How to make a mold for cold casting?
The process for turning a chunk of metal into something with a purpose is a pretty simple one. First you need a pattern, then you turn that pattern into a mold, then you pour the liquid metal into the mold, and finally you cool the metal and remove it from the mold. Let’s take a look at the mold making process a little more in depth.
Step 1: create your pattern
Before you begin any pouring at all, you need to have a mold to pour it into. And before you have a mold, you need a pattern to create it.
The pattern is normally a 3-D model of your final cast. It can be created from wax, sand, plastic, silicone, wood – just about anything you can shape and form into a 3-D structure.
When creating your pattern, it’s important to leave a little wiggle room for any shrinkage when the metal cools.
Step 2: make your mold
Next comes the mold.
Remember, you can make your mold from sand or from actual metal. If you plan on making the same cast a multitude of times, a metal cast is your best option. A sand cast will be destroyed after the metal is poured, whereas a metal cast can be used over and over again. If using a sand mold, the pattern is typically laid in a box and covered completely with the sand mixture. The sand is compacted to make as tight and even a mold as possible.
You can then flip the box upside down and remove the pattern, leaving a nice mold of your intended object.
If using a die cast, the metal (usually aluminum) mold can be created a number of ways, including sand casting, investment casting (lost-wax casting), or even machining it the way you want it to look.
Step 3: pour your metal
This is where the fun begins. At this stage you can actually see your object taking shape.
If it’s a smaller cast, you can simply pour from where your metal was heated directly into the mold. If it’s a larger cast, you may require additional people to get the metal heated, and for transferring the metal to the mold.
Once the metal is poured into the mold, allow the metal to cool and solidify before moving to the next step.And please remember to adhere to all safety protocols when pouring metal, including wearing proper PPE and ensuring a fire extinguisher is close by.
Step 4. Remove the metal from the mold
After the metal has had a chance to cool and solidify, you can safely remove it from the mold. If you used a single use mold like sand casting, you can break the mold away from the metal to retrieve your object.
If you used a permanent mold, you may need to use ejector pins to extract your casting.
Whichever process you used, your extracted project should look pretty close to what your finished object should be. If not, you’ll need to move on to the fifth and final step.
Step 5: Finishing
Finishing can involve polishing, cleaning, or even sanding away excess mold materials or unwanted bumps in your cast.
This is the last step to making your finished object look exactly how you want it, so be sure to take the time to get it just right.
So there you have it. Whether you’re a hobbyist or you work as part of a team in a foundry, getting your mold perfect before you begin casting is of the utmost importance.
If you want to learn more about the casting process, check out our blog here. If you’re interested in working with us, feel free to contact us and one of our experts will be in touch with you as soon as possible.