Superalloys exhibit extreme work hardening. Deep CNC tool marks, thick parting lines and large burrs cannot be eliminated by dry burnishing alone. Prolonged dry grinding will continuously thicken the surface hardened layer, resulting in permanent residual textures and excessive surface roughness.
Remove thick burrs and deep milling marks through robot force-controlled sanding or manual belt grinding. Dry burnishing is only used for shallow surface refinement and brightening equivalent to conventional fabric wheel and sisal wheel finishing.
Completely remove cutting oil, anti-rust oil and release agent via ultrasonic degreasing and fully dry the blanks. Residual grease will carbonize under high temperature, forming irreversible black films and thermal corrosion spots on the workpiece surface.
Superalloys must not be processed with carbon steel, stainless steel or titanium alloy. Mixed iron and titanium debris will cause electrochemical corrosion under high temperature, resulting in mottled surface defects. Use dedicated drums, abrasives and tooling for superalloy processing, and regularly clean foreign metal residues inside the drum.
Thin-walled blades, shell parts (wall thickness < 1.5mm) and slender connecting rods are prohibited from free rolling in ordinary horizontal drums, non-compartment drums and vortex machines. Stacking extrusion combined with frictional high temperature easily causes deformation and edge collapse. Priority shall be given to drag-type and horizontal fixture burnishing machines with independent non-contact single-piece clamping.
Protruding massive metal residues cause localized concentrated frictional heat and instantaneous overheating matrix burns. Trim and level large gate residues manually or by robot before dry burnishing.
High-hardness sharp brown fused alumina and angular broken ceramic particles are prohibited. Excessive cutting force causes intense frictional temperature rise and aggravates work hardening and surface scratching.
Adopt round, medium-low hardness ceramic particles with medium-fine grain size to gently fade shallow textures and reduce instantaneous high temperature. Reuse of broken sharp-edged abrasives is forbidden, as sharp edges will produce deep scratches on high-toughness superalloy surfaces.
Resin abrasives achieve precise surface leveling; walnut shell/corn cob plant abrasives form uniform matte finishes with reduced friction impact and lower heat generation. Reasonably control the proportion of plant abrasives to avoid excessive dust accumulation, which forms gray-black oxidized fog layers under high temperature mixed with fine metal powder.
Screen broken abrasives and superalloy fine metal debris every shift. Residual hard particles inside the drum cause cyclic scratching and increased heat generation. Replace the entire batch immediately when abrasives turn pale, produce excessive dust or lose cutting power obviously, since aged abrasives double friction heat. Keep abrasives dry; damp abrasives cause mottled oxidation on workpieces under high temperature and humid conditions.
The thermal conductivity of superalloys is only 1/3 to 1/5 of ordinary carbon steel. Heat is fully trapped in the surface layer. Local temperature exceeding 280℃ leads to thermal damage, thickened hardened layers and residual tensile stress. Excessive thermal-affected layers are strictly prohibited for aerospace parts.
Small thick-walled standard parts: Compartmentalized drum machine. Compartment isolation reduces concentrated heat accumulation caused by stacking; non-compartment large-capacity horizontal machines are prohibited.
Micro precision turbine parts: Low-speed vortex machine. Reduce chassis speed to lower high-speed impact heat generation.
Blades, long parts and thin-walled precision components: Drag-type / horizontal fixture machine with independent suspension, zero extrusion, uniform stress and optimized heat dissipation.
Not recommended: Open large-capacity drums. Multi-layer stacking causes continuous bottom heat accumulation and batch thermal burns.
Adopt full-process variable low-speed operation, with speed reduced to 55%–65% of the speed for stainless steel processing to lower friction linear velocity.
Implement segmented short-cycle processing: stop and air-cool the drum for 5 minutes after every 8–12 minutes of grinding. Continuous operation over 25 minutes is prohibited.
Increase forward/reverse switching frequency to avoid fixed-point high temperature caused by continuous friction on the same workpiece position.
Control abrasive filling rate at 60%–70% to reserve air convection space for heat dissipation; full filling leads to unventilated heat accumulation.
Suspended superalloy ultra-fine metal dust oxidizes rapidly under friction high temperature and adheres to workpieces to form foggy surfaces. Accumulated dust further increases internal drum heat. Continuous dust removal removes residual heat and metal debris in real time.
Stop processing immediately for cooling when drum wall temperature exceeds 50℃. High temperature alters surface metallographic structure, induces microcracks and significantly reduces fatigue strength. Strict temperature control is mandatory for gas turbine and aerospace components.
The loading volume of each drum compartment shall not exceed 45% of the chamber capacity. Long-term compression and friction of bottom workpieces cause persistent high-temperature burns, indentations and plastic deformation.
Spread sampled workpieces in a single layer for air cooling; closed stacking and residual heat accumulation are prohibited. Continuous air exposure of high-temperature workpieces thickens the oxide layer, resulting in luster attenuation and color deviation.
Drum and vortex machines are prohibited. Adopt fixture clamping to reduce abrasive immersion depth and extrusion load. Implement segmented short-time processing to prevent bending, wave deformation and edge thermal collapse.
Dry burnishing is only applied to outer surface finishing. Inner holes, tiny flow channels and threads are processed by magnetic polishing. Dry abrasive dust easily blocks holes, and the closed internal space features poor heat dissipation, causing irreversible black oxidation and residual dust contamination.
High-cutting abrasives and prolonged continuous grinding are strictly forbidden. Strictly control hardened layer thickness and test surface residual stress after processing. Thermally damaged parts are prone to fatigue fracture and failure after assembly.
Edges feature concentrated stress. Continuous friction easily causes microcracks and edge thermal wear. Shorten single processing duration and increase the proportion of soft plant-based abrasives to reduce grinding intensity.
Spread workpieces immediately for forced air cooling after unloading; closed storage and residual heat accumulation are prohibited.
Thoroughly blow off surface dust and superalloy fine debris with an air gun before cleaning, passivation and coating. Residual metal dust causes pinholes and color spots after high-temperature anodizing and coating.
Yellow and blue-purple thermal burns cannot be repaired by secondary dry burnishing. Slight discoloration can be removed by pickling and passivation; parts with microcracks and thick hardened layers shall be scrapped directly.
Apply passivation, aluminizing or high-temperature protective coatings to finished products in a timely manner. Freshly processed superalloy surfaces have high activity and continue to oxidize and lose luster during long-term storage.
Ultra-fine dry-ground superalloy metal dust is combustible. Clean dust filter elements daily to avoid dust accumulation and spontaneous combustion in pipelines and chambers.
Equip the workshop with Class D dedicated metal fire extinguishers. Water and ordinary dry powder fire extinguishers are prohibited for metal dust fire rescue.
Reliably ground equipment drums and dust removal pipelines to eliminate static accumulation; static sparks may ignite suspended metal dust.
Operators shall wear dust masks and high-temperature resistant gloves to avoid respiratory damage from long-term alloy dust inhalation.
Causes: Excessive rotating speed, overlong single processing time, insufficient segmented cooling, inadequate dust removal airflow.
Solutions: Reduce speed, implement segmented stop-and-cool cycles, and maintain full-power continuous dust removal.
Causes: Unremoved deep pre-processing tool marks, prolonged continuous dry friction, excessive abrasive hardness.
Solutions: Reduce pre-processing load via robotic sanding, replace with round soft ceramic abrasives, and implement strict segmented short-time processing.
Causes: Mixed processing with dissimilar metals, unscreened broken abrasives, accumulated internal metal dust.
Solutions: Adopt exclusive superalloy drums and abrasives, and screen debris completely every shift.
Causes: Stacking extrusion in free-rolling equipment and increased plasticity caused by high-temperature softening.
Solutions: Switch to drag/horizontal independent fixture clamping and reduce abrasive immersion depth.
Causes: Long-term continuous edge friction and localized high-temperature stress concentration.
Solutions: Shorten single grinding duration and use plant-based soft polishing abrasives for edge passivation.
Dry burnishing of nickel-based and cobalt-based superalloys faces four core challenges: easy heat accumulation due to low thermal conductivity, severe work hardening, high risk of scratches from high toughness, and flammable/explosive metal dust hazards.
The standardized processing logic is: remove deep textures via pre-processing coarse grinding to reduce load, adopt low-heat round abrasives, implement low-speed segmented short-cycle processing, maintain full-process forced dust removal and temperature control, apply independent clamping equipment for thin-walled precision parts, and conduct rapid air cooling and surface protection after processing.
Dry burnishing is only suitable for replacing manual sisal wheel and fabric wheel operations for shallow surface refinement and brightening. It cannot independently eliminate deep tool marks and thick heavy burrs. Mass production requires matching robotic pre-sanding for outer surfaces and magnetic polishing for inner holes and threads, so as to comprehensively guarantee surface integrity, mechanical performance and production safety.
TikTok