In this section we will briefly outline the process of how acrylic pool window and wall transparencies are created post design phase.
1) Production of acrylic sheet:
Acrylic sheet (PMMA) is a thermoplastic, produced by reacting methyl methacrylate (MMA) with an initiator inside of a highly polished mold. The initiator is added to start the polymerization reaction, but does not become part of the resulting polymer. After the acrylic sheet has finished the process of bulk polymerization, the molds are cooled and opened. The acrylic sheets are then annealed to remove residual stresses in the material that can cause instabilities.
2) Dimensional rendering:
The finished acrylic sheets are then trimmed to the required size before further processing. This process is performed utilizing specialized tooling in conjunction with water-cooling to prevent the introduction of stress during machining.
If required thermoforming may be used to produce your acrylic pool window transparency. This involves producing a unique male or female mold. The mold and acrylic sheet are placed inside of a large oven that slowly heats and softens the panel allowing it to take contour. This process must be preformed in a very precise manor in order to avoid the introduction of stress. Inexperienced fabricators will often shorten cycle times to save money, resulting in an inferior product.
Acrylic is a poor conductor of heat; uneven heating followed by rapid cooling will introduce high surface stress into the material. During machining attention must be given to ensure excess heat is not generated. When applicable a processed known as annealing is utilized to reduce or eliminate stress that may remain. Following the dimensional rendering, bonding or the thermoforming process, acrylic will be annealed. Annealing is the process of slowly heating the acrylic sheet to just below the glass transition temperature, followed by cooling at a precise rate. If preformed correctly the process will relieve the stress and prevent it from recurring. The cycle temperature and time is dependent upon the cross section thickness of the acrylic panel.
For large panels or ones with complex geometric shapes a process known as bonding can be used. Most fabricators have not invested in scientific evaluation of their bonding methods and use inferior commercially available acrylic adhesives. All of our bonding technologies have been independently lab tested for tensile and shear strength. Our proprietary bonding technology has a tensile strength of over 9,000 PSI, which is far superior to commercially available products that range from 2,000 PSI to 4,000 PSI. In addition to being stronger, our adhesive is clearer, harder and more chemically resistant than commercial adhesives. As a consumer, this gives you the peace of mind that our adhesive won’t cloud or separate. As an added safety factor, we design and manufacture all of our bonded transparencies to withstand more than 11.2 times their maximum load.
6) Polishing an acrylic pool window or wall:
Panels that are designed as 3-side support transparencies or incorporate bonds will require polishing. Polishing an acrylic transparency is a highly laborious process that requires extreme attention to detail. The process starts with an aggressive abrasive and proceeds with incremental steps until a 1-micron optical finish is achieved. Inexperienced fabricators will often leave visible distortions that will reflect light abnormally.