Estimating the amount of silicone rubber raw materials required is usually the first step in making silicone molds. Not having enough material or having too much left over is not only frustrating, but costly. To assist you with these calculations, use the following skills to help determine how much material you need to complete molds and castings of simple shapes.
Calculation principle: To find the volume of mold making of casting material you must first calculate the volume of the mold container and then the volume of the model or pattern you are casting. Then just subtract the pattern volume from the mold container volume.
Note: There are 21 grams per cubic inch of liquid silicone rubber raw material. There are 453 grams in 1lb.
Square or a rectangle
Volume = length x width x height
For example: you have a mold box that needs to be filled up 10 * 5 * 2 = 100 cubic inches in order to completly cover your original.
Now using the same formula subtract the cubic inches (volume) of your original.
If you part is 10 * 5 *1 = 50 cubic inches.Then you would take 100-50 to give you a total of 50 cubic inches. 50 cubic inches x 21 grams per cubic inch = 1050 grams （1050 divided by 453 grams per lb. = 2.32 lbs） of liquid silicone raw material.
Cylinder or tube shape
Volume = π (3.14) x radius squared x height
For example: the diameter of a mold is 4 (the radius would then be half of that being 2) and the height is 3. The part model is 3 diameter (1.5 radius) by 2.5 high.
3.14 * 2*2 * 3 = 37.68 cubic inches.
3.14 * 1.5 * 1.5 * 2.5 = 17.66 cubic inches.
You would take 37.68-17.66 to give you a total of 20.02 cubic inches.
20.02 cubic inches x 21 grams per cubic inch = 420.42 grams (420.42 divided by 453 grams per lb. =0 .93 lbs) of liquid silicone raw material.
See Disclaimer: Remember, these calculators are only used as estimates, No warranty, either expressed or implied, as to the reliability of the information contained herein and our assume no liability for loss or damage associated with use of these calculators.You may consider adding 5% – 10% to any material estimate to account for waste, such as material sticking to the sides of your mixing containers, stir sticks, etc.