The RFQ Package That Gets You a Real Quote

Executive Summary

A quote for custom fabrication or casting is only as accurate as the package it was built from.

• Suppliers do not price your part; they price their interpretation of your drawing. Every ambiguity is resolved in their favour, because it has to be.

Missing information does not stop a quote. It changes one.

• You still get a number. It is simply a number covering a different part from the one you intended to buy.

Six items beyond the 3D model decide quote accuracy

• — critical-to-function tagging, cosmetic zones, before-or-after-coating datums, pressure acceptance criteria, annual volume, and target delivery date. Four gaps typically costs two weeks before anyone touches steel.

The cheapest engineering hour in any programme is the one spent completing the RFQ.

• It is the only point where a change costs nothing but attention.

 

Most Sourcing Guides Are Written Backwards

Search for Die Casting Services or compare Aluminum Die Casting suppliers and you will find page after page explaining what the supplier reviews before quoting: CAD data, alloy, tolerances, volume, tooling strategy. It reads as reassuring diligence.

It is also the wrong half of the transaction to document. The supplier's review process is not the constraint. Your submission is. No amount of engineering review recovers information that was never sent.

So this page is written from the other side. Not what we check, but what you should send — and what specifically happens when each item is missing. Not "it may cause delays", but which assumption gets made, what it costs, and how many days it adds.

 

What Everyone Already Sends

Two items arrive with nearly every enquiry, and they are necessary but not sufficient.

A 3D model — STEP, X_T, IGES or native. This defines geometry. It cannot define intent: for die Casting Parts it does not say which face matters, which dimension is functional, or which surface a customer will ever look at.

A 2D drawing — dimensions, tolerances, threads, revision level. Better, but only if it distinguishes between requirements and defaults. Most do not.

If your package stops here, you will receive a quote. It will be built on six assumptions you never saw.

 

The Six Items That Actually Decide the Number

1. Which Tolerances Are Critical-to-Function

A drawing where every dimension carries a tolerance tells the supplier nothing about priority. Faced with a fully toleranced drawing and no CTF tagging, a quoting engineer has one safe option: treat everything as critical.

The consequence is not a rejection. It is a price. Features that would have been perfectly acceptable as cast get machined, because machining is the only way to guarantee a tolerance the supplier cannot verify was optional.

There is a second cost that surprises people. In any piece of cast metal, the as-cast skin is the strongest material in the part. Rapid solidification against the die produces a dense, fine-grained layer roughly 0.3 to 0.5 mm deep. Machining it away removes the best material and exposes the more porous core beneath. Unnecessary machining does not just add cost — it can make the part weaker.

What to send: mark five to fifteen dimensions as critical-to-function. Leave the rest to a general tolerance note. A drawing with forty critical dimensions has communicated the same thing as a drawing with none.

2. Cosmetic Zones and Viewing Conditions

"No visible defects" is the most expensive phrase in custom die casting procurement, because it is not measurable and therefore cannot be limited. Applied without a zone map, it covers the inside of a mounting boss no one will ever see.

Visibility is not a property of a surface. It is a property of a surface plus a viewing distance plus a lighting condition. State all three.

A workable structure:

Zone	Definition	Typical Criterion
A	Visible during normal use	Inspected at 500 mm, 1000 lux diffuse
B	Visible during installation only	Inspected at 1000 mm, minor tool marks accepted
C	Hidden in the assembly	Functional only, no cosmetic requirement

Key point: without zones, T1 approval stops being an inspection and becomes a negotiation — one you will conduct under schedule pressure, from a weaker position than you have today.

3. Whether Dimensions Apply Before or After Coating

Anodising does not sit on the surface. It converts it. Roughly half the layer thickness penetrates into the base metal and half grows above the original surface. A 25 µm hard anodic coating therefore raises each surface by about 12.5 µm — which means a bore loses 25 µm on diameter and a shaft gains 25 µm.

Specify Ø10.000 mm with no coating note and you have written an ambiguous requirement. The supplier picks one interpretation. You discover which one at assembly.

There is a related trap in electrical design. Anodising is an insulator; chemical conversion coating is conductive. Grounding pads, EMI gaskets and bonding surfaces must be called out as masked areas with a stated resistance limit, not left to be finished like the rest of the part. A die cast housing that fails an EMI test after tooling is a very expensive way to learn this.

What to send: for each coated feature, state the coating type, thickness, and whether the dimension applies before or after. Identify masked areas explicitly.

4. Pressure and Porosity Acceptance Criteria

Every casting contains some porosity, whatever the metal casting service quoting it implies. The question is never whether, but where and how much is acceptable — and that is your decision to make, not the supplier's to guess.

Sending a drawing marked "pressure tight" without a test method is equivalent to sending nothing. Pressure tight at what pressure, with what medium, for how long, at what allowable leak rate?

If the part is structural rather than sealed, the criterion is different again: a named radiographic standard such as ASTM E505 with acceptance levels assigned per region, because the porosity permissible in a flange is not the porosity permissible in a bolted joint. Most metal casting services will accept whichever level you name — but only if you name one.

This is the gap with the longest tail. The others cost email rounds. This one can cost a retool, discovered after T1, when gating and thermal management would have been designed differently had the requirement been known.

5. Annual Volume and Programme Life

Volume is not a commercial detail that can follow later. It is a tooling input.

A die built for 50,000 shots and a die built for 500,000 shots differ in steel grade, cavity count, cooling design, insert modularity and price. Quote a tool without a volume figure and the supplier assumes something — usually the lower end, because it prices better against competitors who assumed the same.

You then run the programme successfully, and the tool wears out in year two.

What to send: initial order quantity, estimated annual usage, and expected programme life. If genuinely unknown, say so and give a range. A stated range is a specification; silence is not.

6. Target Delivery Date

Not "as soon as possible". A date.

Tool rooms and machine slots are scheduled. A stated need-by date lets a supplier tell you truthfully whether it is achievable, and reserve capacity if it is. Without one, your programme enters the standard queue and the first honest conversation about timing happens after you have already lost weeks.

 

The Two Things Worth Sending That Nobody Asks For

A photograph or sample of the failure you are trying to avoid. If this is a redesign, the previous part's failure mode tells an engineer more than three pages of specification. Cracked at a boss, leaked at a seal face, distorted after machining — each points to a different gating and cooling strategy.

The assembly context. What mates to this part, with what clearance, under what load and temperature. Aluminium casting parts are almost never used alone, and a supplier who understands the assembly will flag conflicts that a part-level review cannot see — including cases where a die cast metal component should be split into a casting plus a fabricated bracket.

 

What Comes Back When the Package Is Complete

A complete submission should produce more than a price, whether you are buying OEM casting volume or a single prototype tool. Ask for:

Price at the stated volume

• , with tooling and piece price separated, and the tooling amortisation basis stated

A DFM report

• naming specific features and specific concerns — not a generic checklist

A stage-by-stage schedule

• , with the start point defined (drawing receipt, not tooling approval)

The alloy proposed and why

• , particularly if it differs from your drawing

Named assumptions

• , if any remain

That last item is the tell. A quote listing its own assumptions came from an engineer. A quote with a single number came from a spreadsheet.

Three Constraints We Raise Before Tooling, Not After

Constraints found at T1 cost weeks. These three are raised during RFQ review.

6061 cannot be die cast. Silicon at 0.4 to 0.8% against the 7 to 13% of casting alloys gives a wide freezing range that hot-tears in a steel die. A drawing specifying 6061 needs aluminum fabrication from extrusion, machining from billet, or gravity aluminum casting in a different alloy. We say so rather than substituting quietly.

A380 does not anodise bright. Copper at 3 to 4% produces a mottled dark film. Bright anodised parts need A360 or A413, chosen before steel is cut.

T6 blisters conventional high pressure castings. Air entrained during injection expands during the 500–540 °C solution soak while the matrix softens, lifting the skin. Genuine T6 requirements mean gravity or low pressure casting in A356 — a different process and a different schedule.

 

Our Quoting Scope

Parameter	Value	Qualifier
Quotation turnaround	24 hours	On complete packages; incomplete ones get a question list instead
Clamp force	160 – 3,500 tons	Selected by projected area, not part weight
Process	Cold chamber aluminium · hot chamber zinc casting	Both in-house
Alloys	A380 · A383 / ADC12 · A360 · A413 · ZAMAK 3/5	A360/A413 for bright anodise
Part weight	15 g – 40 kg	—
Minimum wall, aluminium	1.2 mm	Within 80 mm flow length of a gate
Tolerance, as-cast	±0.10 mm / 25 mm	NADCA linear, same die half
Tolerance, across parting line	±0.25 mm	Datum must be stated
Tolerance, machined	±0.02 mm	Secondary operation, quoted separately
Tooling lead time	5 – 8 weeks	Excludes DFM iteration before steel is cut
Certification	ISO 9001 · ISO 14001 · CE · RoHS · SGS	Issued in our own legal entity name

In-house scope: tooling design and manufacture, cold chamber aluminum die casting, hot chamber zinc, 3/4/5-axis CNC machining, blasting, anodising, powder coating, plating, insert installation, sub-assembly and leak testing — a single aluminum alloy processing manufacturing chain with no undeclared handovers.

Our metal fabrication and custom metal fabrication lines — laser cutting, press brake forming, TIG and MIG welding — often let a cast body carry fabricated brackets, removing side actions from the die and shortening tool build. For low-volume structural fabrication no tooling is needed at all.

Typical aluminium casting products: LED heat sinks, telecom enclosures, motor housings, gearbox covers, valve bodies, furniture hardware and mounting brackets. We hold no stock — every custom casting is built to drawing or sample, with 1-to-1 engineering support and permanent tooling ownership, backed by 30+ years of factory processing experience.

 

Frequently Asked Questions

Q1: What is the minimum I need to send to get a meaningful die casting quote?

A 3D model, a 2D drawing identifying critical-to-function dimensions, the alloy or the performance requirement it must meet, annual volume, and a target date. Everything else can be clarified during review, but without those five a quote rests on assumptions rather than requirements. Sending an incomplete package is still better than sending nothing — just expect a question list before a price.

Q2: Why does tagging critical dimensions reduce my cost rather than increase it?

Because untagged drawings force the supplier to treat every dimension as critical, and the only way to guarantee a tolerance is to machine it. Tagging five to fifteen functional dimensions lets everything else stay as cast, which is both cheaper and structurally better — the rapidly solidified skin, roughly 0.3 to 0.5 mm deep, is the densest material in the casting, and machining it away exposes the more porous core.

Q3: How should I define cosmetic requirements?

With zones, distances and lighting. Divide the part into surfaces visible in use, visible only during installation, and hidden in the assembly, then state an inspection distance and light level for each. "No visible defects" is unmeasurable and therefore unlimited, so it gets applied to hidden faces where it adds scrap cost and nothing else.

Q4: Do dimensions on my drawing apply before or after coating?

Whichever one you state. If you do not state it, the supplier chooses. This matters because anodising converts the surface rather than sitting on it — about half the layer grows into the base metal and half above it, so a 25 µm hard anodic coating removes roughly 25 µm from a bore diameter and adds the same to a shaft. Call out coating type, thickness, and datum condition per feature.

Q5: My part needs an electrical ground path. What do I specify?

A masked area with a defined boundary and a stated maximum contact resistance. Anodising is an electrical insulator, while chemical conversion coating remains conductive, so a grounding pad or EMI gasket surface finished like the rest of the part will fail its bonding test. This has to be on the drawing before tooling, because masking fixtures are designed alongside the tool.

Q6: What does "pressure tight" need to say to be quotable?

Test medium, test pressure, hold time, allowable leak rate, and which regions must comply. For structural rather than sealed parts, name a radiographic standard such as ASTM E505 with acceptance levels mapped per region. Without these, the requirement cannot be designed for — gating, overflow placement and thermal management all change depending on where soundness is genuinely required.

Q7: Why do you need annual volume before quoting tooling?

Because it determines the tool, not just the price. Steel grade, cavity count, cooling layout and insert modularity all change between a 50,000-shot programme and a 500,000-shot one. A supplier quoting without a volume figure assumes the low end, which prices attractively and then wears out mid-programme. A stated range is a specification; silence is not.

Q8: What should a good quote contain besides a price?

Separated tooling and piece price with the amortisation basis stated, a DFM report naming specific features rather than generic advice, a stage-by-stage schedule with the start point defined, the proposed alloy with reasoning, and an explicit list of any remaining assumptions. A quote that documents its own assumptions was produced by an engineer; a bare number was produced by a spreadsheet.

Q9: How much time do incomplete packages actually cost?

Each clarification round trip runs two to four days across time zones, and gaps rarely arrive alone. Four missing items typically costs two weeks before anyone touches steel. The worst case is porosity criteria discovered after T1, which can force gating changes and a retool — three to four weeks minimum, against the thirty minutes it would have taken to state a leak rate at RFQ.