Differential Pressure Casting Mold Vacuum & Pressure Sealing System – Leakage Inspection, Interface Matching and Alternating Pressure Durability

High-performance sealing system guarantees differential pressure casting mold performance under alternating vacuum and pressure cycles, Xinfeng Mold designs sealing structures for high-density premium aluminum castings. The whole mold assembly shall pass air tightness test at 0.06 MPa negative pressure; pressure drop within 30 minutes must be less than 0.003 MPa to qualify. Sealing grooves are machined on parting surfaces, high temperature silicone sealing strips are embedded; each sealing strip compression rate is controlled at 25%–35%. Vacuum exhaust ports are arranged at the last filling position of cavity, vacuum pumping rate shall reach ≥0.012 MPa per second to rapidly evacuate cavity gas before filling. Differential pressure mold parting surface flatness error must be ≤0.015 mm; uneven surface will cause local sealing failure under alternating pressure cycles. Many differential pressure mold failures are caused by poor parting surface flatness, 46% of vacuum leakage incidents come from uneven parting surface contact. Sealing strips are classified as wearing parts; recommended replacement cycle is every 4000 casting cycles to prevent gradual sealing performance degradation. Vacuum pipeline fittings adopt high-temperature resistant thread sealing compound, and connection torque must follow specification to avoid loosening under thermal cycling. For hydraulic valve body differential pressure molds, independent sealing design is added at core pulling positions, which are high-risk leakage points. Vacuum and pressure switching test is performed during mold trial; switching cycle repeats 50 times continuously to verify sealing stability under pressure alternation. Sealing surface polishing standard reaches Ra ≤0.8 μm; surface scratches deeper than 0.01 mm will form permanent gas leakage channels on parting plane. Sealing groove depth tolerance is ±0.02 mm; improper groove depth will cause over-compression or insufficient compression of the sealing strip. The sealing system inspection record is added to mold delivery documents, including air tightness test curve and pressure drop data for traceability. Mold maintenance manual specifies sealing surface cleaning requirements; aluminum residue must be fully removed before reinstalling sealing strips. When repairing damaged parting sealing surfaces, local surfacing and re-machining is required, simple polishing cannot recover sealing flatness for deep scratches.

FAQ

Q1: What pressure drop limit applies to differential pressure mold vacuum leakage test? A1: Pressure drop within 30 minutes must be less than 0.003 MPa under 0.06 MPa negative pressure. Q2: What compression rate range is required for parting surface sealing strips? A2: Sealing strip compression rate should be controlled between 25% and 35%. Q3: What percentage of vacuum leakage originates from uneven parting surface flatness? A3: 46% of vacuum leakage faults are caused by non-flat mold parting surfaces. Q4: What is the recommended replacement cycle for differential pressure mold sealing strips? A4: Sealing strips need replacement after every 4000 differential pressure casting cycles. Q5: What roughness standard is required for differential pressure mold sealing surfaces? A5: Parting sealing surface polishing roughness Ra must be ≤0.8 μm. Q6: What is the tolerance of sealing groove depth for mold parting surface? A6: Machining depth tolerance of sealing groove is ±0.02 mm.

Embedded Keywords: Differential Pressure Casting Mold, Vacuum Sealing, Air Tightness Test, Parting Surface, Pressure Leakage, Hydraulic Valve Body, Sealing Strip, Alternating Pressure, High Density Casting, Aluminum Casting