What's your favorite composites processing method? 2

[iluvrabits]

What's your favorite composites processing method?

I know it depends on what kind of part that you're making and the quantity, but I just want to get some current ideas on which methods are most popular right now for which industries.

Which method is easiest and has given the most consistent results?
Which method gives you the best material properties?
Which method is cheapest?

JCF
iluvrabits@yahoo.com

 

[bubb375]

JCF-

The most common process used in the commercial airline business is hand layup with prepreg materials. Typical parts include panels and flight controls. Vacuum bagging with heat pads are used for most manufacturing/repair procedures.

I think this method is almost exclusively used by the airline industry because of its almost fool-proof design.

Brian

 

[BillPSU]

In the aerial lift truck industry booms are made by both filament winding and centrifugal casting. The jib booms are pultruded over foam cores. The leveling rods are pultruded solids. There are several ways to make platforms(buckets). All the different processes has its advantages and disadvantanges. All the parts are fiberglass for non-conductivity. Voids in the booms are unacceptable as they attract moisture and cause conduction down the boom. The typical aerial device must resist 70,000 volts and in special cases some resist 300,000 volts.

 

[Scott5]

You raised some good questions. The correct answer is composites are application dependent. The aspect that I like most about composites (advanced composites - elevated temperature/pressure - mainly fiberglass/graphite) is their ability to fabricated strong, compound contoured parts simply, reliabiably, repeatibly, and with good process control, meaning high quality. Many factors affect the decision of which techique is right; part quality, cost, strength, volume, etc.

The hand layup/vacuum bag/autoclave technique is excellent with pre-preg materials (fiber and resin content are controled) but the materials and process equipment can be expensive and the material requires refrigeration when not in use. Generally low volumes of parts are produced using this method making them costly so high volumes are recommended to ammortize costly labor and tooling. If 'dry' fabric or toes of materials are used you are working 'wet' (refering to resin) then you have more of a potential for resin rich or starved finished product conditions which would significantly reduce the parts strength. Working wet can be messy and has more health concerns if proper engineering controls are not in place. If a RTM (resin tranfer method) is used and refined working wet can be performed with great repeatiblilty on relatively complex parts. Variations of RTM (VARTM and SCRIMP) exist that make wet even more conducive to better quality and less cost. Filament winding and toe placement with either prepreg or wet can used but each has it's limitations in volume, cost, quality.

Room temperature/vacuum, prep-preg/wet material curing composites are an alternative but have service temperature/strength limitations.

For most high strength applications thermoseting resins are prefered as a matrix material but thermoplastic resins are also increasing in use. I can comment confidently on most other composite applications and manufacturing issues but will leave that for another response. I hope that this addresses at least some of your concerns.

 

[CompositesGuy]

Scott5

How much experience/exposure have you had with carbon fiber (continuous or chopped fiber)/thermoplastic composites with a matrix such as PEEK? This is my focus with my new business and I'm just getting started. Thermoplastic composites appear to be the future of the industry and advances are being made much faster than with thermosets.

 

[USACompositeGuy]

CompositesGuy,

I would like to know more about your business, I think that I may be able to help you. Send me an email: Honeycutt@carbonfibersolutions.com.

As for the original question, I think we can all agree that composites are very process critical and the “best” procedure greatly depends on the specific application. Having a great deal of experience in composite repair for the aviation field, I would say that wet lay-up/vacuum process is the most preferred. This is true due to the fact that each repair is unique and this process allows you to repair the damaged structure on wing.

If you have a specific application in mind, I sure that I (and the rest of this forum) could provide you with detailed process advice.

http://www.carbonfibersolutions.com

 

[G1DESIGN]

we tried thermoplastics back in 96 and made and sold hundreds of bikes made from the stuff unfortunately while it was far tougher than the conventional composite frames out there it just couldnt compete in the strength to weight area when the designs were finished we went back to closed mold internal bladder moulding and filament winding they are the two of our favourite composite production techniques at the moment and seem to be doing the job for us at the minute

 

[abygupt]

Most common process is hand-lay up of pre-peg layers followed by mold pressing.