How to Write an EPP Foam RFQ: A Spec Sheet Checklist for Sourcing Teams

Most EPP sourcing projects that go wrong do not go wrong in the mould. They go wrong in the first email. A moulder who receives “we need EPP foam inserts, like the photo, how much?” has three options: price the cheapest possible reading of the photo, price a guess, or write back with eleven questions and lose a week. All three cost the buyer money, and only one of them is visible in the quote.

This article is about the input document — the RFQ package and the terms inside it. It is deliberately not about the other three questions buyers usually ask first. If you want to understand why one quote is higher than another, that is the cost structure of a moulded EPP part. If you want to know whether the parts that arrive are to specification, that is dimensional tolerances and quality control. If you want to know how the tool itself is built, that is EPP mould tooling. This one answers a narrower and earlier question: what has to be written down before any of those answers mean anything.

Why most foam enquiries come back uncomparable

Before fixing the document, it helps to name what usually goes wrong with it. Six failure modes account for almost every RFQ that produces numbers nobody can rank.

1. A photograph instead of geometry. A picture communicates intent. It does not carry a wall thickness, a draft angle, a tolerance or a datum. Every supplier who quotes from a photo is pricing a solid he reverse-engineered himself, and every one of them reverse-engineered a different solid.
2. A density number with no property behind it. “EPP 30” states how much polymer sits in a cubic metre. It says nothing about how the part behaves under load. Two moulders can both deliver 30 kg/m³ and hand you parts that perform differently, because bead grade, fusion and density distribution differ.
3. No annual volume. Tooling amortisation, cavity count and machine scheduling all key off volume. Withhold it and the supplier prices the tool as a standalone purchase and the part at his most conservative rate.
4. Tolerance language lifted from a machined-metal drawing. “±0.2 mm” on a moulded bead part is not a tolerance. It is a dispute with a delayed start date.
5. No delivery basis. At 30–40 kg/m³ foam is volume-limited, not weight-limited, so a part price without packaging, pallet and Incoterm is not a landed price. See the freight section below.
6. Silence on tooling ownership. The most expensive silence in foam sourcing, and the one that surfaces three years later when you try to move the part.

Fix those six and the clarification traffic drops by an order of magnitude. The rest of this article is the replacement text.

The six inputs a moulder needs before a number means anything

Input one: geometry — a STEP file is a start, not a specification

Send STEP AP242 (ISO 10303-242) if your CAD system produces it, or AP214. Both carry a true solid. IGES loses solid identity on complex foam geometry and STL is a mesh — usable for a CNC prototype, useless for a toolpath on a mould.

What the 3D model has to carry, before anything else is discussed:

• One watertight solid per part, single body. Not a surface quilt, not an assembly of six bodies, not a shelled shell.
• Units in millimetres, positioned in a sane coordinate system. Every mould shop has received a model in inches at some point and priced a part twenty-five times too large.
• The model at nominal size, with no shrinkage compensation applied by you. See the warning below.
• Logos and lettering modelled as solids, or omitted here and specified on the drawing with a depth. A flat image dropped on a curved surface will be interpreted six different ways.
• No decorative features you would not pay to mould. Every rib, step and undercut in the solid becomes tooling time.

The drawing does what a solid cannot: it carries decisions. A STEP file tells a moulder where the material is; a drawing tells him which surfaces matter and what he will be judged against.

One phrase does a lot of work on a foam drawing: as moulded. It signals that dimensions are measured on a part that has finished growing, not on a fresh cavity. Put the measurement conditions next to it — 23 °C, unrestrained, at least 24 hours after demoulding — because foam parts continue to move for hours, and two inspectors measuring at different ages will produce different numbers from the same part.

Input two: density is an outcome, not an input

“EPP 30” is a mass per volume. It is a useful cross-check and a poor specification. What the part has to do is carry a load, survive a drop, hold a temperature, resist a flame, dissipate a charge or stay inert in contact with food — and each of those is a property with a test method. If you want the density ladder itself, the guide to choosing EPP density from 20–80 kg/m³ covers it. Here the point is different: how to write the requirement so the answer can be checked.

A note on colour, because it recurs. Black EPP may be pigmented black or filled with carbon black, and the two are not interchangeable — the carbon-filled grade changes electrical behaviour and can affect surface finish. Write the colour as a material requirement with a reference, not as an adjective, and never accept “any colour” as an answer to a question about performance.

Input three: the volume section most buyers leave blank

Volume is the single most under-specified field in foam RFQs, and it is the one that changes the price most. Cavity count, machine choice and whether the tool is invoiced once or amortised into the part all follow from it. A supplier with no volume has to assume the worst case for his own capacity, and he charges for that assumption.

Now the arithmetic that decides how big a call-off should be, because it usually runs the opposite way to instinct. Take a packaging insert of 600 × 400 × 200 mm: 0.048 m³ per part. Annual demand of 12,000 parts is 576 m³ of product — eight 40-foot containers before any packing inefficiency. That is the defining fact about buying foam: you are not buying mass, you are buying space, and space is what you pay to store and to ship.

The large batch is 87 % cheaper per part on set-up and roughly three times more expensive once storage is counted. For a dense machined component the set-up line would dominate and the big batch would win. For bulky foam the cube dominates, and the RFQ is where you decide it — not in a warehouse argument eighteen months later. Set the call-off from your space, not from the moulder's convenience, and say so in the document.

Input four: tolerance — write something a gauge can settle

Two phrases account for most tolerance disputes on EPP parts: “±0.5 mm” and “per ISO 2768-m”. Both were inherited from machined metal. ISO 2768-1 class m on a 100 mm dimension allows ±0.3 mm. A moulded bead part will not hold that, and a supplier who accepts it has either not read the drawing or intends to argue when the report arrives. Unlike machining, there is no single general-tolerance standard that governs moulded EPP: the tolerances are agreed between moulder and customer, which means they have to be written rather than referenced.

Four sentence patterns that reliably cause disputes later:

• “±0.5 mm all over” — no datum, no dimension class, no measurement condition. Unenforceable in both directions.
• “Per ISO 2768-m” — a general tolerance for machined parts applied to a moulded bead part.
• “Match sample” — which sample, approved by whom, on what date, at what age after demoulding?
• “Straightness 0.2 mm” — measured on a part that is still moving and will be straighter tomorrow.

The clean alternative is five lines on the drawing: the datum scheme, six to ten critical dimensions with individual tolerances, a general note for everything else, the measurement conditions, and the acceptance document. The inspection side of that — what actually goes on a first article report and how to read it — is covered in EPP dimensional tolerances and quality control.

Input five: tooling terms, or the paragraph that prevents a year-three argument

Buyers treat tooling as a line item and negotiate it like a price. The money is rarely the problem; ownership is. How the tool is built and what it costs to run are separate questions, covered in EPP mould tooling: aluminium vs steel, T1 samples and cycle time. What belongs in the RFQ is the contract around it.

Two more lines worth adding while you are there. Ask what the T1 sample commitment is: how many samples, in which density and colour, with which report, and how many engineering loops are included in the tool price — usually none, occasionally one. And ask what happens to the tool if the programme is cancelled before SOP, because that clause gets read exactly once, at the worst possible moment.

Input six: commercial and logistics, where EPP quotes diverge most

Foam is manufactured by the cubic metre and sold by the piece, and the gap between those two units is where quotes stop being comparable. A part at 35 kg/m³ has a mass that is negligible next to the space it occupies, so container utilisation — not weight — sets the freight bill.

Two consequences for the document. First, state whether nesting and stacking are permitted, because it can change container utilisation by a factor of two and it is a design decision, not a packing decision. Second, state whether parts may be stacked in the same orientation for weeks — foam creeps under sustained load, and a container on a dock in July can reach temperatures where a stack of soft parts takes a permanent set.

The quote itself should state each of the following as a separate line, not bury them in a total:

• Incoterm and named place, per Incoterms 2020. Note that FOB is sea-only, and the ICC now recommends FCA for containerised cargo — under FOB the container is already at the terminal when risk passes, which is not what most buyers think they bought.
• Packaging: inner bag or none, dividers, pallet type and footprint, maximum stack height, stretch wrap, label content.
• Container loading plan, or at minimum a stated utilisation percentage and whether the load is volume- or weight-limited.
• Pallet cost and treatment: who pays, and whether ISPM 15 heat treatment is included for wood.
• Samples: free or charged, courier paid by whom, how many, and at which stage.
• Documentation: HS classification, certificate of origin, material declaration, and the compliance documents promised earlier.

The document pack: a checklist you can attach

Fourteen items. The right-hand column is what happens when the item is missing, which is the argument to use internally when someone asks why the RFQ has to be four pages.

How to compare quotes that do not look alike

Five quotes for “the same” part will not be the same offer. Normalise before ranking, in this order:

1. Fix the volume. Ask every supplier to price the same annual volume and the same call-off. A quote at 50,000 pieces against one at 5,000 is not a comparison.
2. Separate the tool from the part. Tool price and part price trade against each other; a cheap tool with an expensive part is a financing arrangement wearing a discount.
3. List what is excluded. Packaging, pallets, freight, tool maintenance, colour changes, certificates, samples, engineering changes. Exclusions are where quotes actually differ.
4. Convert to landed cost per 1,000 parts at your door, using your real cube and your real duty rate.
5. Check the assumptions behind density and tolerance. If one supplier assumed 25 kg/m³ and a looser tolerance, he is quoting a different product at a fair price for it.

Six questions worth sending to every supplier before you decide anything:

• What density and bead grade did you price, and what compressive stress does it deliver at 25 % strain?
• What shrinkage factor did you apply, and how was it established — in-house trials, or a table?
• What tolerance table are you committing to, and how will you measure each class?
• How many cavities, and what cycle time did you assume?
• What is included in the tool price — first article, one engineering change, or neither?
• What would move your price by more than 10 %?

A one-page RFQ template

If the checklist is too long to start with, start with these twelve lines. They fit on one page and they will get you comparable numbers.

1. Part name, drawing revision, programme, target SOP date.
2. STEP file name and revision; drawing number and revision.
3. Material: grade family, density, colour, and any flame, ESD or food-contact requirement with its standard.
4. Functional requirements, one line each: what load, what drop, what temperature, what chemical contact.
5. Critical dimensions, and a reference to the tolerance table.
6. Annual volume, call-off size, forecast horizon and ramp.
7. Tooling: cavity count wanted, ownership position, payment milestones.
8. Samples: how many, at which stage, with which report.
9. Packaging: unit pack, pallet, maximum height, label content.
10. Delivery: Incoterm and named place, destination, frequency.
11. Quality: report format at T1, PPAP-equivalent level required, audit rights.
12. Commercial: currency, payment terms, price validity, and whether alternative design proposals are welcome.

That last line is underrated. A moulder who is invited to propose a change will sometimes find a 15 % saving in a rib that was never needed or a wall that was thicker than the load required. A moulder who is handed a frozen drawing will simply quote it, and you will never learn what the other version cost.

What a competent supplier will ask you back

The reply is as diagnostic as the quote. These are the questions a moulder asks when he intends to be responsible for the part:

• Where does this part sit in the assembly, and what does it touch on each side?
• Which surfaces are visible to the end user, and which are hidden?
• If this dimension is 1 mm out, does the assembly still close?
• Is the annual volume firm enough to justify a multi-cavity tool, or would a single cavity be more honest?
• Who owns the design, and am I allowed to propose a change?
• Is there an incumbent part or material we are being compared against, and what did it fail at?
• What is the failure you are trying to design out — impact, load, heat, or cost?

If a supplier asks none of these, he is quoting a commodity and will deliver a commodity. If he asks all seven in his first reply, you are dealing with a moulder rather than a trader, and that is worth more than a four per cent price difference. It is also a reasonable proxy for how he will behave when a tool needs rework in month nine.

Red flags in a returned quote

• A price with no density, no bead grade and no tolerance stated.
• A tool price with no cavity count, no sample commitment and no statement of what is included.
• “Any colour” or “any density” offered as an answer to a performance requirement.
• A delivery date shorter than the tool build time — typically weeks, not days, for a new cavity.
• A quote that quietly improves the design: thinner wall, no draft, fewer ribs, no radii.
• Certification claims with no report number and no test house named.

Where this leaves the sourcing team

None of the above requires a materials engineer. It requires the discipline of writing down what was already decided in the design review, in a form a supplier can price and an inspector can measure. The product itself is not complicated: moulded EPP is a mature process, and the parts on our product pages and in application-specific components are made from the same material under the same constraints.

What varies is the quality of the brief. A four-page RFQ with a drawing, a tolerance table and a volume table will produce comparable quotes inside a week. A photograph and a sentence will produce five numbers, three months, and a tool nobody wants to own. If you are still at the stage where the shape is not final, say so — CNC prototype and sample routes exist precisely so that a tool is not cut against a guess.