Have you ever used a kitchen knife and wondered how the metal went into the grip with such precision?
Well, sorry to break it to you, but it’s not what you think. And you can thank the overmolding process for that!
Overmolding is a process that involves molding another material onto an existing product. You can make the overmolded part look like another item, or it could have extra features.
It’s also possible for manufacturers to create new products. By combining two different materials in one piece, they create a new hybrid. But ever wondered why you should use overmolding over other types of molding?
This article will discuss some of the benefits of using this manufacturing technique.
What Is the Overmolding Process?
The first step in creating an overmolded object or casting bronze is to design the original product. Suppose you know what your final product should look like. Then, you need to decide on which material you want to use and how much of each type of material you would like to include.
You may choose to combine several types of plastics with other materials such as wood, metal, or glass. Which one you use, yet, depends on the result you are trying to achieve.
A common way to achieve this type of manufacturing is through the use of injection molding tools. In general terms, these tools consist of a cavity plate. The plate holds the mold halves together while they are being clamped shut by a clamp mechanism.
Once closed, the mold cavities fill with a molten thermoplastic. This process uses either hot runner technology or direct melt techniques.
After cooling, the molds open up. Then, ejection mechanisms remove the finished parts from the mold. Check out how Prototech Asia talk about the overmolding process for more information.
What Types of Overmolding Exist?
There are two main types of overmolding. Each one treats the process in different ways. These are two-shot sequential overmolding and multi-shot overmolding:
Two Shot Sequential Overmold (TSO)
In a TSO process, the first part or insert enters the mold cavity. It has its runner system that feeds straight from the gate in the bottom half of the mold.
The second part or insert has a separate runner system feeding on the same gate as the first part. But it does so at a different location along the length of the mold. It allows for more complex designs with many inserts engaging in simultaneous molding.
This method uses a single shot of resin per mold. The advantage here is that there is no need for runners. That’s because all the components come from the same source.
Yet, TSO requires careful planning. Since every component must fit within the available space inside the mold, the entire batch might fail if any of them do not meet specifications.
Also, note that in both cases, careful planning of materials is vital. That’s because they need to bond together without the presence of an agent. In turn, this makes the two parts become one unit without the worry of the product falling apart.
Multi-Shot Overmold (MTO)
MTO processes involve injecting components of the entire assembly at the same time. That means there is no need for runners because everything comes out of the same opening in the mold.
Yet, there are disadvantages. For example, if any component fails during production, the whole batch needs scrapping. Also, suppose you’re designing a large number of identical units. The costs associated with making them one by one can become more expensive.
What is Insert Molding?
Insert molding is another form of overmolding. It differs from other forms of overmolding. With insert molding, the design elements enter the mold before it closes. That’s because the insert does not need a separate runner system.
Instead, the material flows around the insert. As such, the insert needs only enough room to accommodate the flow paths needed.
The benefits of insert molding include less complexity than traditional methods. It also makes higher injection pressures possible and increased speed.
On the downside, insert molding may result in a poor surface finish on some products. So you’ll often find it on cheaper quality products.
Overmolding vs. Insert Molding
Insert molding is a little different in that a product’s coated in molded plastic. This one-step process makes it better for small-scale production runs. That’s because it requires less time than overmolding does.
Yet, suppose you plan to mass-produce items. The two-step process of overmolding offers five main advantages, listed below:
1. More Efficient Manufacturing Processes
Since there is no insert molding involved, the entire process takes place at once. Thus, the number of steps required to make a single unit decreases a great deal.
Also, the pieces come out of the same machine. So any problems encountered during the manufacturing process are immediately handled.
Because there is only one step in the process, the cost per unit produced is lower. This advantage comes with a tradeoff, though. The more units manufactured, the higher the total costs become.
When making many inserts, the manufacturer must wait until every component is present. Any delays in the supply chain can be catastrophic for the process.
By contrast, when assembling an overmolded product, the whole thing goes down in one go. As a result, productivity increases a huge amount, and it’s much less risky.
2. Plastic Overmolding Reduces Cost
Plastic overmolding, like all other overmolding, reduces costs. The biggest benefit of overmolding is its ability to reduce labor costs. Most manufacturers have already invested a lot in their equipment.
They don’t see much value in investing even more money into different machinery. Instead, manufacturers opt to invest in new employees who will help them complete projects faster.
Like rubber, plastic provides excellent insulating qualities. Unlike rubber yet, plastic does not absorb water or oil.
Because of these differences, plastic cannot protect electrical parts from liquid damage. Yet, you can solve this problem with proper design.
3. Rubber Overmolding Improves Durability and Reliability
Rubber Overmolding is another popular method for protecting electronics. This type of material offers many advantages, including insulation, strength and durability. These are all vital elements when molding hazardous products like electricals or biohazards.
Cable Overmolding
Cable overmolding occurs in electronic devices like cell phones and tablets. It allows cables to remain hidden inside the device. It’s why we don’t have antennae on cellphones anymore.
The cable stays protected within the casing, preventing damage caused by external forces. Besides, the protective layer prevents moisture from entering the interior of the phone.
Cable overmoldings offer several benefits. These include improved aesthetics, increased durability, and better protection against corrosion. The main reason why cable overmoldings are superior is that they look cleaner. They also look much sleeker than traditional methods that can increase profit margin.
They also provide greater resistance to wear and tear. In doing so, cable overmoldings also improve safety features such as shock absorption.
4. Thermoset Overmolding Is Fast
Thermoset overmolding involves using thermosetting materials which harden after application. These types of materials include epoxies, polyurethanes, phenolics, and silicone overmolding. Thermosets do not need curing time because they are set up immediately upon contact with air.
And, like all the other overmolding processes, everything happens at once. Thus, quality control becomes easier. If something doesn’t work, it’s usually easy to fix without having to start again.
Errors often occur due to human error. For example, if someone puts the wrong part in the right spot, the entire project could fail. Compare that to inserting components one by one.
5. More Design Customizations Available
Unlike injection molding, there are various options available for overmolded products. You can choose between different colors, textures, patterns, and designs.
With overmolding, you’re able to customize your product exactly how you want it. Unlike injection molding, you don’t have to worry about wasting expensive raw materials.
Use Cases of Overmolding
To best illustrate these benefits, let’s take a look at some use cases of overmolding. It occurs in a wide variety of industries for different applications. In itself, this proves overmolding is a fantastic choice for durability and reliability.
Automotive Industry
Manufacturers have used Overmolding since the 1950s to create dashboards for cars. Manufacturers first applied it to dashboard panels. Thus, it became known as “dashboard” molding. Today, automotive companies continue to apply old technology to their vehicles’ interiors.
Medical Devices
Another industry that uses overmolding a lot is medical equipment. Medical devices need to be durable, flexible and reliable. In doing so, patients receive the best care possible. Examples include infusion pumps, blood pressure monitors, defibrillators, pacemakers, and insulin pens.
All these devices must withstand extreme conditions while providing accurate readings. To ensure this, manufacturers turn to overmolding to achieve desired results.
Consumer Electronics
The consumer electronics market continues to grow every year. As more people become tech-savvy, they demand higher-performance gadgets. Manufacturers know that consumers will buy anything that looks good or performs well.
That’s why many electronic device makers opt for overmolding. They combine high-quality plastics with attractive design elements. In doing so, manufacturers make sure customers love what they see.
As we mentioned above, cable overmolding is another popular application of overmolding. The reason behind its popularity? Cable TV boxes, satellite receivers, antennas, modems, and routers all use this process.
These types of cables tend to have exposure to harsh environments. So, overmolding provides them with extra protection from damage.
Industrial Equipment
The industrial sector also relies on overmolding to produce various parts. From machine tools to conveyors, it’s everywhere. Overmolding provides superior protection against damage from heavy loads.
Industrial machinery needs to last as long as possible before a breakdown occurs. So, manufacturers rely on overmolding to protect them from harsh environments.
Aeronautical Industry
Also, if you’ve ever seen an airplane cockpit, chances are you noticed the instrument panel. Instrument panels are often molded into plastic because they need precise tolerances.
But, when it comes time to replace those instruments, costs are sky-high. Why? Because most airplanes come equipped with nonstandard gauges.
For example, older planes may not include digital displays. Or, newer models might lack analog dials altogether. Suppose your plane doesn’t have standard gauge options. Then you’ll likely end up paying hundreds of dollars in replacement costs.
Lucky for everyone, there’s a solution: overmolded instrument panels! By combining two materials, manufacturers can provide a single product. And that offers both strength and flexibility. Thanks to modern manufacturing techniques, they’re able to offer this at affordable prices.
Beauty Industry
Beauty industry companies have used Overmolding since the 1950s. Its origins lie in creating custom products like hair combs, brushes, and wigs. Today, overmoldings are being applied to other areas too.
Overmolding is one way to ensure quality control while keeping production costs low. Some cosmetic brands use it to create eye shadow palettes. Others create lip glosses or nail polish bottles.
Overmolding is perfect for small businesses that want to keep their overheads low. Plus, it allows these companies to customize their products at a low cost as well.
Overmolding Provides Excellent Protection
Overmolding has become one of the best ways to protect electronics. As you’d expect, overmolding increases functionality. But it also improves reliability and aesthetic appeal.
There are so many reasons why people use overmolding techniques today. So, why are you waiting? Start designing your next masterpiece today!
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