Choosing Lexan or Plexiglass

This week we're going to review the differences between Plexiglas and lexan, two of the most popular products we use for windshields doors and the light in our home-built aircraft, which one is better, which one should you choose? Let'S take a look one way to tell these apart is to perform a little test here. I have two sheets same size same thickness. This sheet is polycarbonate. This piece is acrylic, I'm going to start with the polycarbonate, I'm going to place it into a standard sheet, metal bending break and I'm going to attempt to put a 90 degree Bend into it. These are at room temperature. Let'S give it a try, and you see our polycarbonate allowed us to cold form, it very nice. It'S spraying back. I try. I give it a 90 degree bend in it spring back. Let'S try this now with the acrylic sheet. That does not then very very brittle. In comparison on this aircraft, the windshield is made of Plexiglas Plexiglas is a trade name for the material acrylic. The door is made of lexan lexan is a trade name for the material polycarbonate. Why were two different materials used on this aircraft? One for the windshield one for the door. Well, that was a decision made by the Builder. Let'S take a look at the differences in properties of these two materials, so we can decide which is best for our purposes. Let'S make a side-by-side comparison of the two materials. So we can understand their strengths and weaknesses. Neither of these products wins the prize for providing the best answer to your needs. Let'S start with strength. The bending break demo, you saw provides evidence that polycarbonates cannot be broken. This stuff is used for bulletproof glass. You literally cannot tear it close to indestructible as it gets. Acrylic cannot hold a candle to this particular property, something I call workability as a builder. You have to cut and drill these materials to make them fit your aircraft. You can cut and drill polycarbonate with any tool you desire. You will not have to worry about damaging the material as you cut and drill simple acrylics are another story. Drilling acrylics means using a special drill bit that will not stress the plastic and result in cracks same with cutting once a crack starts. It will propagate through the entire piece and action is taken. It is not uncommon for installed acrylic windshields to develop cracks later in life due to stresses around mounting holes and edges that produce stress, risers, follow carefully the manufacturers rules regarding drilling and cutting, and these concerns can all be reduced or eliminated damage from chemical exposures. This refers to how these plastics react with chemicals that come in contact with them. A big concern to aircraft builders is that polycarbonate does not tolerate gasoline or other petroleum. Distillates acrylic is much more forgiving. If gasoline comes in contact with polycarbonate for some length of time, it will splinter and fog up having a fueling neck in the vicinity of a polycarbonate is not a good idea. Resistance to scratches this is where acrylic Wynn's polycarbonate is soft and scratches are more easily formed compared to acrylic and, unlike acrylic, they cannot be buffed or sanded out. This is why many windshields do not use polycarbonate, also appearance. Karley carbonate will discolor from UV over the years unless a special coating is included. Acrylic does not have this failing. If you appreciate these characteristics, you are in good shape to choose wisely for the application at hand. There are millions of motorcycles on the road today find out what percentage of their windscreens use acrylic versus polycarbonate as a material. Your research can include checking your own bike. Looking at your neighbors using Google or checking with manufacturer, there is some wisdom in understanding what percentage is using one material over another, both polycarbonate and acrylic come in sheets four by eight is also a very typical size to purchase and your best value. They come in. Various thicknesses, based on your application, needs and they're available at your home builder supply store or at plastic suppliers. They come with a film that gets peeled off and that protects obviously the surface until you're done cutting and drilling they're, pretty close in price to each other. That is acrylic and polycarbonate, though the acrylic is a bit cheaper. This aircraft door is made of acrylic plexiglass and if you notice, it has a nice curved bubble and that started off its life as a sheet, but then was formed into a bubble using heat vacuum and a form at the factory, and that gives us very nice Shapes that remain nice and rigid same with the windshields that you see formed into complex curves. You remember our bending break demonstration between acrylic and polycarbonate. Remember this door was made of acrylic and we know that acrylic can and does, shatter and tear, and that's exactly what happened to this door. So keep in mind if there is a possibility of breakage that maybe acrylic is not always the best where, as a polycarbonate, which is virtually unparalleled, would not have broken like this. So just trying to depend on your application as to what the best material is for any given situation. This door opened in flight, and that was the result of the violent air turbulence through it. So in this example, possibly a better choice - and this is up to the Builder - would be to make this out of a polycarbonate which would not have been able to tear like this did so remember. You do have a choice as to the best material for your aircraft, understand the properties and you can make the best decision. There'S a future in plastics. Somebody used to say enough of this. Everyone back to building you

  • Choosing Lexan or Plexiglass
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  • Friday, August 2, 2019
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