How to Write an RFQ for Custom Plastic Extrusion

A strong RFQ for custom plastic extrusion does more than ask for a price. It tells the supplier what the profile must do, how it will be checked, which risks matter, and where the design still needs manufacturing feedback. That difference matters because an extruded profile is controlled by material behavior, extrusion die design, cooling, puller stability, cut length, and secondary operations, not by the drawing alone.

For buyers comparing suppliers, the best RFQ is specific enough to quote tooling, sampling, inspection, and production, but open enough for engineering suggestions before the die is built. Use the structure below to make your request clear, comparable, and useful for real supplier selection.

What Should a Custom Plastic Extrusion RFQ Include?

A custom plastic extrusion RFQ should include the part drawing, material or performance requirement, target profile geometry, tolerances, application environment, expected volume, packaging needs, and inspection requirements. It should also ask how the supplier will design, sample, validate, and maintain the extrusion die.

Start with the drawing package. For profile extrusion, the cross-section is the control document because the die head, calibrator, cooling path, and puller all act on that shape continuously. A clean 2D drawing should show outer dimensions, wall thicknesses, radii, slots, lips, hollow chambers, datum references, cut length, and any post-extrusion holes or embossing.¹

If you have a 3D model, send it with the 2D drawing, not instead of it. The model helps the supplier understand assembly and end use, while the 2D drawing defines what must be measured. For complex custom plastic profiles, mark which surfaces seal, slide, snap, guide, or carry load.

RFQ information checklist: Include contact details, project name, revision number, target material, color, surface finish, profile length, annual demand, first-order quantity, and whether prototyping, small batch, or large batch production is needed. If the part is replacing an existing profile, include the current defect or cost problem.

Application context: Explain the operating environment in engineering language. For example, say whether the profile is used indoors or outdoors, near heat, around moisture, under sliding wear, in cable protection, in a guide rail, in a building seal, or in an automotive rail system. This helps the supplier select PVC, ABS, HDPE, PP, PC, PMMA, PA6, PA66, POM, TPE, TPU, TPV, PC/ABS, ASA, or PP/GF from realistic options.

Standards and test language: Use recognized standards when they fit the part. ASTM D638 specifies tensile test methods for plastics and is commonly cited when an extruded profile needs tensile strength, elongation, or modulus data. ASTM D790 covers flexural properties and is useful when stiffness of a profile section matters. ISO 306 defines Vicat softening temperature testing, which can be used as a heat-resistance indicator for thermoplastics.

How Should You Define Material, Tolerance, and Performance?

Define material by resin family, grade requirement, application condition, and measurable performance. Define tolerance by function, not by applying the tightest number everywhere. A good RFQ tells the supplier which dimensions are critical, how they will be checked, and what variation the assembly can accept.

For plastic extrusion, material choice affects melt strength, shrinkage, surface finish, impact behavior, flexibility, weathering, and die swell. PVC may suit window and door profiles, decorative trims, pipes, and sealing strips. ABS is often used for automotive and industrial profiles. HDPE can fit pipes, edge trims, guide rails, and wear strips. PP, PC, PMMA, PA6, PA66, POM, TPE, TPU, TPV, ASA, PC/ABS, and PP/GF each bring different processing and performance tradeoffs.

If you do not know the exact material, write the performance requirement instead. Say that the profile must act as a low-friction guide, a flexible sealing lip, a transparent cover, an outdoor trim, a cable protection tube, or a rigid structural support. Then ask the supplier to recommend a resin and state the assumptions.

Tolerance strategy: Do not ask for one extreme tolerance across the whole profile unless every feature truly needs it. The minimum achievable dimensional tolerance on the profile cross-section can reach ±0.05 mm, subject to material and section geometry. In real extrusion work, thin lips, asymmetric walls, hollow chambers, soft materials, and high-shrink materials may need different control expectations.

Use a critical-to-function table. Label dimensions as critical, important, or reference. Critical dimensions may include snap-fit gaps, sealing lips, sliding rail surfaces, pipe outside diameter, or mating slot width. Reference dimensions may only guide appearance or non-contact boundaries.

Performance requirements: State whether the extruded profile must resist bending, impact, abrasion, UV exposure, heat, flame, or chemical contact. ISO 4892 covers plastics exposure to laboratory light sources and can be relevant when outdoor weathering is a design concern. UL 94 addresses flammability classification of plastic materials for parts used in devices and appliances.

Material documentation: Ask the supplier to identify the proposed resin family, grade or compound basis, color approach, and any relevant processing limitations. This is especially important when the profile combines rigid and flexible zones, requires transparency, or will operate near a temperature that could affect dimensional stability.

Which Drawing Details Help the Supplier Quote the Extrusion Die?

The supplier needs enough geometry to judge die complexity, flow balance, calibration, cooling, puller contact, and downstream handling. Show wall thickness changes, internal chambers, lips, ribs, radii, undercuts, soft-hard interfaces, and cut length, then identify which features control fit or sealing.

An extrusion die is not just a hole in a plate. It must compensate for melt flow, die swell, shrinkage, cooling rate, and puller tension. If the RFQ hides a sharp transition, an unsupported lip, or a thick-to-thin wall change, the quote may miss trial time and later design correction.

Cross-section clarity: Use a drawing scale that makes small features readable. Avoid sending only a screenshot or hand sketch for final quotation. If a sketch is the only starting point, call it a concept RFQ and ask for a manufacturability review before formal tooling quotation.

Co-extrusion details: If the part needs rigid and soft zones, specify which areas require each material. ZetarVac has run combinations such as PP+TPV, PP+TPE, PVC+TPU, ABS+TPU, and TPV+CPVC. Co-extrusion can combine structural support with a flexible seal, wear surface, or wiping edge, but the interface location must be clear on the drawing.

Secondary operations: State whether the profile needs in-line punching, embossing, or printing. These operations affect line layout, registration, tolerance stack-up, and quote structure. A punched hole pattern may be easy on a rigid PVC channel but harder on a soft flexible profile that stretches during pulling.

Tooling ownership and maintenance: Ask whether the quotation includes die design, die fabrication, trial runs, modification rounds, storage, maintenance, and future replacement. For long-term production, the die head and calibrators are project assets, so the RFQ should clarify revision control and who approves tooling changes.

How Do Volume, Sampling, and Inspection Change the RFQ?

Volume changes the quote because tooling, setup time, production line selection, inspection frequency, packaging, and inventory planning all depend on quantity. Sampling defines how the first acceptable profile is approved, while inspection defines how future batches stay consistent.²

For early development, separate prototype needs from production needs. A supplier may support prototyping, small batch production, and large batch production, but the cost structure is different. A short validation run may focus on geometry and material feel, while a larger production order needs packing density, line efficiency, and repeatable measurement control.

Capacity and planning: ZetarVac operates 7+ automated extrusion lines with maximum profile width up to 600 mm, and the plant has 45+ production lines in total. The reference monthly extrusion capacity is about 300–500 tonnes across the extrusion lines, so an RFQ should state expected monthly demand, seasonal peaks, and launch timing.

Sampling plan: Ask for first article samples with a dimensional report. If the profile has visual requirements, request labeled sample zones, not a general statement. If the part fits a mating component, send the mating part or a drawing so the supplier can check assembly, not just caliper dimensions.

Inspection method: Define the measurement tool when possible. A slot width may be checked by caliper, pin gauge, fixture, optical comparator, or coordinate measurement depending on geometry. A flexible lip may need a fixture because the reading changes under contact force. If process capability is important, ask whether the supplier can report sample size, measured values, and capability index for critical dimensions.³

Packaging and logistics: Include profile length, bundle size, carton limits, scratch protection, labeling, and whether parts must stay straight during transport. Long extruded profiles can deform if packed under load or stored hot. Packaging is part of the engineering requirement, not an afterthought.

What Supplier Questions Should You Ask Before Awarding the Project?

Ask questions that reveal process understanding, not only price. The best questions cover die strategy, material recommendation, tolerance risk, sampling steps, inspection method, secondary operations, packaging, and how the supplier handles drawing revisions after trial.

A supplier that quotes quickly but does not ask about critical dimensions may be assuming a simple open profile. That can be risky for custom plastic extrusion with hollow chambers, soft-hard co-extrusion, long lengths, or snap-fit features. Procurement teams should compare assumptions before comparing unit price.

Questions to include in the RFQ: Ask which material they recommend and why. Ask whether the cross-section has flow-balance or cooling concerns. Ask which dimensions may be difficult to hold and what design changes would improve manufacturability. Ask how many sample review rounds are included. Ask whether in-line punching, embossing, or printing can be done during the extrusion run.

Engineering evidence: Request a quotation layout that separates extrusion die cost, sample cost, production unit cost, secondary operation cost, packaging, and inspection documents. If the supplier recommends a material substitution, ask for the reason, likely tradeoff, and whether the change affects stiffness, flexibility, color, weathering, or thermal behavior.

Relevant internal references: If your team is still defining the process, review ZetarVac’s plastic extrusion molding capability page for process scope, then use the DFM checklist for extruded plastic profiles and extrusion dies to check geometry before sending drawings. For supplier evaluation, the China plastic extrusion manufacturer page can help align RFQ questions with production capability.

Case-style examples: A transparent PVC electronic tube profile RFQ should define insulation and cable-guiding function, transparency expectation, wall thickness, cut length, and whether UL 1581-related cable context is relevant. A PVC drainage channel profile RFQ should define channel geometry, drainage function, continuous section length, and building or industrial installation conditions.

For a PP + TPV automotive seat slide rail strip, the RFQ should mark the rigid support and flexible sealing lip as different functional zones. For an ABS + TPU robot vacuum squeegee strip, it should show where ABS provides support and where TPU provides wiping contact and wear resistance. These examples show why custom plastic extrusion RFQs should describe function, not only shape.

FAQ: Writing a Better Custom Plastic Extrusion RFQ

Can I request a quote without a finished CAD drawing?

Yes, but label it as an early engineering review rather than a final production quotation. Send a sketch, target dimensions, function, material idea, expected volume, and photos of the assembly area if available. The supplier can then comment on profile extrusion feasibility before quoting final tooling.

Should I specify the resin grade or let the supplier recommend it?

Specify the resin grade if your design is already validated or regulated by an internal requirement. If the function matters more than the exact grade, state the performance target and ask the supplier to recommend PVC, ABS, HDPE, PP, PC, PMMA, PA, POM, TPE, TPU, TPV, ASA, PC/ABS, or PP/GF options.

How should I write tolerance requirements for an extruded profile?

List only the dimensions that control assembly, sealing, sliding, or strength as critical. Then give realistic tolerance targets and ask the supplier to confirm whether the material and profile section can hold them in production. Avoid applying the tightest tolerance to every line on the drawing.

What documents should I ask for with first samples?

Ask for a dimensional report, material confirmation, drawing revision reference, sample quantity, inspection method, and notes on any process or tooling adjustment. If the part has critical fit, ask for a simple fixture check or mating-part trial in addition to measured dimensions.

What is the next step if my team is ready to compare suppliers?

Prepare your drawing package, material target, volume range, critical dimensions, and inspection expectations, then contact our team to discuss your custom plastic extrusion project. You can also send your part requirements to request a quote without relying on a generic unit-price estimate.