A plastic sheet quotation can look complete and still be impossible to compare. One supplier quotes PET by kilogram, another proposes PP in a different roll format, and a third assumes a thickness tolerance or surface treatment that was never discussed. The prices are different, but so are the products behind them.

This usually happens because the inquiry starts with a short description such as “clear PET sheet roll” or “PP sheet for thermoforming.” That identifies a material category, not a production-ready requirement.

A useful RFQ should turn the application, part drawing, forming equipment and commercial requirements into one written request that every supplier answers on the same basis. In our experience, ten minutes spent defining these inputs can prevent several rounds of unclear quotations and unsuitable samples.

Start the RFQ with the finished application

The first question is not which polymer a supplier recommends. It is what the finished part must do.

Describe the product being formed and its end use. A transparent retail blister, food tray, electronics tray and opaque inner insert may all be thermoformed, but they place different demands on clarity, stiffness, impact behavior, surface condition, denesting, sealing and handling.

Include the following application information where relevant:

• Finished product and end use
• Product or contents held by the package
• Required transparency, color and surface appearance
• Draw depth and important formed features
• Stiffness, impact or stacking expectations
• Nesting and denesting requirements
• Printing, bonding, folding or sealing operations
• ESD or other functional requirements
• Storage, transport and use conditions that affect the part
• The present problem if the RFQ concerns a supplier change

A drawing is especially valuable. It gives the supplier part dimensions, geometry, corners, ribs, flanges and draw depth that cannot be communicated reliably by naming the application alone. If the drawing is confidential, a simplified drawing or dimensioned sketch can still remove much of the uncertainty.

We usually start with the feature most likely to cause rejection. For a clear retail package, that may be visibility and surface appearance. For a tray, it may be wall distribution, rim stiffness, stacking or denesting. For electronics packaging, it may be the required electrical behavior after forming. This tells the supplier what the trial must prove rather than merely what material to send.

Define the material without treating its name as a complete specification

PET, PP and HIPS are useful starting categories, but the material name alone does not establish equivalence. This is also why the common search for the difference between PET and plastic can be misleading: PET is itself a plastic. The real purchasing question is how PET differs from another proposed polymer, structure or formulation in the intended application.

If the material has already been approved, state the required polymer and structure. If it remains open, explain the application and ask each supplier to identify the proposed option clearly. Do not invite substitutions without requiring them to be labelled as alternatives.

For PET plastic sheet, specify whether the request concerns PET, R-PET or another approved PET-based structure, together with any recycled-content requirement. For PP or HIPS, identify the required material category and any functional version. The RFQ should also state whether a surface treatment or special function is required rather than leaving the supplier to infer it.

PUSITE supplies PET and R-PET sheet options, PP sheet, HIPS sheet and functional variants for thermoforming and packaging. Depending on the project, available options include anti-block PET, corona-treated print-grade PET, antistatic PET, antistatic PP and antistatic HIPS. Availability should be confirmed for the selected structure, gauge, colour and roll format.

Functional descriptions need measurable acceptance conditions. For example, writing “antistatic” without the target resistance range, test method, conditioning environment and point of measurement may result in offers that are not comparable. If performance after forming matters, say that explicitly. A value measured on flat sheet does not automatically describe the formed part.

The same discipline applies to appearance. Replace “high clarity,” “good color” or “smooth surface” with an approved reference sample, agreed inspection method or defined acceptance expectation wherever possible. For appearance-sensitive packaging, we place more weight on repeatability than on one unusually good hand sample.

Put dimensions and roll format into one specification block

Dimensions are among the most common sources of quotation errors. State the nominal values, required tolerances and measurement basis separately.

Do not send only the finished-part width when purchasing a roll. The supplier needs the sheet width required by the machine, including trim allowance and any edge requirements. Likewise, “0.5 mm” is incomplete if one offer uses a different tolerance or measurement convention from another.

When a current sheet already runs successfully, provide its written specification and a representative roll label if commercially appropriate. Do not assume that matching its nominal thickness and color will produce the same result. Surface condition, formulation and roll consistency can change heating, forming and trimming behavior even when the basic description looks identical.

Describe the forming process and equipment

Once the material and dimensions are clear, the supplier will need to understand how the sheet will be processed. This is where many promising samples fail: they were selected without enough information about the actual machine or mould.

Include:

• Thermoforming method, such as vacuum, pressure or another applicable process
• Machine make or type if it helps define the process
• Maximum and effective forming width
• Heating arrangement and current operating window
• Mould dimensions, cavity layout and draw depth
• Plug-assist use, where applicable
• Cutting or trimming method
• Target running speed or cycle requirement
• Web handling, feeding and unwind constraints
• Downstream printing, sealing, bonding, folding or assembly steps

The supplier does not need every confidential machine setting before making an initial quotation. It does need enough information to judge whether the proposed sheet and roll format are reasonable for the process.

One mistake we often see is approving a sample because it forms one acceptable part at reduced speed. That proves basic formability, not production suitability. A production-relevant trial should use the intended tooling, operating sequence and downstream conversion steps. Record heating response, wall distribution, trimming, nesting, appearance and any failure that matters to the application.

Change one variable at a time during troubleshooting. If thickness, heater settings, cycle speed and mould conditions all change together, the result may improve without revealing why. A disciplined trial makes the eventual purchasing specification more useful and repeatable.

Make samples comparable before approving a supplier

A request for “a few sample rolls” is not enough. Each sample should correspond to a clearly identified quotation and proposed specification.

Ask the supplier to identify:

• Material and structure
• Nominal thickness and width
• Surface treatment and treated side, if applicable
• Color or appearance reference
• Functional category and applicable test conditions
• Roll and core format
• Sample quantity
• Batch or sample identification
• Any differences between the sample and the proposed production supply

We would not approve a supplier change from thickness and color alone. Two sheets with the same polymer name and gauge may behave differently because their surfaces, formulations or roll consistency are not identical. The safer approach is to compare samples under the same production conditions and convert the successful result into a written purchasing specification.

If the project is still at an early stage, ask for a practical starting proposal rather than a guaranteed final gauge. Finished-part geometry, draw ratio and performance determine the final specification. A trial is the bridge between a supplier recommendation and approval for production.

State quantity, destination and commercial terms precisely

Only after the technical request is defined can the commercial quotation become meaningful. The supplier needs enough information to calculate the requested order basis and logistics correctly.

State the trial quantity and expected production quantity separately. A sample request, first commercial order and forecast volume serve different purposes and should not be blended into one number. If demand will be released in batches, describe the expected order pattern without presenting an uncertain forecast as a firm commitment.

For international supply, include:

• Quantity by material, thickness, width and color
• Destination city, port or delivery location
• Requested Incoterm and named place
• Transport mode if already decided
• Required quotation currency
• Packaging and pallet restrictions
• Import documentation or label requirements
• Requested shipment window
• Whether freight must be quoted separately
• Whether the order mixes several specifications

The destination matters even when the quotation is requested on an ex-works basis. Roll weight, pallet arrangement and protection may need to fit container loading, warehouse handling or local equipment limits.

Avoid asking only for a PET plastic sheet price or PP plastic roll price. Price per kilogram may appear comparable while usable production cost is not. Width mismatch, excessive trim, unsuitable roll size, unstable forming or poor downstream performance can erase a lower material price quickly.

Use one response format for every supplier

A disciplined RFQ makes omissions visible. Ask each supplier to complete the same response table rather than returning a quotation in its preferred format.

Our preference is to reject silent substitutions. An alternative can be useful, but it should appear as a separate option with its technical and commercial differences explained. Otherwise, the purchasing team may compare numbers that represent different materials or delivery scopes.

Final RFQ checklist

Before issuing the inquiry, confirm that it contains:

• The finished application and the most important acceptance requirement
• A drawing, sketch or critical finished-part dimensions
• Required material or permission to propose clearly labelled alternatives
• Structure, recycled-content and surface-treatment requirements where applicable
• Thickness, width, tolerances and measurement basis
• Core, roll diameter, roll weight, winding and splice requirements
• Forming process, effective machine width, tooling and downstream operations
• Trial quantity, production quantity and sample expectations
• Test or inspection methods for critical functional and appearance requirements
• Destination, Incoterm, currency, packaging and shipment requirements
• A standard supplier response table
• A requirement to disclose every exception or assumption

The strongest RFQ is not necessarily the longest. It is the one that defines the finished-part risk, machine interface and commercial basis well enough that every quotation describes a genuinely comparable offer.

Discuss Your Plastic Sheet RFQ with PUSITE

Share your target application, drawing, required material, thickness, width, surface, forming process, estimated quantity and destination market. PUSITE can help review the sourcing requirements and suitable sheet options before samples and quotations are compared.

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