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What are the types of injection molds?

There are many ways to classify injection molds, and according to different classification basis, there are usually the following categories.

1 .According to the overall structural characteristics of the injection mold, it can be divided into the following types.

a. Single parting surface injection mold (two-platen injection mold): Single parting surface injection mold is also called double-platen injection mold. It is the simplest type of injection mold, where one part of the cavity is on the mold and the other part is on the mold.

In the single parting surface injection mold for horizontal or vertical injection molding machine, the mainstream is located on the side of the mold, and the parting channel is located on the parting surface. The mold is equipped with a push-out device to push out the parts and runner condensate (material handle).

b. Double parting surface injection mold (three plate injection mold): Double parting surface injection mold refers to the casting system where the material and the part are taken out from different parting surfaces. It is also called three plate injection mold.

Compared with the single parting surface mold, there is a movable middle plate (also called gate plate), which is used for a single cavity or multi-cavity mold with pinpoint gate feed. When the mold is opened, the middle plate is separated from the fixed template at a fixed distance so that the condensed material of the pouring system between these two plates can be removed.

c. Injection mold with movable molding parts: Due to the special requirements of plastic parts, the mold is equipped with movable molding parts, such as movable convex mold, movable concave mold, movable molding rod, movable molding insert, etc., to facilitate the removal of the parts when the mold is opened.

d. Injection mold with lateral parting and core extraction: When the part has a side hole or a side concave, lateral parting and core extraction mechanisms such as an inclined column or an inclined slider are provided in the automatically operated mold. When the mold is opened, the side core is moved laterally by the mold opening force to make it detach from the part. There are also hydraulic cylinders or pneumatic cylinders installed on the mold to drive the side cores for lateral parting and core extraction.

e. Automatic thread release injection molding mold: When the mold is equipped with a threaded core or ring that can be rotated to automatically release the molded parts with internal or external threads. The rotating or reciprocating motion of the machine tool, or the installation of a special motor (such as an electric motor, hydraulic motor, etc.) and transmission device, drives the threaded core or ring to rotate so that the parts can be released.

f. In general, after the mold is opened, the parts are left on the moving side of the mold, so the push-out device is also located on the moving side of the mold. However, sometimes due to the special requirements of the parts or shape restrictions, the parts are left on the fixed mold (or may be left on the fixed mold), so the push-out device is set on the side of the fixed mold. When the mold is opened, the pull plate or chain drives the push-out device to push out the parts.

g. Runnerless Injection Molds: Runnerless injection molds include hot runner or adiabatic runner injection molds, which use heating or adiabatic (the outer layer of condensed plastic in the runner insulates the molten plastic in the center of the runner) to keep the plastic melting from the injection nozzle to the cavity gate. After each injection, only the part has to be removed and there is no return to the pouring system, which greatly increases labor productivity and ensures the transfer of pressure in the runner. This makes it easy to achieve fully automatic operation.

2. According to the number of cavities in the mold, it is divided into a single-cavity injection mold and a multi-cavity injection mold.

a. Single-cavity molds produce only one part per cycle. A single-cavity mold has a smaller injection mold cost, while the cost per part will be higher. It is suitable for low production volumes. Instead of multiple cavities, multiple single-cavity tools ensure that production is always running, even if one mold fails. Single-cavity molds will have flexibility in controlling the injection molding process.

b. Multi-cavity injection molding tools produce more than one part per cycle. Multi-cavity injection tools have a higher initial investment cost but a lower cost per part.

● Multi-cavity molds are used to increase productivity.

● Compared to single-cavity molds, multi-cavity injection molds are more costly.

● Running a multi-cavity mold requires a higher tonnage machine than a single-cavity mold.

3. According to the mold installation method, the injection molding machine is divided into mobile injection mold and fixed injection mold.

4. According to the type, the injection molding machine is divided into the horizontal injection mold, vertical injection mold right angle injection mold.

5. According to the dimensional accuracy of plastic parts, there are general injection molds and precision injection molds.

6. According to the mold casting system, it is divided into cold runner mold, adiabatic runner cross, hot runner mold, and warm runner mold.

7. According to the plastic material category, there are thermoplastic injection molds and thermosetting plastic injection molds.

In other words, the choice of injection mold type depends on part geometry, tool design, desired quality, and throughput.

ZHXTOYS is a second-generation family-owned and operated full-service plastic injection molding contract manufacturer. We are based in China and work with large companies and start-ups around the world. Contact us today to find out if this process is right for your idea or company. You can also submit an online quote for your injection mold. We will also continue to add more information about the various types of injection molds available.

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