Selecting the right material can determine whether a part performs as it should or fails prematurely. We made this plastic material selection guide to help engineers, designers, and purchasing teams narrow hundreds of polymer choices into a few that can work for their application requirements.
Defining the Application and Functional Demands
Every plastic performs best under certain conditions. Before you look at resin names, start by analyzing what the part is supposed to do, where it will operate, and how long it needs to last.
This step is the foundation for any reliable plastic material selection and criteria guide, as it defines the loads, environments, and processes that your material will have to endure.
Structural Frames and Support Components
If the part is part of a weight-bearing frame or assembly, it’s important to prioritize dimensional integrity. Ultem, glass-reinforced nylon, and PEEK handle continuous compression and torque really well, which is why they’re often used for housing, load arms, and machine bases.
Friction, Motion, and Dynamic Interfaces
Parts that spin, slide, or pivot, such as bearings, bushings, and conveyor guides, need low friction and controlled wear. Some of the best choices for reducing surface wear and eliminating the need for external lubricants are acetal, UHMW-PE, and lubricated nylon.
Optical or Lighting Components
Designs that require light transmission, such as architectural panels or instrument covers, need to offer optical clarity. Acrylic (PMMA) is often the most obvious choice in our plastic material selection guide, thanks to its glass-like transparency. However, polycarbonate can be just as clear in many cases and offers a higher level of impact strength.
As an added bonus, both can be UV-stabilized for outdoor visibility.
Containers, Fluid Systems, and Lines
If the part is meant to hold or transport liquids, check its chemical resistance and leach behavior. Polypropylene, HDPE, and PVC perform well in contact with acids, alkalis, and cleaning agents, which is why they’re often used in healthcare and food-handling systems.
Electronic or Electrical Components
Boards, insulators, and electrical enclosures have specific flame and dielectric strength requirements. For these applications, we recommend ABS, PBT, or polycarbonate blends, as they don’t arc when exposed to high temperatures and provide excellent insulation.
Weather-Exposed and Architectural Parts
Weather-Exposed and Architectural PartsAnything made to sit outdoors, such as panels, glazing, or signage, will inevitably face UV exposure, moisture, temperature changes, and inclement weather. Acrylics and polycarbonates are top choices for outdoor applications, as they retain their strength and color with low UV degradation ratings.
High-Performance or Specialty Applications
For aerospace, defense, and semiconductor programs, it’s important to have materials that can withstand extreme heat and pressure and have a high level of chemical resistance. Most companies in these industries opt for PEEK, PTFE, and polyimide.
Note that each of the above categories accounts for a unique combination of polymer properties, such as stiffness, toughness, clarity, and chemical resistance. When you have the right expectations early on, it makes the next step in your plastic material selection criteria much more measurable.
Make sure to refer back to this plastic material selection guide as your requirements change.
Measure Mechanical Strength and Physical Performance
Once you know how your plastic will function, it’s time to focus on how the material will behave under mechanical stress. The stage of the plastic material selection guide takes a closer look at measurable numbers that engineers can compare in the context of performance goals.
Tensile and Compressive Strength
Tensile strength measures how much pulling force a material can withstand before it deforms, while compressive strength gauges its resistance to crushing under load. Engineers can take a look at these values together to determine how a resin behaves when stressed in opposite directions.
For load-bearing components and press-fit assemblies, plastics with high tensile and compressive ratings, such as PEEK and nylon 6/6, are excellent choices.
Flexural Modulus and Rigidity
The higher the flexural modulus, the better a sheet stays flat under load. This is important for panels, machine guards, frames, and any other types of transparent barriers or precise enclosures.
Impact and Shock Resistance
Environments with vibration or collision risk require materials that can absorb sudden energy without fracturing. While acrylic is an excellent choice for stiffness and clarity in minimal impact applications, plastics like polycarbonate, ABS, and PEEK offer some of the highest impact resilience ratings.
Hardness and Surface Durability
The hardness of the surface influences how resistant it is to wear. Acetal and UHMW-PE have smooth, low-friction finishes, perfect for parts that slide across metal or composite surfaces.
Coefficient of Friction and Lubricity
For moving interfaces, part of your plastic material selection criteria should be how well surfaces glide against one another. For minimal heat buildup and wear, we recommend low-friction materials like PTFE-filled acetal and lubricated UHMW.
Assess Thermal Requirements
Temperature is an important part of our plastic material selection guide, as it has a direct impact on safety and performance, and each resin has limits that define how well it responds to prolonged heat exposure.
Thermal stability should be one of your top plastic material selection criteria. Consider:
- Continuous Service Temperature – The heat range of plastic can endure without significant property loss.
- Heat Deflection Temperature (HDT) – The temperature where material begins to soften under load.
- Dimensional Stability – A material’s ability to maintain tolerance despite thermal expansion or contraction.
High-performance materials like PAI, PBI, and Ultem perform well in high-heat applications.
Meeting Regulatory Standards
Many sectors require materials to comply with agency regulations. Healthcare, food processing, and transit applications often involve FDA, NSF, or ISO 10993 standards, and these standards should guide your plastic material selection.
For instance:
- Food-grade plastics often use polypropylene or HDPE, as they have low extractables.
- Medical-grade plastics like polycarbonate and PEEK meet strict sterilization and biocompatibility requirements.
- Electrical components use UL-rated materials for flame and voltage resistance.
Match the Process to Design and Volume
Once you’ve narrowed down your plastic material selection criteria, the next question is, how will you bring your design to life? Every fabrication method interacts with plastics in its own way:
- Thermoforming works best for broad, detailed shapes. It’s quick to set up, great for medium runs, and offers cleaner contours with better cost-effectiveness compared to molding. If you’re working with signage, vehicle panels, or equipment housings, this is often the most efficient path.
- CNC routing and laser cutting are the most accurate. These processes are better for smaller production runs or products with intricate cuts. If you need prototypes or one-off parts that look finished right off the machine, this should be your go-to.
- Injection molding comes in when you’re ready to scale. Once the tooling is dialed in, you can use this process to produce high volumes of identical parts with exact repeatability and quality.
We have several fabrication capabilities here at Polymershapes, and it can sometimes help to find the right process for your build to determine what type of material you want to use. The plastic material selection guide logic applies here, too.
Factor In Recyclability and Sustainability
More engineers are factoring sustainability into their designs than ever, and engineering plastics are evolving to meet these goals.
PETG, HDPE, and polypropylene are examples of materials that can be reclaimed, reprocessed, and recycled into new products without losing strength. With these materials, you get more flexibility down the road and the benefit of keeping waste out of landfills.
There are a few design moves that can make a big difference here:
- Mark each part with the right resin identification code
- Choose adhesives and coatings that allow for clean separation during the recycling process
- Opt for durable materials that don’t need frequent replacement
Beyond this plastic material selection guide, we can help you choose material that strikes the balance between performance and sustainability. Take a look at our plastic recycling services to learn more about how we help reduce environmental impact.
Finalize Your Material and Prep for Fabrication
In addition to the factors above, there are several other things to consider, including machinability, weight-to-strength ratio, fatigue strength, creep resistance, and more. Here at Polymershapes, we have access to highly detailed mechanical test data that can translate these ultra-technical specifications into real-world performance for you.
Once you’ve weighed all the options, you’ll have a few strong contenders. The last step in our plastic material selection guide is choosing the one that ticks every box for your part’s real-world uses.
Take a look at our lineup of engineering plastic materials and request a consultation with us to match your part with the proper mechanical profile.
Let the Polymershapes team help you with the final details. We’ll confirm that you’re chosen plastic material meets all of your selection criteria.
Request a quote from one of our materials experts today.
