Pressure-Tight Die Casting -Verified Sealing at Working Pressure

Pressure-tight die casting is not a standard product -it is a specific outcome requiring the correct combination of alloy, process, and testing. Most die casting is not pressure-tight. KastMfg's pressure-tight capability is a defined product category with specific process controls and 100% production verification.

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What Pressure-Tight Means

A pressure-tight die casting contains no interconnected pore network connecting internal passages to the external surface or to adjacent passages. In production:

• Passes a specified pressure decay test (no detectable pressure drop in defined hold time), OR
• Passes a helium leak test (no detectable helium transmission below a specified rate)

Both tests are quantitative and produce archived records per part.

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KastMfg's Three-Layer Approach

Layer 1: Alloy -A413 as Standard

A413's near-eutectic silicon (12%) produces the finest solidification microstructure of any standard aluminum die casting alloy -lower shrinkage, smaller pores, less interconnected porosity versus A380. KastMfg specifies A413 for all hydraulic programs with working pressure above 80 bar.

Layer 2: Process -VADC for Demanding Programs

For >150 bar working pressure or helium leak requirements: vacuum-assisted die casting (VADC) removes 60-70% of gas porosity before it forms. Post-VADC X-ray: ASTM E505 Class 1-. This physically eliminates the leak path rather than sealing it.

For 50-150 bar programs: standard A413 HPDC combined with VPI impregnation (post-cast vacuum pressure impregnation) is cost-effective and reliable.

Layer 3: Testing -100% Production Verification

Test	Equipment	Typical Range	Sensitivity
Air decay	Dedicated leak testers	Up to 200 bar	<1 cm³/min
Nitrogen pressure	High-pressure station	Up to 350 bar	Pressure decay
Helium mass spectrometer	Hood method	Any pressure	<10^-8 mbar·L/s

100% testing -not sampling. Records archived 5 years minimum.

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Production Results

Application	Alloy	Process	Working Pressure	Pass Rate
Hydraulic directional valve	A413 + VADC	VADC	250 bar	100% (n=12,000)
Hydraulic manifold	A413 + VADC	VADC	200 bar	100% (n=8,500)
Pneumatic actuator	A380	Standard	10 bar	99.8%
EV cooling jacket	A380 + VADC	VADC	4 bar	100% (n=6,000)

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When to Use Which Approach

Working Pressure	Recommended Approach
<30 bar pneumatic	A380 standard HPDC
30-100 bar hydraulic	A413 standard HPDC
100-200 bar	A413 + VPI, or A413 + VADC
200-250 bar	A413 + VADC
T6 heat treatment needed	VADC mandatory regardless of pressure

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Pressure-tight program inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China