FiberglassBlog.com » composites

Making a Small Mold

AKeson — Sat, 21 Aug 2010 19:42:37 +0000

There are many methods and materials that can be used for making a fiberglass composite mold.

I found a video from Eastbay Composites that demonstrates a method for making small molds in a very quick an inexpensive fashion.

As you see from watching this, the basic construction materials are tooling gelcoat and inexpensive bondo for the support structure.

This mold construction technique certainly has drawbacks, but also has several advantages. None of the materials required spray equipment, which is messy. Brushes are inexpensive and easily disposed. A disadvantage of this method is that surface finish might suffer from a lack of consistency on the coating thicknesses for the gelcoat and the release agents.

Using bondo as the support structure is quick and easy compared to glass and resin, but can cause problems as well. It is more likely to crack, and can warpage issues as it cures and may be hotter in some areas than others. Bondo may have some difficulty maintaining dimensional tolerance as it shrinks during cure. Industrial resins used to create molds have minimal shrinkage in their chemistry and are placed on slower to minimize heat from the chemical reaction.

For quick, inexpensive and easy parts, this method from Eastbay Composites may work well for you. What has not been discussed yet is that the mold model can be the most difficult part. Off the shelf items are easy, but custom ones may be difficult. Creating a shape or surface is time consuming and tenuous. After that is complete, you can make your mold and final production parts!

Making Holes If you are working with fiberglass parts, you may need...
Vacuum Bagging Video Vacuum bagging is a process that requires unique materials and...
Panel Stiffness Composites structures have requirements for stiffness to provide support and...

Related posts brought to you by Yet Another Related Posts Plugin.

Cutting Epoxy/Fiberglass with Ring Saw

AKeson — Sun, 20 Jun 2010 15:25:15 +0000

Cutting and machining of cured composites parts can be challenging. Cured composites can wear cutting blades out very quickly. They are also very dusty when cut without using some sort of cutting fluid.

Many of these problems can be eliminated with the proper equipment. I found a very interesting video of a fiberglass-reinforced epoxy resin block being cut using a water-cooled ring saw. This saw is called the Revolution XT and it uses some neat technology to get a relatively quick and clean cut without making dust. It looks like it would also allow some good freehand movement to cut curves and angles in composites parts.

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.

Cirrus Composite Airframes

AKeson — Tue, 23 Mar 2010 15:44:17 +0000

I found a very interesting Youtube peek inside of the Cirrus airplane assembly factory in Minnesota. While it would be cool to learn more about the actual composites fabrication of the individual parts, there is some great information about part bonding, inspection, and final assembly of the Cirrus aircraft. They use fiberglass and carbon fiber reinforcements to create a very strong and durable fuselage, and it is great to see in action.

Personal jets made of composite materials offer many advantages and unique properties. Design of complex shapes and anti corrosion of aluminum are two advantages. Disadvantages include repeatability and upgrading/modification.

Composites that are properly designed and fabricated can be used in many applications where safety is a big concern. Proper design and inspection during production can create an airplane that can be easily maintained and have a very long life.

Great factory tour courtesy of Aero-TV:

Fiberglass vs. Aluminum A great Youtube video where testing was used to compare...
Composite Dock Building outdoor structures around water require special considerations. Wood rots,...

Related posts brought to you by Yet Another Related Posts Plugin.

Panel Stiffness

AKeson — Wed, 03 Feb 2010 13:40:13 +0000

Composites structures have requirements for stiffness to provide support and stability. Tests can be completed to identify the stiffness of a given area on a composites structure, i.e. how much it will bend for a given force.

The required stiffness of a section of a composites part depends upon the overall design and service expectations. Several factors, including the life expectancy of the object, the load rating of the composites surface, the inter-laminar bond strength, will help determine the threshold requirements. Testing is very important to determine the life expectancy of the part and whether it meets the requirements of its’ job.

Panel stiffness can be modified to meet these requirements using two basic methods. One way to increase the stiffness of an unsupported composites panel is to reduce the size of the panel through additional support structures. The other way is to increase the panel thickness across the same area. Choosing which method to use depends upon the engineering of the part and determining which method is acceptable with the surrounding part layout. If there is room to add supports, this is likely a quick and easy option. If there is room to increase the thickness, adding new or additional coring materials may be a simple solution.

Building a strong and stiff composites structure can be accomplished with the extremes of building a robust “skeleton” with small open areas and a thin skin, or having a basic, limited “skeleton” with a heavy duty cored laminate that supports itself.

A combination of the two usually works out best.

Moldless Car Body Building a custom car body with fiberglass can be achieved...
Non-Destructive Testing with Ultrasound Composite materials can become damaged in many different ways. There...
Infusion-Test Panel and Fuselage Ran across an interesting Youtube video demonstrating an epoxy resin...

Related posts brought to you by Yet Another Related Posts Plugin.

Making Holes

AKeson — Tue, 12 Jan 2010 16:17:22 +0000

If you are working with fiberglass parts, you may need to attach other parts, pieces, and features mechanically with fasteners. Bolts and rivets are the most common mechanical fasteners used to accomplish this.

Composites with a nice, decorative gelcoat finish such as boats and RV’s require special care to make holes in them for placing bolts and rivets. Disturbing the area around your hole in a gelcoated surface can lead to very expensive repairs by a fiberglass expert.

You can make holes yourself, but it requires extra care and attention. I found a great Youtube video that demonstrates this from user CenturionCrew.

Of course the biggest mistake that can be made is improper placement of the hole.

Following the instructions in the video and drilling a nice slow speed hole is the best way to be successful. He also mentions the caution that must be noted to stop the drill chuck from contacting the gelcoated surface. One tip that I have is to place a small piece of rubber hose over the drill bit to contact the gelcoat before the drill chuck.

One other note with holes (all shapes and sizes) in cored composites fiberglass pieces. If there is a layer of balsa or foam core in the cross section, extra precautions should be exercised. One is to coat the inside surface of the hole with gelcoat, resin, or silicone to keep moisture and UV out of the core.

Another concern is compression of the core with mechanical fasteners. Balsa and foam cores typically are low in density, and are not meant to be highly compressed. If you are going to bolt something on, and it is going to be really tight, it is best to use a metal sleeve in the hole that is the same thickness of the fiberglass part. Large washers or backer plates should also be used to distribute the load across a larger surface.

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.

Necky Composites

AKeson — Fri, 17 Jul 2009 02:35:17 +0000

A very basic and well-done video is from Necky Composites.

It demonstrates the toughness of epoxy laminates when he starts the video by beating the kayak with a hammer. He also does a good job of discussing the construction techniques of his kayaks and gives some good detail on materials and processes.

I have used the Soric and Divinycell, and the adhesive he discusses. They all have their places and special techniques for application. Many of these materials have been around a long time, and sometimes they have been misused in applications that they didn’t belong. I have personally witnessed some of these horror stories concerning delamination and improper adhesion.

The video quality and production is very rudimentary, but the content is very good. I am not a kayaker, but it makes me want to get one of these!

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.

Composite RFQ

AKeson — Thu, 18 Jun 2009 13:22:32 +0000

An interesting website that I recently discovered is called CompositeRFQ.com, which is a website dedicated specifically to the composites industry, and filling Requests for Quotes. This website works to match composites fabrication shops with those businesses and individuals needing composites fabrication work completed.

A project is posted by the person with work needing to be performed. The proper industry is selected, choosing from aerospace, architecture, automotive, boating, military, and sporting goods. Additional information documents can be attached for further scope identification. Bidding details can then be specified by the person posting the project.

Composites fabricators with related expertise and experience can bid on these projects in an effort to identify work opportunities for their business. If a bid is accepted, the details are worked out directly between the bidder and the buyer, eliminating any third party costs and delays. Bidders and Buyers can go back and leave feedback after the job is complete.

Composite RFQ has some free accounts to go in and look around. There is a very interesting page about using Composite RFQ that very easily explains how it work s graphically.

This site is a great tool to bring the composites world together between buyers and sellers. The old word of mouth method of finding fabricators and customers is great, but does not always lead down the best path. Small fabrication shops have difficulty advertising their services to the appropriate customers that might be looking for the type of work that they do, and now they can go and bid directly on the types of projects they can handle.

Cirrus Composite Airframes I found a very interesting Youtube peek inside of the...
NASA Composite Crew Module NASA, the space agency for the U.S. government, has investigated...
Composite LPG Bottles Found an interesting article about commercially available filament-wound LPG bottles. ...

Related posts brought to you by Yet Another Related Posts Plugin.

Wind Blades

AKeson — Tue, 16 Jun 2009 13:06:34 +0000

The new composites application that everybody is discussing is composites wind blades. The large, three-bladed wind generators have been around for a few decades, mostly in Europe. The U.S. has been catching on in the last couple of years as a way to make cleaner electricity. These windmills are very tall, and have blades that are 100 to 400 feet long, depending upon output rating and location.

The wind blades use glass carbon fiber, resin, and coring to make a long, stiff and lightweight blade that will attach to the hub of the windmill. These blades are very long, requiring huge manufacturing facilities to make them. The transportation of these blades is important as well, as they require specialized trucks and trailers to handle such large pieces. Large cranse are required to lift them into place at the job site. They are relatively heavy, and must be lifted fairly high, requiring a significant lift capacity.

Resin infusion with epoxy resins is the normal manufacturing technique of which I am aware. They use compsite molds that have a constantly changing surface shape due to the complex geometry of the blade. The holy grail for these blades is to make longer blades at lower weight.

This application again demonstrates the advantages of composites. Complex geometry, high strength to weight ratio, and impact resistance are important aspects of wind blades.

There are several manufacturers of the wind blades in the U.S. MFG is a specialty composites molder that has been around for ages and is in the wind blade market. Vestas is another company with operations in the U.S., along with LM Glasfiber, as well as others.

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.

Increased Fuel Standards Benefit Composites

AKeson — Mon, 08 Jun 2009 01:30:52 +0000

There is lots of discussion about increasing the fuel standards from the present 27.5 of cars and 22.2 for trucks up to 35 mpg for all vehicles by 2020. This legislation is working its way through the U.S. Senate, and might become law. This represents a 40 percent increase in fuel economy standards from the present day. Quite a big change!

In order to achieve this sort of efficiency gains, drastic things must change in regards to the design of the automobile. There are some things that can be accomplished in drive-train design to improve economy, but much of the economy improvement will need to come from mass reduction. Vehicles will need a diet.

Anywhere and everywhere weight can be trimmed, it must. This largely means that steel and cast iron must be removed and replaced with other stronger, yet lighter materials. Therre are some metals such as titanium that will handle some applications. Aerospace-grade composites can handle others, both decorative and non-decorative. All of the exterior body panels will be made from composites. This technology is in some current production vehicles.

Structural composites do not have extensive current application in automobiles. I am sure they will be considered as this problem is faced. Lots of resin and carbon fiber will need to be used in vehicles where impact strength, bending strength, fatigue resistance, UV exposure, and abrasion resistance will be paramount. It will definitely be a tall order.

The amount of composites in future vehicles is very likely to increase in order to meet new fuel economy standards. New processes and engineering design will be necessary. All of these composites resins and reinforcements are expensive as raw materials and the processing will likely be expensive as well. Making composites competitive in this application will be the big achievement!

Panel Stiffness Composites structures have requirements for stiffness to provide support and...

Related posts brought to you by Yet Another Related Posts Plugin.