Plastics are catching up with metals -- at least some of them. We recently told you about DuPont's Zytel HTN that replaced brazed metal in a cross-over coolant component for injection molded Ford engine manifolds. Now RTP Company has developed carbon-fiber-reinforced thermoplastic compounds for injection molding with specs that vie with metals in their stiffness and strength.
The new Ultra Performance series of structural compounds are made of short, carbon-fiber-reinforced resin systems based on PEEK, PPA, PPS, and PEI. RTP Company is known for its high-temperature structural thermoplastic compounds, as well as those with structural and wear-resistant properties. The new high-temperature resin systems are available in a range of carbon-fiber loadings from 20% to 40%. They are aimed at a broad variety of applications in industries such as aerospace, automotive, industrial, medical, and energy. Targeted metals to be replaced are magnesium, zinc, and aluminum.
Rings and seals traditionally machined from thermoset stock shapes can be more efficiently injection molded using RTP Company's Ultra Performance Structural Compounds. These provide higher strength and stiffness properties from carbon or glass fibers that rival those of metals, along with temperature and chemical resistance characteristics of the host polymer: PEEK, PPA, PPS, or PEI. (Source: RTP Company)
The Ultra Performance series uses compounding techniques that maximize the integrity of the fibers, so strength and stiffness are higher than those of the company's previous products, as well as higher than those of some competitors. For example, RTP 2287, using PEEK and 40% carbon fiber, has a tensile strength of 305 MPa, and RTP 4087, using PPA and 40% carbon fiber, has a tensile strength of 360 MPa. This compares with tensile strengths of a zinc die casting alloy (ZAMAK 3) at 2.85 MPa, a tempered aluminum alloy (6061-T6 Al) at 310 MPa, and a cast aluminum alloy (A380 Al) at 324 MPa.
Just making carbon-fiber-reinforced compounds using PEEK isn't something new. "Many companies have produced carbon-fiber-reinforced PEEK compounds," an RTP spokesperson told Design News, in an email. "No one but RTP has been able to achieve these mechanical properties."
The Ultra Performance series uses compounding techniques that maximize the integrity of the carbon fibers, so strength and stiffness are higher than those of the company's previous products, as well as higher than those of some competitors. (Source: RTP Company)
Aside from superior mechanical properties, the new compound series also features high thermal and chemical resistance, as well as improved fatigue and impact resistance, according to a press release. Targeted applications are those in demanding environments such as industrial fluid handling and energy exploration. The compounds also have lower densities than the metals they replace, making them useful in applications where cutting weight is critical. A variety of fiber types are available, including short and long glass fibers in addition to short carbon fibers. You can access specs for the entire series of compounds here.
RTP Company offers custom compounding of additional capabilities, such as resistance to friction and wear at high pressure/velocity ratios without the need for external lubricants. Flame retardants can also be added to PPA compounds. The other resin system materials -- PEEK, PEI, and PPS -- are already inherently flame retardant.
Ann, on further consideration I am not exactly certain of what I was thinking about either. It seems that on occasion something that seems like a good idea at the time turns out to not be such a very wonderful thing. This may have been one of those instances. Fortunately no great harm done this time. Rational thought wins again.
Ann, yes, I have read about it a few times in DN over the years. But I have not seen an online discussion.
And the way to handle a compay slant on an article is by identifiying the author. Consider all of those wonderful articles by Jim Williams and Bob Pease. EAch time they were identified as being with their associated companies, which always prompted me to respect those companies for hiring such brilliant people.So linking author, company, and product would be the best choice. It would instantly identify the bias and also show the basis for credibility.
William, this is a highly specialized area of research. There's tons of information and studies out there about recycling of different materials. Unfortunately, much of it is not independently conducted--for example, a lot has been sponsored by one or another materials industry so it's hardly unbiased. Fortunately, there is some good data here and there, sometimes sponsored or conducted by trade organizations of recycler companies. We've done some reporting on this at DN.
Ann, I have never investigated the details of recycling aluminum, but it certainly would take more energy to melt it than to melt most thermoplastics. A report on recycling might lead to an interesting discussion string.
William, that's a good point about reuse/recycling. Aluminum makers like to talk about how that metal is endlessly reusable. That's true, but it takes a lot more energy and processing than just grinding up and/or melting plastics for reuse.
Greg, that cost/time-saving argument has been a longstanding one for injection molding, but the capabilities of the materials have not made it fully competitive with metals processes. Clearly, that's changing.
Great point Ann about the additional cost advantages of one-step injection molding. While the raw material cost could be slightly higher for this composite material, using injection molding for net shape could bypass more expensive machining methods needed for some metals.
It does sound like the fiber reinforced thermoplastics are a worthwhile replacement for the three metals listed, and certainly a good choice over thermosets, since it would seem that thier scrap can be recycled "short loop", by regrinding, while thermosets can't. At least they could be recycled in less demanding applications. Of course cost is always a concern, but that would need to be calculated for each case because of the numerous variables in each application.
The one thing that was not mentioned was ultraviolet resistance, which is important in some applications.
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