A 3 plates mould is used when part of the runner system is on a different plane to the injection location. The runner system for a three-plate mold sits on a second parting plane parallel to the main parting plane.
The runner system is often used to reduce the number of parts in an injection molding application, or to pressurize an area of an injection mold that does not require plastic flow. The runner system can also be used for secondary operations such as cooling and venting.

Runner systems are typically made from aluminum or steel, depending on the application and design requirements. They can be designed as either single or multiple stages
Gating Into Two Different Plates
3 plate injection moulding is a technique of manufacturing where three different plates produce a single part. The first plate is the core plate, on which the cavity get ready. The second plate is the runner plate, which allows molten plastic to flow into the cavity and cool down. The third plate is the ejector plate, which pushes out the finished product from the cavity after it has cooled down.
Gating Into Two Different Plates
The gating system in a three-plate injection moulding machine can work in two different ways:
Gating From Both Sides – In this process, there will be one gate for each cavity and an ejector system for each runner. With this method, all cavities will share their runner system and ejector; however, each cavity will have its own gate system.
3 plates mould-Gating From One Side Only
This method involves having only one gate per cavity while having separate gates for each runner. This means that there will be one gate per cavity but two or more runners per cavity depending on how many cavities you want to produce at once . With this method, each cavity will have its own ejector system but share the same gate system.
Side-action injection molding is a type of injection molding that uses a side action ram as opposed to a top action ram. The side action ram comes usually together with larger molds and has several advantages over the top action ram.
The Side-Action Ram
The side-action ram is a type of injection molding tool that moves the screw back and forth through a vertical stroke. It has two sides, one for entering material into the cavity and one for ejecting material from the cavity. The side-action ram has its own hydraulic cylinder system for moving it up and down. This allows for high cycle times and fast production rates.
The Top Action Ram
The top action ram is for smaller parts because it can be more delicate than the side action ram. The top action ram moves vertically along with the mold, which allows for faster cycle times than other types of injection machines. This means that you can produce more parts in less time with this type of machine than with others on the market today.
Advantages of a 3 plates mould
The main advantage of a three plate paint bucket mould is the ability to produce complex parts with minimal gate count. This is because the parting line for each cavity is in the middle or at the end of the part which allows for more efficient use of material. One of the biggest challenges facing injection molders is making parts with very thin walls and sharp angles, which can be difficult to achieve with two plate molds due to excessive draft angles.
In addition to its high level of design flexibility, a three plate mold also requires less machining than a two plate mold due to its single cavity design. This makes it easier and less expensive to produce complex parts in small batches without having to retool multiple times.
The disadvantages of a 3 plates mould
Cost of making 3 plates consumer appliance mould is higher than 2 plate molds. The three-plate mold is more complex, which makes it more expensive. Because of this, you’ll typically only see them on high-volume parts or parts that have a complex geometry.
There is less room for the runner. The runner places between two plates, which reduces the amount of material. This results in more expensive tooling and longer cycle times. The three plate mold is more complex, which makes it more expensive. Because of this, you’ll typically only see them on high-volume parts or parts that have a complex geometry. There is less room for the runner. The runner has place between two plates, which reduces the amount of material . This results in more expensive tooling and longer cycle times.
It is harder to make the parting line straight. The parting line has to follow a curve, which gives it a greater chance of being off-center or crooked. This can cause problems when ejecting parts because they may not come out properly.
Takeaway
3-plate molds get application when the part or components has complex shapes with tight tolerances (diameter, wall and holes is one example), unlike 2-plate molds where parts with large cross section or thick walls are avalaible. Therefore, a 3-plate mold is for complex components to ease cost and time to produce. Their complexity means that if you need more than one part from a 3 plate mold, special consideration need.