Renyi Castings
RFQ@renyicastings.com
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Ningbo city
China 315137
Fast Response Email Support
GMT+8
China 315137
Precision permanent mould castings in aluminum and zinc alloys — backed by our in-house tooling engineers and mould workshop. From hand-pour prototypes to high-output machine production.
Hand pouring molten aluminum into a permanent metal mould — Renyi Castings facility, Ningbo
"Gravity casting — also called Permanent Mould casting — is one of the oldest and most reliable processes for fabricating aluminum and non-ferrous alloys. Molten metal is poured from a crucible into a reusable metal mould under the force of gravity alone, without pressurized gas, vacuum, or centrifugal force."
The reusable metal mould is the defining advantage: unlike sand casting (one mould per part), the same permanent mould is used thousands of times, making gravity casting highly cost-effective for small-to-medium production volumes.
Renyi has our own engineers team dedicated to gravity casting tooling design, supported by an in-house tooling machining workshop. This full in-house capability lets us shorten the first-article sample approval cycle, improve casting quality from the start, and deliver tooling at significantly lower cost than outsourcing.
From tooling design to finished, inspected part — every step performed or supervised in our Ningbo facility.
Our in-house engineers review your drawing, advise on design for manufacturability, and create the mould design
The permanent metal mould is CNC-machined in our in-house tooling workshop — no outsourcing, full QC control
Aluminum alloy is melted and the mould is pre-heated to prevent cold shuts and ensure uniform filling
Molten metal is poured by hand or machine into the mould cavity; gravity fills the form under controlled conditions
Gates and risers are removed; parts are shot-blasted, CNC-machined, or surface-treated as required
Dimensional check, visual inspection, and material testing before packaging and shipment with full documentation
Our foundry uses both manual hand moulds and machine-mounted permanent moulds. The choice depends on part complexity, production volume, and budget — and our engineers will recommend the right approach for your project.
Best for: Simple parts · Low to medium volume · Undercut designs
For straightforward parts or small quantity orders, we use manual hand moulds where the operator pours and opens the mould by hand. This approach requires simpler tooling with no ejector pin mechanism, making it significantly cheaper and faster to produce.
Ideal for prototypes, first-article samples, and production runs where part geometry allows manual demoulding. Sand cores can be inserted to create internal cavities and undercuts.
Best for: Complex / large parts · High volume production · Tight cycle times
For large or geometrically complex castings, we mount permanent moulds on gravity casting machines equipped with automatic ejector pins. The ejector pins push the casting out of the mould at the end of each cycle, greatly improving production output and consistency.
The higher tooling investment is quickly offset by reduced cycle times, consistent repeatability, and lower per-piece cost at medium-to-high volumes. This is the recommended approach for ongoing production contracts.
Most foundries outsource tooling design and mould machining to third parties — adding weeks to the lead time and removing direct quality control. Renyi is different: we maintain a dedicated in-house engineering team for gravity casting tooling design, backed by our own CNC tooling workshop.
This means faster turnaround from drawing to first sample, lower tooling cost, and the ability to make rapid modifications based on first-article results — without waiting for an external vendor.
Renyi in-house CNC tooling workshop — gravity casting mould design and machining, Ningbo
2D/3D files reviewed by our tooling engineers; DFM feedback provided within 48 hours
Mould cavity, parting line, gate, riser, vent, and ejector pin layout designed and reviewed with client
H13 tool steel mould machined on our in-house CNC machining centers to tight tolerances
First pour and dimensional inspection; corrections made same-week if needed
T1 sample submitted for customer sign-off; production begins upon approval
Gravity casting bridges the gap between sand casting and die casting — offering better surface finish and mechanical properties than sand, at a fraction of die casting tooling cost.
The rigid metal mould produces repeatable, consistent dimensions — significantly better than sand casting. Typical tolerance of ±0.3 mm achievable without secondary machining.
The smooth metal mould surface delivers a much finer as-cast finish than sand casting (Ra 3.2–6.3 μm), reducing or eliminating extensive post-machining on non-critical surfaces.
Controlled solidification in a metal mould produces a finer grain structure, yielding higher tensile strength, elongation, and fatigue resistance versus equivalent sand-cast parts.
Gravity casting tooling costs approximately 30% of equivalent die casting tooling, making it the most economical option for volumes where die casting is not justified.
Sand cores inserted into the permanent mould create internal cavities, undercuts, and complex passages — giving design flexibility that die casting cannot achieve.
Unlike die casting, gravity casting needs no high-pressure injection machinery, reducing equipment investment and enabling production of a wider range of alloys including copper.
Standard finish — removes flash and improves texture
Secondary machining of critical dimensions to tight tolerances
Corrosion and wear protection for aluminum parts
Wide RAL color range, excellent durabili
Epoxy or polyurethane systems for OEM specifications
Alodine / Iridite for aerospace and military applications
Renyi has established itself as a leading manufacturer of copper, brass and bronze forgings for global industrial and OEM clients. Our copper alloy forgings combine unique material properties with the structural benefits of the forging process.
| Criteria | Gravity Casting ★ | Die Casting | Sand Casting | Investment Casting |
|---|---|---|---|---|
| Tooling Cost | Low (~30% of die cast) | Very High | Very Low | Medium |
| Production Volume | 50 – 50,000 pcs | 10,000+ pcs | 1 – any | 100 – 10,000 |
| Dimensional Accuracy | Good (±0.3 mm) | Excellent (±0.1 mm) | Fair (±1.0 mm) | Excellent (±0.1 mm) |
| Surface Finish (Ra) | Ra 3.2–6.3 μm | Ra 1.6–3.2 μm | Ra 12.5–25 μm | Ra 1.6–3.2 μm |
| Min Wall Thickness | 3–5 mm | 1–2 mm | 5–8 mm | 1–2 mm |
| Undercuts / Cores | Yes (sand cores) | Limited | Yes | Yes |
| Compatible Materials | Al, Zn, Cu alloys | Al, Zn, Mg alloys | Al, Fe, Steel, Brass | Steel, SS, Al alloys |
| T1 Lead Time | 3–5 weeks | 6–10 weeks | 1–3 weeks | 4–8 weeks |
Aluminum gravity castings are widely specified wherever good mechanical properties, moderate geometric complexity, and cost-effective tooling are required at low-to-medium volumes.
All aluminum alloy ingots are checked against material certifications and composition-tested before melting.
Full dimensional report on the first production sample, signed off by the customer before mass production begins.
Every Nth part is measured during production; visual inspection catches porosity, cold shuts, and surface defects.
ASTM E505 X-ray inspection available for pressure-tight or safety-critical components.
Critical dimensions verified on our Coordinate Measuring Machine; full CMM reports available per shipment.
Material cert, dimensional report, surface finish report, packing list, and COC shipped with every order.
Hand moulds typically complete in 2–3 weeks. Machine moulds with ejector pins take 3–5 weeks. Because all mould machining is done in-house, we can often expedite to 2 weeks for urgent projects.
For simple parts at lower quantities, a manual hand mould is more cost-effective. For complex, large, or high-volume parts, a machine-mounted mould with auto ejector delivers better consistency and output. Our engineers will recommend the right option after reviewing your drawing.
There is no strict MOQ. Gravity casting is cost-effective from as few as 50 pieces, making it ideal for low-volume production and small-batch orders where die casting is not economical.
Standard terms are 30% deposit on order confirmation, 70% balance before shipment. T/T bank transfer is preferred. Other arrangements available for established customers.
We issue an 8D corrective action report, rework or replace non-conforming parts at no charge, and implement permanent process improvements to prevent recurrence. All NCRs are resolved within 5 business days.
Send your drawings (2D/3D), material grade, required quantity, and surface finish. Our engineers will review your design and recommend the optimal mould type — quotation returned within 12–48 hours.