overmoolding insert molding

In the plastics industry, injection molding is a significant process that is used to produce a large volume of plastic parts or products. This technique involves the use of a mold, usually of steel-made metal, that has an interior pattern that resembles the intended design of the part or product. The material, usually inserted after melting into a liquified or molten hot plastic state, is forced into a die cavity, eventually cooled, and then released to create thousands of similar pieces by applying high pressure.

Due to high production accuracy, almost all large-scale plastic products on the market today are fabricated through injection molding techniques. The process has many benefits, such as low cost per part production, short time per part manufacturing, accommodating several materials, and high accuracy of the final part meeting exact tolerance requirements.

These include overmolding vs. insert molding techniques. Although both are interchangeably used, there are clear distinctions between them. This blog post specifically provides key details about two techniques: overmold vs. insert mold processes, by highlighting their differences, applications, and situations to choose between the two.

insert molding

Insert Molding: How Does It Work?

Both overmolding and insert molding techniques involve injection molding. In the process, metal parts are placed into a mold cavity, and then plastic is injected. These metal inserts are placed in the mold by hand or with the help of industrial robots used in automated processes. Once the mold is in position, the mold is closed, and a plastic material is injected over the metal inserts to create a single, unbroken part.

These features enable easy assembling and disassembling of the parts without any effect on the quality or appearance. For instance, heat-set threaded inserts are used in the plastic parts to reduce the likelihood of thread damage during assembly.

In addition, insert molding may sometimes even reduce the need for secondary fasteners. This technique involves the direct incorporation of required metal components into the mold to form a strong, single component that increases the mechanical stability of the part and minimizes the chances of part breakage. If you want to know more about insert molding, please go to what is insert molding page.

Why should one opt for Insert Molding?

Insert molding is an adaptive manufacturing process to produce high-strength plastic components. Let’s discuss its extensive use cases:

Reduced Assembly Costs: An injection molding machine is capable of producing thousands of parts in a minimal time frame, and this makes it economical for large batch parts production. In contrast to CNC machining, sheet metal fabrication, or 3D additive manufacturing techniques, where the assembly can become a significant problem, insert molding can minimize or even remove the need for additional assembly and tooling requirements, which will lead to further cost optimization of projects.

Enhanced Part Performance: Plastic parts are typically not as durable as their metal counterparts, but plastic has its benefits, including being cheaper, easier to mold into different shapes, and lighter in weight. Insert-molded products normally entail durability due to the combination of plastic (a substrate on which metal is inserted) and metals (insert both materials). This ensures that the intended part being inserted has the necessary strength and stiffness. Moreover, the plastic matrix helps reduce the overall weight of parts. Furthermore, insert molding imparts in parts the ability to resist cyclical loads and other loads.

Disadvantages of Insert Molding

Despite its several benefits, insert molding also comes with certain limits that product manufacturers must consider: These common drawbacks include;

insert molding vs overmolding

Multiple Manufacturing Technologies: Insert molding may need to be done in two phases in general. Metal-forming processes such as CNC machining may be used when manufacturing custom-designed inserts rather than off-the-shelf parts. These methods are generally costlier per part than fully injection-molded processes. While it is possible to reduce the cost of manufacturing metal inserts by employing techniques such as metal die casting or metal injection molding (MIM), Despite this, the cost of manufacturing parts with metal inserts is still higher than that of parts made entirely out of plastic.

Increased Part Complexity: When producing products that have to have metal inserts made to order, it’s essential to have a deep understanding of both metal and plastic manufacturing. Product designers must know the DFM rules of both technologies and how to combine them into one part that functions as required. This can add to the design and manufacturing time and cost of the product.

An Overview of the Overmolding Process?

Overmolding is a subcategory of insert molding, which is the process of molding one plastic material directly onto a formed part. In this process, the first part is molded by injection molding, and then it is placed in the second mold for the overmolded material. This technique enables the use of two or more plastics in the production of a single product, giving the product both utility and beauty.

For example, overmolding allows for the combination of different Shore hardnesses, providing a soft touch layer on top of a rigid base for better grip and feel. Also, the use of multiple colors in an overmolded part can give it a competitive edge since it is not easily seen in other products. This technique is widely applied to the grips of tools like screwdrivers, power drills, and toothbrushes since both the comfort of the grip and the product’s appearance are essential factors.

Why choose the overmolding process?

Overmolding offers a range of benefits that make it a versatile and advantageous process.

Increased Material Flexibility: Overmolding enables the use of different materials in a single part, and this makes it possible to have different properties in the same part. This process improves the product’s looks, feel, and usability, which is advantageous to both the product and the consumer.

Elimination of Adhesives: Overmolding is a process where two or more different materials are joined together through an injection mold, thus replacing the need for adhesives or other joining techniques. This not only strengthens the final part but also cuts the assembly costs.

Integrated Seals: Overmolding makes it possible to bond soft seals directly onto molded parts. For instance, in electronics enclosures with IP ratings, an overmolded seal is cheaper and more efficient than fitting an o-ring groove. This integration enhances the performance of the part and the structural stability of the whole system.

Limitations of overmolding

Overmolding, despite its numerous benefits, comes with certain drawbacks:

Complex Process: Overmolding is a two-shot process, which means that the part cycle time and the cost are higher than in single-part molding. Also, it calls for the application of two tools or a two-shot mold that is quite expensive to produce. However, these are some of the challenges that one can face when using overmolding, but it can be cheaper than manufacturing two different injection-molded parts and then joining them.

Debonding Risk: The problem of delamination or distortion may occur when two different materials are bonded in an injection mold because the temperatures may not be ideal for the given material combination. This may require the use of mechanical interlocks in order to achieve a secure connection where heat alone is not enough.

If you want to know more about overmolding, please go to the overmolding page to check this out.

Industrial Uses of Overmolding vs Insert Molding

Both overmolding and insert molding are widely used for applications requiring high-quality and stringent products. Nevertheless, all these techniques have similar uses, and they are employed to manufacture numerous parts and products.

Automotive Industry

Both insert molding and overmolding play a vital role in manufacturing numerous automotive parts that contain metal, rubber, or plastic, such as batteries, knobs, dash panels, motors, and handles.

Cosmetic Industry

These techniques are indispensable in the cosmetics industry for producing custom-made items and their containers with the use of various colors and surface treatments of cosmetic items such as perfume flacons, cosmetic brushes, and compacts.

Consumer Products

In the case of household products, insert mold and overmold play a central role in manufacturing items such as toothbrush holders, containers, and cell phone cases. They also reinforce items such as patio chairs and step stools, which are usually found in multiple colors or materials.

Electrical Appliances:

The use of insert molding cannot be overemphasized, particularly in the electrical industry, where wires are coated with rubber insulation. This process helps to stop electrical conduction and increase safety levels. Insert molding also makes electrical appliances safer to handle by providing a proper place for insulators to be installed.

Sincere Tech is one of the top 10 plastic injection molding companies in China that specializes in creating unique products for different sector., With the help of the technical knowledge and skills that the company has gained over the years, the company offers its services at affordable prices. Whether for consumer products, home appliances, or car accessories, you can rely on these processes for quality production.

overmolding vs insert molding

Conclusion: Selecting Between Overmolding, Insert Molding, and Injection Molding

Overmolding and insert molding are the different techniques that fall under the injection molding process, which is a popular and efficient method of manufacturing consumer goods. As for the cost, injection molding is generally considered to be the most cost-effective method compared to other methods such as CNC machining and 3D printing per part.

Overmolding could be an optimal choice if:

  • Your part’s surface has different electrical or thermal properties.
  • It is essential to increase the level of shock absorption or decrease the level of vibrations.
  • It is necessary to produce a part from multi-colored plastic.
  • Your part must offer a comfortable, non-stick surface that the other part can easily grip.

Opt for insert molding when:

  • The substrate can be in the form of wires, electronic components, or circuit boards.
  • It is preferred not to have to spend the money on a two-shot mold or a 2K, which is more complicated.
  • You have to tap this part and install threaded inserts.

When the decision has been made to use injection molding for a certain application, the next choice is between insert molding, overmolding, or conventional injection molding. It is important to provide a clear definition of the product application to be able to make a proper choice. All these processes have their own special benefits suitable for various products. Deciding which method is right for your particular product is not always easy; therefore, it is advisable to consult a professional.

Speaking to a SincereTech representative can be helpful due to over a decade of the company’s experience in manufacturing. We can assist you in the decision-making process of your project and determine which process—insert molding, overmolding, or standard injection molding—will be most beneficial for your project.


Q1. What is the process of TPE overmolding?

TPE overmolding is a process where TPE is injected into an existing substrate or a plastic part to form a chemical bond with the material in order to increase its durability and usefulness.

Q2. Is 2K injection molding the same as insert molding?

No, Insert molding involves placing an additional part on the substrate, while 2K injection molding involves injecting multiple materials into multiple-cavity molds for the production of intricate parts for vehicles.

Q3. What plastic types are suitable for overmolded?

The most commonly engineered plastics suitable for overmolding processes include high-density polyethylene (HDPE), PEEK resin, Delrin or acetal, polymethyl methacrylate acrylic, commonly known as PMMA, ABS, nylon, and PBTR. These plastics have different characteristics that make them suitable for different overmolding processes across industries like automotive and consumer products.

Q4. Overmolding vs. Insert Molding:  Which One Costs More?

Overmolding, however, provides economical scalability at higher production rates for companies, which in turn increases the overall profitability of a company through decreased tooling and assembly costs. Further, it helps with faster production of parts in large-volume runs. If you are going to produce intricate prototypes or low-volume parts, this cost differential becomes apparent due to the requirements of two parts.

two-shot molding

 Mastering Two Shot Molding: A Revolution in Plastic Injection

Two Shot Molding or two shot injection molding has revolutionized the world of plastic injection molding. This advanced manufacturing process offers a level of precision and versatility that is unmatched by traditional injection molding methods. In this comprehensive guide, we’ll delve into the intricacies of Two Shot Molding, exploring its processes, applications, benefits, and challenges. Whether you’re a seasoned industry expert or a curious novice, this article will provide valuable insights into the world of Two Shot Molding.

Two-Shot Molding: Colorful Solutions for Plastic Molding Parts

Two-Shot Molding (also called 2k mold, double injection molding) are a cost-effective method to produce plastic parts with two or more colors moulded at the same time, such as radio control buttons or dashboard faceplates.

Two-Shot molding is a relatively new, rapidly growing technology. It is replacing older, two-step systems, eliminating a secondary process to add logos, graphics or text. New computer technology and advanced materials have promoted the growth of the two-shot process.

The two-shot process first injects one color material into the mold, then injects the second color around or over the first color. There are also multi-shot processes for parts with more than two colours.

two shot injection molding

two shot injection molding

The Two Shot Molding Process

Two Shot Molding is a multi-step process that involves injecting two different materials into a single mold to create a finished part with multiple colors or properties. Let’s break down the process into its key components:

  1. First Shot: The “First Shot” in Two Shot Injection Molding is a crucial step in the two-step injection molding process. This initial injection is where the primary material, typically a rigid thermoplastic, is injected into the mold cavity to create the foundational structure of the part.

    Here’s a more detailed look at the “First Shot” stage:

    1. Material Selection: The selection of the primary material is vital. It should possess the desired mechanical and structural properties required for the finished part. This material serves as the core or substrate upon which the second material will be added.

    2. Mold Preparation: The mold used in Two Shot Molding is designed to accommodate both the “First Shot” and the “Second Shot.” It is crucial to ensure that the mold is appropriately prepared for the first injection. This includes proper alignment and clamping to prevent any material leakage.

    3. Injection: The chosen primary material is heated to its melting point and then injected into the mold cavity. This injection is carried out with precision, ensuring that the material fills the mold cavity uniformly to create the primary structure of the part.

    4. Cooling and Solidification: After the injection, the mold cools and solidifies the primary material. The cooling time and temperature are critical factors in achieving the desired material properties and dimensional accuracy.

    5. Mold open with no ejection: Once the first shot material has sufficiently cooled and solidified, the mold opens, and the core side (moving half) turn over 180 degree to prepare the second shot. This part is known as the “preform” or the “substrate.”

    The “First Shot” sets the stage for the second injection. It determines the part’s core structure, mechanical properties, and the areas where the second material will be added. The precision and accuracy in this step are essential to ensure a successful Two Shot Injection Molding process.

  2. Second Shot: The “Second Shot” is the second and final step in the Two Shot Molding process. In this stage, a different material or same material but different color is injected into the mold to complement or enhance the part created in the “First Shot.” The “Second Shot” provides additional colors, textures, properties, or features to the final product, creating a part with multiple materials or properties in a single mold.

    Here’s a closer look at the “Second Shot” phase:

    1. Material Selection: For the “Second Shot,” a different material is selected, which complements or contrasts with the material used in the “First Shot.” The choice of material depends on the desired characteristics of the final part, such as color, texture, or additional functional properties.

    2. Mold Preparation: The same mold used for the “First Shot” is used for the “Second Shot.”  two shot injection molding including two molds together to be two shot mold. Proper alignment and clamping of the mold are crucial to ensure that the second material is injected accurately and bonds effectively with the first material.

    3. Injection: The second material is heated to its melting point and injected into the mold cavity. This injection must be precise to ensure that the material fills the designated areas of the mold, forming the desired features or properties. The coordination between the “First Shot” and the “Second Shot” is critical to achieve accurate material distribution and bonding.

    4. Cooling and Solidification: After the “Second Shot” is injected, the mold cools and solidifies the second material. The cooling time and temperature are carefully controlled to achieve the desired material properties and ensure a strong bond between the first and second materials.

    5. Ejection: Once the “Second Shot” material has cooled and solidified, the mold opens, and the finished part is ejected from the machine. The final product now features the combination of the “First Shot” material and the “Second Shot” material, creating a multi-material, multi-property part.

    The “Second Shot” injection adds complexity and versatility to the manufacturing process, allowing for the creation of parts with diverse colors, textures, functional properties, and more. It is essential to ensure that the materials used in the “First Shot” and “Second Shot” are compatible and that the injection process is well-controlled to achieve the desired aesthetics and performance in the final product. The result is a finished part that can meet the requirements of a wide range of industries, from automotive and consumer electronics to medical devices and beyond.

Injection Molding Machines for Two Shot Molding

To execute Two Shot Molding effectively, specialized injection molding machines are used. These machines have two injection units, allowing for the sequential injection of different materials. The coordination between the two injection units is crucial to achieve accurate and consistent results. Modern machinery offers sophisticated control systems, ensuring precise material distribution and minimizing waste.

Materials Used in Two Shot Molding

Selecting the right materials is a critical aspect of Two Shot Molding. The choice of materials depends on the desired characteristics of the final part. Common material combinations include:

  • Thermoplastic and TPE: Combining a rigid thermoplastic with a soft thermoplastic elastomer (TPE) can create parts with both structural strength and flexibility.

  • Two Thermoplastics: Using two different thermoplastics can yield parts with varying colors, textures, or properties.

  • Thermoplastic and Overmold: Overmolding a thermoplastic with a second material can enhance grip, aesthetics, or functionality.

  • Multi-Color Combinations: For parts requiring intricate designs or color variations, using different colored thermoplastics is a common choice.

Advantages and Benefits of Two Shot Molding

The Two Shot Molding process offers several advantages and benefits, making it a preferred choice for manufacturers:

two shot molding

2k molding

Improved Product Design and Aesthetics

Two Shot Molding allows for the integration of multiple materials, colors, and textures within a single part. This versatility enhances product aesthetics and design options, making it ideal for consumer products and complex components.

Cost Savings

While the initial investment in Two Shot Molding equipment may be higher, the process can lead to substantial cost savings in the long run. It reduces the need for secondary processes such as assembly and bonding, minimizing labor and material costs.

Reduced Assembly Steps

As mentioned, Two Shot Molding eliminates the need for secondary assembly steps, simplifying production and reducing the risk of errors. This streamlines the manufacturing process and accelerates time-to-market.

Enhanced Material Compatibility

By combining materials with complementary properties, Two Shot Molding offers the advantage of improved material compatibility. This is especially beneficial in applications where different materials need to work together seamlessly.

Environmental Considerations

Reducing waste is a significant environmental benefit of Two Shot Molding. It minimizes material scrap and excess packaging associated with traditional manufacturing processes, contributing to sustainability efforts.

Applications of Two Shot Molding

The versatility of Two Shot Molding extends to various industries:

Automotive Industry

In the automotive sector, Two Shot Molding is used to create components with both functional and aesthetic requirements. It’s commonly employed for creating grip-enhancing surfaces on steering wheels, gearshift knobs, and interior trim pieces.

Consumer Electronics

Consumer electronics benefit from the aesthetic advantages of Two Shot Molding. It’s used to produce products with visually appealing designs and tactile comfort, such as smartphone cases and remote control buttons.

Medical Devices

Two Shot Molding ensures the precision and functionality required for medical devices. It’s employed in creating components like ergonomic surgical tools and drug delivery devices.


In the packaging industry, Two Shot Molding is used for designing containers with built-in seals, grips, or color variations. This simplifies the packaging process and enhances the user experience.

Other Industries

Two Shot Molding is not limited to the above-mentioned industries. It finds applications in countless other sectors, wherever the combination of materials and intricate designs is required.

Challenges and Considerations

While Two Shot Injection Molding offers numerous benefits, it also presents some challenges:

Part design and mold design for Two-shot mold 

Part design & mold design for 2K injection molding is totally different, because the molding machine is different to single colour molding machines, there are two shot molding machine has two nozzles in one machine, but there are three types of different Multi-Component Injection Molding machines (vertical nozzle, parallel nozzle, 45 degree nozzle), each type of machine needs different mold design, before design the 2K mold you must know the data of 2K molding machine in advance, to know how to design the two color mold you can download the Multi-Component Injection Mold Design Guild document below,

Two color molding

Two color molding

Material Selection

Choosing the right materials is critical. Compatibility and adhesion between materials are paramount to avoid defects or part failure, wrong material will make thing west.

Quality Control and Inspection

Quality control becomes more critical in Two Shot Molding. Ensuring that each part meets the required specifications demands rigorous testing and inspection processes.

Cost Factors

The initial investment in Two Shot Molding equipment can be higher than traditional molding machines. However, the long-term cost savings often outweigh the initial capital expenditure.

Case Studies and Examples

Let’s explore some real-world examples of case studies and examples that highlight the versatility and effectiveness of Two Shot Molding in various industries:

1. Automotive Shift Knobs:

  • Industry: Automotive
  • Application: Two Shot Molding is commonly used to manufacture shift knobs for automobiles. The process involves using a rigid thermoplastic for the core of the knob, providing structural integrity, and a soft thermoplastic elastomer (TPE) for the outer layer, ensuring a comfortable and non-slip grip.
  • Benefits: This approach combines durability with ergonomic design, creating shift knobs that are not only visually appealing but also comfortable and functional.

2. Medical Device Handles:

  • Industry: Medical
  • Application: Two Shot Molding is utilized for manufacturing handles for various medical instruments, such as surgical tools. The first shot involves a rigid material for the core structure, and the second shot consists of a different material to enhance the grip and ergonomics.
  • Benefits: The process results in handles that provide surgeons with a secure grip during delicate procedures while maintaining the necessary structural integrity.

3. Consumer Electronics Casings:

  • Industry: Consumer Electronics
  • Application: In the consumer electronics sector, Two Shot Molding is employed for creating smartphone and tablet casings. The first shot forms the core structure, while the second shot allows for the integration of different colors and textures, giving electronic devices a premium and customized appearance.
  • Benefits: Two Shot Molding enhances the visual appeal of electronic devices, making them stand out in a competitive market.

4. Multi-Color Packaging Seals:

  • Industry: Packaging
  • Application: Two Shot Molding is used to create packaging components with built-in seals, grips, or color variations. For example, closures for food containers that require both a sealing function and a different color for branding.
  • Benefits: This application streamlines the packaging process, reduces assembly steps, and enhances the user experience by providing secure seals and branding opportunities in a single manufacturing step.

5. Automotive Interior Trim:

  • Industry: Automotive
  • Application: Two Shot Molding is instrumental in producing automotive interior trim components, such as door handles and dashboard accents. The process allows for a combination of materials to achieve desired aesthetics and functionality.
  • Benefits: Interior trim pieces created through Two Shot Molding are not only visually appealing but also durable and functional, enhancing the overall quality of the vehicle interior.

These case studies demonstrate the adaptability of Two Shot Molding across diverse industries. By combining different materials in a single manufacturing process, it enables the creation of parts with enhanced aesthetics, improved functionality, and cost-efficient production. Whether it’s for automotive components, medical devices, consumer electronics, or packaging solutions, Two Shot Molding continues to play a pivotal role in modern manufacturing by offering design flexibility and process efficiency.

Future Trends and Developments in Two Shot Molding

Two Shot Molding is constantly evolving with emerging technologies and industry trends. Some key developments to watch for include:

Emerging Technologies

Advancements in injection molding machinery and materials are driving innovation in Two Shot Molding. New technologies offer even more precise control and efficiency.

Sustainability Initiatives

As the world places greater emphasis on sustainability, Two Shot Molding’s reduced waste and material efficiency make it an environmentally friendly choice.

Market Growth and Opportunities

The growth of Two Shot Molding is expected to continue, opening up new opportunities in various industries. Being prepared to harness these opportunities is essential for manufacturers.


Two Shot injection Molding has cemented its place as a game-changer in the world of plastic injection molding. Its ability to create intricate, multi-material parts with precision and cost-efficiency makes it a valuable technique for manufacturers across industries. As technology advances and environmental concerns grow, Two Shot Molding is poised to play an even more significant role in shaping the future of manufacturing. Whether it’s for enhancing product aesthetics or streamlining production processes, Two Shot Molding is a technique worth exploring and mastering in the world of modern manufacturing.

SINCERE TECH provides two-shot molding, and custom Plastic injection Molds & plastic injection molding service to all of the industries. Our state-of-the-art mold facilities and molding machines include a variety of processing and finishing equipment to manufacture plastic molds and parts from many types of industries, including complex specialty injection molds, such as:

  • two-shot injection molding
  • Unscrewing molds
  • Insert molding
  • Stack molds
  • Two shot mold (2K injection molding)
  • And many other types

2-K Mold, Multi-Component Injection Mold Design Guild Line

If you have a new project that wants to know the best manufacturing process and solutions? Send us an email to [email protected]. if you want to know more detail about our advantages, please go to our home page by https://www.plasticmold.net/.

precision plastic injection molding

What is precision plastic injection molding?

Precision Plastic Injection Molding is tight tolerance requirement plastic injection molding parts. Normally tolerance on the plastic molding part is around 0.05-0.1mm, if the part tolerance requirement is about 0.01-0.03mm, that means this is precision plastic injection molding, to make high precision plastic injection molding parts, the first thing is making the precision injection mold, all of the mold components must have tolerance within 0.005-0.01mm.

This is min requirement for high precision plastic injection mold after mold is completed finished, then take mold trial to verify the dimension according to 2D drawing requirement, to trial the mold and make stable tolerance.

High Precision plastic injection mold is number one key point to making high precision plastic injection molding parts, but not limited to this, you still need use high precision injection molding machine to produce the part, by this two min requirement we can make sure that we can make precision injection molded plastics continually, there are few issues that we make still need to know for the high precision plastic injection molding.

Precision Plastic Injection Molding

Plastic precision Connector-overmolding

Question I:

The determination of the structure of the precision plastic mold is the key, and the overall structure is the embodiment of the final effect of the product: the determination of the overall structure of the mold, the determination of the gate system, the determination of the ejection system and the determination of the water transportation system, and others should be conducive to the post-processing orientation of the product.

Question II:

What about the feeding problem? First of all, we will choose a reasonable injection scheme according to the structure, weight, volume, and cost of the product, which can meet the requirements of customers as well as the requirements of quality.

Second, we will design in strict accordance with the injection design standards: the layout of the runner should be uniform, especially the size of the cross load surface of the main and sub runner, the shape and size of the gate.

Question III:

What about the ejection problem? Firstly, we will determine the ejection mode according to product orientation and structure. Secondly, we will evaluate the ejection balance and coexist with other systems, such as interference with water transportation and recycling marks, date clock, etc.

Question IV:

The design of the water channel system is based on four requirements (the cooling line should be as balanced as possible. The water cooling line shall not interfere with other mechanisms. The water channel equipment shall meet the customer’s standards and be easy to install. Each water channel line shall be displayed with identification numbers or marks (in and out).

 Question V:

How to ensure the manufacturing accuracy of the mold and the accuracy of the molding products to get precision injection molding, this mainly depends on the manufacturing accuracy of the mold cavity, the insert, and the mold core size. The accuracy of the mold cavity number or the accuracy of the parting line will directly affect the size of the product. Firstly, we need to make the manufacturing process plan and flow chart.

Each completed manufacturing process must be fully inspected and the data inspection list must be recorded in the datasheet. After the manufacturing is completed, the workpiece shall be processed and maintained.

The design of the parting line of plastic mold is also an important part. If the design is not reasonable, the part is not easy to demoulding or even damage the mold. Here are the design principles for the parting line of mold

It is convenient to eject out the plastic part and simplify the structure of the plastic mold. After the demoulding direction is selected, the position of the parting line should make the plastic part fall done without any interference, like sliders, etc.

For the plastic part with high coaxiality accuracy, the parting line should be selected at the position where two diameters can be placed on the lower mold or upper mold at the same time.

When the precision plastic injection molding along the height direction is required to be high, the half overflow cavity should be used. If the transverse flash is formed at the parting line, it is easy to ensure the height precision, while the non-overflow cavity is not easy to ensure.

When the radial dimension accuracy is high, the influence of flash thickness on the accuracy of the plastic part should be considered, as shown in the figure. If the vertical parting of plastic parts is easy to ensure, the horizontal profile is difficult to control due to the thickness of the flash, which affects the accuracy of plastic parts.

Ensure the appearance of the plastic part, it shall be easy to clean the flash and not easy to damage the appearance. The flash produced by the parting surface as shown in the figure shall be easy to clean and not easy to damage the appearance of the plastic part.

It is convenient for the manufacture of plastic mold and the processing of forming parts. The improved parting surface makes the processing concentricity of plastic mold low, easy to manufacture and the flash does not damage the appearance of plastic parts.

Ensure the strength of the formed parts, for example, when determining the parting surface, avoid the thin wall and sharp corner of the formed parts.

In addition to the design elements of general molds, the following points should also be considered in the design of precision injection molds:

  •  Adopt proper mold dimension tolerance;
  •  Prevent forming shrinkage error;
  •  Prevent deformation of injection part;
  •  Prevent the deformation of demoulding;
  •  The manufacturing error of the die/mold is minimized;
  •  Prevent the error of mould precision;
  •  Maintain mold accuracy.

Prevent the error of mold precision; classification of processing molds in plastic mold factory and requirements of various points for attention

There are many kinds of plastic injection molds, which can be roughly divided into ten categories. According to different requirements of a part material, physical and chemical properties, mechanical strength, dimensional accuracy, surface finish, service life, economy, etc, different types of injection mold are selected.

The plastic mould with high precision needs to be processed by a high precision CNC machine, and the material and molding process of the mould have strict requirements. Mould technology is also needed to design and analyze.

Some of the parts have special requirements during molding, so advanced technologies such as hot runner, gas-assisted injection molding, nitrogen cylinder, etc. are needed for plastic mold.

Plastic mold manufacturers shall have CNC machine tools, EDM machine tools, wire cutting machine tools, and CNC profiling milling equipment, high-precision grinder, high-precision three coordinate measuring instruments, computer design, and related software, etc.

In general, large metal stamping dies (such as automobile cover part die) should consider whether the machine tool has a blank holder mechanism, even edge lubricant, multi-position progressive, etc. In addition to the punching tonnage, the punching times, feeding device, machine tool and die protection device should be considered.

The plastic mold manufacturing capacity and process of the above are not possessed and mastered by every enterprise. When choosing a cooperative plastic mold manufacturer, we must know its processing ability, not only look at the hardware equipment, but also combine the management level, manufacturing experience, and technical force.

For the same set of mould, there is sometimes a big gap in the quotation of different mould manufacturers. You should not pay more than the value of the mold, but also should not be less than the cost of the mold. Plastic mold manufacturers, like you, want to make a reasonable profit in business, ordering a set of molds with a much lower price will be the beginning of trouble. You should start with your own requirements and measure them comprehensively.

If you have a plastic parts that needs precision injection molding manufacturing services, you are welcome to contact us, Sincere Tech is customized precision plastic injection molding company in China. We offer precision injection molds and molding services to customers all over the world.