Overmolding

YOUR RELIABLE OVERMOLDING MANUFACTURER

At TX Mold, we understand that each project is unique and may require different injection molding approaches. This is why we have invested in top-grade equipment and a team of professionals that is fully trained in overmolding techniques. Our team comprises designers, mold engineers, and production engineers that all work in harmony. This ensures that each product and mold design is optimized for overmolding and that the resin materials that are chosen are ideal.

Overmolding is applicable in a variety of industries. Currently, we offer overmolding services to home appliance, automotive, furniture, bucket, and baby product industries and many others. We also serve both local and overseas clients spread across different parts of the world.

ADVANTAGES OF TX MOLD’S OVERMOLDING

Overmolding is a step two-process that, in some instances, may also require the use of more than one type of resin. As a result, it requires careful attention during execution as well as in the mold and product design stage. We are experienced overmolding professionals that offer these and other advantages such as:

Reduced Assembly Costs: We offer seamless overmolding for parts that require the use of different resin materials to achieve improved stability or structural features. It is much cheaper than molding the parts separately and then assembling them at a later stage.

Flexible Use of Material: The thermoplastic materials used in overmolding have to be compatible. Our team of design and engineering experts have all it takes to advise you on different material options based on your budget and the desired finished product.

Completion of Complex Parts: The FOW Mould factory facility is equipped with the latest overmolding equipment. This, coupled with our exceptionally talented team, enables us to achieve even the most complex designs with precision and on time.

High-Efficiency: Our goal is to help our clients realize high-quality products while also maintaining profitability and running their businesses on schedule. To this end, we design product parts and molds that are highly optimized for the overmolding insert molding process. They are tested also for manufacturability and all-round production efficiency.

OVER MOLDING VS. INSERT MOLDING

Overmolding is a unique injection molding process that is used for making seamless combinations of several materials into a single part or component. Its highlights can be summed up as below:

  • It usually involves a double injection of one or more resins. The second shot of molding resin covers the first layer while the use of adhesives is no longer required to adhesives a solid bond, hence the term, overmolding.
  • This technique gives the manufacturer more control over the texture of their products and can be used to enhance grip or add a stylish appearance to the end product, something that many customers will truly appreciate.
  • In some instances, overmolding reduces vibration and shock, making the parts made through it ideal for use in heavy machinery like cars.
  • This type of injection molding improves UV and chemical resistances, provides electrical insulation for complicated wires thereby helping to increase the shelf life of such products.
  • Overmolding is a cost-effective process that does not require too much labor and does not consume too much electric power. It is an ideal injection molding technique for a manufacturer looking to increase efficiency without spending an extra dollar.

Insert molding, on the other hand, is defined as a variation of injection molding techniques that involves the insertion of a metal part into a mold before the actual injection molding. It can best be described as in the summary below.

  • The insertion process can be done manually or through automated processes such as the use of a robotic arm. Once the insertion is completed, the mold is closed, and plastic is molded over the insert to transform the different parts into a single component.
  • Insert Molding does not follow a particular standardized method; different approaches can be taken based on the needs of the project or the manufacturer. It is applicable for simple designs like electrical insulations or more advanced manufacturing processes like those used in the automotive and aerospace industries.

OVERMOLDING PROCESS

The overmolding injection molding process is a straightforward process. It is performed as explained below.

  • Clamping: A mold comprises two parts; a core and a cavity. Clamping refers to the core being tightly secured over the cavity in preparation for the injection process.
  • Injection: In this stage, molten thermoplastic material is shot into the mold structure at high pressure and predetermined temperatures. Both of these parameters will depend on the material being used as thermoplastics have different melting points and viscosities. The amount of resin that is injected is based on the design of the part and how much more resin will be injected in the second phase.
  • Cooling: Once the injection is complete, the material has to be allowed to set and cool. Depending on the material, cooling aids such as water can be applied outside the mold to help quicken the process. However, because there is usually a second injection process in overmolding, the part is only allowed to cool to a certain degree.
  • The second injection: When the material from the first injection has cooled enough and acquired its required shape, the second injection begins. It too involves the injection of molten thermoplastic material into the same mold at high pressure and a set temperature. The material may, nonetheless, be of a different type and color from the one used in the first injection.
  • The second cooling phase: With the second layer of resin injected, the cooling process begins all over again. It may take a little longer than the first to allow the resins to fully bond and form one cohesive structure.
  • Ejection: When the entire structure has cooled and is fully bonded, the mold is opened and automated ejector pins slowly push the formed part out of the mold. Draft angles play a crucial role in ensuring that ejection of the part is smooth without any bits sticking to the walls of the mold.

PRECISION MOLD DESIGN FOR OVERMOLDING

Overmolded structures are often larger than typical injection molding parts. Their designs are equally more structurally complex. More so due to the fact that they may involve the use of different materials that shrink at different rates. Precision is, therefore, very important when developing mold designs for overmolding processes.

TX Mold has worked on numerous overmolding projects and we have perfected our skills through these experiences. We take into consideration the part design and the materials that will be used for overmolding, right from the start. This enables us to design molds with precise dimensions, draft angles, and high tolerances. We further test each mold design to ascertain its accuracy. Subsequently, our clients are able to realize quality overmolded parts because all their manufacturing needs are anticipated and addressed accordingly.

OVERMOLDING MATERIALS OPTION

Material options are fundamental in overmolding. First, the chosen materials have to be suitable for the part being produced. Secondly, where more than one thermoplastic material is being used, the materials have to be compatible. Our in-house production engineering team is well-versed in resin compatibility. We also test materials to ascertain their viability with regard to manufacturing and product performance. Our list of material options includes:

PPABSPC
PEPA6Nylon
POMPVCPS
PMMAPLA

APPLICATIONS OF PLASTIC OVERMOLDING

Overmolding products are utilized in both domestic and commercial spaces in varying ways. The following are some of the notable plastic overmolding.

BABY PRODUCTS
Baby products such as toys and furniture are more appealing to children when they are colorful and have interesting shapes. Overmolding helps achieve this by introducing different colors of resins to form a part. It also makes it possible to create seamless designs instead of assembling baby products bit by bit. This is crucial because if small assembled components fall off they would be a choking hazard.

AUTOMOBILE INDUSTRY
The automobile industry often relies on overmolding when a plastic part needs to be made stronger or its texture needs to be altered to improve its grip. Examples of parts that are often overmolded include dashboards.

ELECTRONIC DEVICES
Electronic parts are made safer for consumers and more durable by insulating electronic components in plastic. This is because plastic is a non-conductive material. Encapsulating electronic components in plastic can also be used to increase their IP rating. Both insulation and encapsulation can be achieved through overmolding.

MEDICAL EQUIPMENT
Medical equipment has to be designed in a manner that makes it possible to keep it sterile. Durability and operational safety are equally non-negotiable. For this reason, devices such as defibrillators are overmolded in plastic to form a well-encapsulated structure that is lightweight, can easily be sterilized, and strong enough to survive long-term use.