IM is a popular manufacturing process because it is fast and efficient. It also allows for a high degree of precision, meaning that products made using insert molding are typical of high quality.

The Way to Combine Metal and Plastic: Insert Molding

Article from | RapidDirect

The plastic industry has been booming lately, with new technologies and processes being developed every day. One such process is insert molding.  

Insert molding can offer an inexpensive method of producing quality parts. However, if you're not careful about how you design your part, you might end up wasting money. A good designer should consider factors such as material type, strength requirements, and functionality before they begin designing a part. This process can be used to create various products, including medical devices, automotive parts, and electrical components.

In this blog, we will discuss the way to combine metal and plastic with the help of insert molding. 


What is insert molding?

In insert molding (IM), a pre-formed insert is used to fill an injection mold. A robotic arm is used to insert the insert, which might be made of metal or plastic. The force generated upon injection then serves to secure the insert. Products containing metal or plastic cores are manufactured using insert molding. These include medical tools, electronic components, and automobile parts.

This process is another type of plastic injection molding. But in insert molding, the metal is put into the molten resin beforehand. 

Insert molding

In doing so, the plastic can easily flow around the metal, forming a seamless seal. Because the metal is included throughout the process, fasteners like screws and bolts are unnecessary. Insert molding results in sturdy, well-graspable items that are a pleasure to handle.

IM is a popular manufacturing process because it is fast and efficient. It also allows for a high degree of precision, meaning that products made using insert molding are typical of high quality. Additionally, IM can be used to create products with complex shapes and designs. 

There are two main types of insert molding: hot runner and cold runner. In a hot runner insert molding system, the insert is placed into the mold using a robotic arm. The mold is then heated to a high temperature, which melts the plastic. 

In a cold runner insert molding system, the insert is placed into the mold using a robotic arm. The mold is then cooled to a low temperature, which solidifies the plastic. The solidified plastic is then injected into the mold, and the insert is held in place by the force of the injection process. 

Besides, when talking about insert molding, you shouldn’t ignore overmolding. Overmolding is similar to insert molding. Insert molding and overmolding are two efficient ways to allow you to produce parts with complex applications.


The Benefits of insert molding

The insert molding process was originally developed to facilitate the assembly of large quantities of identical products. It is widely used in the plastic industry to reduce the cost of plastic products. 

Among the benefits of insert molding are reduced costs, improved quality control, and faster cycle times. These benefits can help manufacturers reduce production time and improve efficiency. Here are the details: 

  • Reduces Costs: Assembly and labor expenses decreased (Molded as one assembly)

  • Increased Reliability: Injection molding maintains good alignment, eliminates loosening, and improves vibration and shock resistance.

  • Size, weight reduced:  Insert molding minimizes parts' size and weight by bonding them with durable, lightweight plastic resin. Eliminating fasteners and connectors eliminates extra material and labor costs associated with assembling components and simplifies production processes.

  • Strong components: Strengthened component structure Insert molding combines the plastic resin and insert's strength to create a seamless product.

  • Improves flexibility: Custom plastic insert moldings allow for almost limitless configurations and materials combinations.

  • Parts consolidation: Insert molded components to enable part and inventory cost reductions)


The application of insert molding

Insert molding is a flexible manufacturing process that enables the production of a wide range of parts and components from a variety of different materials. The method is ideally suited for production on a large scale and has the capacity to generate components with extremely close tolerances. Producing parts with many characteristics in a cost-effective manner can also be accomplished through the use of insert molding. Here are some of the top applications of insert molding

  • Tube valves and needle hubs are medical devices.

  • Weaponry

  • Bushings, studs, and tubes encapsulated

  • Control and appliance knobs

  • Screws

  • Encapsulated electronic components

  • IML and IMD inject a printed film into the mold cavity. Injecting plastic resin against a film creates a cost-effective and durable product.



Mixing metals and plastics can be a tricky process. One of the biggest issues is that metals and plastics expand and contract at different rates. If you're not careful, you could end up with a part that doesn't fit together correctly or that breaks. Therefore, we suggest you pick a provider with good expertise in this field. 

The content & opinions in this article are the author’s and do not necessarily represent the views of ManufacturingTomorrow

Comments (0)

This post does not have any comments. Be the first to leave a comment below.

Post A Comment

You must be logged in before you can post a comment. Login now.

Featured Product

PI USA - Need 6-Axis Precision Motion Control?

PI USA - Need 6-Axis Precision Motion Control?

With six degrees of freedom and extremely versatile motion and positioning capabilities, hexapods find applications in Aero-Space, Automation/Assembly, Life Sciences, Microscopy, Optics, Photonics. How can a hexapod help your application?