Introduction

Injection molds feature various styles and multiple classification standards in the plastic and thermoset molding industry. According to actual production demands, manufacturers can classify injection molds based on installation methods, matched injection machine types, cavity quantity and product size. Among all classification rules, classification by overall structural characteristics is the most practical and widely adopted method.

1. Basic Classification Standards

• By installation mode: Mobile injection mold and fixed injection mold. The mobile type is only applicable to vertical injection machines, while fixed molds fit most mainstream injection equipment.

• By injection machine type: Horizontal injection mold, vertical injection mold and angle-type injection mold

• By cavity quantity: Single-cavity injection mold and multi-cavity injection mold

• By product dimension: Large-size, medium-size and small-size injection molds

  
  

2. Seven Types of Injection Molds by Structural Features

2.1 Single Parting Surface Injection Mold (Two-Plate Mold)

It is the simplest and most cost-effective standard mold structure. The mold cavity is divided into two parts, separately arranged on the fixed mold and movable mold. For horizontal and vertical injection machines, the main sprue is located on the fixed mold, and diversion runners are set on the parting surface.

After mold opening, molded products and runner scraps remain on the movable mold side. The ejection device installed on the movable mold will push out finished parts integrally. With stable operation and low maintenance cost, this mold is widely used for shell-type and box-type industrial products.

2.2 Double Parting Surface Injection Mold (Three-Plate Mold)

Different from two-plate molds, this structure adds an independent movable middle plate, also known as gate plate, forming two parallel parting surfaces. The whole mold consists of three core components: fixed runner plate, movable middle plate and movable mold plate.

During mold opening, the middle plate separates from the fixed plate and movable plate synchronously. It can separate finished products and sprue wastes automatically, which is suitable for products requiring hidden gate feeding and automatic material sorting.

2.3 Transverse Parting and Core-Pulling Injection Mold

When industrial products have side holes, undercuts and irregular side structures, ordinary molds cannot complete demolding. This kind of mold is equipped with oblique guide pins, oblique sliders and other transverse core-pulling mechanisms.

It uses mold opening power to drive lateral cores to move horizontally and separate from products. For large-scale and high-precision parts, oil cylinders and air cylinders can be equipped to realize stable automatic core pulling, avoiding product damage.

2.4 Automatic Thread Demolding Injection Mold

For molded parts with internal and external threads, manual thread stripping will cause low efficiency and thread damage. The automatic thread demolding mold is equipped with rotatable threaded cores and thread rings.

Relying on the transmission system of injection machines or independent hydraulic motors, the threaded components rotate steadily to release products, realizing full-automatic demolding of threaded insulating parts and plastic fasteners.

2.5 Runnerless Injection Mold

Runnerless molds are divided into hot runner molds and adiabatic runner molds. Instead of cooling and solidifying pouring materials, it adopts heating or heat insulation technology to keep resin molten from nozzle to gate.

This structure eliminates solid sprue waste, saves raw material cost, shortens molding cycle, and reduces mold venting defects. It is the preferred mold type for high-efficiency and high-precision mass production.

2.6 Injection Mold With Movable Inserts

Some special-shaped products cannot be demolded along the regular mold opening direction. Thus, molds are assembled with movable threaded cores, side cores and split half inserts.

During demolding, the movable inserts are ejected out together with finished products, then separated manually. All movable inserts must be positioned accurately before mold closing, otherwise it will cause mold collision and batch product scrapping.

2.7 Fixed-Side Ejection Injection Mold

Conventionally, most products shrink and adhere to the movable mold after curing, so ejection devices are installed on the movable side. However, individual products with special surface structure are easy to stick to the fixed mold.

This customized mold arranges the complete ejection system on the fixed mold side, balancing demolding force, protecting product appearance and dimensional accuracy, and preventing surface cracking of brittle thermoset parts such as bakelite.

Conclusion

Each type of injection mold matches different product structures, molding efficiency and cost demands. Reasonable mold selection can optimize injection parameters, stabilize product tolerance and cut manufacturing failure rate. Whether for thermoplastic or thermoset insulating parts, standardized mold structure design is the premise of stable mass production.

Hitech(HK) International Limited provides customized design and manufacturing services for all types of injection molds. We focus on thermoset mold development, support precision mold manufacturing and one-stop injection molding production, and deliver reliable mold solutions for global industrial clients.