After reading this short set of instructions you will be able to:
>Understand the basics of sand casting
>Make your own molds
>Make a sand casted object in a safe manner
Step 1: Basics of Sand Casting
Sand casting is a process that uses a mold made from either metal, wood, or wax to create a negative impression in a special sand that will be the mold for the molten metal. This mold is then filled with a molten metal that is left to cool and solidify. Once the metal has solidified the mold can be hit with a hammer, pipe, or any hard object to crack the sand mold and expose the metal object.
Step 2: Preparation for Sand Casting
The first step in making a sand casted object is deciding on the object. For this set of instructions I will be using a mug as my object. Once you have decided on the object you want to make you will need to figure out how you can cast said object and still be able to remove the sand mold from the form. This leads me to an important point about sand casting, because you need to be able to remove the sand mold from the form the complexity of the objects that can be molded is limited. It is also important to remember that you will need to leave a hole in the sand cast to pour the molten metal through when it is assembled.
1) Silica Sand
2) Mold of object
3) Some type of kiln/oven to melt the metal you will be using
4) Ladle to pour molten metal
5) Block of solid metal to melt
6) Hammer or some other object to crack the sand mold after metal solidifies
Step 3: Filling the Form With Sand
Once you have your object/s that you will be casting made into forms it is time to pour sand over the top to make your negative impression into the sand. When pouring in the sand it is important that all the sand gets packed in tightly to prevent any gaps in the mold that will cause the molten metal to flow someplace it is not supposed to flow. it is also important that you make the sand thick enough to prevent cracking and burn through when the molten metal is poured into the mold.
1) Ensure mold is clean and free of any debris
2) Pour sand into mold ensuring that it is packed tightly around all corners and edges
3) Let the sand solidify for roughly 40 minutes before removing the sand mold from the form
Step 4: Removing the Sand Mold
Removing the sand mold is probably the most delicate part of this process. While the sand is hard enough to hold together it is not strong enough to withstand any sort of drop or sudden impact. It is recommended that you get assistance when removing the sand mold depending on the size and awkwardness of the mold. For the mold that I was using it worked best to tap the bottom side of the mold with a hammer to jar it lose, then one person slowly flipped the mold over while another person held the sand mold to prevent it from falling out and breaking into many small pieces. While removing one of the molds that was used in making the mug it fell apart because it was not completely solidified and is shown below.
1) Ensure the sand is hard before attempting to remove the mold
2) Obtain assistance if needed to remove the sand mold
3) Tap the bottom of the mold to jar the sand lose from the edges
4) Remove the sand mold and place it in an area where it will not get knocked or dropped
5) Repeat for all parts of the sand mold that are needed
Step 5: Assembling the Sand Mold
When assembling the sand mold ensure that the cavities that will be filled with metal are free of any debris or lose sand that may be present. It is also very important that the cavities line up exactly to ensure the object you are casting turns out how you intend it to.
1) Clean all debris from sand mold cavities
2) Properly align cavities to ensure proper metal solidification
Step 6: Pouring the Molten Metal
This is the most dangerous part of sand casting, and it is highly recommended that you read through the safety precautions on slide 9 if you have not already done so to ensure that this is done in the safest manner possible. Below is a video of how the molten metal should be poured and the personal protective equipment that should be worn while pouring the metal.
1) Put on the proper protective equipment
2) Clear area of any hazards that are present
3) Carefully fill the ladle with metal and transport over to your sand mold
4) Pour metal into mold slowly ensuring not to spill any metal
Special Note: Mold needs to be filled with metal in one pour to ensure that the metal does not cool at different rates and cause discontinuities in the object.
Step 7: Cracking the Mold
As with any project there is always some destruction involved and this is it for sand casting, grab a hammer or metal rod and give the mold a good swing to crack the sand shell away from the metal object. Have fun with this and enjoy some destruction!
Special Note: Ensure that the metal has completely solidified before breaking the mold, time will vary based on the size and shape of the object being made.
Step 8: Quench Your Object in Water
It is obvious that this newly formed object is going to be very hot, after all it was molten metal just a short time ago. It is best to use a pliers if the object is small enough and allows it, or you can always dump water over the top of the object to cool it down and prevent any burns from touching the hot surface.
Step 9: Safety Concerns and Precautions
Safety is extremely important when working with molten metal because of the temperature at which the metal is at. For this reason it is important that you have a clear work area and make a plan for how you are going to move the molten metal prior to making any movements with metal in hand. Listed below are some primary safety concerns and as always this list is incomplete but with some common sense and by following these rules sand casting can be a fun and exciting time.
1) Wear the personal protective equipment as shown below in the image
2) Clear any hazards that are in the workspace
3) Do not spill any metal onto the floor, especially concrete floor as it can cause an explosion
4) Be cautious of your surroundings
5) Be wary of any surfaces that may be hot
6) As with any unfamiliar task be cautious and pay attention to your surroundings
7) USE COMMON SENSE, often forgotten but a very useful tool to always use
Step 10: Enjoy Your Newly Sand Casted Object
Congratulations on completing your sand casting, enjoy and I hope this set of instructions was helpful.
Please leave any questions or comments below and I will try to answer them as soon as possible.