How to Make Composites Processing and Fabrication Sustainable

#composites, #sustainability, #energyefficiency, #renewableenergy, #fabrication, #processequipment

This week’s newsletter is the third in my series laying out the roadmap to sustainability in composites.  But before I get started, I need to let everyone know that my second book, “Sustainable Composite Materials, A Roadmap to a Circular Economy” is officially released as of April 6 (Monday).  The book covers the watershed of the issue of sustainability for these wonderful materials and provides a workable roadmap for the industry to follow to make the composites industry truly circular.  And I have them in stock and ready to send to anyone that is interested in buying one from my website – www.nedpatton.com.

In the previous two posts in this short series, I have covered the precursors to fiber and resin and the sustainable production of the fibers and resins that make up the building blocks to making a composite part.  So this week I’m going to talk about how to enhance the sustainability of the processes and machinery needed to make the parts themselves.  And while the lead pic here does not necessarily have a connection to the way the wind turbine blades shown here are made, it does demonstrate that given that we can transform the parts of the industry I have written about in the two previous posts in this series, it provides a sense of the scale of the manufacturing capacity needed to meet the coming demand. 

So, the question that I want to answer here is what sorts of things need to change to make the process of turning raw fiber and liquid resin sustainably into advanced composite material parts.  First, however, I have to describe the current processes so that I can describe how they have to change to make all of the processes, equipment, and machinery sustainable and operate on sustainable energy sources.  This needs to include the manufacturers of the processing equipment and what energy sources they use to manufacture the equipment as well as what processes their equipment is designed to be used for, the equipment that fabricators use to make composite parts, and finally the energy sources that fabricators use to make composite parts.  I also need to describe in this what new and emerging manufacturing technologies and processes can be and are being implemented to make these processes sustainable. 

Bio-Composite Processing Equipment from Autonation (IJIst, the Netherlands)

This is an example from a company in IJIst, the Netherlands that makes processing equipment solely for use to make biocomposites.  And while this looks a lot like almost any other filament winding machine, what Autonation has done is to tune the operating parameters of their machinery to accommodate bio-derived and natural fibers as well as the newer bio-derived resin systems. 

What this picture represents is the fact that the machinery used to make composites is typically large and complex.  While nearly all of this machinery is run using electricity as the energy source, some of the older and larger equipment is still run using steam power or other petroleum based energy sources to provide the energy or motive power required for operation.  So, this is just the first piece of the equipment and process puzzle that needs to be updated. 

Fortunately, most of the modern machinery that is used in the larger composites manufacturing organizations is not only electrically powered, it is also digitally controlled and increasingly automated.  With the advent of AI in machinery and process control this has become fairly standard in this industry. 

The electricity that is used to power this manufacturing infrastructure is typically drawn directly from the grid since most of the larger manufacturing facilities are in populated areas where there is skilled labor to run the machinery.  And while the companies that use the grid to drive their machinery and processes typically are agnostic as to where that electricity comes from, there are a few instances in the industry, mostly in Europe, where the large manufacturing centers are beginning to demand that they only be provided electricity from renewable sources.  As it turns out, since these industrial customers are high electricity demand companies, they have much more clout that any single residential household, so they can have much more influence over where their electricity comes from. 

World's Largest Autoclave - ASC Systems, Valencia, CA

But this is just one piece of the overall puzzle in sustainable composites manufacturing.  The next question that must be answered is where does the process heat come from to cure the composite part when it is made.  The picture above provides at least part of the answer.  This is the largest autoclave in the world, built by ASC Systems in Valencia, CA, just north of Los Angeles.  While some of the smaller autoclaves in some of the smaller composite shops that have bought fairly new autoclaves in the last decade or so are driven by electricity, these large autoclaves that are used primarily by large aircraft manufacturers (Boeing and Airbus) and wind turbine blade manufacturers are typically driven by either fuel oil or natural gas.

This represents probably the largest use of petroleum or natural gas in the materials processing and parts manufacture part of this industry.  The resins used for structures like the fuselages of the Boeing 787 or Airbus A350 are very slow and high temperature cure epoxies.  They have to be because the structures are so large that it takes a long time just to get all of the fiber and resin laid down and ready to cure.  The large composites manufacturers like Spirit Aerosystems (recently acquired by both Boeing and Airbus) have to watch their composite out-time or pot life (the time that the resin or prepreg is out of the freezer) to make sure that the resin hasn’t kicked off before the part is completely fabricated.  The resins that Boeing and Airbus use typically have pot lives on the order of 30 days or so (TorayCA T800/3900 system).  These resins, to give them that much time that they can be out of the freezer at room temperature makes them take a lot longer to cure than the typical epoxies that cure in an hour or so.  That means that these autoclaves need to be at temperatures like 350 degrees F for as much as 8 hours just to cook each fuselage.  This includes a slow ramp up in temperature, 2-3 hours at 350F and about 100 psi pressure, and a slow cooling period to make sure that the part doesn’t crack or warp.  So they can run two fuselage sections in these huge autoclaves per day.  Since the autoclaves are able to cook a part 30 feet in diameter and 70 feet long, that’s a lot of natural gas. 

The problem with switching to electricity for these large autoclaves is that the current means of heating that much air or a gas to the temperatures required if you use resistance heating elements is going to take too long and cost too much in electricity at today’s rates for this to be a feasible process for production of large parts.  And with the current state of the utility grid being largely fueled by natural gas or oil, or even some coal in the Eastern part of the country, converting natural gas to electricity just to heat air for this process heat is less efficient than just using the natural gas in the first place.  So, we do have a long way to go for electricity to be used for process heat for large composite parts.

The last thing I’m going to talk about this week is the use of automated processes to lay down fiber and resin to make a part.  These processes, aside from automating and substantially speeding up the process of readying a part for cure in the autoclave, also reduce the scrap associated with hand layup of prepreg.  In other words, they reduce the pile of scrap that is common in most large and small composite fabrication facilities.  While I used the picture above in a post about recycling of composites, what I want to mention here is that the industry, especially for the higher rate manufacturing part of the industry that uses the most raw material, the automation involved in laying up parts before they are cured has allowed a number of composites manufacturing facilities to lower their scrap rate to nearly zero.  That is certainly the case for companies like what used to be Spirit Aerosystems that makes the fuselages for the 787 and A350.  It is also true of companies like LM Wind, Vestas, Siemens Gamesa, and Broadwind, all of whom make wind turbine blades.  In fact, Vestas has specialized in the large offshore blades that are longer than a football field and fairly recently set the world record for wind turbine blade size.  While these blades used to be hand laid up in molds and joined together, the hand layup processes have been overtaken by automated tape laying machines and other low scrap automated processes.  This is primarily because the old traditional hand layup processes are not fast or efficient enough to enable the manufacture of a composite structure that is on the order of 350 to 400 feet long.  So, this is an example where a sustainable, low scrap, high rate process was a technological enabler for an entire industry, the offshore wind industry. 

So, that’s it for this week’s post.  Next week I plan to write about what happens at the end of life for composite parts.  This is the last piece of the puzzle in unlocking circularity in the composites industry, and arguably one of the most important.  So, as always, I hope everyone that reads these posts enjoys them as much as I enjoy writing them.  And I hope people who are interested find something they can use in their lives or at least some ideas that they might be able to put into practice.  At least I hope that these make people think a bit about sustainability and some of the major issues looming before us. 

I will post this first on my updated website – www.nedpatton.com – and then on LinkedIn.  And if anyone wants to provide comments to this, I welcome them with open arms.  Comments, criticisms, etc. are all quite welcome.  I really do want to engage in a conversation with all of you about composites because we can learn so much from each other as long as we share our own perspectives.  And that is especially true of the companies and research institutions that I mention in these posts.  The more we communicate the message the better we will be able to effect the changes in the industry that are needed. 

My second book, which is now officially released and is in stock at Amazon, Barnes and Nobles, my publisher McFarland, and on my website, is a roadmap to a circular and sustainable business model for the industry which I hope that at least at some level the industry will follow.  Only time will tell.  Maybe it will get noticed – as always that is just a crap shoot.  I’ve included a picture of the cover at the end of this post along with the cover from my first book.  Let me know whether or not you like the cover.  Hopefully people will like it enough and will be interested enough in composites sustainability that they will buy it.  And of course I hope that they read it and get engaged.  We need all the help we can get. 

Last but not least, I still need to plug my first book.  “The String and Glue of our World” pretty much covers the watershed in composites, starting with a brief history of composites, then introducing the Periodic Table and why Carbon is such an important and interesting element.  The book was published and made available August of 2023 and is available on Amazon, Barnes and Nobles, from McFarland Books – my publisher, and of course my website which is the best place to buy a signed copy.

Of course the only place where you can get a signed copy of either book is to order one from my website.  I will send you a signed copy of either or both books for the same price you would get charged on Amazon for an unsigned one, except that I have to charge for shipping.  Just go to the link to the product page on my website (https://www.nedpatton.com/product-page) and order either book.    And as usual, here are pictures of the covers of both books.