Metals, because of their densities and high melting points, consume a lot of energy for the fabrication and the use of parts and goods. Generally, the heavier the parts are, the more energy they consume during their service life. The ousting of metals by plastics leading to lighter products benefits the processing steps and performance during the complete service life.
Moreover the most common metals are ferro-alloys that are often susceptible to corrosion and rusting and thus, need to be re-painted often during their service life or even be replaced.
Consequently, metal substitution with weight reduction is the need of the hour for the industry.
Generally speaking, polymers do not perform like metals from a mechanical point of view but the design freedom allows a better suitability to adapt the local part geometry and the effective local constraints leading to a better exploitation of the characteristics. This was anticipated for markets such as Automotive and Transportation where the running energy and the emitted pollution are directly subjected to the total transported mass (fuel consumption and CO2 emission...). The construction and civil engineering sector values the ease of set ups with lighter weight handling machines while E&E takes into account the insulating properties of polymers and the possibilities of miniaturization.
To compete with metals, the main requirements for polymers are good dimensional stability, high mechanical performances, and temperature resistance. This is followed by the need for other properties such as better durability, FR and higher barrier performance notably to fuel. Lastly the breakthrough of bio-sourced polymers is a buoyant green point.
Many ways are being investigated - from polypropylene up to high performing engineering plastics reinforced with unidirectional or random glass or carbon fibres, plastic/metal hybrids, sandwich composites…
Metal replacement isn't a simple issue of polymer choice but must take into account complete solution systems including the plastic and its formulation, the obtained mechanical performances and collateral properties, the design, the processing method and the environmental impact.
I agree with Patrick. This is an excellent overview. Showing the advantages of plastic over metals but also the disadvantages.
How can I get the reference to the pictures/graphs attached?
Omnexus Team : Dear Alfredo, here are further details on the table and figure references: Figure 1: Diagram based on Michel Biron's analysis Table 1: Synthesis from data gathered in "Thermosets and Composites, 2004, Michel Biron, pp 5 to 7" and "Thermoplastics and Thermoplastic Composites, 2007, Michel Biron, pp 5 to 7" Figure 2: Diagram built from Michel Biron's own database on selected announcements made on metal replacement, e.g:
“First PA-based reinforcement beam for truck radiator grilles: the choice of this material allows cost saving of 30% compared with an equivalent metallic beam as well as a reduction of 10% of part weight” “GM currently has developments in progress for a plastic structural oil pan and a timing chain cover — two parts that would replace existing metal parts at a 50% weight reduction.”
“Carbon fiber-based composite replace aluminum for dampers: As a result the new composite dampers that include a complete suspension strut with integrated wheel carrier weigh nearly 50% less than aluminum-based ones.”
“The composite solution using the 3B glass fibers allowed a 40% weight reduction compared to the traditional metal CNG tanks”
Metals Will Never Do The Job at Such Low Weights - May 12, 2010
posted by Patrick Ellis at Patrick Ellis Consultants
An excellent overview of a subject which is now getting well-deserved attention. The choice of materials and systems is extremely broad and must be confusing to non-plastics engineers. This is an excellent opportunity for plastics engineers to assist in the development of high-performance systems. Companies who have the courage and foresight to invest in such support, will see the positive results of their labours return to them, many times over.