Like the two-shot molding process, the overmolding process also starts with the molding of the substrate. Although the substrate can be any kind of material, it’s best to use the more rigid material as the base. The next step involves placing the substrate in an overmold cavity within the same molding tool.

We can’t discuss overmolding vs. two-shot molding without mentioning their advantages and disadvantages. Although these processes are essentially similar, there are peculiarities you must look out for.

Double-shot molding is ideal for complex, multi-material, and multi-color products. It is a highly versatile method, useful for many applications in different industries, including:

It is important to note that the method of transferring the substrate can affect the speed of 2-shot injection molding. Manual transfers or the use of robotic arms often take longer than transferring with a rotary plane. However, using rotary planes is more expensive and may be more efficient for high-volume productions.

By comparison, thermal and ultrasonic hardware installation post molding can reduce the mechanical retention of the insert in the part. These processes locally heat the plastic and flow it around rib and knurled geometry in the hardware to create mechanical retention. Inserts designed for insert molding utilize much more significant retention features as the molding process can fully pack material around the body of the insert to achieve much higher strength ratings for insert molded components.

In some cases a part can be progressively overmolded in a series of tools to build plastic thicknesses that would be impossible to mold in a single shot. This allows for parts with extreme thick, thin or other detailed geometry to be produced for ergonomic and aesthetic purposes. Soft gasket features can also be molded into sealing glands so critical sealing geometry is permanently captured in place.

The tooling involved in this technique is complex. There is also a need to remove previous materials from the machine before the next production run. As a result, setup time may be quite long. Therefore, using the two-shot technique for small runs may be too expensive.

Two-shot molding and overmolding are simple but effective molding processes, helping to create durable, high-quality components. However, there are times when you may need to compare two-shot molding vs. overmolding to ensure you get the best result.

The second phase involves the introduction of the second material. Once the mold opens, the part of the mold holding the substrate will rotate 180 degrees to meet the injection molding nozzle and the other mold chamber. With the substrate in place, the engineer injects the second plastic resin. This resin forms a molecular bond with the substrate to create a firm hold. The second layer is also allowed to cool before ejecting the final component.

However, design teams and engineers must evaluate critical considerations against their project requirements. This way, you can ensure the benefits outweigh the risks and make the best choices.

Insert molding and overmolding combine multiple components into a single assembled part during the plastic injection molding process. In these variations preformed components are placed into the mold tool and then captured and joined into a single combined part as new plastic geometry is molded over them.

Two-shot injection molding involves in-depth and careful designing, testing, and mold tooling. Initial designing and prototyping may be done via CNC machining or 3D printing. Then the development of mold tooling follows, helping to create replicas of the intended part. Extensive functional and market testing is done to ensure the efficiency of the process before final production begins. Therefore, the initial costs involved in this injection molding process are usually high.

Although the technique enhances product performance, there are some downsides involved in its use. They include the following:

Remember that 2-shot injection molding is best for high-volume production while overmolding is ideal for low-volume production runs. Contact us at RapidDirect today, and let’s discuss your injection molding project.

A wide variety of materials such as metal hardware, plastics and fabrics are commonly used across an extensive range of molding applications today. In particular, these types of processes enable design freedom and improved part performance in molded parts that otherwise would be cost prohibitive or impossible.

Plastic substrates can be shifted or easily deformed by overmolding pressures if not supported properly. To accomplish this the tool needs to be designed with geometry that captures the insert. This is most often done with features in the tool steel that the insert can be placed onto and clamped against as the tool closes. Designers need to be aware of this because these support locations will prevent overmold material from flowing into these areas, meaning they will be exposed in the resulting part. Care should be taken to design adequate support features in the substrate that are either hidden or functional in the component.

This article covered two-shot molding vs. overmolding, detailing the steps involved in the two techniques. These injection molding techniques are ideal for creating functional and aesthetically pleasing components for various industries. The various benefits and downsides of the processes will help you make the right selection for your project.

Therefore, this article aims to give a detailed overview of overmolding and two-shot molding, helping you understand their various differences. We will also discuss the benefits and drawbacks of these techniques. At the end of this article, you will be able to decide on the best molding services for your applications.

Overmolding injection molding is a vital industrial process with many diverse applications. Some of the uses are highlighted below:

It is also critical the seams between the overmold and insert or substrate are designed so the tool steel can successfully shutoff against the substrate to prevent overmold material from flashing outside of the intended geometry. Shutoffs are best made when the action of the tool closing can create a small amount of preload or crush on the part to successfully seal the overmold cavity. When the overmold parting line is more dynamic, special attention must be given to the shutoff geometry and substrate support in the tool to prevent flash from occurring.

Knowing the comparison between overmolding vs. two-shot molding may not be enough. Working with a skilled and experienced manufacturing partner like RapidDirect will streamline your decision. We boast a team of designers, engineers, and machinists with many years of experience. Our expert teams are ready to see you through every part of the production process, from design to process selection and final manufacturing.

Overmolding eliminates the need for adhesives and fasteners since separate pieces can merge. As a result, the products’ durability improves. There is also a reduction in total production costs.

The types of components that can to be overmolded to incorporate features in parts include a wide variety of materials and design opportunities. Common examples include clear windows, decorative features (IMD), electronics and magnets.

Overmolding is excellent for creating aesthetically appealing structures. It is the best approach since it is available in a range of colors and materials. They may also be modified for other surface finishes to improve their cosmetic appearance further.

When an insert gets overmolded the bond between the two needs to survive the end application requirements. This can be accomplished through a mechanical interlock or with a chemical bond.

Mechanical hardware is another common application benefitting from insert molding. By placing and capturing items like threaded inserts, pins, bushings, etc. in the tool before injecting the plastic, it is possible to mold around these components to mechanically capture the hardware into the molded part. In most cases this replaces secondary hardware installation processes accomplished via bonding, ultrasonics or thermal insertion. Depending on the application and volumes of the product, this could yield cost savings and increase manufacturing throughput.

When two separate pieces are fused together in a mold, there is a danger of delamination. Delamination will occur when the ideal temperature range fluctuates. Mechanical interlocks are required when the available heat cannot properly fuse the materials.

The two-shot process follows the traditional injection molding rules. Therefore, aluminum or steel injection molds are still used in this process, making design iterations quite difficult. Reducing tool cavity size may be difficult and sometimes result in scrapping the entire batch of product. As a result, you may be incurring cost overruns.

The extremely high level of precision needed within the aerospace industry makes CNC machining a suitable manufacturing process for the sector.

Manufacturers who require innovative product design, ergonomics, and a distinctive product appearance are all fans of plastic injection overmolding. The overmolding method has evolved over time, resulting in high customer satisfaction.

Once the substrate is in the cavity, the molten secondary material (overmold) is molded onto or around the substrate. After cooling, the overmold and the substrate become mechanically or chemically bonded to give the end product.

The mechanical method is achieved by making sure the substrate has undercuts or pass through features to allow the overmold material to fill and hold the component in place. If the part will experience mechanical stresses the retention features should be designed to take this into account to avoid overmold separation.

Tool design for an overmold has several specific requirements the part design should consider. When an operator or robot places an insert or substrate into the overmold tool it needs to be located successfully and held sufficiently while the tool closes, as well as during the injection molding process where high pressures can be working to shift the substrate out of place. This is critical because failure can result in scrap parts or even tool damage that is often lengthy and expensive to repair.

Some products may require two or more overmolds. An important point to note is that the plastic resins used in overmolding must be thermally or chemically compatible with one another. Incompatibility between the substrate and overmold may give a poorly bonded or deformed product. Sometimes, plastic resins can also be molded over metal substrates. In this case, compatibility may not be a big issue.

This process improves the product’s performance, including shock and vibration reduction, chemical resistance, and electrical insulation. TPE is one such material that, when employed to make various items, produces a non-grip feature. It can also operate as an environmental barrier due to the abovementioned qualities.

Overmolding is another multi-shot injection molding technique that creates an end product from two or more plastic materials. This process is applicable to various manufacturing and industrial uses. It is ideal for building high-quality functional and aesthetically pleasing components. Many manufacturers also use this method for plastic prototype development and to produce sub-sections of components.

Two-shot molding is ideal for larger production runs, considering the difference between two-shot molding and overmolding. A significant drawback to the 2-shot injection molding process is the higher initial costs and expensive tooling. Therefore, it will be better to choose this process for larger productions. It is also great for flexibility, control, quality, and efficiency.

Injection molding has proven to be incredibly valuable for the fast and precise creation of high-quality plastic parts. It is a practical choice for a wide range of applications for various industries. However, different processes fall under the umbrella of injection molding. Two of the most popular techniques in this category are two-shot molding and overmolding.

Overmolding involves two processes in the production line, which increases the part’s cycle time. When you need to mold a single item in a single operation, the production cost tends to rise. Furthermore, because overmolding is a two-step procedure, it necessitates the use of additional equipment than single molding.

With this technique, designers have more freedom for innovative designs. The process can accommodate complex mold designs, incorporating multiple materials and making parts with complex geometries.

On the other hand, overmolding is best suitable for low-volume production. It is also ideal for rubber parts that do not have strict tolerance requirements. Overmolding services can be done on standard injection molding machines. Therefore, this technique is a great choice for manufacturers that do not want to invest in new machining tools.

Such combination possibilities solve not only production difficulties but also the ability to produce components for applications in different industries.

Additionally, these processes can be combined. For instance plastic can be molded over plastic that has already been molded over plastic. Plastic also can be overmolded over plastic that as already had metal insert molded into it. Another application may call for two materials, e.g. metal and rubber, to be insert molded into plastic at the same time.

Generally insert molding and overmolding are differentiated by the materials being used. Overmolding is typically defined as plastic over plastic, while plastic over metal, or another material, is generally referred to as insert molding. Although the terms can be used in various ways for certain applications.

Although it is a two-phase process, it uses only one machining cycle. Within the single cycle, the initial mold is rotated out of the way, giving room for the insertion of the second molding material. With just one cycle involved, two-shot molding involves fewer costs and labor requirements. It also creates more items within a short period.

Overmolding necessitates the assembly of several materials. This enhances the part’s flexibility by utilizing all of the capabilities of the materials involved. Furthermore, manufacturers can boost flexibility by using the overmolding design guide.

Mold design may affect the ease of bonding between the molding materials. Therefore, machinists and engineers must ensure the correct alignment of molds to ensure easy adhesion and prevent defects.

Many medical tools that require sterilization further benefit from this process by creating tight seals around instrument substrates and handle shafts. This helps to prevent areas for bacteria to collect and ensures the sterilization process is effective between procedures.

When discussing two-shot molding vs. overmolding, it is pretty easy to confuse the two processes. They share several similar characteristics, and they offer similar benefits in manufacturing. However, there are major distinctions you must note to get the best results. The difference between two-shot molding and overmolding will help you choose the best option for your projects.

Alternatively it can also be possible to achieve a chemical bond between substrate and overmold. This method is typically only viable if the substrate is also a plastic material. By selecting substrate and overmold materials that are compatible it is possible to form chemical bonds during overmolding that will entirely lock the overmold in place over the substrate. In some cases resins will be specifically rated to bond with particular substrate materials, especially when working with TPEs.

Overmolding and insert molding offer creative opportunities to get innovative with new part designs. If you have a part design that could be insert or overmolded please consider reaching out to Mack Molding to get feedback on the design and cost of your product. Mack has experience with hundreds of overmolded product in its portfolio to guide you in the right direction.

It is also possible to promote bonding by prepping the substrate surface with primers, etching chemicals or plasma treatment.

Insert molding is used on applications like handles and grips because they require a high level of aesthetic and tactile focus due to the amount of interaction with end users. Designers can enhance the ergonomics and feel of these components by overmolding them with soft elastomeric materials known as Thermoplastic Elastomers or TPEs. These polymers come in a variety of material types and durometers so the overmold material can be tailored to a specific set of product requirements.

The two-shot injection molding process consists of two phases. The first phase is similar to the conventional plastic injection molding technique. It involves injecting a shot of the first plastic resin into the mold to create the substrate for the other material (s) to be molded around. The substrate is then allowed to solidify and cool before transferring to the other mold chamber.

This process is also referred to as multi-shot, double-shot, or dual-shot molding. This injection molding process involves the molding together of two separate plastic resins in a single machining cycle. As a result, engineers can easily create multi-material and multi-colored parts without extra machining steps.

The fundamentals for overmolding a component are the same in all cases. The design of the components needs to consider several process-related factors such as tooling and material compatibility. As a prerequisite, the substrate material getting overmolded needs to be robust enough to survive the injection molding process where it will be exposed to high heat and extreme pressures as molten plastic flows past it.

If you want to produce high-quality machined parts with a sleek appearance, it’s essential to consider some critical factors related to CNC machining.

2-shot molding allows the combination of different materials and colors for functional and attractive final products. There are many possibilities available with this process, including:

RapidDirect is ready to work with your team to choose the suitable technique for your project. Our injection molding services are ideal for prototyping and production for applications in various industries. We assure fast turnarounds of high-quality products are competitive prices. Upload your CAD files today to get an instant online quote.