Mold Flaw Analysis—Sticking on Gate and Plastic Products Warping Deformation
The defect on the gate of a molding in plastic products is always a concerning issue that many engineers encounter, and sometimes, it could even cause the production to be certain, leading to huge economic losses. Commonly, the reasons of the gate sticking and products warping are related to the design of gate, mold cooling, molding condition and process reasons.
Gate Design
The gate design is one of the major elements that can affect the integrity of the production. The size, shape and location of a gate can have huge influence to the product design and plastic injection, thus, it is extremely important to grasp the molding technology of different types of plastic. For example, a large gate area and correct gate location is required for HIPS plastic. In contrary, with HDPE, Since the endothermic shrinking could result in heavy side wall shrinkage, a small gate area is better for the product consistency and integrity.
Mold Cooling
Mold cooling is closely related to gate sticking and plastic warping due to incorrect injection cooling. This can end up as inconsistent cooling, which can lead to warping, sticking and less product strength. Generally, to solve the issue of product warping, the injection time and hold pressure should be adjusted to provide enough time for cooling, or changing to improved mold inserts with better cooling.
Molding Parameters
injection speed, pressure and temperature are the main parameters that affect the plastic product quality. Excessive injection pressure will simplify the appearance and create surface bubbles and losses, while lower temperature will cause poor filling efficiency. When setting the molding parameters, it is important to find the best balance between speed, temperature and pressure to avoid product surface defects and optimize the injection complete process.
Process Reasons
The cleanness of the plastic material and runner system is also a reason of gate sticking and product warping deformation. As the gate is where the plastic enters the cavity, any foreign material here may affect the gate adhesion, leading to useless production. Thus, frequent checking and maintenance of the machine, mold and runner system is essential to make sure that there is no debris remaining in the gate area.
In conclusion, to eliminate the issue of gate sticking and plastic products warping deformation, comprehensive checking should be conducted to the design of gate, mold cooling, molding condition and process. The finished production will be more reliable and consistent as long as there is no defect on the gate.
