The efficiency, and ease of manufacturing complex large volumes of identical parts that injection molding offers is why it is still relevant in modern day manufacturing. Its application cuts across different industries, and its two specialised techniques insert molding and overmolding offer unique benefits to the material and function of the components.
While both methods produce quality finished products, understanding the differences, and similarities in their distinct processes and how this affects their application after manufacturing and this article will help you understand that. Read this article to understand insert molding vs overmolding techniques, where they are applicable, and how to choose which multi-material molding is best for your next project.
Insert Molding vs. Overmolding: Core Differences in Process
The debate of insert molding vs overmolding often comes up with both being injection molding processes. However similar, there are notable differences in their processes that will help make this clearer. Some of them include:
| Category | Insert Molding | Overmolding |
| Process | The insert molding injection process involves placing an already formed insert component, usually metal, into a mold, and pouring a molten material around it which, after cooling seals into place to form a single item. | Overmolding injection molding, on the other hand, is a multiple material molding process that requires a two-step injection beginning with a substrate, and adding another molten material into the mold to get the finished product. |
| Objective | This is typically done to combine important parts of the product being formed with different materials together. This insert injection molding process reduces assembly steps, while improving durability. | The process is used to enhance durability, increase aesthetics, or comfortability of the finished product. |
| Application | They are applied in manufacturing electrical components (e.g., threaded fasteners), automotive sensors, surgical tools etc. Due to their strong bonding of dissimilar materials, they are ideal for components like this. | Overmolding injection molding is ideal for tool handles, toothbrush handles, grips, keypads, etc. And helps to enhance grip, vibration absorption, and overall user comfort. |
A Critical Comparison of Insert Molding and Overmolding
Deciding on the type of injection molding method you need for your next project should be an informed decision. Understanding key details like material compatibility, product efficiency, applications, etc. will help ensure you make the right decision. This section will explore these key details for insert injection molding and overmolding injection molding so keep reading!
Material Compatibility
Understanding material compatibility is important especially in multiple material molding operations. Both metal insert plastic injection molding and overmolding have primary use and temperature control specifics you should know such as:
Insert Molding: Primary Use& Temperature Control
Insert injection molding is used in the manufacturing of components that require integrating dissimilar materials such as metal and plastic to a single component. This manufacturing process enhances strength and durability of the finished product. Due to the dissimilar material, temperature control is key to ensure both materials are not damaged. The inserts must be able to withstand the temperature of the molten plastic which is typically between 200–300°C (392–572°F) that is needed for thermoplastics.
Overmolding: Primary Use& Temperature Control
In overmolding, the additional material layer is more for better ergonomics and aesthetics and is done with soft elastomer or rubber-like material being molded over a rigid thermoplastic base. Due to the use of thermoplastic elastomer over ABS plastics, the temperatures are lower compared to insert molding and are often between 180–250°C (356–482°F) to avoid damaging the substrate.
Equipment & Costs
Both overmolding injection molding and insert injection molding process require different equipment and costing due to their distinct processes. The equipments and cost expectation for both of them include;
Insert Molding:
Insert injection molding process requires the use of a standard injection molding machine with insert-handling capabilities. It can be automated to enhance production time and increase output. However, if done manually it increases the labor costs largely making it expensive.
Overmolding:
overmolding manufacturers need a two-shot injection molding machine at least to make it work due to the two-step process.This two step process, makes overmolding more cost intensive as it requires manufacturing two separate tools with specialized molds,
Production Efficiency
The quality of your finished product is very important in deciding between insert molding vs overmolding. Some information that can help include;
Cycle Time
Insert molding has an average cycle time of about 30–60 seconds per part. This time is increased by about 5-15 seconds per cycle if it is done manually and depending on the insert placement and cooling
If overmolding is done with an automated two-shot machine, it can be achieved quickly, completing a cycle in about 20-40 seconds.
Defect Rates
The defect rates from both injection mould methods vary depending on various reasons such as the manufacturer, material, process control, etc. These defects show up as burn masks, warping, etc.
Insert molding defect rates often run to 1-3% and are caused by voids in the molten materials, poor bonding, or misalignment of inserts.
In overmolding however, the defect rate runs to 0.5–2%, and this is as a result of poor adhesion between the different layers, injection pressure, etc.
Applications
The applications of both insert and overmolding injection molding are versatile and can be applied in various industries such as electrical appliances, household goods, consumer supplies, etc. Some of them include:
Insert Molding:
Insert molding technologies are applied in the automotive field, aerospace, electronics, medical devices, etc. Coating the metal parts with rubber in electrical appliances helps with preventing them from conducting electricity. They are also used in electrical connectors with brass inserts, molded handles, surgical tools with stainless steel shafts, etc.
Overmolding:
This is commonly applied in consumer goods, medical equipment, power industrial tools, electronics, etc. Some examples include toothbrush handles with rubber grips, dual-material design smartphone cases, etc.
Insert Molding or Overmolding: How to Make the Right Choice
Choosing the right injection mold technique ultimately lies on your unique project as both insert molding and overmolding injection molding both have unique advantages on the finished product. The right technique will help ensure durability of finished products, selection of the right materials, and ensuring that the finished products fits all products requirements while also being cost effective. In making the right choice for your next project, the following tips will help you know when to choose either technique.
When Should You Choose Insert Molding?
You should choose insert molding technologies when:
- Your project’s design requires combining preformed parts such as metal inserts with plastic for structural strength.
- You’re designing a component for the electrical industry, a threaded insert, or fasteners where bonding requirement is critical.
- The volume of production you need is high, and they demand durability and precision.
- Your project requires accurate dimensional stability and tight tolerances.
When Should You Choose Overmolding?
- When additional layers are needed to add a soft-touch surface for grip, or comfort as required in power tools or consumer electronics.
- When your product requires multi-material integration without secondary assembly.
- When applying brand elements or color contrast for aesthetic enhancement.
- When you want to increase vibration dampening.
After careful consideration and you are still unsure on the best fit between insert molding vs overmolding, getting a professional’s opinion will help you make the right decision and that is where the experts at Fox Mold come in.
Why Choose Fox Mold for Quality Injection Molding?
Finding the right team of experts for your insert molding and overmolding injection moldinginjection molding project is vital in ensuring quality finished products in whichever field they will be applied in and Fox Mold have proven to be that team since its establishment. Built in 2013, Fox Mold is a professional injection molding and custom mold production manufacturer, specializing in plastic injection molding, overmolding, insert molding, and liquid silicone rubber injection molding.
With over 10 years in the industry providing stellar services, they have proven records to be industry leaders in injection molding. Their expertise in the industry cuts across plastic injection, overmolding, insert molding, LSR molding. With a vast range of services from simple to complex mold design, prototyping, creating durable and highly detailed molds for long term production, and on demand mass manufacturing, etc., the team of experts are available to meet your specific needs, and aftersales.
The core engineering team is made up of 15 expert engineers who ensure they understand your unique design needs, provide guidance where necessary and deliver the best finished products. With modern workshops and advanced machinery across their facilities, quality control, 99% accuracy of manufactured products, and fast delivery on items is guaranteed.
At Fox Mold, it goes beyond a business, to a group of dedicated teams that are committed to not only providing the best injection mold services, but also ensuring compliance, quality delivery, maintaining safe practices for their clients and the environment. Fox Gold is an establishment you’ll be glad to do business with.
Conclusion
Understanding insert molding vs overmolding is key if you have a project that requires injection moulding, in order to make the right decision. Having seen the processes involved in both, their applications, and how to make the right decision, your choice of finished product is what should influence your final decision.
Contact Fox Mold today. We will help ensure you get an expert’s opinion in making the right decision. Their years of expertise, quality engineers, and equipped factories is what you need to bring your projects to life ensuring zero quality compromise and timely delivery.
