Project Description

STRONG MAGNETS ON PLASTIC PRODUCTS

As magnets become more and more familiar to the public, many designers will consider adding magnets to their products when designing household products to achieve a simpler appearance, flexible fixing and other functions.

From toys to lipstick caps, from magnetic clip to silicone cable ties, from remote controls to LED lamp holders, from Bluetooth headsets to sports cameras, these products made of plastic are embedded with powerful magnets.

In these products, plastic and magnets, two completely different materials, complement each other: the magnet provides invisible and powerful attraction to the plastic, and the plastic provides a shelter for the magnet, protecting it from corrosion and damage.

OVERMOLDING MAGNETS INTO PLASTIC PIECES

There are two common types of injection molding: overmolding and insert molding.

Overmolding is a manufacturing process where one material is molded over another. This method is often used when the product requires two different colors or two different materials. It can be used in the production of consumer goods, toys, handles, and electronic housings.

Insert molding is the process of molding plastic around a prefabricated part or inserts, such as metal parts, electronics, or other materials. It includes three types of molding processes, namely multi-component molding, multi-shot molding, and insert molding. Magnets, as hardware, are mainly combined with plastics by insert molding.

The insert molding can integrate multiple materials into one part, forming a strong bond between the insert (strong magnet) and the plastic material, thereby enhancing durability. In addition, it can provide an attractive seamless surface finish and reduce the amount of material required for the finished part, thereby saving costs.

overmold magnets

INJECTION MOULDED MAGNET ASSEMBLIES

Many magnet assemblies look very simply, but when it comes to specific production and processing, we will we will encounter many problems. For example, the appearance of injection molded magnet components will be affected by the shrinkage rate of the plastic, injection holes and seams of the treatment and so on.

And in production, how to feed the magnet quickly to speed up the injection molding efficiency is also a problem that needs to be paid attention to and solved. Therefore, looking for a supplier with rich experience in injection molding + magnets can quickly help you transform concepts into products.

Working closely with our mold and injection molding workshop, we are not only able to successfully solve the various magnetic-plastic bonding challenges encountered in production, but also have the flexibility to produce insert molded parts from small to large batches.

If your goal is to have magnet snap fit into an injection molded part, then you need a stepped magnet. If your goal is to overmold magnets, then you need a magnetic plastic component. And you don’t need to worry about whether the magnets can handle the heat or not.

Please feel free to contact us for a quote on magnets, magnet plastic components, magnet assembly services.

    Magnet Quote Now!



    WHY OVERMOLDING WOULD WORK WITH N42, N45 or N52 NEO MAGNET AS I KNOW THE INJECTION TEMPERATURE OF ABS IS OVER 200°C?

    Indeed, all magnets are affected by heat. And the maximum operating temperatures of neodymium magnets from the N to AH series range from 80 °C to 220 °C, most of which are below the injection molding temperature. Only ferrites, SMCO, AlNiCo and others can work at higher temperatures.

    We insist on using NdFeB magnets, even though they are not so resistant to high temperatures, because of their strong magnetic force. In addition, the magnetic force of magnets wrapped in plastic/rubber/silicone will be reduced accordingly. For example, if the magnet’s pull force is used directly, N35 may be enough, but if it is coated with a layer of plastic, it may be necessary to choose higher performance materials such as N42 or N52 to achieve the same pull force.

    ARE YOU ABLE TO OVERMOLDING THE MAGNETS WITH THE PLASTIC WITHOUT LOSING THEIR MAGNETIC PROPERTIES?

    Yes, overmolding magnets with plastic can be done in a way that preserves their magnetic properties. The neo magnets are not afraid of high temperatures due to the current optimization of the production process.

    This optimization is actually very simple, that is, when the injection molding is carried out, the embedded magnets are non-magnetic. Wait for the silicone to be formed, and then magnetize the entire assembly.

    Magnetization” is the most critical step for a magnet to obtain magnetism, which is generally completed by a magnetizer. How much power does the magnetizer need? How to design the magnetizing fixture? How much product can be magnetized at one time? What size of product can the machine magnetize? How thick of product can be magnetized? These questions are a big challenge for injection molding factories. For magnet factories, it is just a piece of cake.

    The magnetizer is a tool for magnetizing magnets or magnetic assemblies, through which a magnetic field is applied to the NdFeB product that needs to be magnetized. I If the magnetizing magnetic field does not reach the technical saturation magnetic field, the remanent Br and the endowed coercivity Hcj of the permanent magnet will not reach the expected values.

    The energy of the magnetizer first determines the size of the magnetizing tooling according to the size of the magnet to be magnetized and the magnetization direction, and then calculates the size of the magnetic field in the center of the tooling. The size of the magnetic field of the tooling should be 3-5 times the coercive force of the magnet, and then calculates the magnetization current. The energy storage capacitor capacity of the magnetizer is determined according to the current and the voltage of the magnetizer, and finally the energy of the magnetizer is determined.

    PROCESS OPTIONS YOU CAN CHOOSE FOR OVERMOLDING WITH MAGNETS

    • Overmold 80 ℃ sintered neodymium magnet (unmagnetized), and then magnetize the full component (depends on the size of assembly).
    • Overmold a standard 80℃ sintered NdFeB magnet (magnetized), and then re-charged the assembly (depends on the size of assembly).
    • Overmold a higher Hci NdFeB magnet (magnetized), but it cost more.