Polystyrene Pre-Expander

Project Summary

Northrop Grumman Corporation (NG) and the St. Thomas design team partnered together to design and build a polystyrene pre-expander for use at NG’s facility. The problem at hand pertains to the supply chain of polystyrene beads. During the traditional molding process, beads with a stock density are pre-expanded to a density of only 3%, increasing their volume, creating a lightweight material for molding products. NG requires their beads to be produced to a variety of densities at lower quantities. Since bead producers develop beads at a single density in high quantities, NG required a custom polystyrene pre-expander.

Design Goal

Develop a polystyrene pre-expander that alters the physical characteristics of the material through precise and controlled heat transfer processes. Utilizing the pre-expander will provide a more efficient and sustainable manufacturing process for NG’s facilities.

The deliverables for this machine include a functional automated pre-expander that meets the specific density requirements, a comprehensive user manual that includes operation and setup, servicing/trouble shooting guide, and a CAD model of the updated machine.

Design Constraints

• The developed machine shall take stock beads and pre-expand them to a desired density within the range.
• The GUI shall have control of the temperature with readouts between ambient and 200°C +/- 1°C.
• The machine shall fit within a 5-foot by 5-foot floor space with a maximum height of 7 feet.
• The GUI shall store historical data from previous runs including lot number, temperature, expansion time, and expansion date.