Good electrical properties makes PBT ideal for power components as well as automotive applications. The strength ranges from moderate to high depending on glass fill, with unfilled grades being tough and flexible. PBT also shows fuels, oils, fats and many solvents, and it also doesn’t absorb flavours.

Two-shot injection molding, also known as dual injection, multi-shot, or 2K molding, is a highly specialized process that combines two different materials or colors into a single injection molded part. This advanced molding technique involves injecting two types of polymers into the same mold through separate injections but within the same molding cycle. The result is a complex part that can have varying colors, textures, or material properties, seamlessly integrated without the need for post-molding assembly.

The most common types of plastic used are high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Polyethylene offers a number of advantages including high ductility levels, good tensile strength, strong impact resistance, resistance to moisture absorption, and recyclability.

Injection moulding is used for a range of applications where a repeatable manufacturing process is required. This includes manufacturing items such as wire spools, packaging, bottle tops, toys, combs, musical instruments (and components), chairs, small tables, storage containers, mechanical parts, and automotive parts and components.

Injection moulding is a manufacturing process that allows for parts to be produced in large volumes. It works by injecting molten materials into a mould (or ‘mold’ in the United States). It is typically used as a mass production process to manufacture thousands of identical items. Injection moulding materials include metals, glasses, elastomers and confections, although it is most commonly used with thermoplastic and thermosetting polymers.

Two-shot injection molding is particularly valuable in industries where part durability, aesthetic qualities, and production efficiency are paramount. Common applications include:

Bearing these factors in mind, a small single cavity injection mould costs between $1,000 and $5,000. Larger or more complex moulds can cost $80,000 or more. However, on average, a typical mould costs around $12,000.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

Our trained employees ensure your parts will be delivered on time and to spec.

Throughout production, the accuracy of the molds is checked using a coordinate measurement machine (CMM, a three-dimensional measurement device) to prevent injection molding flaws that can occur from misalignment, such as flash.

It is important to determine how many parts you wish to manufacture so as to decide whether injection moulding is the most cost-effective production method.

PMMA, also known as acrylic, provides good optical properties, high gloss and scratch resistance. It also offers low shrinkage and less sink for geometries with thin and think sections.

In the world of injection molding services, manufacturers and designers have several techniques at their disposal to create high-quality, functional, and aesthetically pleasing plastic parts. Among the most advanced and versatile techniques are two-shot injection molding and overmolding. Both techniques offer unique advantages and are suited for different applications, yet they are often confused or misunderstood. By understanding the intricacies of each method, professionals can optimize their manufacturing processes and leverage the strengths of each technique for their specific project needs.

Although there is some material waste with injection moulding it is less than with many other manufacturing processes. Of course, the exact materials used also have a bearing on the environment in relation to how long they last, if they can come from recycled materials and how they are disposed of. There are also considerations around the carbon footprint of the lifetime of the products that are created, including during manufacture.

Injection moulding is mainly used where there is a need to manufacture many thousands or millions of identical parts from a mould.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

Two-shot injection molding typically has shorter cycle times because it completes the part in one continuous, automated cycle. Overmolding requires multiple cycles (one for each material layer), potentially increasing total production time, especially if manual labor is involved in transferring substrates between molds.

The process of two-shot injection molding is executed in a specialized molding machine that is equipped with two or more injection units. The core of the process lies in the precise control of the injection units and the mold design, which needs to accommodate multiple injections. Here’s how it typically unfolds:

Both two-shot injection molding and overmolding are employed to create multi-material components, enhancing functionality, aesthetic appeal, and product performance. However, they diverge significantly in their methods, applications, and ideal production scenarios.

Injection moulding has a great many applications for manufacturing, particularly for producing high volume parts. While the tooling and moulding can be expensive, the cost of production once this is completed is low. Providing the ability to produce near-identical parts, injection moulding is used for parts in a variety of material types.

The entry cost for injection moulding manufacture can be high – given the cost of the machinery and the moulds themselves.

The first stage of injection moulding is to create the mould itself. Most moulds are made from metal, usually aluminium or steel, and precision machined to match the features of the product they are to produce.

The main advantage of injection moulding is being able to scale up production to produce a large number of parts. Once the initial costs of the design and the moulds have been covered, the price of manufacturing is very low. The cost of production drops as more parts are produced.

Advancements in modern injection moulding machinery mean that they now use between 20 and 50% less energy as compared to ten years ago.

Overmolding is used in a wide range of industries due to its ability to add enhanced properties to a part, such as improved grip, aesthetics, and durability. Typical applications include:

Separate materials can be combined in one part in a type of injection moulding called a two-shot mould. This technique can be used to add a soft touch to plastic products, add colours to a part or produce items with different performance characteristics.

Two-shot injection molding generally becomes more cost-effective at higher volumes due to its ability to produce complex multi-material parts in a single cycle, reducing labor and operational costs. However, the initial investment in setup and tooling is significant. Overmolding, while potentially higher in per-part cost due to longer cycle times and additional labor, requires less upfront investment and can be more cost-effective for smaller production runs.

The final disadvantage is that large undercuts require experienced design to avoid and can add even more expense to your project.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

Cost and Volume Efficiency: Two-shot molding is generally more cost-effective at high volumes due to its efficiency and speed, while overmolding can be more suitable for lower volumes or prototypes due to its simpler setup and lower initial costs.

Once the mould has been created by the mould-maker, the material for the part is fed into a heated barrel and mixed using a helical shaped screw. Heating bands melt the material in the barrel and the molten metal or molten plastic material is then fed into the mould cavity where it cools and hardens, matching the shape of the mould. The cooling time can be reduced through the use of cooling lines that circulate water or oil from an external temperature controller. Mould tools are mounted on plate moulds (or ‘platens’), which open once the material has solidified so that ejector pins can eject the part from the mould.

Kasirajan also points out the importance of precision throughout the process, “Because the mold shifts or rotates along the axis, the interchangeability of the core and cavity at both sides must be ensured.”

Injection moulding is becoming more environmentally friendly as machinery becomes more efficient and materials such as thermosetting polymers are capable of withstanding extreme temperatures and conditions.

The most cost-effective type of injection moulding is rubber injection moulding, which produces a high yield of durable products. In addition, consistent vulcanisation processes with precise temperature controls can lower costs by reducing waste material.

This inexpensive resin material delivers high impact resistance in certain grades but can be brittle in cold temperatures (in the case of propylene homopolymer). Copolymers offer greater resistance to impact while PP is also wear-resistant, flexible and can provide very high elongation, as well as being resistant to acids and bases.

3D printing and injection moulding are both techniques for producing plastic parts and components, but each manufacturing process has its own advantages and can be used together as complementary manufacturing methods.

Injection moulding is used to make a range of widely used products, including common plastic items like bottle tops as well as remote control casings, syringes and more. It is also commonly used for manufacturing larger items such as car body panels.

Minimising the cycle time will aid production as will using machines with hot runner moulds and well thought-out tooling. Such small changes and use of hot runner systems can equal production savings for your parts. There will also be cost savings from minimising assembly requirements, especially if you are producing many thousands of even millions of parts.

Moulds can be made of single or multiple cavities. Multiple cavity moulds can have identical parts in each cavity or can be unique to create parts of different geometries. Aluminium moulds are not best suited to high volume production or parts with narrow dimensional tolerances since they have inferior mechanical properties and can be prone to wear, deformation and damage due to the injection and clamping forces. While steel moulds are more durable they are also more expensive than aluminium moulds.

The final advantage of injection moulding is that it allows for the production of many identical parts, which allows for part reliability and consistency in high volume production.

This strong, impact resistant plastic has low shrinkage and good dimensional stability. A transparent plastic that is available in different optically clear grades, PC can provide a high cosmetic finish and good heat resistance.

Moulding costs correlate with the number of cavities in a mould. Fewer cavities require less tooling work, which lowers the manufacturing costs to create an injection mould. The complexity of a part’s design also impact the cost, including factors such as surface finishing, tolerance, threads, detailing and the number of undercuts. Added details such as these will increase the cost, as they require more tooling.

Up-front costs can be high for injection moulding, particularly with regard to tooling. Before you can produce any parts, a prototype part needs to be created. Once this has been completed, a prototype mould tool needs to be created and tested. This all takes time and money to complete and can be a costly process.

The entire process is highly automated and controlled, requiring less labor and minimizing the risk of human error, which is crucial for the high-volume production of complex parts.

A dimensionally stable material with high toughness, temperature and heat resistance, PPSU is also resistant to radiation sterilisation, alkalis and weak acids.

“However,” he advises, “depending on the part’s structure, some features can only be accomplished by double-shot injection molding, while others can only be completed by overmolding.”

Ashwin Kasirajan is a Fictiv Manufacturing Engineer who works with customers on their injection molding programs. To understand the importance of tool design in two-shot injection molding, he explains, “The tool must allow both stages of the part to be molded in the same tool in order to achieve maximum production efficiency. The design must consider two separate injection stages that can be rotated 180 degrees or oriented to allow a robot to transfer the components. Each injection station is run by an independent injection unit, which allows injection speeds and pressures to be controlled for each material being utilized.”

In both two-shot injection molding and overmolding, thermoplastics are commonly used due to their versatility and ease of molding. For two-shot injection molding, materials like ABS (Acrylonitrile Butadiene Styrene), polycarbonate, TPE (Thermoplastic Elastomers), and TPU (Thermoplastic Polyurethane) are popular. These materials are chosen for their ability to bond well during the molding process and withstand the rigors of repeated use.

With over 85,000 commercial plastic material option available and 45 polymer families, there is a wealth of different plastics that can be used for injection moulding. Of these, the polymers can be broadly placed into two groups; thermosets and thermoplastics.

Injection moulding also produces minimal wastage when compared to traditional manufacturing processes like CNC machining, which cuts away excess materials. Despite this, injection moulding does produce some waste, mainly from the sprue, the runners, the gate locations, and any overflow material that leaks out of the part cavity (also called ‘flash’).

Overmolding is a versatile manufacturing technique where a single part is created through the sequential injection of two or more materials onto a base part or substrate. The primary material, usually a rigid plastic, forms the substrate, while the secondary material, often a softer plastic or rubber, is molded over the first. This process not only enhances the product’s functionality but also improves its aesthetic appeal and tactile experience.

Accelerate development with instant quotes, expert DFM, and automated production updates.

3D printing, also known as additive manufacturing, is a method of creating a three dimensional object layer-by-layer using a computer created design.

Injection moulding can be an expensive process, but there are several ways in which you can reduce mould costs, including:

This high temperature, high-performance resin provides heat resistance and flame retardancy, excellent strength and dimensional stability, as well as good chemical resistance.

Two-shot injection molding is a preferred choice for many high-end applications in these sectors because it can mold parts that meet strict technical specifications while also addressing the need for visually appealing designs.

Injection moulding is also not ideal for producing large parts as a single piece. This is because of the size limitations of injection mould machines and the mould tools. Items that are too large for an injection moulding machine’s capability need to be created as multiple parts and joined together later.

Overmolding offers more design flexibility due to its ability to combine a wide range of materials that do not necessarily have to be closely compatible. It allows for the addition of different textures, colors, and properties with fewer constraints on the molding environment. Two-shot injection molding is precise and efficient for producing complex, multi-material parts. However, material compatibility and design precision are required for the positioning and bonding of materials.

There are many different types of PPA (or nylons), each of which has its own advantages. Generally-speaking, nylons offer high strength and temperature resistance as well as being chemically resistant, apart from against strong acids and bases. Some nylons are abrasion resistant and offer good hardness and stiffness with good impact strength.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

This tough, impact-resistant plastic is widely used across industry. With good resistance to acids and bases, ABS also offers low shrinkage rates and high dimensional stability.

By thoroughly assessing the requirements of your specific application and considering the pros and cons of each method, the injection molding experts at Fictiv can help you select the most appropriate injection molding process to achieve your manufacturing goals.

Injection moulding can be performed with a variety of different materials including metals, glass, elastomers, confections and, most commonly, thermoplastic and thermosetting polymers.

The versatility of overmolding makes it ideal for customizing parts that require tactile and aesthetic qualities in addition to functional performance. This method is especially beneficial where the production scale or budget constraints do not justify the higher initial costs associated with two-shot injection molding.

Kasirajan puts it simply, “Choose overmolding if the quantity is not too high—only a few thousand or ten thousand—to save some money on molds. If your program requires quantities of 500,000 or more, the more cost-effective process is two-shot injection molding.”

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

We exist to eliminate bottlenecks in new product development by integrating the people, processes, and platform you need to source custom parts.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

PEI (or Ultem) offers high temperature resistance and flame retardancy, along with excellent strength, dimensional stability and chemical resistance.

Create high quality custom mechanicals with precision and accuracy.

By signing up, you agree to our Terms of Use and Privacy Policy. We may use the info you submit to contact you and use data from third parties to personalize your experience.

Access a wide breadth of capabilities through our highly vetted network.

We provide streamlined access to a Fortune 500-class supply chain, complete with extensive capabilities, hands-on quality management, and a best-in-class technology platform for quoting, DFM, and order tracking. Request a free quote to get started!

Choosing the right injection molding materials is crucial for the success of both processes. For two-shot injection molding, materials must be carefully selected to ensure they can bond well and withstand the molding temperatures and pressures without degrading. Typically, materials with similar melting temperatures and chemical properties are chosen.

Minimising the number of parts and simplifying the geometry of your items will make injection moulding easier. In addition, the design of the mould tool is important to prevent defects during production.

In contrast, overmolding offers more flexibility with material selection since the secondary material only needs to adhere mechanically to the substrate or use adhesives or primers for chemical bonding. This allows the use of materials with different properties, such as a rigid plastic base with a soft silicone or rubber overlay.It’s not uncommon to need support when reviewing and selecting the right material for your project needs. When requesting an injection molding quote, Fictiv’s global team of manufacturing engineers can provide valuable guidance to ensure your manufacturing success. We also created Materials.AI, a first-of-its-kind AI assistant, to help you navigate the complex landscape of materials choices.

The injection moulding process requires careful design, including the shape and features of the part, the materials for the part and the mould and the properties of the moulding machine. As a result, there are various considerations that need to be taken into account when injection moulding.

Two-shot injection molding often results in a higher consistency and stronger bond between materials, as the process is fully automated and materials are chosen for their chemical compatibility. This can lead to improved structural integrity and performance. Overmolding, while providing good quality and functional enhancements, may face challenges with material bonding if not properly designed, potentially affecting durability.

Commonly known as acetal, this plastic has high hardness, stiffness, strength and toughness. It also has good lubricity and is resistant to hydrocarbons and organic solvents. Good elasticity and slipperiness also provide advantages for some applications.

As we compare overmolding to two-shot injection molding, understanding their specific applications and the subtleties of each process will be crucial in determining the best approach for any given manufacturing requirement.

Deciding between two-shot injection molding and overmolding depends on several factors, including the project’s scale, budget, material requirements, and final product application.

We exist to eliminate bottlenecks in new product development by integrating the people, processes, and platform you need to source custom parts.

Overmolding frequently uses similar base materials, such as ABS and polycarbonate, but often pairs them with softer, more flexible materials like silicone or soft PVC. These combinations provide enhanced grip, aesthetic qualities, or additional functionality, such as shock absorption or water resistance.