Thursday 23 May 2024

Designing Parts With Polymers - Material Selection Checklist [Free Download]

Hello and welcome to this blog post. Today’s topic is on designing with plastics and in particular i will provide you with a material selection checklist as a guidance tool for your next project. 

Polymer material selection - an important step in the plastics part design process

Unlike the typical process of finishing the design and then searching for a suitable material, material selection is best done in tandem with the design development.

Design can adjust to material restrictions and capabilities when material selection is developed concurrently.

Technical data sheets (TDS) and material selection tools can be used to compare potential materials to design criteria and component service conditions. The data can be entered into a checklist, highlighting qualities that are not relevant.

A checklist is useful since it makes sure that no manufacturing detail, property, or service requirement is missed.

Covering effectively the product requirements, a combination of functionality questions and selection factor questions can support you to achieve this. The functionally and selection factor questions can be found here.

A Polymer Part Design Checklist, I published together with design engineer Vatsal Kapadia here.

Polymer Material Selection Checklist

My checklist consists of 12 sections and next we have a detailed view on all the sections. You can download the Material Checklist here. The checklist is in line with Step 1 of my  Polymer Funnel methodology

In this first stage we map out the true part functions and material requirements. After this we translate the requirements into material selection factors.

This can be done with the support of questions (summarized in the checklist) such as what load does the plastic part need to carry? Or/and will the part be exposed to chemicals? 

Figure 1: Designing with Plastics - Polymer Material Selection Checklist 

1. General

-Performance requirements (structural, etc.)

-Combining multiple parts or functions

-Structural load (static, dynamic, cycling, impact, etc.)

-Environment (Chemical, temperature, time)

-Tolerance requirements

-Lifetime of product

-Quantity of product vs. manufacturing process

-Secondary operations

-Packaging and shipping


2. Environment

-Temperature

-Time

-Load

-Chemicals, water, humidity, etc.


3. Engineering Design Data

-Type of load

-Frequency of load

-Stress rate (compression, tensile, flexural)

-Strain amplitude

-Load deformation (tensile, compression, shear, etc.)

-Apparent modulus (includes strain due to creep)

-Direction of load

-Correlating test data with end use

-Safety factor


4. Part Geometry Data

-Part volume

-Size restrictions for design?

-Thickness restrictions for design?


5. Material and Process

-Directional layout of reinforcements

-Regrinding

-Pre-drying

-Prototyping (machining, moulding, additive manufacturing)


6. Appearance

-Style

-Shape

-Colour

-Surface finish/ weld lines / flow lines/ parting line / gate location


7. Tests (UL, SAE, ATIM, etc.)

-Tension

-Compression

-Creep

-Dynamic/ fatigue/torsion

-Impact

-Poisson’s ratio

-Continuous service temperature / UL temp. index


8. Economic Factors

-Cost of present part and cost aim

-Cost estimate of part with plastics

-Faster assembly and elimination of finishing operation

-Redesign part to simplify product


9. Sustainability Factors

-Use of regrind

-Post industrial recycling (PIR)

-Post consumer recycling (PCR)

-Biosourcing

-Lifecycle assessments (ISO 14040)


10. Temperature Range of Part

-Short term and long term heat exposure

-Heat aging - retention of properties over time and temperature

-Dimensional stability at elevated temperature

-Hydrolysis stability needed


11. Flammability and Electrical Requirements

-Parts needs flame rating (UL 94 - V0, HB, etc.)? If yes, at which thickness?

-Glow wire or unattended appliance requirement?

-Electrostatic Discharge Shielding (ESD)

-Electro Magnetic Interference (EMI) shielding


12. Special Requirements

-UV exposure?

-Chemical exposure

-Additional approvals and RoHS

-Material restrictions (halogen, copper, etc.)?

-Special environments (nuclear protection needed)?

-Overmoulding concerns

-Warpage concerns due to mating with another part

-Laser welding needs?

-Special colorability?

-Conductive requirements (thermal conductive and electrical isolating)?


You can download the Material Checklist here

I offer to select the optimal polymer for your project, doing the polymer material selection together with you, and also teaching polymer material selection as a training in a group - let me know how I can help you here.

Thanks for reading and #findoutaboutplastics

Greetings

Herwig Juster

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.

!NEW! Ultra and High Performance Polymer Selection - new online course coming soon - join the waiting list

Literature: 

[1] https://www.findoutaboutplastics.com/2020/08/what-is-difference-between-industrial.html

[2]  https://www.hardiepolymers.com/knowledge/designing-with-plastics/

[3] https://www.findoutaboutplastics.com/2022/08/polymer-material-selection-defining.html

[4] https://www.polymermaterialselection.com/online-selection-tools

[5] https://www.polymermaterialselection.com/contact-me


Tuesday 14 May 2024

My Comment on the Article “Ocean floor a 'reservoir' for plastic pollution, world-first study finds”

Hello and welcome to this post in which I share my comment on the article I recently read on plastics pollution on the ocean floor. 

Here you can access the original article by CSIRO/Natalie Kikken and the research paper here.

The ocean ground pollution study

The research was conducted in the collaboration of different research institutes from Australia and Canada and the highlights of the study are summarized as follows: 

-that the deep sea plastic sampling efforts to date are concentrated in coastal marine environments.

-the ocean floor reservoir contains 3–11 million metric tons of plastic pollution. This number was estimated by models and the raw data came from remote operated vehicles (ROVs) and another source used the data from bottom trawls.

-Macroplastic clusters (definition: particles larger than 5 mm) around located around continents, close to human populations.

-And the researchers highlight where gaps in sampling effort can be filled to improve future models.

How do I see the result of this research and what is my assessment of this study?

On the one hand it is good to investigate the topic of current plastic pollution on the ocean floor, on the other hand, I miss the comparisons to other polluting materials which are also present on the bottom of our seas. 

Apart from plastics, which only represent a small percentage in overall materials (1 vol.%), which other pollution can one find on the ground of our seas?

The infographic below highlights other materials which were purposely discharged to the bottom of our seas. They represent a danger for sea life and us humans too: 

-Oil & Wrecks: 6,300 wrecks containing 15 million tons of oil

-Radioactive waste: 200,000 tons nuclear waste

-Heavy metals:  over 1 million tons of heavy metals in industrial wastes

- Ocean dumping prior to 1972: 100 million tons of petroleum products

-2-4 million tons of acid chemical wastes from pulp mills

>100,000 tons of organic chemical wastes

Infographic: Ocean ground pollution - it's not only plastics. 

Takeaways

In conclusion, plastics should not end up in the oceans in the first place. It is mainly due to littering of people. We have littering problem and not a plastic problem. They are part of the solution and should be collected and recycled (ranging from thermal recycling over downcycling to new products). 

Also, when reading such articles, always keep a critical eye on the data presented and start asking yourself questions. I did the same when I came across the article from the CSIRO organization and added some more data on other polluting materials. 

If you are interested in the Ocean plastic topic, check out these two posts: 

What The Media Does Not Tell You About Ocean Plastics

Ocean Plastics Episode 2 - What The Media, NGOs and Others Still Not Tell You

Thanks for reading and #findoutaboutplastics

Greetings,

Herwig Juster

Interested in having a second opinion on your material selection and high performance polymers, including price evaluation or  discuss with me about your current sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.

!NEW! Ultra and High Performance Polymer Selection - new online course coming soon - join the waiting list join the waiting list

Literature: 

[1] https://www.csiro.au/en/news/All/News/2024/April/Ocean-floor-a-reservoir-for-plastic-pollution-world-first-study-finds

[2] https://www.sciencedirect.com/science/article/abs/pii/S0967063724000360?dgcid=coauthor

[3] https://www.findoutaboutplastics.com/2022/06/ocean-plastics-episode-2-what-media.html

[4] https://www.linkedin.com/pulse/plastic-fact-over-fiction-chris-dearmitt-phd-frsc-fimmm/

[5] https://www.newscientist.com/article/mg20727761-600-why-wartime-wrecks-are-slicking-time-bombs/

[6] https://www.youtube.com/watch?v=XgdE55ZAFvs&t=4s

[7] Michael F. Ashby: Materials and the Environment: Eco-informed Material Choice

[8] https://assembly.coe.int/nw/xml/XRef/Xref-XML2HTML-en.asp?fileid=18077&lang=en

[9] https://www.envirotech-online.com/news/water-wastewater/9/breaking-news/why-is-there-heavy-metal-in-our-oceans/32291

[10]https://www.todayifoundout.com/index.php/2020/12/the-bizarre-market-for-old-battleship-steel/

[11] https://inis.iaea.org/search/searchsinglerecord.aspx?recordsFor=SingleRecord&RN=21044010

[12] https://www.epa.gov/ocean-dumping/learn-about-ocean-dumping#Before



 

Wednesday 1 May 2024

Design Data for Polymer Engineers: Creep Performance of High Performance Polymers (ISO 899; Multipoint data)

Hello and welcome to this new blog post. Today's topic is the creep performance of high performance polymers such as LCP, PEEK, PPS, and PPA. It is another important multipoint and long-term data set for polymer material selection and part design. 

The creep strength and toughness of High Performance Plastics at different temperatures we discuss here.

Introduction to creep in plastics

Creep, also known as cold flow, is the deformation under a static load over time and helps to gain insights over the product lifetime. Understanding the creep behavior is one puzzle key during polymer material selection. Creep resistance materials are needed for applications such as structural components, joints, fittings and hydrostatic pressure vessels.  In general we can distinguish between primary, secondary, and tertiary creep.  When you conduct a creep test (for example according to ISO 899-1 or ASTM D2990) it is important to keep the applied stress on the material at a constant level. This allows in turn to plot  the lifespan of your product.

Relevance of creep performance data for polymer material selection 

As a polymer design engineer you are interested in creep data when you are dealing with application parts which are under high load for a long period of time. Overall, environmental changes impact the creep behavior too. Especially the increase of the temperature decreases creep performance dramatically. Also, for metal-to-plastic conversion, creep data are of essence. 

Comparison long term creep performance of high performance polymers and die casting metals

Figure 1 presents the creep deformation data as a function of time for several ultra- and high performance polymers (PEEK, PAEK, PPS, LCP, PPA, PPA+PA66 blend, PARA, and PESU). Also, the creep performance of two die-casting metals (zinc alloy - ZAMAK3; aluminium alloy - AG3) is shown. 

Comparing the results of the high performance polymers it can be shown that the initial elongation is higher compared to that of the aluminum alloy. However, the slope of the curve is in a similar range. Opposite is the case with the zinc alloy which displays severe creep after 100 hours at room temperature and a strength level of 100 MPa. In the case of zinc and also magnesium alloys, high performance polymers are able to outperform die-casting metals in a metal replacement scenario. 

Figure 1: Creep data of high performance polymers vs. die casting metals (ISO 899-1).

Conclusions

Considering creep data as long-term performance data during polymer material selection is a vital part during a metal-to-plastic conversion. It allows access to the handling of a static load at different temperatures and different times.

Thanks for reading and #findoutaboutplastics

Greetings 

Herwig Juster

Interested in having a second opinion on your material selection and high performance polymers, including price evaluation or  discuss with me about your current sustainability, and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.

!NEW! Ultra and High Performance Polymer Selection - new online course coming soon - join the waiting list

New to my Find Out About Plastics Blog – null



Literature: 

[1] https://www.findoutaboutplastics.com/2022/11/plastic-multipoint-design-data-creep.html

[2] Ketaspire PEEK Design Guide: https://www.syensqo.com/en/brands/ketaspire-peek/documents

[3] https://businessdocbox.com/Metals/95576253-Ems-grivory-material-technology-metal-replacement-with-engineering-polyamides-ron-hamilton-consultant-ems-grivory-uk.html

[4] https://www.sumitomo-chem.co.jp/sep/english/products/lcp/lcp_bs_kikai.html

[5] Ixef PARA Design Guide: https://www.syensqo.com/en/brands/ixef-para/documents