Insert Molding Services
Insert molding is a process in which metal inserts are encapsulated in plastic parts during injection. It involves pre-placed inserts (usually metal) in the mold cavity and then encapsulating it by injecting molten plastic around it to produce a single integrated plastic parts.
We provides design assistance and material selection guidance to help customers optimize their insert molding projects for cost, performance, and manufacturability, while employing advanced quality control measures to ensure every part meets tight specifications and tolerances.
  • 7/24 Engineering support
  • ISO 9001: 2015, IATF 16949 certified
  • Tolerance within +/- 0.0004 in (0.01mm)
  • Multip types of inserts molding experience
How does Insert Molding Work?
1. Preparing
Plastic resin is added to a hopper, heat to melt, wait for start to inject, also prepare inserts and servo system.
2. Inserts Placement
Manual or servo robot loading inserts accurately into the cavity, close mold.
3. Injection filling
Molten plastic is injected into the mold and flows around the insert to fill the entire cavity, forming a strong bond between the insert and the plastic.
4. Cooling & Stripping
Once the part is cooled and solidified, open the mold, ejector system discharge the parts to the outside.
Types of Inserts
Inserts can be just about anything, from brass to electrical contacts. Common metal inserts include brass, steel, aluminum, strainless steel, filter net, magnets etc.
In order to maintain the quality of insert molding products and protect the mold, inserts must be held to tight tolerances and stay within ±0.01mm whenever possible.
Because of the wide array of potential applications, it’s important to understand the insert molding process, design the part correctly, and consider how the production process works.
Alloy Threads
Threaded Fasteners
Electronic Connectors
Why Choose Attractive Plastics for Insert Molding
Scientific Molding
Scientific molding is the key to the success of injection molding, especially for plastic parts with multiple undercut, slider, insert molding, overmolding and other extreme complex structures feature and high surface requirement.
Quality Assurance
We rely on advanced measuring equipment, as well as a skilled team of quality engineers, technicians and inspectors. We will take the careful measurements necessary for each project to ensure that you receive the highest quality components.
Strong Engineering Team
Our engineering team with over 20 years of experience provides strong professional knowledge and technical support in precision insert molding tooling manufacturing. we will work closely with you to formulate a reliable mold design and machining plan.
We offer design for manufacturability analysis to ensure that your insert molding parts balance quality, efficiency and cost. Our advantages of automation and upfront mold design translate into more competitive pricing when running in high volumes, which also enables our customers to reach a larger market.
Insert Molding Design Key Factors
High quality plastic parts mainly rely on good part design and advanced mold design and manufacturing technology. Support through early supplier involvement, DFM, project management, R&D, in-house tooling making, and material selection are key factors in the success of an insert molding project.
  • Product Design
  • The main challenge in developing insert plastic parts is part geometry and structure.
  • Insert Tolerance
  • The insert tight tolerance is the prime necessity in any insert molding process. A small misalignment can cause failure.
  • The Cost
  • The complexity of insert molding determines that its mold and molding costs will be higher than conventional injection molding projects.
  • The Mold
  • When choosing a mold design, it is important to consider the way the insert is fixed and whether the pick-up and placement are smooth.
  • Mass Production
  • Inserts loading can be done manually by an operator or robotically. Manufacturers need to conduct cost analysis based on production needs, optimize efficiency, and improve competitiveness.
Advantages of Insert Molding
Insert molding can improve components stability by combining the strength of metal with the design flexibility of plastic. Insert molding is an effective alternative to components made with traditional untrasonic welding, adhesives or fasteners.
Improve Durability
Insert molding through one-step bonding combines plastic and metal tightly to improve product functionality, performance and durability.
Robotic automation in the insert molding process allows for quick and precise placement of inserts, increasing production efficiency.
Eliminate Assembly
Product production can be completed in one process, so no assembly is required
Reduced part size and weight
Insert molding parts that weigh less than all-metal parts, and it is an effective alternative to components made with traditional welding, adhesives or fasteners.
Improve Part Strength
This process seamlessly bonds plastic and metal inserts, greatly increasing the strength of the part.
Reduce Costs
Insert molding products don't require manual assembly, and with the popularity of automation, the cost is greatly reduced compared to other methods of molding.
Increased Design Flexibility
This process allows designers to use multiple materials and colors, multiple inserts to create plastic parts with complex geometries and unique features.
Increased Component Reliability
Insert molding plastic parts prevent loosening, and plastic improves resistance to vibration and shock for robust reliability.
Insert Molding Materials
At Attractive Plastics, in addition to providing a variety of conventional insert molding materials, we also offer a variety of additive plastics to meet special requirements. We can modify materials by incorporating additives to enhance specific properties.
Regular Plastic Materials
We provide a variety of insert molding plastic materials with different properties to meet applications in different environments.
Common Insert Molding plastic materials include: PP, ABS, PC, PMMA, Nylon, Nylon+glass fiber, PE, PBT, POM, SAN, PS, PC/ABS.
More Details>>
Additives & Fibers Plastics
If standard plastic materials can't meet the requirements of customized insert molding parts, additives and fibers can be added to improve mechanical properties or other requirements to help your injection molded parts successfully go on the market.
Examples of common additives include:
  • UV absorbers
  • Flame retardants
  • Plasticizers
  • Carbon fibers
  • Antistatic additives
  • Glass fibers
More Details>>
Gallery of Insert Molding Parts
Dive into Attractive Plastics' extensive gallery that showcases some of our completed insert molding parts and take confidence that we can create your insert molding project according to your strict specifications.
Inserts Loading Operations for Insert Molding
During the insert molding process, inserts are placed manually or by collaborative robots. For low-volume inserts loading operations, manual loading of inserts are preferred, and Depending on the complexity and quantity of parts, robotic automatic loading may be the future trend.
1. Manual Loading Inserts
Manual loading is simple and effective for low-volume applications. In manual insert loading operations, an operator loads the inserts into the mold during the molding process.
Manual loading gives you the option to have detailed part inspections, assembly to no added cost. With higher volume projects, however, it may become too costly or inefficient to load inserts manually.
Manual operators are able to check part quality and insert placement, while maintaining quality control.
2. Robots loading Inserts
The speed and accuracy of robot loading of inserts can't be compared with manual loading, and it is also one of the important way to improve competitiveness. It have multip benefits:
  • Reduce cost: Since there is no longer a full-time operator at the machine, the injection operational costs will be reduced. These lower operational costs can then be passed onto the customer.
  • Improve Efficiency: Robotic automation system can load inserts into molds faster and more accurately than operator, increasing hourly output and improving efficiency.
  • Improve quality consistency: An advanced vision scanning system ensures that robots load and place inserts accurately and in a consistent cycle, potentially eliminating the cost of adjusting molds and improving part quality consistency.
Reviews from Our Customers
A customer’s words have a more substantial persuasion than a company’s claims. We have served hundreds of satisfied customers and here are some reviews they give us.
They are definitely a reliable insert molding manufacturer. They worked closely with us to design and build insert-molded connectors that incorporate precision metal terminals. They tested and optimized the material molding process, and the copper core was firmly encapsulated in plastic.
David Moon
Vice President
They helped us make a drone connector with 4 copper cores, and the male and female plugs into each other. This poses huge challenges to mold design, copper core tolerances, mold production, and injection molding. The successful mass production of this product also verified that they have rich experience in making various types of connectors.
Carl Harris
Pruchasing Manager
Years of procurement experience have made me very interested in technology-based companies. Attractive Plastics is an engineering-led injection molding factory. Great help was provided at different stages of our product development, especially the initial stages. This is exactly what we want.
Tony Jones
We found their quoting team to be very responsive, especially for urgent orders. The detailed project proposal, timetable and cost control are very clear, which is of great significance to our buyers who need quick turnaround and stable shipping time. Relatively speaking, they have great advantages in all aspects.
Ben Holder
When our part design requirements change, their engineers proactively determine the most cost-effective modifications in a timely manner. Their value engineering expertise helps optimize the cost of our products. They rarely delay shipping. This is also one of the worthy core competitiveness.
Anne Zaremba
Our Insert Molding Service for Various Industries
Our custom insert molding process is suitable for solve the various demands of industries, including the automotive, medical, electronic & electrical and consumer goods fields etc.
Optical Clear Products
Consumer Goods
Electronic & Electrical
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Insert Molding FAQs

What is insert molding?

Insert molding involves placing a pre-formed insert (generally is metal) into the mold cavity before the injection molding process begins. The molten plastic material is then injected into the cavity to encapsulate the insert, creating a strong and seamless integration of plastic and metal. Inserts are mainly metal, such as magnets, screws, nuts, copper fasteners, rivets, etc., but the inserts must be able to withstand the high temperature and pressure of injection molding.

What’s insert loading method of Insert molding

Loading inserts into the mold usually is accomplished using manual handloads or automation. Automation minimizes human error, improves efficiencies, and ensures optimal cycle times.

What is difference between insert molding and overmolding?

The main difference between them is that: The substrate used for molding is different. In insert molding, the insert is placed in a cavity and molten plastic is molding around the insert to form a component that integrates the plastic and the insert, and the insert is usually metal. In overforming, the substrate is first molding and then placed in the cavity, and the molten plastic is molding around the substrate formed for the first time to form an integrated component of the two types of plastics.

What is the lead time for an insert molding project?

Depending on the complexity of the part, size, and insert material, shape, etc., it usually takes 4 to 6 weeks to complete the insert project.

When should I use Insert molding?

Generally, when you need to encapsulate a metal part in plastic, and to be economical and durable, insert molding is the most ideal, the most cost-effective process.

Do you have insert molding magnets capabilities?

Yes, we have more than 10 years of experience in insert molding magnets and overmolding magnets. Factors to consider regarding magnet inserts:

First, the injection mold is generally made of steel. If it has been magnetized before molding, the defect that the magnet will be attracted to the mold during molding must be considered. This should be taken into consideration when designing and making molds.

Second, magnetization must be considered before or after injection molding. Because the injection molding temperature exceeds 200 degrees, excessively high temperatures demagnetize.

Third, magnets are very fragile, and the placement of the magnets must be considered when designing the mold. Once crushed, if it is magnetic, it will be more difficult to handle in the mold.

Insert Molding Resources
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