Hello everyone, There is a great deal of interest in forming and fabricating with acrylic. There is also a great deal of misinformation. This is will be the first post, in a series of posts, discussing and explaining just about everything you ever wanted to know about working with acrylic. We have been fabricating for over 40 years using acrylic and almost every other plastic. What you will see here is based on our experiences along with technical specifications from the industry. Some of the topics may not directly apply to aquariums and related but the intent is to give you as broad a background explainer as possible. I tend to go into the details but sometimes it is necessary as simple explanations are not always correct. I will use the phrase "Plexiglas®" which is a registered trademark. However the information will apply to other brands as well. So... Here we go.
Topic One. Cell Cast or Extruded. What is each and when and where should they be used?
The common answer to this question always is cell cast is stronger and more durable and welds better and so on without any backup technical data. We will begin with the graph below:
As you can see, the extruded Plexiglas® MC acrylic sheet, when heated to a given forming temperature, is somewhat softer than similarly heated cell cast acrylic sheet. This makes it an excellent choice for heat formed fabrications but not necessarily for load bearing applications.
The forming temperature range of Plexiglas® MC acrylic sheet is 275°F to 350°F. The recommended forming temperature is 325°F. At this temperature, the material has good extensibility and will vacuum thermoform to detail that is adequate for most applications. Forced forming methods such as plug and ring and free blowing are best performed at this temperature also. The higher forming temperatures should be used only when maximum vacuum detail is needed.