Casting, Multi-Material Injection Molding and best solutions for plastic products – Part 2

Following what we already know of part 1, we will continue to discuss this and other issues surrounding multi-material injection molding and related solutions.

Index Plate Multi-Point Casting

The MSM index plate is similar to the MSM of the rotating roller, adding features: The rotating spindle can now be pulled out of the half of the core.In addition, the cavities and cores of each stage have different geometric shapes.Indexing makes switching between different core sets/compartments.The figure below shows a simple diagram of the index msm mold.

Multi-point injection molding
Multi-point injection casting

The injection molding process can be described as follows:

Injection molding process
Injection molding process

(1) First check if the mold has reached a stable state.That has the potential to create a complete plastic part.Make sure the mold can create a complete plastic part.Mold and withdraw the index plate (as shown in (a) of the figure).Plastic part A is pre-completed in Compartment A, and plastic part A is semi-finished.When the index plate returns, part A plastic enters compartment B.

(2) Materials A and B are pumped simultaneously into their respective compartments and left to cool. This creates a complete ab component plastic part in compartment B, creating part of plastic A in compartment A (as shown in (b) of the figure).

(3) The mold opens and the indicator table pops up (as in (c) of the figure).

(4) Then push the complete component AB (as in (d) of the figure).The cross section of the entire AB assembly is shown in (f) of the figure.

(5) The index disk is rotated 180°, the core is captured and the mold is closed (as shown in (e) of the shape).

Pros and Cons

MSM index plates are more complex than rotating MSM and require more complex molding. This complexity adds to the cost and duration of the mold, but it allows for the production of more complex plastic parts.

Core Toggle Multi-Shot Molding

The core conversion MSM process is the easiest because the core and cavity of the mold do not need to move.In contrast, change the geometric shape of the mold by moving the slider.

Description of the Core Toggle Multi-Shot Molding Process
Describes the Core Toggle Multi-Shot Molding process

(1) inject material A into the cavity so that the slider is in a fully extended position (far right in this example, Figure (a)).

(2) Record the slider to reveal a new part of the cavity (left in this example, Figure (b)).

(3) Material B is re-configured through a separate port (not shown), and the remaining space is filled by moving the slider (Figure (c)).

(4) The plastic part (Figure (d)) hardens and is pushed out of the mold.

(5) Sequence from (1) to (4).

Pros and Cons:

Adding a slider to the mold will increase the cost of the tool, but it can still be much less expensive than rotating a rollingshaft or index plate mold. Unfortunately, it is not possible to produce complex plastic parts.

Overview of overmolding

       Overmolding is a casting variant. This process is the addition of additional shapes and layers of structure to existing components by squeezing liquid plastic spray. That the first material (sometimes called the background) is partially or completely covered by the next material (covering material) during the manufacturing process.

Among them, the substrate can be anything. For example, processing metal parts, casting plastic parts, and even existing products such as lace inserts, screws or electrical connectors.

In a sense, the pressing process consists of insertion casting and injection molding.

Overmolding application

    Overmolding can be a combination of any two types of materials. However, the compatibility issue between the two materials must be considered.

Plastic: is a combination of plastics of different materials and colors. In fact, it’s a bit like 2k injection molding.

Plastic-rubber: a combination of hard plastic and soft rubber /TPE. It is usually provided with a soft grip surface for hard plastic parts. Metal and rubber can do the same.

Metal-Plastic: Reduces the next processing with a one-step casting process. Remove assembly time.

Casting 2 steps

Part of the material is formed on the injection molder, after which this part is placed as an insertion material in another mold. And a second material is injected.

In fact, 2-step squeezing and 2k injection molding are similar. The difference is that casting 2 steps does not require a specific injection molding machine. This can be done using a standard injection mold. But two different sets of molds are needed.

Compared to 2k injection molding, plastic parts have a high error rate and high mold cost. However, the 2-step mold uses a high level of flexibility. The foundation mold can be combined with a variety of cladding materials to create different types of products.

Insert mold

Casting insertion is the insertion of a insertion into the mold and injection molding of the part. The insertion part is usually a metal part. Insertion molding can enhance the mechanical properties of plastic parts. This avoids secondary installation and reduces costs.

Insert casting app

A typical application for casting inserts is to include one or more metal inserts with lace in a plastic part. For example, lace in plastic parts can wear out during repeated use, which can lead to damage to the part. Metal inserts help improve the performance of plastics and ensure reliable fastening when reusing parts.

This combination of plastic and metal allows the designer to take advantage of the weight of the plastic and the durability of the metal.Mold insertion can also be used as a package for electronic components to improve the performance of electronic components.You can click here to learn more about LPM.

Multi-component injection molding

It’s also called copper juice. Also known as copper casting spray. Multi-component injection molding describes the simultaneous spraying of many viscous materials. Instead of using one material as an additional layer compared to another.

In other words, it creates a sandwich structure.That is, one material is completely overlaid with another as shown in the picture:


This advanced casting technology has been around for decades. Early success in professional applications such as ketchup containers, stadium beer bottles and medical jars. With the upgrading of production services, it can work better.

Pros and cons

  1. Reduce costs by using cheaper filly materials as the invisible core of the product
  2. Change the density and elasticity of the product so that the product floats in water or absorbs shock.

Despite these advantages, copper spraying requires more expensive machines and is harder to maintain than standard single sprayers. The copper spraying process also has difficulty handling complex geometries.


     Multi-material injection molding gives the product more casting options. If you want to improve the form of the plastic part, so that it is layered, you can consider multi-shot injection pressing. You want to make your product lighter, do you consider squeezing copper? You want plastic parts to have better mechanical properties, consider casting inserts. Unleash your creativity. Don’t find a better solution? Maybe you can give it to us. Please contact us immediately via Hotline: 0934 683 166. or via email: for free advice and quotes.

Vietnam Capacity Precision Mold Joint Stock Company

Address: Lot B2-3-3b, Nam Thang Long Industrial Park, Thu Phuong, Bac Tu Liem, Bac Tu Liem, Hanoi

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