SpecialFocus
Best Practices for Certifying That Plastic Materials Meet External Specifications

Distributor Best Practices

by Keith Hechtel, DBA, Curbell Plastics, Inc.
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achine shops will often ask distributors to provide pricing on plastic stock shapes that meet various external specifications. Examples include ASTM, ISO, MIL and SAE AMS specs. Responding to these inquiries with detailed and accurate quotations is a great way to build credibility with customers and grow sales. Additionally, supplying plastics that conform to the required specifications ensures that the correct materials will be put into service, reducing the chance of costly part failures.

Some documents such as MIL specs are available online at no charge. Others such as ASTM and SAE AMS specifications can be obtained from the publishing agency for a nominal fee. Material specifications are lengthy by design since they include granular detail about the properties and composition of the plastic. That being said, spending 20 minutes reviewing a spec is time well invested prior to sending a quotation to a customer.

The purpose of this article is to provide some tips for responding to RFQs (requests for quotation) that involve certifying that plastic materials meet external specifications.

Check the Scope of the Specification
The first step when reviewing a spec is to read the “scope” section at the beginning of the document. This defines the materials that the specification applies to. Some specs describe the resin used for manufacturing stock shapes and others apply to the stock shapes themselves. This has implications for the wording that will appear on the distributor’s quotation. If the spec on the RFQ applies to resin (typically pellets or powder), the quote should indicate that the shape is manufactured from resin that meets the specification. This is an important distinction since the properties of the resin, which are typically tested using molded specimens, may be quite different from the properties of the stock shape.
Review the Classification and Material Property Requirements
Most specifications include numbers and letters that indicate various “types,” “classes” and “grades” for a family of plastic materials. These numbers and letters provide important information such as the required base resin, fillers, reinforcements, UV stabilizers and color. They also indicate property requirements such as minimum values for tensile strength, tensile elongation, specific gravity and dielectric strength.

Carefully Review Requirements for Test Reports

Some material specifications require laboratory test reports for either the resin or the stock shape itself. If the spec requires lot testing, the test reports must be provided with each shipment of material. Other specifications note that the end user may require test reports with each shipment. In these cases, it is important to clarify the customer’s requirements prior to providing a quote on the material. In any case, it is important to note lot testing requirements on the quotation including any extra charges for the tests.

It’s OK to Take Exceptions

A surprising number of the material specifications that appear on engineering drawings include errors that make it impossible to certify that a material meets the spec. The following are some of the more common errors that distribution salespeople are likely to encounter:

  • The spec requires a grade of resin that can’t be manufactured as a stock shape due to its rheology.
  • The spec includes incorrect nomenclature, lacking the required numbers and letters to fully describe the material.
  • The plastic material is outside of the scope of the specification and therefore can’t be certified as meeting the spec.
  • The minimum property values specified are not feasible for the requested material.
  • The spec is for a plastic that is not commercially available as a stock shape.

In these cases, it is preferable to still provide a quotation, but list exceptions for the customer to review. The following is an example of an exception that might appear on a quotation:

“The PAEK material quoted meets ASTM D6262-17 grade 1 — general purpose, made using 100% virgin resin instead of grade 2 — recycled, which was specified on your RFQ dated 5/5/25.”

This type of notation ensures that the customer knows exactly what is being quoted and how it may be different from the material specified on their RFQ.

Never Certify to Performance Specifications
It is important to differentiate between a material specification, which describes the formulation and properties of a plastic and a performance specification, which certifies the suitability of a material for use in a given application. Certifying that a plastic stock shape conforms to a material specification is a normal and customary practice and it is a reasonable expectation for plastics manufacturers and distributors. However, certifying to performance specifications requires design expertise and this should be left to qualified plastic part designers. The following RFQs illustrate the difference between material specifications and performance specifications.
three sheets of paper with information on the Standard Specification for Extruded, Compression Molded, and Injection Molded Basic Shapes of Poly(aryl ether ketone) (PAEK)

Photo courtesy of Curbell Plastics, Inc.

A typical request for quotation for a plastic that meets a material specification would be:

“Please provide pricing on 30 feet of 2″ diameter acetal rod per ASTM D6100-17 S-POM0111.”

The scope ASTM D6100-17 shows that the standard applies to extruded, compression molded and injection molded acetal, plate, rod and tubular bar. “S-POM0111” indicates that the material is an unfilled general purpose homopolymer acetal with certain mechanical property and dimensional stability requirements. These requirements can be certified to by plastics manufacturers and distributors as a normal part of doing business.

In contrast, this RFQ includes performance requirements:

“Please provide pricing on 30 feet of 2″ diameter acetal rod per ASTM D6100-17 S-POM0111. The material must be suitable for use in direct sunlight and with incidental contact with aircraft fluids.”

In this case, the distribution salesperson should take exception to the second sentence since it is the customer’s responsibility to determine the suitability of the material for use in sunlight and in contact with chemicals.

Suggested Best Practices for Plastics Distributors

  • Carefully review plastic material specifications that appear on RFQs.
  • If the specifications are complex, involve a quality management professional for guidance.
  • Collaborate with manufacturers to quote on materials that meet external specifications.
  • Clarify if quotations include lot test reports and if there are any additional charges for testing.
  • Take exceptions to specifications as required.
  • Never certify to a specification that guarantees performance in a given application.
Suggested Best Practices for Plastic Stock Shapes Manufacturers
  • Provide distributors with ready access to compliance professionals who can answer questions about external specifications.
  • Whenever possible, include both a resin specification and a shapes specification on material properties sheets. This saves time when distributors are responding to RFQs.
  • Take the time to explain exceptions and offer alternatives rather than simply no-quoting an opportunity.

The purpose of this article has been to provide some guidelines for responding to requests for quotation that include conformance to external material specifications. Distributors and manufacturers who wish to take a deeper dive into this topic are encouraged to participate in material specification training, which is offered by academic institutions, quality process training companies and standards organizations such as ASTM International.

Dr. Keith Hechtel is the Vice President – Business Development & Marketing for Curbell Plastics, Inc. For more information contact Curbell Plastics, Inc. at 7 Cobham Drive, Orchard Park NY 14127-4180, USA; by phone at (716) 667-3377 or (888) CURBELL; or online at www.curbellplastics.com.
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