Unscrewing Mold 101: Guide to Working, Importance, and Types

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Unscrewing molds are a crucial component in the plastic injection molding industry, particularly when it comes to manufacturing threaded parts. These molds enable the production of high-quality threaded components with precision and efficiency. This article provides a comprehensive guide to the working principles, importance, and various types of unscrewing molds.

 

How Unscrewing Molds Work

Unscrewing molds are designed to create threaded plastic parts through an intricate molding process. Unlike standard molds, which simply open and eject the part, unscrewing molds have a unique mechanism to handle threaded components. Here’s a step-by-step overview of how they work:

ㆍInjection Phase: Molten plastic is injected into the mold cavity, filling it completely, including the threaded section.
ㆍCooling Phase: The plastic is allowed to cool and solidify within the mold.
ㆍUnscrewing Mechanism Activation: Once the plastic has cooled, the unscrewing mechanism is activated. This can be mechanical, hydraulic, or motor-driven, depending on the mold design.
ㆍThreaded Core Rotation: The core of the mold, which forms the threaded part of the component, begins to rotate. This rotation unscrews the newly formed plastic thread from the mold cavity.
ㆍEjection Phase: After the threaded core has completely unscrewed, the mold opens, and the part is ejected.

This process ensures that the threaded parts are not damaged during ejection, maintaining their integrity and functionality.

Importance of Unscrewing Molds

The importance of unscrewing molds in manufacturing cannot be overstated. Here are some key reasons why they are essential:

Precision and Accuracy: Unscrewing molds allow for the precise production of threaded parts, ensuring consistency and accuracy in every component.
ㆍEfficiency: These molds streamline the production process for threaded components, reducing the time and effort required compared to manual threading.
ㆍQuality Assurance: By using unscrewing molds, manufacturers can produce parts with high-quality threads that meet stringent standards, reducing the likelihood of defects.
ㆍCost-Effectiveness: While the initial investment in unscrewing molds may be higher, the efficiency and reduction in labor costs make them a cost-effective solution in the long run.
ㆍVersatility: Unscrewing molds can be used to produce a wide range of threaded components, making them versatile tools in various industries, from automotive to consumer goods.

Types of Unscrewing Molds

There are several types of unscrewing molds, each designed to meet specific production needs. The main types include:

ㆍMechanical Unscrewing Molds
Mechanical unscrewing molds use a system of gears, cams, and racks to rotate the threaded core. This type of mold is often preferred for its simplicity and reliability. The mechanical components are typically integrated into the mold base, making them durable and easy to maintain.

ㆍHydraulic Unscrewing Molds
Hydraulic unscrewing molds employ hydraulic cylinders to drive the rotation of the threaded core. These molds are highly effective for producing large, heavy-threaded components. The hydraulic system provides powerful and precise control over the unscrewing process, ensuring smooth and accurate thread formation.

ㆍMotor-Driven Unscrewing Molds
Motor-driven unscrewing molds use electric motors to rotate the threaded core. These molds offer high precision and are particularly suitable for complex and fine-threaded components. The motors can be programmed for various speeds and rotations, providing flexibility and control in the molding process.

Conclusion

Understanding unscrewing molds is essential for anyone involved in the plastic injection molding industry, especially when producing threaded components. These molds offer precision, efficiency, and high-quality results, making them a valuable asset in manufacturing. By choosing the right type of unscrewing mold—whether mechanical, hydraulic, or motor-driven—manufacturers can optimize their production processes and ensure the integrity of their threaded parts.

If you need more information or assistance in selecting the appropriate unscrewing mold for your needs, please contact us. Our suppliers are ready to provide expert guidance and support to help you achieve the best results in your manufacturing endeavors.

Beginner’s Guide to Design for Unscrewing Molds

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Designing molds for unscrewing parts is a crucial skill in the realm of injection molding. Unscrewing molds are commonly used for producing threaded parts, such as caps, lids, and closures. Understanding the fundamentals of design for unscrewing molds is essential for beginners looking to venture into this area. In this guide, we’ll cover the basics of designing molds for unscrewing parts, including key considerations and best practices.

 

Understanding Unscrewing Molds

Unscrewing molds are a type of injection mold designed to produce threaded parts with helical features. Unlike standard molds, which rely on straight-pull actions to release parts from the mold cavity, unscrewing molds utilize rotational movements to release threaded parts from the mold core. This rotational action mimics the process of unscrewing a cap or lid from a bottle.

Key Components of Unscrewing Molds

Unscrewing molds consist of several key components, each playing a vital role in the molding process:

Core and cavity: The core and cavity form the mold cavity where the plastic part is formed. In unscrewing molds, the core typically contains the helical threads, while the cavity corresponds to the exterior shape of the part.
Threaded core: The threaded core is a specialized component that forms the internal threads of the molded part. It is designed to rotate within the mold to facilitate the unscrewing action.
Actuation mechanism: The actuation mechanism is responsible for rotating the threaded core to release the molded part. It can be driven by hydraulic, pneumatic, or mechanical means, depending on the specific design requirements.

Design Considerations for Unscrewing Molds

When designing molds for unscrewing parts, several factors must be taken into account to ensure successful molding operations:

Thread design: The design of the threads plays a crucial role in the functionality of the molded part. Threads must be properly sized and shaped to achieve a secure fit and proper sealing when the part is assembled.
Undercut features: Unscrewing molds often involve the presence of undercut features, which can complicate mold design and tooling. Careful consideration must be given to the location and geometry of undercut features to ensure they can be adequately released during the molding process.
Draft angles: Draft angles are essential for facilitating part ejection from the mold cavity. Adequate draft must be incorporated into the design of both the core and cavity to prevent friction and binding during the unscrewing process.

Best Practices for Designing Unscrewing Molds

To optimize the design of unscrewing molds and ensure efficient molding operations, consider the following best practices:

Simplify the design: Minimize the complexity of the mold design wherever possible to reduce costs and manufacturing time. Simplifying the design can also improve mold longevity and reliability.
Optimize cooling: Proper cooling is essential for maintaining consistent part quality and minimizing cycle times. Design the mold with adequate cooling channels to ensure efficient heat dissipation during the molding process.
Choose suitable materials: Select materials with the necessary strength, durability, and wear resistance for the components of the unscrewing mold. High-quality materials will contribute to the longevity and performance of the mold.

Conclusion

Designing molds for unscrewing parts requires careful consideration of various factors, including thread design, undercut features, and draft angles. By understanding the fundamentals of design for unscrewing molds and following best practices, beginners can create molds that produce high-quality threaded parts efficiently and reliably.

For further assistance or to explore our range of molding solutions, please don’t hesitate to contact us.

NPE 2024 – WIT MOLD Invitation

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WIT MOLD will be participating in the NPE 2024 exhibition, which is scheduled to take place from May 6th to 10th in Orlando, Florida. Sincerely invite all of customers & friends to visit our booth South hall, S14207.

 

What Is Thermoset Molding?

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Many people are not aware of the advantages of thermoset materials. This guide describes the thermoset molding process and how it can benefit you.

 

Thermoset Molding

Thermoset molding is an irreversible molding process by which malleable forms of plastic are forced into a heated mold and formed into their final shape.

Thermoplastic molding is the reverse process where heated material is injected into a cool mold. The material is then cooled to maintain the final shape of the part.

Why Use Thermoset Molding?

Thermoset materials are generally stronger than thermoplastic materials due to the catalysts that are added to the base compound that cause chemical reactions at the molecular level, forming a harder, irreversible final form. Thermoset plastics cannot be re-melted, only ground and recycled as filler for different applications.

Thermoset molded products have electrical and thermal insulation properties, which make them ideal for electrical and electronic applications. They are resistant to corrosion and have high impact strength, depending on the resin, and are cost competitive with engineered thermoplastics. Using thermoset molding allows producers to maintain tighter tolerances during the molding process compared to similar thermoplastic materials.

Pros of Thermoset Injection Molding

Injection molded pieces may be the best fit for a piece for several reasons:

Many different types of materials may be used in injection molding, including thermoplastic and thermosetting resins, polymers, and elastomers. This offers the engineer a great deal of control over which blend of materials will yield the best outcome, especially when needing to meet specific property requirements.

Fantastic for high-volume runs.

Precision and low waste. Because of the specific tooling and material mix, there is less waste with injection-molded parts than with other processes.

Short cooling time – Injection molded pieces cool quickly, reducing the time required to release the injected piece from the mold.

Cons of Thermoset Injection Molding

While injection molding is a fantastic process for the reasons mentioned above, there are certain limitations and drawbacks. A few of these drawbacks include:

Tooling costs – These costs can be significant as precision crafted molds are required.

Flash – Flash is unavoidable when injection molding thermosets. Once the part has been created and ejected from the mold, an automated or manual next step is necessary to remove the flash (excess material). Flash isn’t an issue with thermoplastics due to the higher viscosity of the liquid plastic.

Part size – The size of the piece being created definitely matters when it comes to the molding process. Typically, smaller part sizes (0.1 lbs to 6 lbs) are injection molded, while larger parts are transfer or compression molded. The volume of the order will also dictate which molding process will be the best fit for the project. Compression molding would likely be used for larger parts with a low (or high) volume, while transfer molding would be used for medium to high volume projects. Injection molding would be ideal for high volume runs with smaller pieces.

 

WIT Mold offers Custom Plastic Molding and Tooling services, Contact us now for a competitive offer!

Three Questions You Need to Consider before Choosing Precision Molding

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If you need a plastic part molded with extreme precision—for example, to ensure there’s no air leak between two molded sections or to be certain there’s no visible seal gap line—you likely require precision molding. The difference between a typical injection molded part and a precision molded part is the tolerance, or acceptable range of variation in dimension: While the majority of injection molded parts have a tolerance of +/- .005″, precision molding holds tolerances between +/- .002″ and +/- .001″ (or less, in some cases).

Let’s say, for example, you’re planning to manufacture a military projectile. In order for the projectile to fit properly in the firearm, handle the acceleration when it’s launched, and explode on impact, it requires very high precision.

If your application requires precision molding, you can’t leave anything to chance—so you’ll want to ask yourself the following three questions before you begin the process:

 

1. Have you selected a plastic material with low shrinkage?

The plastic material you select for your part makes a big difference in whether you’ll be able to do precision molding. For example, polypropylene has a shrinkage range of +/- .014″ to +/- .022″, with an average of +/- .018″. This is a wide range for shrinkage, which makes hitting a specific tolerance extremely difficult. If you’re molding a toothbrush (which commonly uses polypropylene), dealing with shrinkage isn’t a big concern, as the toothbrush will function appropriately regardless of whether it’s slightly bigger or smaller than its counterparts. Acrylonitrile butadiene styrene (ABS)—another common thermoplastic polymer—has a much narrower shrinkage average of +/- .006″. That gives you a much better chance of hitting a tighter tolerance, but it still won’t reach the +/- .001″ or +/- .002″ tolerance needed for a precision part.

One way to hit high tolerances with your plastic material is to add glass or another filler resin (like carbon fiber or mica) into the material. This can minimize shrinkage and warp by providing more structure in the material. For example, if you include long glass fibers in a polymer material, the part will shrink more perpendicular to those fibers.

2. Have you determined which areas of the mold require precision?

Because precision molding is more expensive than typical injection molding, be certain which aspects of your part require tight tolerances—and whether those tolerances can be achieved through injection molding—before moving forward. For example, a surgical handle may only require precision for the piece that will connect with a pin, not the entire handle. Identifying your precision requirements from the get-go ensures you’ll get what you need without wasting money. In the case of the surgical handle, your injection molding partner may advise you to add the tolerances you need through tooling after the injection molding process is complete.

3. Can the mold manufacturer you’ve selected tool with high precision?

The process of creating plastic parts with tight tolerances begins with a high-precision mold. If each plastic part you create is not identical, you won’t have a precise product—and a precise mold ensures there’s no variation for each part. Because of this, it’s extremely important to select a mold manufacturer who understands the slow, steady process of building a high-precision tool. Keep in mind that selecting a mold manufacturer that specializes in rapid tooling is likely not your best option, as the goal of rapid tooling is to finish the mold quickly—but not necessarily precisely.

Let’s get your precision molding project started

We have years of experience in precision molding, and would love to answer any and all of your questions. You can either contact us with those questions, or, if you’re ready to get your project started now, simply contact us and request a free quote.

Advantages And Disadvantages of Two-shot Injection Molding

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There are a variety of manufacturing methods used to create products using plastic polymers, including two-shot injection molding, compression thermoset molding and extrusion. While all of these are viable manufacturing processes, there are several advantages to this process that make it the top choice for many plastics manufacturers. The process is relatively simple; one material is injected into a mold in order to make the initial section of the product, followed by a second injection of a secondary material that is compatible with the original material. There are three good reasons many manufacturers use this method of manufacturing plastics or polymers.

Advantages of two-shot injection molding

Two-shot injection molding  is cost-effective

The two-step process needs only one machine cycle, rotating the initial mold out of the way and putting the secondary mold around the product so that the second, compatible thermoplastic can be inserted into the second mold. Because the technique uses only one cycle instead of separate machine cycles, it costs less for any production run and requires fewer employees to make the finished product while delivering more items per run. It also ensures a strong bond between the materials without the need for further assembly down the line.

Enhanced product quality

Two-shot injection molding enhances the quality of most thermoplastic items in several ways:

ㆍImproved esthetics: Items look better and are more appealing to the consumer when they are crafted of different colored plastics or polymers. The merchandise looks more expensive if it utilizes more than one color or texture
ㆍImproved ergonomics: Because the process allows for the use of soft-touch surfaces, the resulting items can have ergonomically designed handles or other parts. This is particularly important for tools, medical devices, and other hand-held items.
ㆍEnhanced sealing capabilities: It provides for a better seal when silicone plastics and other rubbery materials are used for gaskets and other parts that require a strong seal.
ㆍCombination of hard and soft polymers: It lets you combine both hard and soft polymers for outstanding comfort and utility for even the smallest of products.
ㆍReduced misalignments: It can greatly reduce the number of misalignments when compared to over-molding or more traditional insert processes.
ㆍComplex mold designs: It enables manufacturers to create more complex mold designs using multiple materials that can’t be effectively bonded using other processes.
ㆍExceptionally strong bond: The bond created is exceptionally strong, creating a product that is more durable, more reliable, and with longer life.

Versatility

Product manufacturers favor a wide range of applications for two-shot injection molding, including automotive interior parts, medical equipment, tools, and toys. It allows manufacturers to combine various materials and colors to create a strong and attractive final product. Some materials can be effectively combined with this process, including silicone and thermoplastics, nylon and thermoplastic elastomers, or hard nylon and soft-touch materials.

Two-shot injection molding can solve your company’s product production difficulties. An experienced plastic manufacturer can guide you from concept to finished product and ensure a cost-effective solution.

Producing an assembly with multiple components

Compared to other methods of plastic molding, two-shot is ultimately a more cost-efficient way of producing an assembly with multiple components. Here’s why:

Part Consolidation: Two-shot injection molding reduces the number of components in a finished assembly, eliminating an average of $40K in development, engineering, and validation costs associated with each additional part number.

Improved Efficiency: Two-shot molding allows multiple components to be molded with a single tool, reducing the amount of labor needed to run your parts and eliminating the need to weld or join components after the molding process.

Improved Quality: Two-shot is carried out within a single tool, allowing for lower tolerances than other molding processes, a high level of accuracy and repeat-ability, and reduced scrap rates.

Complex Moldings: Two-shot injection molding allows for the creation of complex mold designs that incorporate multiple materials for functionality that cannot be achieved through other molding processes.

Disadvantages of two-shot injection molding

1) High tooling costs and long setup lead times. Up-front costs are high due to the design, testing, and tooling required. There is the initial design and prototyping (probably via CNC or 3D printing), then the design of a prototype mold tool to produce replicas of the part in volume. Lastly, and only after extensive testing during both stages, you can finally inject mold a part.

2) Part design restrictions. Plastic parts must be designed with injection molding consideration and must follow the basic rules of injection molding, for example:

Avoid undercuts and sharp edges as much as possible

Use uniform wall thicknesses to prevent inconsistencies in the cooling process resulting in defects like sink marks.

Draft angles are encouraged for better de-molding.

Don’t forget, because tools are typically made from steel or aluminum, it can be difficult to make design changes. If you need to add plastic to the part, you can make the tool cavity larger by cutting away steel or aluminum. But in order to take away plastic, you need to decrease the size of the tool cavity by adding aluminum or metal to it. This is extremely difficult and in many cases might mean scrapping the tool (or part of it) and starting over.

Also, the weight and size of the part will determine the tool size and necessary press size. The larger the part, the more difficult and expensive it will be.

3) Small runs of parts can be costly. Due to the complexity of tooling, and the necessity to rid the machine of all previous material before the next product can be made, the setup time can be quite lengthy. Therefore small runs of parts have traditionally always been thought of as too expensive to injection mold.

 

We are a professional plastic injection mold manufacturer. If you have projects on hand, please feel free to contact us via [email protected]

Difference between Thermoset & Thermoplastic Injection Molding

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Thermoplastics and thermosetting plastics are two separate classes of polymers that are widely used in the process of injection molding to create products of various types. Both these categories of plastics possess different properties and characteristics. Hence, choosing the right category of polymer, between the two, is of paramount importance to achieve the expected results when used in applications.  Most of the injection molding service providers usually receive a question from their clients about the differences between thermoplastic and thermoset molding process. Here, in this post, let’s see thermoset & thermoplastic injection molding comparison.

 

Defining Thermoplastic and Thermosets

Before we go deeper into the topic, it is important to understand the two terms thermoset and thermoplastic. Let’s first find out what are thermosets and thermoplastics.

What are Thermosets?

Thermoset plastics “set” after they cure and are generally stronger than thermoplastic materials. Initially, the polymer is a liquid or soft solid, which becomes rigid later when cured. Owing to their high mechanical and physical strength, resistance to heat, corrosion, and mechanical creep, thermosets are used in a variety of applications. A few amongst the common thermoset materials used in the injection molding process include alkyds, epoxy, phenolic, polyimides, thermoset polyester, and so on.

What are Thermoplastics?

In contrast to thermoset, thermoplastics liquefy and become pliable when heat is applied. Thermoplastic polymers can be reheated and reprocessed many times, which is impossible when it comes to thermosets. Usually stored in the form of pellets prior to the molding process, these categories of polymers can withstand multiple re-shaping without causing any damage to the material. They possess high strength, shrink-resistance, flexibility, high-Impact resistance, and chemical resistant, among others. A few amongst the common thermoset materials used in the injection molding process include ABS, nylon, PET, polypropylene, polyethylene and TPE, among others.

Difference between Thermoset & Thermoplastic Injection Molding

The way thermosets are molded differs with respect to thermoplastics in several aspects and both the categories require varied treatment during the injection molding process. Let’s check a few differences when molding thermosets and thermoplastics.

Where and How They’re Used

The differences inherent to thermosets and thermoplastics make them uniquely suited for differing applications.

Appliance fabrication may require a thermoset such as epoxy — the material’s high-impact resistance, microbial resistance, and general inert properties are ideal in the kitchen and cooling environment. Conversely, a thermoplastic such as polyethylene makes a great packaging film, since the material shrinks and conforms to the packaging when heated.

As a general rule, thermosets are often affiliated with manufacturing and utilities — appliances, electrical applications, and anything else involving heat that may otherwise warp thermoplastics. Thermoplastics, on the other hand, are broadly diverse and used in everything from aerospace fabrication to consumer goods and toys. The nature of the polymer used depends on the final application.

 

Now that you know how thermoset injection molding differs with respect to thermoplastic injection molding. With the information provided in the post, you would be able to make a judgment on the type of polymer category you should opt to produce molded parts. However, just knowing the differences between the materials won’t be enough, instead you would need an injection molding service provider who can mold your parts as per the right specifications provided. Partner with leading injection molding companies like WIT MOLD who own a comprehensive working knowledge regarding thermoplastic vs thermoset molding.

injection mold

Common Defects Of Injection Molds And Their Solutions

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An injection mold is a tool for producing plastic products and for giving them a complete structure and precise dimensions. Read on for more information about common problems and solutions for injection molds.

 

injection mold

 

A mismatch between mold and injection molding machine

Causes:

1. Positioning ring position is not correct, size is too big or too small.

2. Wrong position and size of the ejector hole of the mold; wrong position and size of the forced pull reset hole.

3. Mold width size is too big; mold height size is too small.

Solution:

1. Adjust the ejector hole position and size; adjust the reset hole position and size.

2. Replace the positioning ring; adjust the position and size of the positioning ring.

3. Change the tonnage of a large injection molding machine; increase the thickness of the mold.

 

Bad quality of parts

Causes:

1. The fit-gap is too large.

2. Poor glue walking, trapped air.

3. Ejector pin is too small, uneven ejection.

4. Too small bevel, burr, hardness is not enough.

5. Uneven injection pressure, insufficient strength of product form.

6. Processing error.

7. Far from the gate, low mold temperature.

Solution:

1. Trim the gate, pressure uniformity, strengthen the product strength.

2. Reasonable adjustment of clearance and grinding work part of the parting surface.

3. Improve the gate, increase the mold temperature.

4. Add local glue, add exhaust.

5. Re-processing.

6. Increase the ejector pin, evenly distributed.

7. Repair burr, increase slope, nitriding.

 

injection mold

 

The parts are difficult to fill and difficult to take

Causes:

1. The pouring system is blocked, the runner cross-section size is too small, the gate arrangement is unreasonable, and the gate size is small.

2. The limit stroke of the mold is not enough, the extraction stroke of the mold is not enough, the ejecting stroke of the mold is not enough.

Solution:

1. Check whether the limit, core extraction, and ejection strokes meet the design requirements and adjust the strokes that do not meet the requirements.

2. Check the runner and gate of each section of the pouring system, and fix the parts concerned.

 

Mold opening and closing ejecting reset action is not smooth

Causes:

1. Slanting ejector, ejector pin sliding is not smooth.

2. Mold frame guide column, guide sleeve sliding is not smooth, with too tight

3. Reset spring elasticity or pre-pressure is not enough.

Solution:

1. Increase or replace the spring.

2. Repair or replace the guide pillar, guide bush.

3. Check and repair the slanting top, ejector pin.

 

Mold water transportation is not working or water leakage

Causes:

1. Water sealing rubber ring and water pipe joint are not sealed enough.

2. The mold water channel is blocked and the inlet and outlet water pipe joints are connected in the wrong way.

Solution:

1. Check the cooling system inlet and outlet water pipe joints connection and each section of the waterway, repair the relevant parts.

2. Check the water sealing rubber ring and water pipe joints, repair or replace the parts.

 

WIT MOLD is a very professional mold design and mold manufacturer located in southern China and has passed the ISO2009:2015 international quality Our injection molding process can be customized according to your unique project. If you are interested, please feel free to contact us.

Advantages And Differences Of Two Shot Injection Molding

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There are a variety of manufacturing methods used to manufacture products that use plastic polymers, including two-shot injection molding, compression thermoset molding, and extrusion. Although all of these are viable manufacturing processes, this process has several advantages that make it the first choice of many plastic manufacturers. The process is relatively simple; inject one material into the mold to make the initial part of the product, and then inject a second material that is compatible with the raw material. Many manufacturers use this method to make plastics or polymers for three good reasons.

 

Two-shot injection molding is cost-effective

The two-step process only requires one machine cycle, the way the initial mold is rotated and the product placed around the second mold, so that a second, compatible thermoplastic can be inserted into the second mold. Because this technology uses only one cycle, rather than a separate machine cycle, any production operation cost is lower, and fewer employees are required to manufacture the finished product while delivering more projects per run. It also ensures a firm bond between the materials without the need for further assembly down the line.

Two-shot injection molding

Two-shot injection molding

 

Strengthen product quality

Two-shot injection molding improves the quality of most thermoplastics in the following aspects:
Improved aesthetics. When products are made of different colored plastics or polymers, they look better and are more attractive to consumers. If more than one color or texture is used, the product will look more expensive.
Improve ergonomics. Because this process allows the use of a soft-touch surface, as a result, items can have ergonomically designed handles or other parts. This is especially important for tools, medical equipment, and other hand-held items.
When silicone plastic and other rubber materials are used for gaskets and other parts that require a strong seal, it provides a better seal.
It allows you to combine the outstanding comfort and practicality of hard and soft polymers with even the smallest products.
Compared with overmolding or a more traditional insertion process, it can greatly reduce the number of dislocations.
It enables manufacturers to create more complex mold designs using multiple materials that cannot be effectively bonded by other processes.
The bond created is very strong, creating products that are more durable, more reliable, and have a longer lifespan.

 

Versatility

Product manufacturers favor two-shot injection molding, with a wide range of applications, including automotive interior parts, medical equipment, tools, and toys. It allows manufacturers to combine various materials and colors to create final products that are both strong and attractive. Some materials can be effectively combined with this process, including silicone and thermoplastics, nylon and thermoplastic elastomers, or hard nylon and soft-touch materials.
Two-shot injection molding can solve your company’s product production dilemma. An experienced plastic manufacturer can guide you through the process from concept to finished product and ensure a cost-effective solution.
We are Two-shot injection molding suppliers. Please feel free to contact us if you need or want to know about our products.

Two-Shot Molding vs. Overmolding

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Two-Shot Molding vs. Overmolding

Injection molding is a popular manufacturing process, which can quickly produce complex-shaped precise parts without wasting a lot of materials.

Many different processes belong to the category of injection molding, including over-molding and two-shot molding. The two processes are similar, but there are some key differences-here are what engineers and designers need to know:

What is two-shot molding?

 

Two Shot Injection Molds, also known as dual-molds, double-shot molds, or multi-shot molds, are a subcategory of injection molding that allows engineers to create multi-material or multi-colored parts without adding additional assembly steps.

Through the different layers of materials or colors created by the injection molding machine, the two-shot injection molding process is best understood. The first material is injected into the mold to create the substrate, and other materials or materials will be molded around the substrate. After the substrate solidifies and cools, it is transferred by hand, robotic arm, or rotating plane to another cavity of the mold.

From there, the mold opens and rotates 180° with one side of the substrate to meet the other mold chamber and injection molding nozzle. Once the substrate is in place, the second material is injected and combined with the substrate to form a firm hold. Once the second layer has cooled, the last part will be sprayed out.

Engineers should know that Two Shot Mold can be accelerated or slowed down, depending on how the substrate is transferred to another cavity of the mold. Hand and robot arm transfer takes longer than the rotating plane, but the rotating platen molding is more expensive, usually, there are only high-efficiency options, mass production runs.

In addition, it is very important that the material of the mold is easy to bond, and the mold must be aligned to prevent deformation of the parts.

Advantages and disadvantages of two-shot molding

 

Two-shot injection molding is efficient and economical manufacturing technology. This process also produces highly durable terminal parts and assemblies.

From a design point of view, two-shot molding provides designers with a lot of flexibility, because this process can create complex geometric shapes and adapt to multiple colors to produce more beautiful parts.

In addition, because one machine manufactures the entire part, no post-processing is required, and engineers can greatly reduce manufacturing time, thereby reducing costs. However, it is worth noting that the initial two-shot injection molding machine may be costly, and the two-shot injection molding machine is more expensive than the standard injection molding machine. Fortunately, these costs are usually offset by labor savings and assembly costs for large-scale production runs.

What is over-molding?

 

Overmolding, like Two Shot Moulding, is a multi-shot injection molding process that produces a single final product from two or more different thermoplastics. This process is ideal for engineers who want to build components that are powerful, functional, beautiful, and that will not separate over time.

At the beginning of the over-molding process, engineers inject the substrate with a harder over-molding material. Then, the substrate is placed in an over-mold tool or an over-mold cavity within the same mold. The molten-over mold material is then sprayed into, onto, or around the substrate. After the molten material is cooled, the substrate and the over-mold are chemically or mechanically combined. The entire over-molding process only takes 30 seconds.

The product team must remember that all thermoplastics used in the over-molding process must be chemically or thermally compatible with each other. Compatibility with metal substrates is usually not a problem, because they can be used with any plastic over mold, but the product team may encounter compatibility issues when using plastic over molds. If the substrate and mold are not compatible, the final product may be deformed or poorly bound.

However, if two less compatible plastics must be used, the team can design mechanical bonding properties for the part after the fact, although this may result in higher costs.

Advantages and disadvantages of over-molding

 

Overmolding and two-shot injection molding have many of the same advantages. They are ideal for quickly creating durable, reliable, and vibration-resistant parts with complex geometries, but over-molding is best suited for low-volume production runs.

Compared with two-shot molding, over-mold design is also easier, because engineers can use any standard injection molding machine to carry out this process.

In terms of disadvantages, the tolerances of over-molded parts are often lower than those of two-shot injection molding. It is also important to remember that plastic compatibility requirements may constrain designers.