Considering the effect of finished product quality on the gate location, we have to consider some general rules as below main points:

• It is crucial to locate gates away from the area on the finished part because of the potential degradation of the plastic that is likely to occur in such areas.
• The thinned walled area must require additional gates to offer enough plastic volume in minimum cycle time.
• We will design the gate is away from internal obstructions, cores, and pins as this may cause mark lines because of the flow of molten plastic around them, which causes reforms on the other side.

• Jetting – this usually occurs with small gates, where instead of flowing smoothly, the resulting pressure sprays into the cavity, causing wavy falsifications known as worming. As a result, we need to enlarge the gate or decrease in force or even both.

• Overheating – friction from the high injection speed causes this defect. Overheating causes decay of the resin that destroys molecular bonds. When the injection is slowed, other defects like poor mechanical strength are likely to occur. So the best way to minimize this defect is to divide the given volume of resin over several gate openings as this aids in dissipating pressure.

The Difference between Hot and Cold Runner Systems

For a hot runner system

• They use an electrically heated cylinder during plastic parts manufacturing into the fluid cavity.
• Using hot runner systems conserve resources, minimizes cycle times, and enables control of temperature precisely.
• Nevertheless, it is more expensive and complicated.

For a cold runner system

• Increases cycle times and costs
• Involves the consumption of material because of longer runners.
• It is more cost-effective.

• Easy to enlarge when needed
• Inexpensive to manufacture and design.

• Easier to build
• Ideal where concentricity is crucial for cylindrical parts.
• Capable of injecting a high amount of plastic.