A356 vs ADC12 Aluminum Casting RFQ Guide

# A356 vs ADC12 Aluminum Casting RFQ Guide

Choosing between A356 and ADC12 is not just an alloy question. It affects the casting process, wall thickness, tooling design, heat-treatment plan, machining allowance, inspection records, and the way suppliers build a quotation. A useful RFQ should explain the part function and approval evidence before asking a supplier to recommend one route.

This guide gives procurement engineers and SQE teams a conservative comparison framework for A356 and ADC12 aluminum casting. Use it to prepare a drawing-based RFQ, not as a substitute for the drawing, standard, customer specification, or validation plan.

Fast Comparison For RFQ Screening

The right choice still depends on drawing geometry, alloy standard, annual volume, validation requirements, and the buyer's approval route.

A356 In A Buyer RFQ

A356 is an Al-Si-Mg casting alloy commonly used when the buyer needs gravity casting, low-pressure casting, sand casting, and possible T6 heat treatment. It is often considered for pump housings, brackets, manifolds, covers, and structural or pressure-sensitive components when the drawing and validation plan support that route.

In an RFQ, do not only write "A356" and ask for a price. Add the expected temper, mechanical-property requirement if any, machining datums, leak-test scope, and the inspection records needed for approval. A356-T6 quote quality depends heavily on heat-treatment assumptions, wall thickness, fixture planning, and whether machining happens before or after heat treatment.

Useful internal routes:

• •A356 material page
• •Gravity casting process
• •Low-pressure casting process
• •A356 casting plus CNC machining RFQ package

ADC12 In A Buyer RFQ

ADC12 is an Al-Si-Cu die-casting alloy commonly used for high-pressure die-cast housings, covers, brackets, motor parts, appliance components, and other parts where thin-wall castability and dimensional repeatability matter. It is usually quoted as a die-casting route rather than a gravity-casting route.

In an RFQ, ADC12 buyers should define wall thickness, cosmetic surfaces, coating or plating expectation, machining scope, flatness, thread or insert requirements, and any porosity-sensitive features. If a part has pressure, sealing, or structural approval requirements, ask the supplier to explain how the die-cast route will be validated instead of assuming alloy name alone solves the risk.

Useful internal routes:

• •ADC12 material page
• •Die casting process
• •Casting process selection guide
• •Quote readiness checklist

What To Send Before Asking For A356 vs ADC12 Advice

Send the supplier enough information to compare process risk, not only alloy cost:

• •2D PDF drawing with revision status.
• •STEP or other 3D model if available.
• •Required alloy, allowed equivalents, and required temper if specified.
• •Annual volume, pilot quantity, and expected launch timing.
• •Critical wall thickness, ribs, bosses, sealing faces, and cosmetic surfaces.
• •CNC machining scope, datum structure, bore or flatness requirements, and surface finish.
• •Leak-test, pressure-test, fatigue, coating, or corrosion requirements if applicable.
• •Inspection records needed, such as CMM, material certificate, heat-treatment record, X-ray/NDT, FAI, PPAP, or traceability format.
• •Destination country, Incoterm, packaging expectation, and tooling ownership assumptions.

When this information is missing, a supplier can still discuss feasibility, but the answer should be treated as preliminary.

A356 vs ADC12 RFQ Route Matrix

Use this route matrix when a buyer is comparing alloy and process at sourcing stage:

The goal is not to force one alloy. The goal is to make the supplier state the route, assumptions, exclusions, inspection evidence, and drawing risks before a buyer compares price.

Practical Selection Notes

Pressure-sensitive housings

For pump housings, valve bodies, compressor housings, or other pressure-sensitive parts, start with the leak-test requirement, sealing faces, machining datums, and inspection evidence. A356 may be a better discussion starting point when heat treatment, feeding control, and leak-test planning are central to the RFQ. ADC12 may still be considered for some housings if the drawing, pressure requirement, and die-cast validation plan support it.

Thin-wall or high-volume die-cast parts

For covers, enclosures, brackets, motor housings, and parts with thin ribs or integrated features, ADC12 may be the more practical starting point because the process is designed for high-pressure die casting. The RFQ should still ask how the supplier controls porosity, trimming, machining, coating, and dimensional checks.

Machined datum parts

For both alloys, machining strategy can matter more than nominal casting weight. Tell suppliers which faces become datums, which bores control assembly, which areas are cosmetic, and which surfaces must remain free of exposed porosity after machining.

Heat-treatment-sensitive parts

If T6 is required, make it explicit. A356 is commonly used in heat-treated casting routes, but the final result depends on wall thickness, solution treatment, quench control, aging, distortion control, and inspection. ADC12 is generally not treated as a standard T6 route in ordinary HPDC sourcing, so buyers should challenge any quote that assumes heat treatment without explaining the process and validation evidence.

RFQ Worksheet

Use this worksheet when sending an alloy-selection RFQ:

> Part family:

> Drawing revision:

> Current alloy or target alloy:

> Accepted equivalent standards:

> Annual volume:

> Process preference: gravity / low-pressure / die casting / open to supplier review

> Wall thickness concerns:

> Machining datums and critical dimensions:

> Leak, pressure, fatigue, or sealing requirement:

> Heat treatment or temper requirement:

> Surface finish or coating:

> Inspection records required:

> Approval route: FAI / PPAP / internal buyer approval / supplier recommendation

> Destination and Incoterm:

FAQ

Can I switch from ADC12 to A356 without redesigning the part?

Usually the supplier should review the design again. HPDC and gravity or low-pressure casting use different tooling, draft, wall thickness, gating, feeding, machining allowance, and tolerance assumptions. Treat a material switch as a process-review event.

Is A356 always stronger than ADC12?

No. Strength depends on alloy condition, casting process, heat treatment, wall thickness, defect level, and the test standard. If strength or elongation matters, specify the required property and the evidence format instead of relying on a general alloy comparison.

Is ADC12 always cheaper?

Not always. ADC12 die casting can be cost-effective at higher volume and thin-wall geometry, but tooling, machining, scrap risk, coating, inspection, and validation can change the comparison. Ask suppliers to separate tooling, part price, machining, inspection, and logistics assumptions.

Which route should I use for a leak-test housing?

Start from the leak-test medium, pressure, hold time, acceptance criteria, sealing faces, and machining datums. Then ask the supplier to recommend the alloy and process route with inspection evidence. For A356 pressure-sensitive RFQs, the A356-T6 pressure-tight pump housing RFQ is a useful reference route.

How should I ask Bohua to review A356 vs ADC12?

Send the drawing package and approval requirements through the A356 vs ADC12 process-selection RFQ path. Include whether the supplier may recommend A356, ADC12, ZL114, A380/A383, or another drawing-approved equivalent.