fastest / automated manufacturing methods?

[tehstig]

hi,

i am wondering about manufacturing methods for composites. what are the fastest production methods to date? are there certain companies / factories that specialize in specific methods?

thank you everyone for your help!

 

[Albigger]

It _really_ depends on your part and quantity requirements. You need to define those first, then tailor the process to suit your needs.

For some parts, semi-automated RTM may be the way to go. For others, VARTM or Prepreg may be the most efficient. You can even get into automated tape layup or pultrusion for some composites.

Each of these has its pros and cons - secondary operations (trimming) vs no trimming required. Injecting a resin vs no injection, etc...

 

[Compositepro]

Compression molding can be one of the fastest molding processes. It is not suitable for all geometries. Cycle time is often determined mostly by cure cycle. Thermosets can be cured very rapidly but this often causes problems like exotherm, cracking, low toughness due to stored stresses, excessive shrinkage, warping, etc. These are caused by large temperature gradients in the part during cure. The way to prevent large temperature gradients is to cure slowly.

 

[joeswoes]

We compression mold thick wall, greater than 1-1/2" THK, thermoset composites and agree with compositepro. The key to consistent quality is a slow repeatable cure. Compression molding does allow for more intricate geometries and better 3-dimensional physical properties than oriented processes such as filament winding. With respect to cycle times, thermoplastics aren't any different. Rapid cooling of these materials results in the same molded-in stresses, cracks, and surface sink marks.

The fastest thermoset process is injection molding, no doubt. There are limitations here, as well, but none of the above referenced processes can come close to this for speed/repeatability.

 

[RPstress]

Looking at a good book on manufacture of advanced composites will tell you most of these things.

A couple of modern trends that are developing, and might not be quite up to date in a book, are 2-1/2D and 3D weaving with subsequent infusion and automated laydown of dry fibres for subsequent infusion. These are all becoming increasingly practical for complex parts. Many companies worldwide are developing these sorts of technology. The weaving technology is quite different from the laydown, and companies tend to specialise.

Automated layup of prepreg for complex geometry is effectively here, mainly developed by the companies which are developing dry fibre laydown.

These sorts of methods are appropriate to high quality (low porosity and fibre waviness) parts with high fibre volume fraction and high curvatures. (This is less true for the weaving, which tends to produce a slightly cruder-appearing preform. However, it can be very effective.)

If you're more interested in the sorts of processes which lead to truck chassis and chunks of bridge decks then traditional pultrusion may still be faster and cheaper, albeit with modern methods giving angle plies and the like. This is also highly specialised.

Unless you have a specific type of structure in mind then it's probably not possible to be much more specific.

I suppose for curiosity's sake it might be possible to come up with the method that comes up with the maximum rate of poundage produced per unit time. That would might be for large, relatively cheap structures such as ship hulls and windmill blades, or it might be for higher rate with large bits of bulk moulding compound being used in cars and trucks. Arguably, the most rapid mthods would be for short fibre refinforced thermoplastic being injection moulded...

 

[MechanicalChef]

It all depends on what you're trying to build.

Filament winding can be an extremely fast method of building composite parts. Up to several hundred pounds per hour. Tailorability issues keep it from mainstream composite-aircraft applications, however.

 

[PanelGuy]

Go back to what you want to build. We are the largest laminator of industrial lightwieght panels...Lots of aluminum skins with aluminum core. I have capability in excess of 20K sf per shift. Lightweight, kinda composite. For the money it is hard to pass up, aluminum is very cost competitive.

Even open molding is competitive in speed, as long as you have a gajillion molds to keep up with.

Ultimately, in any curing system, you must apply a certain amount of energy over a certain amount of time to get the cure to happen. Too much, or too little, and things go bad.

Polyester systems can be very flexible in some aspects, but also are particular on catalyzation. Epoxies can do a ton if formulated right. You can get snap cure systems where you apply and they just sit there and do nothing until you UV activate or hit with the right temperature and the "BAM" they go in 30 seconds.

We specialize in high speed, technical panels with largely monolithic skins. It really depends on what you want to make. You can do a million little pieces a day in an injection mold with glass-filled polywhatever. Just depends...