Low-Pressure Aluminum Casting RFQ
Controlled-fill permanent-mold casting for leak-test housings, pressure-sensitive A356/ZL114 parts, and CNC-machined sealing surfaces that need process review before tooling.
When low-pressure casting is worth quoting for leak-test parts
Low-pressure casting is the right route for dense, pressure-sensitive aluminum parts where the buyer needs controlled fill, stable feeding, and fewer leak-test surprises after machining. The RFQ should name the alloy target, pressure medium, leak-rate or hold-time requirement, sealing-face datum plan, annual volume, and whether gravity casting or low-pressure casting should be compared before tooling. Typical applications include EV drivetrain housings, hydraulic manifolds, and leak-tight pump bodies where sealing-surface integrity is a program-level requirement.
Process selection RFQ examples
Product pages to prepare before choosing gravity or low-pressure casting
These examples show the product-level RFQ package Bohua needs before confirming whether gravity casting, low-pressure casting, machining, and leak-test scope fit the drawing.
Pump housing RFQ package
Use this A356-T6 pump housing page to prepare pressure, leak-test, machining, and inspection inputs before Bohua confirms the casting route.
View product RFQ package →Hydraulic valve body RFQ package
Useful for valve RFQs with sealing faces, ports, threaded features, CMM requirements, and pressure-related review.
View product RFQ package →Gearbox housing RFQ package
Industrial housing example for buyers comparing gravity, low-pressure, tooling, T6, CNC, and documentation assumptions.
View product RFQ package →Quote-ready package
What to send before Bohua confirms low-pressure casting
Low-pressure casting is most useful when the drawing exposes leak, pressure, X-ray, or machining-datum risk. A complete RFQ lets Bohua compare low-pressure casting against gravity casting before the buyer commits to tooling.
| RFQ input | What Bohua needs to review |
|---|---|
| Drawing package | 2D PDF, STEP file, drawing revision, critical sections, and any pressure-path notes. |
| Material route | A356, ZL114, A356-T6, T5/T6 target, or request Bohua to compare the alloy route. |
| Process question | State whether low-pressure casting is required or whether gravity casting should be compared before tooling. |
| Leak / pressure scope | Test medium, pressure, hold time, leak-rate limit, sampling plan, and whether impregnation is allowed. |
| Machining datums | Sealing faces, bearing seats, threaded ports, flange flatness, and datum features exposed after CNC. |
| Records needed | X-ray scope, CMM report, material certificate, heat-treatment record, FAI, or PPAP-style documents if required. |
| Commercial context | Annual forecast, pilot quantity, destination, Incoterm, target packaging, and launch timing assumptions. |
Gravity casting vs low-pressure casting
| Criterion | Gravity casting | Low-pressure casting |
|---|---|---|
| Filling | Top-pour, gravity | Bottom-up, controlled pressure |
| Porosity | Lower risk when planned well | Lower scatter when pressure-fill assumptions fit the part |
| Best for | Structural / general | Pressure-tight / sealing |
| Cycle time | Slightly faster | Slightly slower |
| Tooling cost | Lower | Higher (pressure chamber) |
| Typical alloys | A356 / ZL114 | A356 / ZL114 |
Typical RFQ inputs for low-pressure casting
- 1.Pressure / leak-test standard
- 2.Sealing face flatness + Ra requirement
- 3.Machining datum strategy
- 4.Alloy + temper target (A356 / ZL114, T5/T6)
- 5.Annual volume
- 6.Inspection package (X-ray scope, CMM, leak)
- 7.Tooling pressure-chamber compatibility
Inspection considerations
- • X-ray for pressure-path porosity
- • Air-decay or helium leak test for sealing surfaces
- • CMM for bearing-seat and datum control
- • IATF 16949-compliant traceability on all inspection records
When low-pressure casting makes sense
Low-pressure casting fills the mold from the bottom by using controlled gas pressure instead of gravity alone. That changes the quality story in a useful way: the metal front is calmer, feeding stays active during solidification, and internal quality is usually more consistent in demanding sections.
For buyers, that usually means fewer leak-test surprises, fewer machining rejects caused by subsurface porosity, and better repeatability on programs where X-ray standards or pressure performance matter.
Better internal quality
Bottom-up filling lowers turbulence and helps reduce oxide-related defects in critical housings.
Active feeding
Pressure is maintained during solidification, which improves shrinkage control in heavier sections.
Heat-treatment compatible
A356 and ZL114 LPDC parts can be paired with T5 or T6 treatment when higher strength is required.
Stable for serial production
A disciplined LPDC process supports repeatable leak testing, dimensional control, and PPAP-style documentation.
Selection logic for buyers
| Requirement | Why LPDC fits |
|---|---|
| Pressure-tight housing | Lower turbulence and better feeding reduce leak-risk zones after machining. |
| Wheel or symmetric geometry | Bottom-up filling is naturally suited to balanced cavity filling. |
| Structural aluminum part | A356 / ZL114 with heat treatment supports stronger property targets. |
| Medium to higher annual volume | Tooling investment is justified when quality yield and metal utilization matter. |
| X-ray-sensitive customer program | LPDC usually delivers lower defect scatter than simpler top-pour routes. |
Technical scope
- • Common alloys: A356 and ZL114
- • Typical part range: 2–30 kg, up to roughly 800 mm depending on geometry
- • Typical use cases: powertrain housings, wheels, leak-sensitive industrial parts, structural housings
- • Inspection path can include spectrometer checks, X-ray review, CMM, hardness, and leak test
Quick reference
Low-pressure casting FAQ
What is low-pressure aluminum casting?
Low-pressure casting uses controlled gas pressure to push molten aluminum upward into a permanent mold from below. The bottom-up fill is smoother than top-pour methods, which helps reduce turbulence, oxide films, and porosity.
When should buyers choose low-pressure casting?
Low-pressure casting is a strong choice for pressure-tight housings, wheel-type geometries, powertrain parts, and components that need tighter internal quality control than standard gravity casting can deliver. It is usually selected when leak performance, X-ray quality, or property consistency matters more than tooling simplicity.
Which alloys are common for low-pressure casting?
A356 and ZL114 are the most common low-pressure casting alloys at Bohua because they combine good castability with heat-treatment potential. These alloys are widely used where strength, corrosion resistance, and dimensional stability matter.
What tolerances can low-pressure casting achieve?
Typical low-pressure casting tolerances fall around CT7 to CT9 depending on geometry, wall thickness, and machining strategy. Critical interfaces are normally machined after casting to achieve final sealing or bearing requirements.
How long does low-pressure casting tooling take?
Tooling timing is confirmed after RFQ review because part complexity, cooling design, pressure-chamber assumptions, machining scope, and sample validation can all change the schedule.
What should buyers send for a low-pressure casting RFQ?
Send a 2D PDF, STEP file, alloy target, annual forecast, pressure or leak-test requirement, sealing-face datum plan, machining scope, X-ray or CMM record needs, destination, and Incoterm. If the process route is not fixed, ask Bohua to compare gravity casting and low-pressure casting before tooling.
Should low-pressure casting be compared with gravity casting before tooling?
Yes when the part is a pump body, hydraulic housing, EV drivetrain housing, or other pressure-sensitive casting where leak performance, X-ray quality, machining exposure, and tooling investment need to be weighed together. The comparison should happen during RFQ review, before the mold route is locked.
Related Resources
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