Introduction: General Steps to Sand Casting

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. 

Tools Needed
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.

Comments

author
plantprof (author)2013-09-24

This reminded me of doing this in 9th grade shop many, many years ago, and I've wanted to try it again.  Thanks for the inspiration.  But as I remember, the very fine sand--almost like powdered "dirt" in consistency--was a barely moistened mix of sand and water with something added to the water to make it sticky.  Then we'd add sand and pound it in place so when the upper mold was taken off the lower, the sand would not fall out [at least after a few tries].  Are you using dry sand or adding something to it to allow it to stick together in the mold?  Source for your sand?  Did you dust the mold and the separation area with talc or chalk to facilitate separating the mold halves?  How did you remove the original model and leave the central sand core intact?  

author
ThomasS372 made it! (author)plantprof2017-01-23

Hello, I'm a master patternmaker and I can answer your questions. The "dirt" you're referring to is indeed, a "sand", but not like normal sand. There are many different types, fineness of granules, etc., how the sand is "bound" together and their selection can be made based on the type of metal that will be poured, the type of surface finish you want on the outside and inside of the casting as examples. Most sand mixtures contain a "binding" agent, along with a very minimal amount of water. (Excess water will turn to steam, creating voids in the casting). Talcum powder is commonly used as a "parting agent" on the patterns to release them from the sand mold.

To create a "cavity" within a casting (such as the coolant pathways in an engine block), requires that a separate, female tool (Called a "Core-box") is made to create the shape of the cavity and register it to the master pattern. This "male" sand shape is called a "Core". To put it simply, the Master Pattern which generally creates the "outside shape", has registrations built onto the pattern (Called Core-prints), that the Core will align with. The drag and cope sides of the sand mold are rammed up against the master pattern. The sand mold halves are separated, the master pattern is removed, the sand "core" made from the core-box is placed into the lower half of the sand mold, aligning it with the "core-print" areas molded within the lower half of the mold. The cope side, or "upper half" of the sand mold is closed over the lower, encapsulating the core inside. After the metal is poured, the sand core is broken loose and out from the casting, creating the desired cavity shape. (See the attached pdf for more details.)

CORES AND COREPRINTS IN SAND MOLDS.pdf
author
astral_mage (author)2013-12-24

a simple way is a screen from a screen door to check 4 unwanted items.

author
astral_mage (author)2013-09-21

or old soda cans. if yr over 21 yr empty beer cans. or u can get them from a local park. i love trash can diving tho(wear gloves, the good kind with long sleeves if u can afford them) and anti germ wash to wash yr hands an arms!!!!

author
astral_mage (author)astral_mage2013-12-24

got it. also yr local vacum repiar shop an bike shop are great place 4 scrap metal . also be kind to the employees, even if yr having a bad day. remember this they will remember wat u did. and that source of free metal will dry up fast.

author
acuchetto (author)2013-11-29

This studio looks like where I studied sculpture in Little Rock.

author
sublingual (author)2013-09-25

Just a quick terminology correction: A mold is a negative image, like your sand. The object you are using as a stand-in for the final object is a pattern.

In lost-wax casting, you can use a resin mold to create multiple wax patterns. When you invest the pattern and burn out the wax, the casting flask itself is also a mold.

author
baecker03 (author)2013-09-24

I remember hearing that there is something that can be applied to the negative to allow the sand to more easily come loose.... wax or cooking oil? not sure if I missed it, but what additive is used to facilitate the mold hardening?

author
TDaddy (author)2013-09-24

How does the sand solidify by just sitting for 40 minutes?

author
EmmettO (author)2013-09-24

I'm curious about the sand. It's not regular silica sand, what do you use?

author
SinAmos (author)2013-09-23

This video is private?

author
kylehausladen (author)2013-09-23

Sorry about the video mishap, it was showing in the editor but got lost when I published. Seems to be working now thanks for the notification.

author
astral_mage (author)2013-09-21

make sure the coat is leather or a heat resistant materiel. not some cheap cloth type!

author
astral_mage (author)2013-09-21

here where very heavy gloves will come in handy. I.E. high quality stick welding gloves will work in a pinch also use a remote temp senor unit as well. or if u wanna use the heat cumin off to charge those batteries use a thermal electric generator of some kind

author
astral_mage (author)2013-09-21

i.e. best to wait a day or 2 if yr not in a hurry. if yr in a hurry then wait 4 hr.s or so

author
astral_mage (author)2013-09-21

un i think u 4 got the video

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