Microwave Casting Pt. 1

A project log for Microwave Aluminium Printing

Metal parts for people other than blacksmiths. A system to perform aluminium "lost PLA" casting with no propane, and no danger to humans.

Julia LongtinJulia Longtin 08/20/2014 at 21:310 Comments

We're going to microwave out our molds. Here's some science about whats happening. 

Two important stages:

Stage 1: Remove all water - will sweat profusely the water content in the form of vapor - may need towel to keep microwave from flooding.

[] Warning []  Use safety precautions! We did this outside and stood atleast 30 feet away from the microwave.

During this stage, we have seen conditions where the mold could split and explode. This was mostly in part due to heating the water in the mold too rapidly in one spot. The microwave that caused this problem had no spinning plate. This is bad because then the microwaves will target one particular point and will begin to overheat the mold. We observed a chain reaction when this happened. Once a section of the mold began to overheat, a hot-spot forms and it grows as it absorbs microwaves at a higher rate [becoming a susceptor!]. This is what caused Porygon's brains to blow out of the mold and become captured in aluminium.

Stage 2:

 It was hard to capture the smoke escape the mold. Microwave in short bursts starting at a lower temperature.

We set our microwave at 50% [1100 watts] and zapped it in short bursts of around 5 to 15 minutes on average.

The investment will of evaporated and start smoking (non-profusely). The susceptor absorbs the microwaves at a higher rate at which the contents from the mold incinerate and create the cavity inside. Make sure that no plastic is visible in the bottom of the sprues and wells and use a form of compressed air [we had a hairdryer) to blow out the ash and residue from the inside. 

You're ready to move onto the next step when the mold has been cleared of ash and residue, making aluminium!!

** Don't reuse the microwave for food again **