KASA Labs

Metal parts made in a 1200W microwave:

How Does It Work?

1. Polymer/wax pattern printed with sprue & additional geometry for casting

2. Mold is made from powdered Silicon Carbide combined with Sodium Silicate which has a wet sand texture

3. Mold goes into microwave, SiC absorbs the microwaves and heats, plastic evaporates at ~350C, metal is placed as billets in the sprue of the mold and melts through conduction at ~700C

4. Break mold, trim, blast, finish.

Description: 

We have all worked at startups and felt the pain of getting metal prototypes quickly and cheaply. For our final year capstone, we came up with a solution. Using powdered SiC, we shape this around a 3D printed pattern (that we want to cast), and throw this into a kitchen microwave. SiC absorbs microwaves, heating the mold to around 800C. The plastic evaporates and metal chunks are added that sit on top of the mold. Through conduction, the metal melts and casts the part.

What did I work on: 

Microwave interfacing and thermal model, aswell as general R&D at the beginning of our project

Biggest learnings: 

• Programming a numerical iterative transient thermal model

• Discrete PID controller integration

• Inside electronics of microwaves

What would I do different next time: 

• Add more than 1 thermocouple to interior of microwave, and use a pyrometer for more accurate and repeatable sensing

• Electronically control potentiometer rather than use a servo to spin it, to eliminate need for standalone psu

• Hook failsafes up to HV hardware in microwave, for safety reasons

Interfacing To Microwave

Button presses are emulated using electrical relays,

and a servo on the time dial sets the cook time

PD Control on Mold Temperature

Coded as a Finite State Machine

Mold Progression

Quality

Team

Low Lights

Misc