How do you calculate shot size in an injection moulding machine?

 Calculating shot size in an injection moulding machine is a crucial step in the manufacturing process. The shot size determines the amount of material that is injected into the mould, and it is essential to get it right to ensure the final product meets the required specifications.

If it is Hot runner, No of cavities (layman's words number of parts to be filled) multiplied by each part weight is Total shot weight or Shot Size.

if it is a cold runner, No cavities multiplied by each part weight added to Runner weight is Shot weight or Shot Size.

Remember the shot size mentioned by the Machine manufacturer for PS. If your material is other than PS, then you have to identify the specific gravity of the material to be processed and then multiply it with the Total shot weight of the machine mentioned in the catalog.

 

To calculate the shot size, you need to consider several factors. These include the size of the mould, the material being used, and the desired part weight. Here's how to calculate the shot size step by step:

1. Determine the size of the mould

The first step is to determine the size of the mould that will be used in the injection moulding machine. This will give you an idea of the volume of material that will be needed to fill the mould.

2. Calculate the volume of the mould

Once you know the size of the mould, you can calculate its volume. This is done by multiplying the length, width, and height of the mould. For example, if your mould is 10cm x 10cm x 10cm, the volume would be 1000 cubic centimeters (cc).

3. Determine the material being used

The next step is to determine the material that will be used in the injection moulding machine. Different materials have different densities, which means they require different volumes to achieve the same weight.

4. Calculate the density of the material

Once you know the material being used, you can calculate its density. This is done by dividing its mass by its volume. The density is usually expressed in grams per cubic centimeter (g/cc).

5. Determine the desired part weight

The final step is to determine the desired weight of the finished part. This will depend on the specifications of the product being manufactured.

6. Calculate the shot size

With all of this information, you can now calculate the shot size. The shot size is calculated by multiplying the volume of the mould by the density of the material and the desired part weight. The formula is as follows:

Shot size = (mould volume) x (material density) x (desired part weight)

For example, if your mould has a volume of 1000cc, the material being used has a density of 1.2g/cc, and the desired part weight is 50 grams, the shot size would be:

Shot size = 1000cc x 1.2g/cc x 50g = 60,000 cubic millimeters (mm3)

In conclusion, calculating shot size in an injection moulding machine is a critical step in the manufacturing process. By following these steps, you can ensure that the final product meets the required specifications and is of high quality.