Plastic Molding For China Manufacturers:?Common Overmolding Materials?
Plastic Overmolding is an injection molding method in which one material (typically TPE) manufacturers mold one material onto another material (usually a stiff plastic). They do this molding process through pressure and heat alongside liquid silicon. The TPE over-molding design establishes a solid bond with plastic maintained in an end-user environment. There is no need for adhesives or primers for achieving a solid bond between both materials. Plastic molding for china is known as a highly reliable method of molding plastic for various applications.
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Common Overmolding Materials for Plastic Molding for China
When choosing Overmolding materials you must make sure that the selected materials are fully compatible. There must be a solid bond between the two materials both physically and chemically. Otherwise, the finishing and life of the component will never be as you desire. If there is a compatibility issue, then you will experience issues, such as Overmolding failures and component deformation.
There are literally thousands of materials available that you can use for Overmolding, but you really need to choose the best one. This selection process normally involves an engineered resin specialist. Specialists can help you on bonding compatibilities, innate properties, appearance, cost, regulatory compliance and other major aspects.
Here are a few common over-molding materials that you may choose to make the best combination:
- POM (Acetal Copolymer)
- Acrylic (PMMA)
Selection of the appropriate material is not only critical in the success of your component in the application, but it is also equally important in marketplace.
Why Plastic Overmolding?
One major reason why Overmolding designs are selected for plastic molding for china is that they actually improve the functionality and aesthetic design of the product. With the help of plastic Overmolding, you can practically create several color options. Critical details can also be added easily to the products keeping in mind the specific use of the consumer. For instance, you can fit a screwdriver with a comfortable and colorful handle with the help of Overmolding method.
Here are more reasons why plastic Overmolding is a popular choice:
- Plastic Overmolding ensures a soft surface grip around the parts of a separate material.
- Breakup color (aesthetically important).
- Adds Flexibility to the rigid parts.
- Removes the assembly line time. Rather than manufacturing plastic grip and metal tool separately and joining them together afterwards with automation or manually, you can simply over-mold both together at the same time. This makes the process really fast.
- With plastic Overmolding, one part can be captured inside another without even using adhesives or fasteners.
So, now you can understand that why Overmolding is a preferred option for plastic molding for china over may other methods.
Different Types of Plastic Injection Overmolding Process
There are basically two types of plastic molding processes available that govern the manufacturing of a substrate molded part.?Here are those two types:
- Insert Molding
Insert molding is currently recognized as the most widely used and common molding process used for plastic molding in china. The process happens when you place a e-molded insert into the mold and TPE is directly shot over it. One major benefit of using this molding design type is that you can simply use the traditional single shot machines (IM) and the cost of tooling linked with the insert plastic molding are also very low in comparison to multi-shot processing.
Multi-Material Plastic Overmolding
This is a pressure and heat substrate molding that needs a unique plastic injection molding mechanism. You need to fit the mechanism or machine with at least two barrels that ensure that a minimum of two materials can be shot easily into the mold during the molding cycle. This plastic Overmolding type is ideal when reducing cycle times is important and you also want to achieve enhanced part quality. Another advantage is that it also reduces the labor costs.
Benefits of Plastic Overmolding
Plastic Overmolding is popular because it helps create high quality, durable end products at low labor costs. Some other benefits include, but not limited to:
- The overmolded parts ensure appropriate alignment and prevent loosening.
- The plastic resin ensures enhanced resistance to shock and vibration.
- Enhanced part structure and strength.
- Improved multi-material components and design flexibility.
- Less secondary operations, labor and assembly costs.
- The bonding process in manufacturing is eliminated that results in enhanced component reliability.
Above were just a few advantages that come with Overmolding process. There are many other factors for which a molder chooses this method.
Manufacturers use Overmolding for a number of purposes in different application areas including electronic devices, controls, automotive, medical devices, appliances, and more. Many products that you see around are made using this technology.
Overmolding Material Selection
There are various types of Overmolding design materials available. Those materials can be softer, harder, or a blend of both. Such designs need a “squishy” or “grippy” quality about the handle. So, what are the factors that determine which materials manufacturers need to use in order to ensure the quality requirements? Here is what you need to know to determine what materials you need for the required effect.
A designer may opt for the softest available material for the soft touch TPE. What he might be missing is the fact that the TPE’s soft durometer offers a little value to “cushion” concept when the TPE thickness is under a specific point (usually > 0.040). Keeping this in mind, the TPE overmold will get harder as it gets thinner. One solution to this problem is that you should incorporate various ribs and place them together closely to create thickness perception without the use of large material amount.
Modulus vs. Hardness
The hardness (or durmeter) of the material is directly linked with its flexibility, which is a common myth in TPE industry. However, this thing isn’t always true. For instance, the material 65 Shore A SEBS has greater flexibility than the material 65 Shore A TPU. Rather than using the Shore Hardness, flexural modulus is a more appropriate flexibility measure that measures the bending resistance of the material. If the flexural modulus is high, then it means that the material will be more unyielding and stiff.
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Coefficient of Friction
A force creates between two surfaces that slide or try to slide across each other. We call this force friction. The COF (coefficient of friction) describes the amount of force you need to move a surface across the other surface - either from the static friction or kinetic friction.
Normally, we describe TPE as “grippy” or rubbery. The relationship between COF ad durometer is an important area that designers misunderstand quite often. Most designers think that the softer TPE means greater COF which is not a true statement in all cases.
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