ with high purity.
Q4: Does ZhenAn supply F88 in high-purity green SiC?
A: Yes, we offer F88 in both standard high-purity and green SiC (>99%) for ultra-precision needs.
Q5: How do I integrate F88 into a multi-stage polishing sequence?
A: Use progressively finer grits (e.g., F120 → F88 → F220) with clean transitions to avoid compounding scratches.
Why Choose ZhenAn
Stable, Verified Quality – Controlled sourcing and batch inspection ensure consistent metallurgical performance.
One-Stop Product Range – Silicon carbide, ferro alloys, silicon metal, cored wire, zinc wire, Electrolytic Manganese Metal Flakes.
Custom Specifications – Flexible grades, sizes, and packaging to fit different production processes.
Proven Export Experience – Professional handling of inspection, documents, and international shipping.
Reliable Supply – Stable factory partnerships and dependable delivery schedules.
Fast Support – Quick quotations and practical technical guidance.
Strong Cost–Performance – Balanced pricing with real process value.
