Document Type

Restricted Campus Only

Publication Date

4-23-2024

Abstract

This report outlines the process, tests, and research conducted to develop a desktop plastic injection molding machine for use in K-12 classrooms as an educational tool to introduce engineering topics earlier in children's education. The key objectives were to create a functional prototype that is safe for classroom use, is easily integrated into curricula, weighs under 80 lbs for portability, and can produce an 8 inch3 molded piece in a reasonable timeframe.

The final design features a single-screw extruder coupled with a hand-cranked planetary gear system for interactivity. A 2x2x2 inch maximum mold volume was chosen to reduce the pressure and torque required, enabling the use of a hand crank. The machine incorporates a clear housing for visual understanding while shielding users from heating elements. All components are modular for easier cleaning and modification. The prototype weighs approximately 70 lbs and measures 3.75 ft in length, allowing it to be easily moved by two adults and placed on a standard desk.

Extensive research and development went into each subsystem design. The screw features feeding, transition, and metering zones with different heating requirements and geometry to efficiently melt and mix the plastic. The nozzle interfaces the barrel to the mold. Electric heating bands controlled by PID controllers and thermocouples heat the outside of the barrel. The planetary gear system with hand crank enables sufficient torque while keeping the machine interactive. The aluminum extrusion and acrylic housing protects users from hot components.

We tested the functionality of key subsystems. The screw successfully transported unmelted pellets through the barrel without deformation. Heating elements reached target temperatures within 8 minutes and maintained stable temperatures, while the acrylic housing remained safe to touch. Calculations confirmed the gearbox provides enough torque reduction for hand cranking by older students and teachers.

While not yet fully functional, the prototype has met several key objectives - it fits on a desktop, weighs under 80 lbs, is safe for children, and meets temperature, pressure and VOC safety considerations. To reach full functionality, the screw still needs to be connected to the gearbox through a part that is soon to be delivered, after which subsequent testing can be conducted on clamping force, gear torque, and the heated feeding system.

Substantial progress has been made towards creating an educational desktop injection molding machine that can enhance K-12 STEM education. The machine incorporates an efficient extruder design, an interactive hand crank, visual clarity for learning, and safety features suitable for classroom use. With a clear path outlined to complete the remaining tasks, the project is well-positioned to produce a working prototype that achieves the goal of introducing students to engineering concepts through hands-on experience with injection molding. Recommended future work includes finalizing the mechanical connections, conducting the identified additional tests, and developing curricular materials to help educators integrate the machine into their lesson plans. Overall, this desktop injection molder shows great promise as an engaging teaching tool to inspire the next generation of engineers.

Comments

Dr. Eliseo Iglesias, Team Adviser

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