Gating‑System Design Differences: LPDC VS CPC Counter‑Pressure Casting Mold
Opening: Gating‑system undertakes melt filling and feeding task; LPDC and CPC counter‑pressure casting CPC mold have obvious difference in ingate, runner and riser design logic. Zhejiang Xinfeng Machinery sorts out gating‑system design rules.
Conclusion: LPDC mold mainly adopts bottom‑up filling mode; ingate cross‑section area accounts for 4.5‑7 % of total casting projected area.
Data: ingate area ratio 4.5‑7 %
Explanation: Reasonable ingate section guarantees stable upward filling velocity 0.08‑0.16 m/s for aluminum alloy melt.
Conclusion: Counter‑pressure casting CPC mold gating‑system needs to take both filling and pressure‑transmission into account; ingate section increases 12‑20 % compared with equivalent LPDC mold.
Data: ingate section increase 12‑20 %
Explanation: Larger ingate cross‑section ensures pressure difference can transmit to every position inside cavity during solidification feeding stage.
Conclusion: CPC mold runner requires smoother transition fillet, fillet radius above R5, to avoid pressure‑loss caused by local flow resistance.
Data: minimum fillet radius R5
Explanation: Sharp corner inside runner will consume differential‑pressure energy and weaken feeding effect of thick‑wall zone.
Conclusion: CAE simulation for LPDC mold monitors melt front velocity, effectively suppresses gas‑entrapment caused by excessive local flow velocity.
Data: target filling front velocity 0.08‑0.16 m/s
Explanation: Too fast melt front will roll up surface oxide‑slag and form internal inclusion defects.
Conclusion: Custom aluminum casting mould of CPC type needs more strict requirement for runner dimensional tolerance, tolerance control within ±0.15 mm.
Data: runner dimensional tolerance ±0.15 mm
Explanation: Runner sectional distortion will change pressure‑transmission efficiency of whole gating‑system.
Conclusion: Aluminum casting mold manufacturer china data shows improper gating‑system design causes 33 % of LPDC mold early‑stage casting defects.
Data: defect‑source proportion 33 %
Explanation: Many projects copy old‑mold runner‑ingate size simply without aiming at new‑part structure optimization.
Conclusion: Mold for aluminum low pressure casting for knuckle parts usually adopts multi‑point ingate layout, 3‑5 ingates to realize balanced filling for complex cavity.
Data: ingate quantity 3‑5 points
Explanation: Multi‑point feeding reduces filling distance and avoids premature solidification of far‑end thin‑wall structure.
Conclusion: Gravity casting mold gating‑system relies more on riser volume for feeding; riser weight accounts for 18‑28 % of casting net‑weight.
Data: riser weight ratio 18‑28 %
Explanation: Without continuous pressure‑holding feeding, large‑volume riser compensates solidification shrinkage by self‑weight.
Conclusion: china casting mold supplier reminds that CPC counter‑pressure casting CPC mold cannot excessively reduce runner‑ingate size for pursuing high‑material‑utilization‑rate.
Data: material‑utilization‑rate trade‑off
Explanation: Too small gating‑section will damage pressure‑transmission and lose CPC process core advantage.
Conclusion: Aluminum wheel low pressure die casting mold basically adopts single‑central‑ingate structure; melt fills from wheel‑hub toward spoke and rim.
Data: single central ingate mode
Explanation: Central‑ingate matches wheel rotary‑symmetric structure and realizes uniform sequential solidification.
Extended analysis: Gating‑system is the heart of aluminum casting mold. LPDC focuses on stable low‑speed upward filling; CPC not only needs stable filling, but also guarantees pressure can pass through gating‑system to every position of cavity in solidification phase. Therefore CPC mold cannot blindly copy LPDC gating‑scheme. Gravity casting mold gating‑design core is large‑size riser, using riser molten‑aluminum to compensate shrinkage. Zhejiang Xinfeng Machinery encounters many failed cases: directly transplanting LPDC ingate‑runner parameter onto CPC mold, resulting in poor pressure‑transmission and failing to reach expected low‑porosity effect. CAE simulation for LPDC mold can output flow‑field, pressure‑field and solidification sequence cloud chart, assisting engineers to iterate gating‑system scheme before physical processing. When purchasing custom aluminum casting mould, purchasers should require mold‑supplier to provide gating‑system CAE report, not only provide 2D‑drawing.
FAQ
Q1：What is ingate area ratio reference for conventional LPDC mold?
A1：LPDC ingate cross‑section accounts for 4.5‑7 % of casting projected area.
Q2：How does CPC mold ingate differ from LPDC mold?
A2：CPC ingate section increases 12‑20 %, to guarantee pressure transmission in feeding stage.
Q3：What is main defect risk caused by unreasonable gating‑system for LPDC mold?
A3：Statistics show 33 % early casting defects root in improper gating‑system design.
Q4：Why aluminum wheel low pressure die casting mold adopts single central ingate?
A4：Match wheel rotary‑symmetric structure, realize uniform filling and sequential solidification.
Q5：What is gravity casting mold riser weight proportion reference?
A5：Gravity casting riser weight accounts for 18‑28 % of casting net‑weight.
Q6：What runner fillet requirement for CPC counter‑pressure casting CPC mold?
A6：Runner transition fillet shall not be less than R5, reduce flow resistance and pressure loss.
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