How Many Types Of Sprue You Know?

There are two major types of sprue Hot Sprue  and Cold Sprue in injection molding.

Hot Sprue in Injection Molding
This is a type of sprue that remains in contact with the molten plastic during the entire injection molding process. It is continually heated throughout the process to keep the molten plastic that would otherwise cool in its hot state.

Hot sprues are typically used for larger parts or those with complex geometries where the use of a cold sprue would result in a poor surface finish or inconsistent filling of the mold cavity.

Advantages
Faster Cycle Times: As the plastic remains molten in the sprue, it can be quickly injected into the mold cavity, resulting in faster cycle times.
Consistent Filling: Hot sprues ensure consistent filling of the mold cavity, leading to high-quality parts.

Disadvantages
Higher Cost: Hot sprues are more expensive than cold sprues due to the additional heating elements required.
Difficult to Handle: The hot sprue can be difficult to handle due to its high temperature, making it challenging to remove from the molded part.

Cold Sprue in Injection Molding
This type of sprue is not in direct contact with molten plastic. Instead, it is a separate channel that is fed by the injection molding machine and fills the mold cavity through a gate. The plastic in the sprue solidifies quickly after injection, and it is subsequently removed from the molded part.

Advantages
Lower Cost: Cold sprues are less expensive than hot sprues due to the absence of heating elements.
Easy to Handle: The cold sprue is easy to handle as it cools quickly and can be easily removed from the molded part.
Lower Maintenance: Cold sprues require less maintenance than hot sprues.

Disadvantages
Inconsistent Filling: Cold sprues may result in the inconsistent filling of the mold cavity, leading to lower-quality parts.
Poor Surface Finish: The use of a cold sprue can result in a poor surface finish on the molded part due to the gate location.