An industry partner came to the Design, Fabrication and Testing research team with a challenge – to create a transparent pump housing which would demonstrate cavitation (when bubbles form in low pressure areas side the pump, then collapse and trigger shockwaves that damage the pump housing).
“The client was sending employees away for training, and wanted to have an in-house teaching tool,” explained researcher Stefan Dalberg. “In order to do this, we decided to make the pump housing out of clear acrylic.”
The client sent the team the pump unit. From there, the pump housing was reverse engineered – internal and external components were measured and then put into a Computer Aided Design program. Once the elements were recreated, the acrylic was annealed (slowly heating and cooling a material to remove internal stress) before it was machined.
“Materials can often have internal stresses, which can cause deformation or cracking during machining” explained researcher Emerson Burns. “We annealed the acrylic for four days in our Thermotron oven. The cycle involved heating the acrylic up to 100 degrees Celsius, holding it there for 48 hours, and then slowly cooling it to room temperature.”
Due to the nature of acrylic, special considerations were made in the machining process.
“Acrylic is a soft material,” explained ARIS machinist Mike Shewchuk. “If it is machined too quickly, the material can heat, causing more internal stresses. The surface finishing also had to be considered. The client wanted the pump housing to be clear, which meant choosing specific cutters for the acrylic.”
Once machined, the finished acrylic pump housings were annealed at the same temperature cycle to ensure all internal stresses were removed.
“This project demonstrates what our team is often asked to do. Take something apart and recreate it for a new purpose, such as a teaching tool,” said Dalberg. “It also showcases our many skills and capabilities.”