Silicone Molding with 3D Printed Masters

Silicone molding is a powerful production method that, when combined with 3D printing, can allow you to make several copies of one product. You can also create a product in a material that is not supported by your 3D printer.

In this How To, we will show you some of the best practices associated with creating silicone molds around 3D printed parts.

Working time will vary depending on a number of factors. Creating a mold around our 3D printed part took us about 1.5 hours. Casting into our mold took about 15 minutes.

Supplies


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Supplies

Step 1: Choose a file to cast a mold around

Obtain a file that you would like to either make several of, or create in a material not supported by your printer.

We chose the cap to a perfume bottle to understand what the process would look like for a product development team attempting to produce several concept models of a prototype.

Mold

Step 3: Prepare and Print

Because the silicone molding process is not very demanding on the 3D printed mold box or master, you can select standard print settings.

Prepare Mold Box

TIP

You can suspend your master using popsicle sticks, skewers, or 3D printed rods glued to the surface of the master in an inconspicuous place. The holes left in their place after your mold has cured will aid in resin flow through the mold.


Step 5: Open Bottles of Silicone (Parts A and B) and Stir Thoroughly

Supplies Used: Silicone (Part A & B), Mixing Sticks

As silicone comes in two parts, it needs to be mixed both individually and once combined with its hardener.

Mix slowly using separate mixing sticks.

Open Silicone Parts
Vacuum Forming

TIP

We calculated our mold volume by filling our 3D printed mold box with water and pouring the water into a measuring cup to find exact volume.


TIP

For two part molds like the one shown, you only need to mix enough silicone to fill half of the volume of your mold.


Curing Begins

TIP

Read instructions on your silicone for “pot-life”. This is how long you have to work with the silicone before it cures.


Step 8: Pour into Mold Part One

Supplies Used: Mixed silicone, prepared mold box and master

Pour silicone into the first half of your mold box.

When pouring, pour slowly into one corner of the mold box and allow the silicone to run to other parts of the mold box as it fills.

Stop when the silicone reaches the top of the first half of your mold box.

Once you have poured your silicone place small keys into the silicone. These will create negative spaces and allow the mold halves to fit together once poured. We will remove them before pouring the second half of our mold.

Pour Into Mold

Step 9: Let Cure

Depending on what type of silicone you are using it can take anywhere from 75 minutes to overnight to cure.

Temperature and humidity will affect curing times, so we recommend this process be done in a room temperature environment.

Step 10: Attach and Prepare Mold Part Two

Supplies Used: Mold box part two, hardware (nuts & bolts)

Once our mold has set, we will prepare to pour the second half of our mold.

A: Remove the keys you inserted in step 9.
B: Attach and secure second half of mold box.
C: Spray with mold release

Mold Part 2

Step 11: Pour into Mold Part Two

Next, repeat steps 5-9 and create the second half of your mold using the methods mentioned above.

Step 12: Let Cure

Mold Part 2 Curing

Step 13: Breakdown Mold and Remove

Supplies Used: Pliers or Ex-Acto knife

Once both halves of your mold have cured you are ready to remove them from the mold box and begin using them to recreate parts.

A. Remove the hardware

Breakdown Mold

TIP

Another great application for 3D printing would be to design and print a box to hold the mold together when pouring resin, or modify the mold box we used to serve the same purpose.


TIP

If your vents leave holes in areas where resin can spill out during the pour, they will need to be plugged.


Add dye to the part of the resin mixture specified in the instructions.

Add Dye

Step 16: Mix Resin

Combine both parts of the resin mixture and mix thoroughly being sure not to stir in air bubbles.

Combine Parts

TIP

Resins typically have a shorter “pot-life” than silicone meaning they will cure faster.


Step 17: Pour Resin

Supplies: Funnel

Once mixed, pour immediately into the opening of your mold using a funnel.

Pour slowly as not to overfill and spill resin.

Any resin that remains in the mixing cup will harden, but can typically be removed afterwards.

Pour Resin

Step 18: Let Cure

Once poured, allow the resin to cure for the appropriate amount of time.

Let Resin Cure

Final Part

Below, you can see that we were able to recreate our perfume bottle cap in several different colors and opacities using silicone molding.

Breakdown Mold

What’s Next

Visit one of our other applications pages for tips on how to take your print even further.

We recommend that you visit our pages on:

Silicone Molding Part II
Vacuum Forming
Sanding

Last but not least, remember to share your work with us on Thingiverse and social media @MakerBot.

We can’t wait to see what you make!


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