A356-T6 Pump Housing: Leak Test RFQ Checklist

# A356-T6 Pump Housing Leak Test RFQ Checklist

A356-T6 pump housings should not be quoted as ordinary aluminum castings. If the RFQ does not define leak-test expectations, suppliers may quote different assumptions: one supplier may include 100% leak testing after machining, another may include sample-only pressure checks, and another may not include test equipment time at all.

That difference changes cost, lead time, tooling review, machining sequence, and supplier risk. It can also create sample-stage disputes when a buyer expects pressure-tight validation but the supplier priced only a visual casting review.

This guide explains how OEM buyers can describe leak-test acceptance criteria before asking for an A356 or A356-T6 pump housing quote. It is not a replacement for the buyer's engineering standard. It is a practical RFQ checklist for making supplier quotes comparable.

For related quote paths, see Bohua's pump housing OEM quote guide, pressure-tight aluminum casting page, A356 material RFQ guide, and aluminum casting RFQ checklist.

Start with the functional risk

Leak testing is not one single requirement. It depends on how the part works.

An A356 pump housing may need to contain coolant, oil, hydraulic fluid, or water under pressure. The casting route, heat-treatment condition, sealing-face machining, and leak-test method all affect whether the quote is realistic.

Before asking for price, describe the functional risk:

• •What fluid or gas does the part contain?
• •Which cavities are pressure paths?
• •Which surfaces are sealing faces?
• •Is the pressure internal, external, or both?
• •Is the leak-test requirement for first samples, every part, or selected batches?
• •Does the part need testing before or after machining?

This information helps the supplier evaluate casting process, alloy, porosity control, machining order, and inspection cost.

Define the test method

Common leak-test methods for A356 pump housings include air pressure decay, air-under-water testing, helium leak testing, and customer-specific functional testing. Each method has a different sensitivity, cycle time, fixture need, and cost profile.

An early RFQ does not always need a final standard. It should at least say which method is expected or whether the supplier should recommend one.

Useful RFQ language:

> Leak-test method is not final. Please quote with your recommended method for pressure-tight validation and state whether air decay, air-under-water, or helium leak testing is assumed.

If the method is already fixed by the buyer's drawing or internal standard, attach that requirement and ask the supplier to confirm fixture and cycle-time assumptions.

State pressure, medium, and hold time if known

The supplier cannot price leak testing accurately if pressure and timing are missing. A useful RFQ should include:

• •test pressure
• •test medium, such as air, water, oil, or helium
• •hold time
• •allowed pressure drop or leak rate
• •temperature condition if relevant
• •whether the part is tested dry or with seals installed

If those values are not final, give a preliminary range and state that the final acceptance criterion will be confirmed before tooling release.

Avoid vague wording such as "must be leak free." For a supplier, that phrase is not a measurable specification. A better note is:

> Preliminary requirement: pressure-tight validation required after machining. Final pressure and leak-rate criteria are still under buyer review. Please state the test method, fixture assumption, and cost impact you are quoting.

Identify the inspection stage

Leak testing can happen at different stages:

• •raw casting trial
• •after heat treatment
• •after rough machining
• •after final machining
• •after coating or surface treatment
• •before packing

For pump housings, final testing often needs to happen after machining because ports, threads, sealing lands, and bores can expose porosity that was not open in the raw casting. If a supplier tests only the raw casting, the buyer may still discover leaks after CNC.

The RFQ should ask:

• •At what process stage is leak testing included?
• •Are sealing faces machined before the test?
• •Are threaded ports plugged during the test?
• •Does the supplier include fixture design in tooling or inspection cost?
• •Is retest after rework included or quoted separately?

These questions prevent an incomplete quote from looking cheaper than a complete one.

Clarify sampling level

Sampling level is a major quote driver. The buyer should state whether leak testing is expected for:

• •first article only
• •first batch validation
• •100% production inspection
• •periodic sampling
• •customer audit samples
• •special characteristics only

For pressure-containing parts, many buyers expect 100% production leak testing, but that should be stated. If the buyer is still deciding, the RFQ can request two quote lines: one with 100% leak test and one with defined sampling.

This is especially useful when comparing suppliers. A quote that includes 100% leak testing should not be compared directly against a quote that includes only first-sample testing.

Connect leak testing with casting process choice

Leak-test expectations influence the casting route. A pressure-tight pump housing may favor A356 or ZL114 gravity or low-pressure casting when wall thickness, sealing surfaces, and mechanical performance matter. A thin non-structural cover may fit die casting better when the main goal is volume and surface finish.

The buyer does not need to pick the final route alone. The RFQ should give the supplier enough information to recommend a process. Include:

• •wall thickness around pressure paths
• •alloy preference or mechanical requirement
• •annual volume
• •expected test pressure or leak criterion
• •machining scope
• •coating or impregnation restrictions if any

If the buyer does not want impregnation except as a contingency, say that early. If impregnation is allowed for a mature part, state how it will be approved and documented.

Ask for documentation, not only pass/fail

A pass/fail statement may be enough for a simple bracket. It is usually not enough for pressure-tight A356 pump housings. Buyers should ask what evidence will be delivered.

Possible documentation includes:

Ask for documents only when they are useful. Overloading a low-risk RFQ with unnecessary reports can add cost without improving sourcing decisions.

A practical RFQ wording template

Buyers can adapt this short note:

> This part includes pressure or sealing requirements. Please quote the casting and machining scope with leak-test assumptions clearly stated. Include the assumed test method, test pressure or range, test stage, sampling level, fixture assumption, documentation output, and any open questions that must be resolved before tooling release.

If the project has multiple parts, attach a small table:

This table is simple, but it makes quotes far easier to compare.

Supplier questions before nomination

Before approving a supplier for A356 pump housing work, ask:

• •Which leak-test method are you assuming in the quote?
• •Is the test performed before or after final machining?
• •What fixture or plugging method is required?
• •Is the test 100%, sample-based, or first-article only?
• •How are failed parts recorded and separated?
• •What documentation will be provided with samples and production batches?
• •Which drawing areas create the highest porosity or sealing risk?
• •Which RFQ details are missing before you can quote confidently?

A serious supplier should be able to explain both the test and the manufacturing controls that make the test pass repeatably.

Practical buyer takeaway

Leak-test acceptance criteria should be part of the RFQ, not a late-stage quality surprise. Even when the final standard is not frozen, the buyer can still state the expected method, stage, sampling level, and documentation output.

If your team is sourcing an A356 or A356-T6 aluminum pump housing, send the drawing, pressure expectation, sealing-face notes, CMM datum scope, annual volume, and leak-test requirements through Bohua's RFQ form. Bohua can review the package and clarify which assumptions should be fixed before quote comparison.

FAQ

What leak-test details should I include in an A356 pump housing RFQ?

Include the test method if known, pressure or pressure range, hold time, allowed pressure drop or leak rate, test stage, sampling level, and documentation requirement. If the final standard is not ready, ask the supplier to state the assumption used for quoting.

Should leak testing happen before or after machining?

For many A356 pump housings, the most meaningful test happens after final machining because ports, bores, and sealing faces can expose leak paths. Some programs also use earlier checks during sample development.

Is helium leak testing always required?

No. Helium testing is useful when higher sensitivity is needed, but air decay or air-under-water testing may fit many industrial programs. The correct method depends on the buyer's acceptance criterion and the part function.

Why do leak-test requirements change the quote?

They affect fixture design, cycle time, inspection labor, documentation, rework handling, and sometimes casting process choice. A quote with 100% leak testing is not the same scope as a quote with first-sample testing only.