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Importance Of Gates: A Mold Spare Parts Manufacturer’s View

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To every mold spare parts manufacturer, gates are a core component of the injection molding machine.

Gates are usually formed during the process when molten plastic flows into a sprue and the runner system through the machine’s nozzle.

In most cases, gates are usually the final section of the runner system which attach the nozzle to other parts of the mold.

As a major spare part of the molding machine, gates determines to a great extent the design of the mold.

For this reason, the type, number, and location of gates can greatly affect the whole molding process such as the cycle time of the mold.

With such a key role to play, it is always advisable to source for gates from a reputable mold spare parts manufacturer for the best deal.

Gates Trimming

Gates exist in two major categories thus; automatically trimmed gates and manually trimmed gates. However, we shall be focusing on the automatically trimmed gates 

1.Automatically Trimmed Gates

Compared to the manually trimmed gates, the automatically trimmed gates are better due to their low cost of production. This means that there is no secondary operation.

Also, they offer greater consistency of the product as well as s shorter cycle time.

However, despite these good sides about the automatically trimmed gates, there are instances where the manually trimmed gates are needed.

This usually occurs when the part is unable to tolerate the automatic shearing force.

Also, the manually trimmed gates may be required when the gates are too big, and cant is removed automatically. 

Types of Automatically Trimmed Gates and When To Use Them

1.Sub Gates or Submarine Gates

These are very small gates that are usually trimmed automatically by shearing. This happens when the mold opens up at the end of the entire cycle.  

The advantage of submarine gates is the fact that the mark produced after the gate has been trimmed is very small, and so can easily be concealed.

Submarine gates are mostly used in two-plate mold designs by a mold spare parts manufacturer.

2.Pin Gates or Pinpoint Gates

These are also small gates that are usually trimmed automatically.

Pinpoint gates are usually employed in 3-plate molds. This is because the runner is on its own separate plate.

Pinpoint gates are usually used in multiple pin gates in different locations. Once this happens the resin flowing through the pinpoint gates is spread evenly among them. 


This 'separation and conquer' approach in the pinpoint gates usually removes long resin flow paths. This also ensures that the mold cavity is filled symmetrically.

Nevertheless, one disadvantage of the pinpoint gates is the fact that their runners are usually big.

This, you can tell will lead to a large chunk of scrap which is a total waste of resources.

Choosing The Right Gates Location

1.To reduce voids and sinks, always put gates around the thickest cross-section of the mold part.

2.Always put gates on a non-cosmetic/ non-functional area of the mold part.

3.For ease of removal, always put gates in places where they can easily be removed either automatically or manually.

4.Avoid putting gates close to areas such as cores and pins. This is so because these features may act as an obstruction to flow.

5.The location of gates can also impact the strength of the final products and not just cosmetics.

6.Keen attention to the location as well as the number of gates can greatly enhance the flow of resin. This, you can tell will prevent weld lines and flow marks.

Take Away

Gates are a very important part of an injection molding machine.

Depending on the choice of a mold spare parts manufacturer gates can be trimmed automatically or manually.

Pinpoint and Submarine gates are two examples of automatically trimmed gates.

For the best injection mold spare parts, contacting a professional mold spare parts manufacturer will afford you the opportunity to have the best product. 


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