Injection Molding Resin Selection Workbook


Injection Molding Resin Selection


When designed intelligently, injection molded parts can offer product designers durable, light-weight, and cost-effective alternatives to metal parts. But ensuring that an injection molded part lives up to this potential depends in large part on choosing the best resin. Every resin manufacturer publishes in-depth specifications on the properties of their products, but trying to sort out which ones are right for the performance of a specific part can be overwhelming.

Unfortunately, there’s no simple formula or algorithm to follow to select the most appropriate resin for a particular part or application. That’s why Ferriot’s veteran team of engineers works closely with our customers to help them choose the resin that best suits their design goals, performance and budget specifications. We typically have more than 150 varieties of resin in stock at any given time and can obtain non-stock resins from the industry’s leading resin manufacturers quickly to address unique requirements.

To streamline the process and move your components into production as seamlessly as possible, we have developed this Injection Molding Resin Selection Workbook. Taking the time to note your
requirements in advance of meeting with your Ferriot representative will not only speed the selection process but help ensure that the resin chosen is the most appropriate and cost-effective one for the design of the mold and the injection molding process to be used.

Part geometry


Is your part designed to be injection molded?Particular geometries can be difficult to injection mold. Part size, shape and wall thickness could make the part especially prone to warpage, bow, and other defects. The sooner our engineers can review the part’s configuration with Moldflow® analysis and suggest changes to optimize its moldability, the earlier we can begin to narrow the list of appropriate resins.

Design goals for the part (check all that apply)


▢ Reduce weight by replacing another material (such as sheet metal, wood, concrete, or fiberglass) with plastic

▢ Consolidate an existing assembly into fewer parts

▢ Incorporate molded-in assembly features

▢ Improve strength-to-weight ratio

▢ Cut manufacturing costs

▢ Eliminate painting or other surface treatment operations

▢ Improve impact resistance

▢ Improve chemical resistance

▢ Other

Describe the key physical attributes required of the finished part


Chemical and environmental resistance:

Flexible strength

Temperature operating range

Fatigue resistance

Electrical properties

Impact strength


Surface texture

Required approvals (check all that apply)


Depending on your part’s use, it may need to be tested and approved by various governmental
and/or private agencies. Ferriot can help ensure your part is in compliance with the appropriate
agencies by noting such requirements as soon as possible.

▢ Other global agencies
▢ Federal Regulations, ANSI, SAE, FMVSS
▢ Standards for Medical



Must the molded part color-match or texture-match a component made by some other method?:

Do you require a custom color?

Must the part be transparent?

Does it require a surface finish (painted, plated, hard coat, texture, etc.)?

Required markings (logos, warnings, instructions, control labels)

Chemical exposure (check all that apply)


Help us ensure the resin you choose for your part can stand up to the chemicals it will encounter over its lifespan, including during manufacturing/assembly and in its intended environment.

▢ Adhesives
▢ Automotive fluids
▢ Cleaning solvents
▢ Cooking grease
▢ Cutting oils
▢ Degreasers
▢ Lubricant
▢ Mold release
▢ Paints
▢ Printing dyes
▢ Other:

Electrical performance


Depending on your part’s use, it may need to be tested and approved by various governmental and/or private agencies. Help us help you ensure your part is in compliance with the appropriate agencies by noting such requirements as soon as possible.

What will the impact of its electrical environment be on your part?

Will the part be subjected to any electrical load?

Will your part require EMI/RFI shielding or UL testing?

Radiation exposure


HID lamps, fluorescent lights, gamma sterilization units and other artificial sources emit radiation. This radiation can affect the strength and appearance of the parts. If that is likely for your
part, consider UV-stabilized resins

Size tolerance


Tolerances on many parts must be tight to ensure proper fit and function of an assembly.

Note the tolerances your part must adhere to as well as any information you can provide on end-use temperature, creep, load, environment, etc.

Temperature limits


A molded part’s impact and tensile strength, creep resistance, modulus, and other material properties often vary greatly depending on temperature. Note the full range of end-use environment temperatures and consider possible extremes

Lot Size


Number of parts to be produced in each production run and Estimated Annual Usage (EAU):

This will help determine mold cavitation and the most appropriate press to use, thereby helping to determine the most cost-effective lot size.

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NOTICE: Ferriot is Monitoring the Resin Shortage Situation. Read More
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