What is Injection Molding, classification & General Structure?

To learn about plastic mold design and plastic injection technology, you must have a good understanding of:

1. mold structure

2. technical requirements

3. and classification of plastic injection molds according to mold cavity and channel

For those who are starting to learn about plastic mold design, we must first understand the concepts of plastic injection molds, structure as well as the most basic knowledge about molds.

We will also learn together an overview of plastic molds, types of molds and mold texture.

Concept of plastic mold and injection molding technology

A mold is a cluster of many parts that is a tool used to shape products according to the shaping method; the mold is processed and shaped based on the shape of the product.

Injection molding technology is the process of injecting molten plastic into the mold cavity. Once the plastic is cooled and solidified in the mold cavity, the mold is opened and the product is removed.

The role of plastic injection mold

• Plastic injection mold is known as the common form of molding, the process itself is extremely fast compared to other methods to make      products with high output, more efficient and cost-effective.
• The mold can process and produce extremely complex and homogenous parts.
• Durability is one of the important factors that need to be taken into account; the designer only needs to determine whether the part needs stiffness or flexibility to choose the right material. Detailed color is also an important factor to be flexible in the material selection process.
• The molding of a part also reduces the amount of excess material in the machining process.

• Labor costs in the injection molding industry are also relatively low compared to other types of processing.

Plastic mold texture

The plastic mold structure consists of two main parts, the Cavity part (also known as the female mold) and the Core part (also known as the male mold), in addition to other parts to assemble into a complete mold.

- Cavity part - female mold

The cavity part (the female mold part, the fixed mold part): is stationary during the whole molding process, mounted on the fixed plate of the plastic injection machine.

- Core part – male mold

The core part (male mold part, movable mold part): is the part that moves when opening and closing the plastic mold during the injection process, mounted on the movable plate of the plastic injection machine.

The structure and size of the mold designed and manufactured depends on the shape, size, quality, and quantity of the product to be produced. A set of plastic molds can have one or more cavity and core, the contact between the cavity and the core is called the parting surface.

General structure of a set of plastic molds

In addition to the core and cavity, there are many other parts in the mold set. These parts are assembled together to form a complete set of molds.

Upper clamping plate:  This plate has the effect of clamping the upper mold plate and the upper clamping plate into a block and clamping both the block and the stationary table of the plastic injection machine.

Upper mold plate:  The most important part because it is the outer shape of the product. It determines the accuracy of the mold as well as the accuracy of the product. The outer surface of the product is beautiful or ugly, whether it is correct or not depends entirely on when we process this mold plate.

Positioning Silver:  Ensure the proper position of the mold with the nozzle.

Positioner:  Ensures a proper fit between the fixed part and the moving part of the die. It includes locating pin and locating silver.

Support plate:  Keeps the mold piece from falling out.

Bar:  Used as a divider between the support plate and the bottom clamp to allow the trolley to work.

Lower clamp plate:  This plate clamps the entire lower mold assembly into one block and clamps this block to the dynamic table of the injection molding machine.

Push pin:  Used to push the product out of the mold when the mold is open.

Push clamp plate:  Hold push pin, return pin, stem pull pin.

Push plate:  Used to block the mounting pins on the ejector clamp plate during the ejection of the product so that the pins cannot fall out. The push plate and the push clamp plate are fastened into one block and are called the push rod. The pusher is located below the lower die and above the lower clamping plate.

Return latch:  Enables the push rod to return when the mold is closed.

Pillar: Guide the movement and support for the ejector plate, preventing the mold plate from being bent due to high pushing pressure, increasing the life of the mold.

Lower mold plate:  As a very important part, it is the contour that determines the internal shape of the product. The lower mold and the upper die combine to create the complete shape of the part. The upper die is the stationary part; the lower die is the movable part.

There is also a cooling system including water lines, grooves, heat pipes, etc., which is responsible for stabilizing mold temperature and cooling products quickly.

Classification of injection molds

- According to the number of layers of the mold cavity:

• 1 tier mold
• Multi-layer mold

- By channel type:

• Mold using hot channel
• Mold using cold channel

- According to the channel layout:

• Two-plate mold
• Three-plate mold

- According to the number of plastic colors creating the product:

• Mold for single color products

• Molds for multi-colored products

Technical requirements for plastic molds

• Ensure the exact size, shape and shape of the product.
• Ensure the necessary gloss for both the cavity surface and the core to ensure the gloss of the product.
• Ensure the relative position accuracy between the two halves of the die.
• Make sure to remove the product from the mold easily.
• Mold materials must have high wear resistance and be easy to process.
• The mold ensures rigidity when working, all parts of the mold must not deform or deviate from the required position when subjected to      great pressure.
• The mold has a cooling system that surrounds the mold cavity so that the mold cavity must have a stable temperature so that the plastic      material can easily enter the mold cavity as quickly as possible and achieve productivity.

• The mold has a reasonable structure, not too complicated to suit the purpose of use.

Which is the best plastic injection molding company?

It is necessary to turn to a company specialized in the segment, the only one capable of guaranteeing the efficiency of the parts produced by strictly. Moreover, it should have a state-of-the-art technology and qualified professionals, in order to guarantee the performance of each part and, also, safety in its application.

FirstPart Reliable Injection Molding Company

In the search for plastic injection molding serviceis US or Europe, First Part is the solution. With vast experience in the area, the company has all the factors that guarantee the quality of the molds; it is capable of producing custom-made parts for several product lines and segment.