Design a 3D mold, machine it, and cast parts from it
DESIGN
To design the 3D object and the double mold I used Rhino.
Export your model as Stl. Be sure that is on and under the 0.0.0 origin point of the axes
MILLING
/Software:
//Fab Modules
/Modela milling machine
/Tools:
1/8 end mill = 3.175 mm 1/16 end mill = 1.5875 mm 1/32 end mill = 0.79375 1/64 end mill = 0.396875 mm
//For Roughing i used the 1/8" end mill = 3.175 mm
//For Finishing 1/64" i used the end mill = 0.396875 mm .Because of the details of my model i needed the tool to be the smallest possible for more precision
/Steps:
/Open Fab Modules on terminal: sudo fab
/Choose Modela .stl
/Select your 3D STL file
/Select your molding step: Roughing (1/8")
/Click Make Path
/Set your 0,0 point at the top-bottom-left corner
/Click on make rml
/Send the job to Modela Machine
For the finishing we have to change the tool to 1/64".
Repeat the same process as roughing process but remember to change the diameter of the tool manualy
/Material:
//Machinable Wax
/Steps:
//Open Fab Modules (terminal> sudo fab)
//Choose Modela .stl
//Select the STL file
//Select your tool (for Roughing or Finishing)
//Make Path
//Set the 0,0 point
//Make rml
//Send the job
//Begin Milling
DEGASING SILICONE:
/Vacuum Pump
/Vacuum Chamber
Building a vacuum chamber:
/Materials:
//Vacuum Gauge
//Valve
//Plexiglass
//Silicone ruber hose
/Links:
//DIY Vacuum Purging Chamber
//DIY Vacuum Chamber Setup
//Make a Vacuum Chamber
MOLDING:
/Materials:
//Mold Max 60 High Temperature Silicone
Mold Max® 60 is a Shore 60A condensation-cure silicone rubber formulated for applications requiring high heat resistance (up to 294°C). It features a low mixed viscosity and cured rubber exhibits very low linear shrinkage. Parts A & B are mixed 100A:3B by weight. Pot life is 40 minutes and cure time is 24 hours.
//Universal Mold Release
/Steps:
//mix the 2 parts of the silicone(100A:3B)
//degas silicone(vacuum, vacuum chamber)
//pour the rubber onto the mold, filling to the top
//Allow the rubber to cure for 24 hours
//Demold
CASTING:
/Materials:
metal(Aluminum Alloys)
metal kiln for melting aluminum
Personal Protective Equipment! (heat gloves for protecting hands and goggles for eyes)
/Steps:
//Heat metal in kiln.
//When liquid, carefully pour into mold
//Wait for metal to cool
//Open mold and remove!
TIPS:
/It is very important, especially if you have lots of details on your mold, to degass the silicone prior to using making the mold. The degassing removes air bubbles when the silicone is still liquid. If you do not degass, the air bubbles will cause imperfections in the mold and will then show up in the part.
/I don’t have to emphasize the dangers of melted metal going on your skin or your eyes so it is very important to wear proper safety equipment like heat resistant gloves and goggles to protect your eyes.
/Try to keep any residual metals at the surface by continuously adding more metal, so that they don’t clog the bottom (exit) of the kiln. Occasionally remove the residual metals from the surface using a metal tool.
/If your kiln becomes clogged, carefully use a paperclip to unclog it.
/Try not to pour the liquid metal from too high, so it does not have time to cool before going into the mold
/Choose a metal alloy that has a melting temperature less than the melting temperature of your mold material! In my case the silicone can withstand temperatures up to 294°C and the aluminum-zinc alloy has a melting point of about 282°C.
/Warm the mold using a heat gun or oven before you pour so that the metal doesn’t immediately cool upon contact with the mold and create incontinuity in the final product.
/Pour continuously so that you don’t create incontinuity in the final product
/When you finish the pour place the mold in a container with water so that it can cool quicker.
Files: