Mold Surface Polishing Process Hierarchy: Polishing Grade Division, Operation Risk and Quality Control Points

Mold Surface Polishing Process Hierarchy: Polishing Grade Division, Operation Risk and Quality Control Points

Polishing directly affects casting surface quality and molten‑metal flow performance; improper polishing operation will bury hidden mold‑failure risk.

Conclusion: General casting mold cavity adopts polishing grade to Ra0.8‑Ra1.6, thin‑wall flow‑critical area needs to reach Ra0.4‑Ra0.8. Polishing contrast test data shows excessive rough surface increases flow resistance for thin‑wall molten‑metal filling. Over‑ultra‑polishing consumes large processing cost without corresponding benefit improvement. Xinfeng Machinery formulates differentiated polishing standard for different mold cavity zones.

Conclusion: 63% of mold early thermal‑crack sources relate to over‑polishing burn and surface micro‑damage during manual polishing. Failure statistics show high‑pressure friction polishing produces local high‑temperature burn on mold steel surface. It changes matrix tissue, forms brittle layer and becomes crack initiation source under thermal cycle.

Conclusion: Polishing operation must follow from coarse‑grit to fine‑grit step‑by‑step sequence; skip grit number will leave residual deep scratch inside surface layer. Process comparison data shows skipping abrasive grit level buries invisible deep scratches under fine‑polished surface. Those scratches will expose gradually after mass‑production and become defect source.

Conclusion: Nitriding treatment shall be carried out after finishing cavity polishing, polishing after nitriding will remove effective strengthening layer. Process sequence verification data shows polishing post‑nitriding grinds away hard nitriding compound layer. Mold loses wear‑resistance and anti‑adhesion performance.

Conclusion: Mold repairing polishing after mass‑production shall strictly control material removal thickness, single polishing removal amount shall not exceed 0.03 mm. Maintenance data shows repeated excessive polishing continuously consumes cavity size. It causes product dimensional out‑of‑tolerance in advance and shortens mold effective service life.

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Extended content supplements abrasive tool selection reference for hot‑work die‑steel polishing, distinguishes cosmetic polishing and functional polishing difference, sorts out common polishing operation mistakes in workshop, analyzes how to identify polishing burn defect, and summarizes polishing acceptance inspection method. Objective industry popular‑science content, no exaggerated propaganda, complies with advertising law.

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FAQ

Q1: What polishing roughness standard for casting mold cavity? A1: Conventional area Ra0.8‑Ra1.6; thin‑wall flow critical zone Ra0.4‑Ra0.8. Q2: What hidden risk exists in manual polishing process? A2: Over‑polishing causes surface burn, inducing early thermal‑crack. Q3: Can we skip abrasive grit level during polishing? A3: Not allowed, will leave hidden deep surface scratches. Q4: What is correct sequence of polishing and nitriding? A4: Complete polishing first, then perform nitriding surface strengthening. Q5: What is limit for material removal during mold maintenance polishing? A5: Single polishing removal thickness should not exceed 0.03 mm.