Material selection for mass-production applications

Which material properties matter in series production?

A plastic bearing used in shipbuilding must be capable of performing very different functions than a food-grade ring in a filling machine. At ANKRO, we have built up this knowledge and experience over many years. Depending on the application, various properties come into play, such as:

• Mechanical: tensile strength, wear resistance, stiffness (E-modulus), and impact resistance. For moving parts or components under load, these factors determine whether a product functions properly.
• Thermal: temperature resistance, thermal expansion, and heat deflection temperature (HDT). Particularly relevant when a part heats up or is in a hot environment.
• Moisture and chemistry: moisture absorption (notorious in nylon / PA6), chemical resistance, and corrosion behavior. Moisture is often underestimated and can measurably alter a part’s dimensions.
• Other: electrical insulation, coefficient of friction, and FDA/Food Grade suitability.

The latter, in particular, is sometimes underestimated in practice. When a part comes into contact with food, the Food Grade requirement significantly limits the number of suitable plastics. This directly affects both the choice of material and the unit price.

The above may seem like a checklist, but in practice it involves weighing options. A material that excels in one area may fall short in another. That is where the expertise lies: knowing which property is decisive in your application and which ones you can compromise on in exchange for a better price or better machinability.

You won’t find these details in a datasheet. A plastic may look good on paper but still fall short in production. Understanding the difference between the datasheet and reality requires experience with how materials behave in mass production, not just how they’re supposed to behave. We’d be happy to share that experience with you upfront, rather than after the fact.

What determines your unit price in mass production?

Purchasers naturally look at the price per kilogram, but we then emphasize to them: in mass production, only the unit price matters. And that is determined by more than just the material.

There are significant price differences between different plastics. For example, the price difference between POM and PEEK can easily be a factor of ten or more, and that is not an exception. POM is the workhorse for many applications: easy to machine, dimensionally stable, and strong enough for most tasks. PA6, PETP, or PE are also more than sufficient in many cases. PEEK is technically impressive, but overkill for most production runs. The trick lies in choosing the most cost-effective material that still meets your specifications.

In addition to material selection, four other factors contribute to the unit cost:

• Machinability - Soft plastics are often more difficult to machine and cause faster tool wear, which drives up your unit cost.
• Scrap and waste - Materials that behave unpredictably during the process result in more scrap, and every rejected part represents lost time and material.
• Batch size - Larger batches mean a lower unit cost, provided the process runs smoothly. With unstable processes, scaling up actually works against you.
• Post-processing - Deburring, polishing, or conditioning adds costs, but is sometimes necessary to stay within specifications. Determining which post-processing steps are truly necessary and which can be omitted makes a significant difference in batch costs.

At ANKRO, we factor in workability and post-processing right from the start when providing material recommendations and cost estimates. This helps prevent a material choice that seems cost-effective on paper from ending up being more expensive than necessary during production. When you take everything into account, you get a realistic picture.