Reasonable gating and riser layout is the foundation to eliminate shrinkage porosity and ensure consistent mechanical properties for LPDC aluminum castings. Poorly designed feeding system raises internal shrinkage rejection rate by 34% during X-ray inspection. This article summarizes Xinfeng mould design rules, parameter thresholds and simulation verification standards for bottom filling LPDC gating and riser.
LPDC adopts bottom laminar filling design, runner cross-section gradually reduces to stabilize flow velocity below 0.17 m/s. Turbulent flow above 0.22 m/s entrains oxide film and increases folded inclusion defects by 46%.
Sprue height matched to mold stacking height to control melt lifting speed. Too fast lifting speed causes melt splashing and oxide entrapment; slow speed reduces production takt time by 22%.
Ingate thickness controlled at 4–7 mm, ingate area accounts for 12–18% of total casting projected area. Smaller ingate area leads to insufficient feeding; oversized ingate prolongs solidification and increases material waste.
Riser placed at hot spot positions of thick bosses and flange areas. Riser solidification time must be 28–35% longer than casting solidification time to achieve sequential solidification.
Riser volume ratio kept at 16–22% of casting weight for thick structural aluminum parts. Riser volume below 15% cannot compensate volume shrinkage during aluminum solidification.
Exothermic riser sleeve applied on large hot spots, extending riser feeding duration by 33% and reducing riser volume requirement, saving raw aluminum material by 14%.
Runner slope designed at 3°–5° for smooth residual aluminum removal after casting. Runner dead pocket reserved at runner end to trap slag and oxide impurities, preventing impurities entering cavity.
Sequential solidification simulation must be executed at design stage. Optimize cooling channel and riser position to push hot spots toward riser, reducing shrinkage defect probability by 37%.
Gate cutting allowance reserved 2.5–4 mm for CNC trimming. Insufficient allowance causes gate remnant on casting surface and affects assembly flatness.
For CPC counter pressure LPDC molds, runner sealing surface flatness controlled within 0.025 mm to avoid argon leakage at runner joint.
Runner surface nitriding treatment with 0.08–0.11 mm layer thickness to resist long-term aluminum melt erosion and soldering.
Q1: What filling velocity is required for LPDC bottom gating system? A1: Maintain laminar filling speed below 0.17 m/s to avoid oxide film entrapment. Q2: What is the recommended riser volume ratio for LPDC structural castings? A2: Riser volume accounts for 16–22% of casting weight to guarantee feeding capacity. Q3: What is the function of runner dead pocket? A3: Runner dead pocket collects slag and oxide inclusions, preventing impurities from entering product cavity.
Copyright © Zhejiang Xinfeng Machinery Co., Ltd. All Rights Reserved.