 Golden Plastics had been supplying vacuum formed plastic Radome Assemblies to our customer for years. The Radome Assemblies consisted of a Base and Dome which enclose a satellite communication system for offshore ship communications. Our customer was developing a new system that would require a new Radome Assembly.
The design goals were: 1) To form the customer’s name into the side wall of the Base 2) To minimize the amount of secondary parts 3) To increase the overall strength of the assembly
Working with our customer, we used Solid Works solid modeling program to create and finalize the design.
Pressure Forming Process
The pressure forming process was selected to produce the Base of the assembly. This process enabled the customer’s name to be formed into the side of the Base and also allowed for a large undercut step around the entire top edge. The .375” thick Base was formed on a MAAC three-station rotary pressure forming machine. Due to the thickness of the material being formed, the ability to precisely control the oven zones for a uniform sheet temperature was critical to this application. The use of locking platens was also required, due to the high pressure needed to successfully pressure form the undercut area.
The Dome part of the assembly utilized the snap-back vacuum forming process. By snap-back forming the Dome, a uniform wall thickness was achieved. The Dome also has a vacuum formed Internal Mounting Ring that is bonded in for extra rigidity.
Tooling
The tooling for this project included both in-house and out-sourced tooling. Portage Casting and Mold provided the temperature controlled cast aluminum pressure forming mold for the Base. Portage engineered the undercut ring design by constructing four pneumatically retractable ring sections. The Dome and Internal Dome Ring molds were built by Golden Plastics as high temperature aluminum filled epoxy molds.
Materials Selection
The material for this project had to be able to withstand extreme weather conditions and the rigors of a service life at sea. A co-extruded sheet consisting of an ABS substrate with an Acrylic Cap sheet was selected. The ABS provided excellent structural strength characteristics while the Acrylic Cap provided excellent UV protection. The high gloss finish of the Acrylic Cap also eliminated the need to paint the parts.
All of the Radome Assembly parts were trimmed on Motion Master 5-Axis CNC routers. Automated part trimming ensured repeatable results and consistent part quality.
Cost Savings and Durability
Cost savings and durability are the primary benefits of this assembly. Cost saving over the previous all vacuum formed design was accomplished by the elimination of secondary parts and assembly labor. The monolithic pressure formed Base cut labor costs and also produced a very durable finished assembly. |