Aluminium heated tooling allows the controlled manufacture of 32mm OD Shaped Tubing in this case for Outrigger Canoe “Aiko’s” or stick used to connect the “Ama” or float to the canoe to allow adjustment for the ocean conditions.
This type of tooling allows the manufacture of many products with heat control at your fingertips.
John Hayes
www.bladerunneroutriggers.com
Looks like a nice operation. are those tubes all carbon sleeve, or do they have uni in them as well?
How does the mold seal for vacuuming the lay up? or is it a pressure bladder? If bladder do you have a photo?
Thank you for posting this. I’m getting ready to make a 25mm angled tube that will be bladder molded.
My only concern is how to seal the ends of my mold so the bladder doesn’t squeeze out, not sure if it does?
Also can you recomend what size sleeve to use for a 1 inch (25mm) tube?
Hello Hojo & Fastrr,
I will answer both, there is no vacuum process used with this type of tooling, I use a product called Expancell, it is heat activated and it expands 20:1 at 80-100C it pushes your stacked laminate against whatever tooling you dream up, it has to be captured with stop ends etc. but it has to be strong, hence the 32mm thick Aluminium Plate and 1/2" bolts, 100psi plus is exerted on your stacked laminate, which in this case is 200gsm Twill against the tooling-apperance etc. then 3 layers of Unis, then one layer of D/Bias, they are very strong and light and look better than black painted Aluminium Tube!.
I hope this explains the process.
Please explain your process of using Expancel. I noticed on their site they produce it in a variety of forms. Which one do you use?
Jon
The expancel is left in the product? Does it also act as a structural core?
Here is a link to the Expancel product - http://www.akzonobel.com/expancel/products/expancel_du/ - you must choose the most suitable for your application, especially the resin system specs. also your ability to control the heat.
You can leave the expancel in your product after curing, some products are completely enclosed by your laminate, in my case with the open ended tubing the customers want the lightest outcome so I drill out the core to accomodate, although I would prefer to leave it in for added structural properties, if it has not shrunk back from the inner wall of the tube, this scenario is the nature of the product - expand 20-33:1 over X amt. of hrs. to suit your resin system which should be cured, this outcome has a specific time frame, then by heating too long you kill it - by this I mean it shrinks so you loose this added support if required, so you have to trial your outcome!.
Bladerunner, I had a couple of questions if you don’t mind…
First, the expancel product that you are using, how is it provided to you, just as microspheres? What do you need to do to get if from the microspheres to inside your laminate? Do you mix it with additional epoxy or…?
In terms of purchase volumes and cost Is this something that is available to purchase in small quantities to experiment with (fairly inexpensive) or is this something that requires a large purchase and is therefore a large commitment which limits it to a production environment?
Question 1: the Expancel comes in powder form, you have to make a sealed “Sausage” or bag out of stretchalon or similar to conform to your tooling etc. it only has to be filled with powder to aprox. 1/3 volume of the internal space of your part, so it is relatively easy to create a sealed bag, this powder is heat activate to expand 20:1 at 100-115deg.C for aprox. 2 -3hrs. depending on pre-preg resin system etc. this expansion exerts aprox. 100psi. internally on your laminate against the Tooling, preferably Aluminium etc. bolted appropriately to take this pressure!.
COST: you can purchase this powder in smaller quantities from some suppliers who “might” pack it off in smaller containers other than 50 - 100kg Containers, cost varies aprox. $50-60 kg. keep in mind its expansion rate and the end result which for me was perfect compared to inflating internal bladders etc. and still not achieving any shape you choose to tool up for within reason!. see my. pics. I have produced Rudders and Foil sections in the same way, if your part is not open ended after stripping from your tooling the foam acts as a reinforcement, or in the case of the 32mmID Tubing I remove the expanded powder with a special drill or arbour to reduce the weight.
I hope this answers your questions?, PM me if you want more detail etc.
Dear Bladerunner, i am very intrested in Expancel…
I make windsurf fins using aluminum molds and carbon pre-preg layup(under vacuum), after the cure both part they are bonded together by filing the mold with epoxy resin.
I hope expancel can reduce our production time by making the fins in one single cure cycle, the pre-preg shell and epoxy core(+expancel). Therefore expancel/epoxy core should provide sufficient pressure(2-3 Bar) for adequate resin flow in the pre-preg shell. For structural reasons the epoxy/expancel core must also obtain a good bonding with the pre-preg shell, hence there is no room to for a presure bag type approach.
Is there a chance this could work?
It might work. You need over 100 degrees for the expancel to expand.
I can give you the phone number of the Dutch rep of Expancel if you wish? However, I doubt the material will generate that amount of pressure. Did you test epoxy foam already?
best regards,
Herman
(Brands Structural Products)
I don’t think 100 degrees will be a problem with faster cure cycles and aluminium moulds. What kind of prepreg do you use? I know ACG has prepregs with a cure time of 10 minutes at 120 celcius I believe, don’t know the ramp up. Epoxy foam needs a proper post cure to get to its optimal properties, with out it, it’s not much. What epoxy are you using now? You could inform if there is a faster curing epoxy. Or you could just glue the two halves together with a MMA glue. Should be strong enough, lighter, and not as brittle as epoxy filled fins.
(and if you want a core, like PVC or SAN foam. You could cnc mill them. I don’t know your output, but in larger numbers the costs are less.)
And one run cycles: I would use a rubber contra mould. Do a layup in the 2 open halves. One halve you trim flush, the other keeps 5-10 mm. Fold it in somewhat, close mould, and check/push your flap against the other part. Insert the rubber mould, apply pressure and heat. I’ve used silicone based rubbers wich can go up to 145 celcius. With fast curing prepregs you can have a nice production that way. But I’m a bit worried about the trailing edge. The fibre needs some room too 
I have checked epoxy foams(not tried), but the mechanical properties are just not good enough…
Temp and ramp rate are not my main concern, there are a variety of pre-preg fabrics and epoxy to match that with expancel…
Is resin-expancel mix under pressure, without a seal between the pre-preg and the resin going to work?( the resin can just flow around the pre-preg shell… )And if, why would I use expancel anyway and not just put the resin under pressure?
@Herman, graag, denk dat je mijn mail adres wel hebt…
Thought of glue at the edges, foam in the center? Does the epoxy only bonds the shells, or also has some threaded ends or something to attach the fin?
(maybe this last posts should be transferred to their own thread? )
If you choose to use the Expancel it needs to be encapsulated in a high temp stretchalon type bag, you make this yourself undersize to suit your tooling, fill this bag with the powder 1/3 the volume of your part, then seal using flash breaker tape around the edge of the bag, remember the Expancel expands 20-1 plus and exerts 100psi plus, so if you use it without the stretchalon bag the Expancel will migrate through your laminate and spoil your carbon finish against your tooling.
I use a low temp epoxy pre-preg aprox. 70deg.C this is cooked for 2 1/2 hrs., the expancel needs to be heated over 80deg. C up to 100deg. during this cycle, in my case I can either remove the expancel because my tubing is open ended or leave it in for extra strength, thats if you dont “kill” the expancel which takes place over 110deg.C, it then shrinks back after its expansion cycle leaving voids.
Without knowing what your fin/foil looks like or your fixings and top termination detail, I would go for a CNC 80 or 130kg. Divinycel core allowing for your pre-preg stacked laminate and I would use an extra glue film against the Div-cel to ensure adhesion and a full fill or resin so you dont have dry/boney carbon against the aluminium tool.
PM me for pics. etc. if you need anymore info, hope this helps?.
pieter we have made a number of boat foils rudders with Ampreg f230 epoxy foam.
"Ampreg F230-1 is a Foaming Epoxy system designed for the manufacture of marine foils. It is a high strength and toughness expanding foam and has an expansion rate of up to 4 times the initial mixed volume.
Ampreg F230-1 has been formulated to use the Ampreg 21 range of hardeners. The compatibility of the Ampreg F230-1 and Ampreg 21 ensures a high strength bond is achieved between the foil skins and the expanded epoxy foam.
Compared to competitive products, which typically only have 1 or 2 hardeners, the Ampreg F230-1 is available with a range of hardeners from Fast to Extraslow. This allows the speed of the system to be tailored to the size of the cavity, which reduces exotherm and shrinkage, leading to higher quality parts.
Ampreg F230-1 combined with Ampreg 21 is the ideal package of materials for the manufacture of high quality marine foils."
You can get a good bond by weting out the back of the part to be joined with standard Ampreg 21 epoxy resin which the foam is based on its really tough stuff.
Just ordered some more for myself yesterday. Here is a link to the data sheet.
Yesterday I cast a block of foam 2x1 meter, and 30cm high. Was a nice project. I used Sicomin PB250 and DM02 (slow) hardener.
I guess for the fins, if Expancel does not work as discussed on the phone, you might get away with the 600 kg/m3 version.
herman, have you used the Sicomin PB 170? I am thinking of giving it a try for some lighter parts. Do you like the Sicomin product?
I tend to stay with the SP sytems as much as I can, a lot of it it is manufactured about 3 miles away from me by Gurit. There is a daily courier service with their distributer for the Island which makes supply easy.
I’ve used it in automotive application, The foils I made where always hollow
The PB170 works ok, I like sicomin products in general(just like ampreg btw.) It is very brittle without postcure. Be carefull with flexy foils. If the core goes, the foil goes too.
(didn’t make that foil, just broke it, well, 2 that weekend :S)
PB170 works OK. It is the same stuff, just more or less blowing agent. (PB170, PB250, PB400, PB600)
They also have another (cold curing) hardener, which leaves the foam slightly flexible. Very good for filling hollows.
And they have a range of machine foams, which can be pumped, and fire retardant versions.
In the past I used Ciba (at the time) 5054 series. we started with that when a request came from the government to fill the throughs of a bridge (the stiffeners below the bridge). I was delivered a piece of bridge that they cut out to do tests. (for the Dutch people: The Brienenoord, Rotterdam).
In the end they did reinforce the bridge in a different manner, as my boss was reluctant to do the job, as the curing agent used was toxic like nothing else. With the knowledge I have now, and the Sicomin materials, I would easily tackle such a project.