Composites vs. Steel

Unlikely...composites generally need laying up rather than just pressing.

Maybe polycarbonate sheet?

The thing with plastics and composites is it's the structure that will give it strength ... honeycombs,laminates and such like would be too expensive but maybe if you design the piece parts carefully enough you might get away with polycarbonate, watch out for crack propagation though. Maybe a couple of thin conroured pieces glued together.

Depends what you are making.

These guys probably have an answer

http://www.geplastics.com/gep/en/ProductsAndServices/ProductsAndServices/products_and_services.html

A little more information as to the intended use...I am currently using 3/16" Plate to produce a truck body (upfit application). The parts I intend on building from the material(s) will not be a part of the structural integrity of the working parts. These sections, once formed will hold a maximum of 200#. My goal is to shave 1/2 the weight of current production methods, and offer a little forgiveness when hit with objects that would otherwise leave dents, etc. Problem(s): must be able to allow urethane enamels to adhere, no wash boarding when finished, and hold up under daily use in the elements. Fiberglass, while addressing the issue of corrossion is still heavy and expensive to produce.

Thanks in Advance for the Responses

Sheet molding compound- fiberglass in a sheet that you mold and cure. Saturn used to use it for car bodies, but they stopped when all Saturns became Opels instead.

This is most likely still fiberglass. SMC may give you sufficient control over the fiber length and volume fraction to improve strength / weight.

You would need to invest in appropriate tooling, cold storage for the SMC and an oven to cure it.

Why not a higher grade of steel?

I remember my first metallurgy class, where the instructor showed us two almost identical snow shovels, the push type with a curved rectangular blade, except one had a blade of thicker steel.

He asked which one we thought was better. Most gravitated toward the thicker gauge.

Then he let us have our way with them with ball peen hammers. The thicker gauge shovel blade was soon mangled, while the other one basically laughed at us.

Steel is a wonderful material. Get to know it.

-This message brought to you by the Society of Mechanical Designers that work on Canadian & U.S. Steel Mill expansions.

Well.....been building this particular design for over 25 years, produce in Carbon & Stainless Steels as well as aluminum. Unfortunately, steel just keeps going up. In the past two years alone, gone from $$ to $$$$$$$$$ and no end in site. I have actually looked into lighter gauge stamped sections, while material drops, labor and equipment or contracts push it right back above process and materials used currently. I have changed to a lighter gauge and from cold rolled to hot rolled sheets on a few of the products, where the material(s) require little to no fab work of any kind. If you can suggest a cheap alternative to the stamping process, that would be a huge help. I have a large customer base from B.C to Nova Scotia.

Thanks for the response

No problem.

I hear you re: the cost of steel going up. Blame worldwide (mostly Chinese) demand.

Ironically, outsourcing (at least your stamped blanks) from China may be your best bet (even more ironically, guess where the fabricated components for the Canadian & U.S. steel mill expansions come from?).

I regularly hear of examples where fabricated parts from China are acquired for less money than the material alone would cost here. And as your parts are simple, as you describe further on in this thread, you have a good chance of getting them done right.

Just make sure you do business through a reputable and experienced agent (I can get a name for you if you are serious about pursuing this). And, like the companies I contract for, don't go out of your way to broadcast where they are coming from. You may have noticed a recent groundswell of anti-Chinese sentiment (both deserved and otherwise, sort of reminds me of the same toward Japan in the '80s). It's not as bad here as it is in the U.S., but it's still grief you don't need.

I have had parts molded with a polycrystaline material, ppa or pps (don't ask me to spell the chemical names) with carbon fiber filler. They mold at around 500deg. F. and are very hard for a plastic. It would be better if you could describe the usage and there may be more ideas.

Heat treated acrlic has a very hard surface which is resistant to glues and solvents.

Talk to Lotus Cars UK all their body panels are pressed in a plastic compound

contact wwww.grouplotus.com/grp/

I'm trying to remember the name of a product I've used in the past when designing architectural cladding. This was two thin sheets of aluminium bonded to a hard foam plastic core & I think the overall thickness was around 3mm. The material was light & stiff and could be cut and punched like sheet metal. It could also be formed using a router to cut vee grooves through 1 layer of aluminium & the foam core which then allowed the sheet to be hand folded. The material was often used to form things like the canopies of petrol filling stations. I may have some information at home which I will look for later today.

right Nigh. it might have been the AlucoBond product (there are a number of competitors, but that is the most common): a sandwich of polycarbonite core and aluminum sheets. I've spec'ed it on a couple projects and see it in (relatively) common use now. It can be radiused and formed, but I haven't seen much in the way of complicated shapes. Perhaps, because in the architectural realm we have to make the panel edges come together rather than be free standing.

That looks like the material I was thinking of. I have seen it formed into quite complex shapes with large & small curves and some clever 'origami' type shapes formed by routing all the fold lines into the sheet.

in answer to the original poster: it probably depends on what your ultimate use for the material is. I'm always looking for new products that might make its way into our next building design, but there are few substitutes for load bearing steel or load bearing masonry. Composites have promise, but until they can "mill" composites in the lengths and dimensions that I can get structural steel... I'll be using steel for some time to come.

Picture a Wrecker Body, or Hauler (5th Wheel) Body, or similar. These pieces of equipment are based on a subframe design which is the true meat of the unit. A Fender assembly is attached to either side of the center section, approx 22"-24"w x 94"-96" in length. Currently using 11 gauge (single sheet) folded or pressed into intended shape. Currently, a single toolbox is welded to that section. Toolbox on one side is for Hydraulic Valving, Manifold, Electrical Connections, etc., and the other side for tools of the trade...up to approx 200# max currently. All of the other manufacturers build a duplicate of this design as the patent has expired, and one does build the entire body assembly from fiberglass composite...they are now $3,000-$4,000 USD higher due to that change. Each Fender Section uses 48"x114" sheet @ 99.2% of material. It only has (2) Two 90 deg radiused breaks and (1) One 30 deg radiused brake. Nothing more complex that that is used.

Thanks Again in advance.

At affordable price 20% of Carbon steel-cold-rolled& formed price:

Assam Bamboo--solid, split,and woven fabrics-

----felted with steel wires+ moulded in Epoxy or in PF.

coming up :

www.assambambooworld.com

Ya know...I may be leaving out one of the most important aspects of my situation. I manufacture in an area where ship building is the biggest industry. Thus, Ship welders are in abundance. Also the Labor rates are tremendously lower than elswhere. I usually get the left overs, left behinds, work release workers, etc. to keep the labor low. While these guys can work wonders with regular old every day ordinary steel components, trying to teach them new...well, you get the idea. Composites, Plastics, and even steel that requires more processing than just laying it on the jig a putting the stick to it, may be an issue for most. All of the true machining and metal work is done by guys & girls that have been here since the beginning. Anyway, you get the idea.

So again, if your large and simple stamped/bent steel parts are coming cheap from China, and you have cheap labor for weldment assembly where you are, do you not have the best of both worlds?

I would be interested to hear what you (all of you) think would be the downside to this approach (practical, ethical, etc.), if any. This is not a rhetorical question. I think it would be valuable to gain insight and perspective on this issue.

Nature's fibre-composite?.....Wood.