Essentials of Plastic Material Selection: Key Steps Simplified

Materials selection can be challenging if one doesn’t have a structured plan. Madison Group shared some insights to get your material selection right.

Plastic materials selection involves choosing materials that meet some important characteristics like performance, cosmetics, and costs. But there is not a playbook for doing materials selection. On the contrary, this means doing some property research, taking into account product lifetime and even in some cases, regulation.

You can also read: Solving Material Development Bottlenecks With AI

Exclusion Method for Material Selection

The first thing Paul Gramann, President of the Madison Group, mentions is that as material engineers you need to start with a broad list of materials. He calls them “the Nifty Fifty”, which are the 50 most common polymers in the market due to their availability, cost advantages, molder experience with them, and a decent amount of properties information from materials suppliers as well as the web or testing.

There is a question that you should ask your team before starting the exclusion. Why are you selecting a new material? This will give you some insights into the properties you need to check on your material’s requirements.

Another important thing about materials selection and specifically about plastics is that you need to identify your application conditions, as plastic’s mechanical properties are sensitive to temperature and time.

Single-Point Properties

Once you have a list of the requirements that the material must meet for your application conditions, you can start exploring single-point properties. Most of the time, a material datasheet gives that information.

For instance, parameters like strength modulus, room temperature stiffness, melting or softening temperature, and melt flow index aid in narrowing down material choices. However, since properties can vary with temperature and time, and often exhibit high non-linearity, a graphical approach can be a potent tool.

Another valuable consideration is to examine whether the material under consideration has experienced failures in applications akin to your specific use case.

Multipoint properties

After narrowing down the list of materials, you need graphical data to make an appropriate material selection. This includes Dynamic Mechanical Analysis (DMA) at various temperatures, stress-strain curves across temperature ranges, isochronous stress-strain data, creep and fatigue data, viscosity against shear rate, and Pressure-volume-temperature (PvT). Since much of this data is not readily available on data sheets, thorough database research is essential, and testing may be required at this stage. CampusPlastics can be a good start to database research. Also, SPE has a Material Database for plastics & elastomers and polymer additives to look at.

Validation through simulation

Simulation provides predictive insights into the performance of materials under various conditions, allowing for informed decision-making without the need for extensive physical testing. This not only accelerates the materials’ selection process but also minimizes the costs associated with trial and error. Additionally, simulation enables the exploration of a wide range of parameters, considering factors like temperature, stress, and time, which may be challenging to achieve comprehensively through traditional testing alone.