Anticipating Weaknesses - Sink Marking

 

The plastic molding error known as sink marking can occur in thick featured regions of plastic components that shrink more than they should. Plastic in thicker regions tends to cool more slowly than others, creating a depression in the component that can ruin its value. Molded components that require a smooth, flat surface like computer monitors and other commercial products can be rendered worthless if sink marked. In other products it does not matter as much. Small and medium sized parts at Plastic Components are not immune to sink marking, but the plastic injection molding process that we use is designed accurately to prevent sink marking.

 

What Causes Sinking

 

The error causing some parts of a component to shrink too rapidly can be the result of a number of mold design flaws. Plastic processing methods must be closely monitored, along with the raw plastic used, the design of the mold and the shape of the part to be molded. The ways in which Plastic Components manipulates the molding process are designed to minimize the appearance of sink marks. Depending on the design of the mold, Plastics will alter the gate type and size. Packing extra material into the mold cavity after the part has been molded can also help reduced sink marking. Shorter packing phases can increase the risk of marking, so PCI makes sure to allow an appropriate amount of time for packing.

 

The PCI Solution

 

Other options for the reduction of sink marking include gas assist and foaming; both of which are considered by Plastic Components' engineers before the plastic injection molding process begins. Heat removal methods do well. Contact Plastic Components to learn more about how the plastic injection molding process will apply to your particular molding need. Plastic Components designs and molds custom plastic components so that the product you order will be exactly what you need. If you already know about the process, and would simply like to price plastic molding at our company, please fill out our plastics quick quote form.