Plastics Material Selection Support

Design

The design of a component or finished assembly is generally defined with the goal of satisfying the functional needs of the application. However, it is critical to review the design to ensure there are no oversights in either the manufacturing process or the material that could be detrimental to the performance of the end-product and to define any features that could be critical to the material selection process. Some common criteria to consider include:

Wall Thickness: uniformity, rib-to-wall thickness ratios, and thin or thick areas that are critical to part performance
Corners: proper use of radii and avoidance of sharp corners
Stress: locations at risk of high stress concentration
Dimensional: areas at risk for non-uniform shrink or warp
Cooling: geometry that may impart cooling challenges

It is important to carefully consider the design and to be prepared and flexible to alternatives or changes during the material selection process. It is sometimes best to accommodate a design change that will enable a lower performance (and less expensive) material to work in the application.

Performance and Functional Requirements

Along with design considerations, it is critical to define the end-use performance requirements of the application, including any regulatory or agency ratings that may apply. Questions to consider include:

What are the market and end-use requirements?
What are the mechanical considerations?
Stiffness, strength, impact, fatigue, creep, hardness, requirements at elevated temperatures or humidity, etc.
What are the dimensional and tolerance needs?
What are the environmental conditions to which the product or component will be exposed?
Temperature extremes, moisture considerations, UV exposure, chemical exposure, etc.
Are there any wear, abrasion, or friction requirements?
What are the aesthetic requirements (e.g., gloss, texture, color, etc.)?
Are there market, product, or government agency regulatory requirements?
Flame rating, electrical properties, FDA, ISO10993 or USP Class VI, NSF, UL, Mil Standard, FMVSS, CSA, Auto Approvals, RoHS, REACH, CA Prop 65, Etc.
Do sterilization requirements need to be considered, such as autoclave, EtO, radiation, etc.?
Are there any sustainability requirements?
Recycled content, bio-content, compostability, etc.

Process and Tooling

The manufacturing process must also be carefully considered during the material selection process to ensure that relevant details are not overlooked and that associated requirements can be accommodated by the material selected.

Define the Process: injection, extrusion, extrusion blow, injection blow, thermoforming, rotational, film, etc.
Process Needs: flow, shrinkage, release or slip, anti-block, low water carryover, pellet or mesh size, etc.
Tooling: cavitation, draft considerations, gating and melt delivery, venting, cooling, steel types, blow ratio, blow mold pinch-off and land design, blow pin alignment, etc.
Secondary Processes and Automation: trimming, drilling, fastening, adhesive bonding, thermal welding, decoration or painting, etc.

Rank Requirements

It is important to prioritize what material attributes are most critical to an application or component. To achieve this objective, the application requirements must be reviewed and prioritized such that the most important requirements are used to guide the material selection process.

For example, if an application requires a transparent material, with excellent light transmittance and outdoor UV resistance, the number of material options may be limited to a single material such as Acrylic (PMMA).

Another application may require a transparent material with other functional attributes being less critical. Therefore, several materials may be considered, such as:

Acrylic (PMMA)
PC
GPPS
SAN

Ranking and reviewing the requirements most critical to the application will help ensure that the appropriate materials are considered for the application and will also support achieving the goal of finding lower cost materials that also meet the defined requirements.

Evaluating Materials

After establishing and ranking the requirements, our technical experts will help you evaluate and compare potential material solutions for your application. The final selection you make should be based on:

Material Properties – data sheets and supplemental material test data
Regional and global availability
Producer preference
Supply availability
Previous experience
Competitive assessments

End Use Testing

Testing of the actual end-product or component is necessary to confirm the material selected, part design, and manufacturing process deliver the performance required for the application. This step is completed at various phases within the product development cycle, such as at initial prototyping, production validation, or both. Our experts can help you establish a test plan, analyze the test data to help you determine if the material, part design, or process will meet your needs, and offer suggestions for improvements if needed.

Test verification steps used to evaluate end results may include:

3D Printing: For basic “proof of concept.”
Prototyping: Rapid cut tooling to confirm form, fit, and function needs are met, as well as initial assembly and mechanical requirements.
Prototype Testing: Lab simulations, or real word tests, of components or assemblies to provide an early indication of how the product will perform. Keep in mind that prototype parts are not 100% production representative, which may need considered when reviewing results.
Production Scale-Up:

Establish a validation and test plan strategy, based on a risk and failure mode assessment of the components and end-product or assembly.
Develop Bridge to Production (low cavitation) or final production tooling.
Use a scientific approach to develop the manufacturing process, with metrology assessments that may include data collection though DOE’s, capability studies, and first article inspections.
Confirm that the parts meet the specified design and performance requirements as originally defined in the validation and test plan.
Perform component or assembly testing, such as weathering, UL flame or electrical, drop testing, fatigue/vibration, chemical compatibility, etc.
Adjust design, tooling, process, or material as needed.
Perform final end-use product testing prior to launch.

Your partner in selecting the ideal resin