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.

 

What is Two-shot Molding

Two-shot injection molding is a multi-material injection molding process. The molded plastic part can be a combination of two different materials or a combination of different colors of the same material.

Two-shot molding can also be called 2k injection molding, double shot molding, multiple injection molding (sequential injection molding).

When two-shot molding be used?

ㆍProduct function requirements

For example, power switches, phone buttons, keyboard indicators, car switches, etc. Portion with an LED capable of transmitting light.

ㆍImprove the handle feeling

Some handheld products require the use of rubber in hand-held parts, which makes the hand feel more comfortable. For example, walkie-talkie housing, power tool handle, wrench, screwdriver handle, toothbrush handle, thermos, etc.

ㆍEnhance beauty

For example, some plastic parts have a logo. If you use two-shot injection molding, you don’t have to worry about it being erased.

ㆍA localized area of the product that needs to be plated

In the plastic range, only ABS and PSUsurfaces can be plated. If it is necessary to plate a part or a single side of the product, the plating area should be injected into the ABS. Areas that do not require plating are injected with other materials such as PC.

7 Suggestions for Product Design

 

Two-shot molding frees the designer’s creativity. However, the following factors should also be noted in the product design process.

No.1

Choose the right material. The figure below shows the compatibility of different plastics.

1 ) The core material can use low viscosity materials to reduce the injection pressure.

2) Consider from the perspective of environmental protection. The recycled material can be used as a core material.

3) Optimize the product according to the characteristics of different materials. For thick parts, the finished skin layer uses soft materials. The core material uses hard or foamed plastic to reduce weight.

No.2

If the material is not chemically compatible, the two materials can be integrated by mechanical interlocking.

No.3

Maintain proper draft angle, uniform wall thickness and smooth transition lines.

No.4

The surface of the part should be flush or slightly lower than any adjacent substrate surface.

No.5

The surface of the substrate is textured to improve the adhesion of the two materials.

No.6

The mass ratio of the two materials should not be too large. Factors such as material forming time and injection pressure should be considered.

No.7

By increasing the contact area of the two parts, the weld strength of the two materials can be enhanced.

>> Check our two shot injection molds here

9 Suggestions for Two-shot Molding

 

No.1

The hard plastic is molded for the first time, and the soft plastic is molded for the second time. Transparent for the first time, non-transparent for the second time. The plastic with high molding temperature is molded for the first time, and the plastic with low molding temperature is used for the second molding.

No.2

Before the official production, test the mold to produce a complete product.

No.3

Identify all possible defects in the process and eliminate them before the mold is manufactured.

No.4

Consider the shrinkage of the two materials.In general, shrinkage is determined by the material that is first formed.

No.5

A second injection can only be made after the first injection has been completely completed.

No.6

Consider the molded position, to prevent damage in the process.

No.7

Allow the edge of the first injection molded part to be too large. This ensures a higher pressure during the second injection.

No.8

Ensure that the parameters of the injection unit provide the required pressure, flow rate and cooling capacity.

No.9

Ensure that the structural strength of the first molded part can withstand the injection pressure of the second molding.

6 Suggestions for Maintenance of Two-shot Mold

No.1

Check for loose or damaged fastening parts of the double shot mold. The solution is to find parts of the same specification for replacement.

No.2

After the mold has been used for a long time, the cutting edge must be cleaned and ground. After grinding, the surface of the cutting edge must be demagnetized, otherwise it will easily block the material.

No.3

Elastic parts such as springs of the two-shot mold are most susceptible to damage during use. Breakage and deformation usually occur.

No.4

The method adopted is to replace, and the specifications and model of the spring must be paid attention to during the replacement process.

No.5

Two-shotmold punch during use prone to breakage or bending. Damage to the punch and the sleeve is generally replaced with parts of the same specification. The parameters of the punch mainly include the working part size, the mounting part size, and the length size.

No.6

Check the pressure plate, top plate and other parts of the double shot mold. During maintenance, check the accessories of each part and whether there is any damage, and repair the damaged parts. Pneumatic ejector check for air leaks, and specific measures taken.

Conclusion

Two-shot molding increases the added value and productivity of the product. At the same time, plastics are becoming more and more colorful.

Correspondingly, the cost of two-shot molding is higher. Master the design points and avoid risks in advance. Avoid cost waste.

If you have any questions about two-shot injection molds, please contact us directly. Get a free quote.

At WIT MOLD, we streamline the entire process of plastic injection molding, from mold design to the final production of molded parts. Our advanced online quotation system and mold base sharing technology make it easier and faster to get instant quotes and begin manufacturing customized injection molds. We are dedicated to delivering high-quality and cost-effective solutions for your plastic molding needs.

Instant Quotes for Your Plastic Molding Projects

One of the key advantages we offer at WIT MOLD is our instant online quotation system. By simply uploading your 3D CAD files, you can quickly receive a detailed quote for both mold production and part manufacturing. This eliminates lengthy back-and-forth discussions and accelerates the entire process, ensuring you get your project moving without delays. Once the quote is accepted and the order is confirmed, we begin the mold and part production process right away.

Comprehensive Tool Design Review

Before we start building your mold, our team of experienced engineers conducts a thorough tool design review to ensure everything is perfect. At this stage, we collaborate with you to fine-tune any design elements to meet your exact specifications. This careful review not only optimizes the mold design but also ensures the highest quality standards for the final product.

Precision Mold Manufacturing

Once the tool design is approved, mold production begins. Our highly skilled engineers and cutting-edge manufacturing equipment allow us to build molds that are both precise and durable, capable of producing high-quality parts consistently. The production process is closely monitored to ensure that every mold meets our stringent quality standards. This guarantees that the molds we create deliver the precision needed for complex plastic injection projects.

Sample Approval and Final Production

After the mold is completed, we provide sample parts for your approval. This gives you the opportunity to review the initial results and confirm that the molded parts meet your expectations. Once the samples are approved, we proceed to full-scale production, ensuring every part is produced to the highest standards of quality.

High-Quality Custom Plastic Molds and Parts

At WIT MOLD, our commitment to excellence drives us to continuously invest in the best talent and technology available in the plastic molding industry. Our team of experts, combined with state-of-the-art machines, ensures that each order—whether for small or large production runs—is handled with the utmost care and precision. We focus on providing customized plastic molds and molded parts that not only meet but exceed your expectations.

Reliable, Cost-Effective Plastic Molding Solutions

Our goal is to provide you with cost-effective, customized plastic molding solutions that meet your specific needs. We achieve this by combining our expertise with advanced manufacturing techniques, allowing us to reduce production time and costs without sacrificing quality. Whether you need molds for prototypes or high-volume production, WIT MOLD has the capabilities to deliver on time and within budget.

Contact Us for Customized Plastic Molding Services

WIT MOLD is a trusted supplier of plastic injection molds and parts, known for delivering exceptional quality and service. Whether you’re looking for a reliable plastic injection molding manufacturer or need expert assistance with mold design, we’re here to help. Contact us today to learn more about how we can provide you with high-quality, customized molding solutions tailored to your needs.

 

There are various sub-processes within injection molding that add further capabilities to this already versatile technology. This article will explore insert molding vs overmolding and the advantages of each.

Injection molding is a broad term used to describe one of the most important processes in the manufacturing industry. It’s a process that requires a mold, typically made of metal with a cavity in the shape of the desired part. Molten plastic is injected into the mold and ejected. The process repeats to produce thousands of identical parts. It’s safe to assume that every large-volume plastic part on the market has come from an injection molding machine because the benefits of using injection molding for production are numerous. These benefits include low cost per part, short cycle times, extensive materials, and compatible, in-tolerance parts.

Various sub-processes add further capabilities to this already versatile technology. This article will specifically explore insert molding vs. overmolding and the advantages of each.

What is Insert Molding?

Insert molding is a subset of injection molding techniques similar to overmolding where metal components are placed into a mold cavity before the actual plastic injection. The insert is precisely positioned inside the mold either manually or by a robotic arm. The mold then closes, and plastic is molded over the insert, creating a single part.

One of the most common applications for insert molding is the creation of metal attachment features for fasteners. Fasteners enable assemblies to be securely assembled and disassembled without product damage. Heat-set threaded inserts are molded into plastic to reduce the risks of thread damage during installation.

Insert molding can also eliminate the need for fasteners by including the necessary metal parts in the mold, thus firmly securing the parts into a single bonded component.

Why Choose Insert Molding?

Insert molding is a versatile process that has numerous benefits, some of which are listed below.

Reduced Assembly Cost – An injection molding machine can create thousands of parts per day. Such economies of scale can significantly reduce the cost of the individual parts. In a typical CNC machining, sheet metal, or additive manufactured part, any required assembly can be a major bottleneck. Insert molding can be used to eliminate assembly and thus maximize cost savings.

Part Performance – In general, plastic parts are less robust than their metal counterparts. However, plastic offers other benefits such as reduced cost, superior design flexibility, and lighter weight. Combining both metal and plastic materials into one part can capitalize on the benefits of both. Metal inserts can be used where strength and stiffness are required and the remainder of the part can be made of plastic to reduce weight. Moreover, plastic parts do not fare well against wear and tear and metal inserts add an element of durability to parts to withstand any kind of cyclical loading.

What are the Disadvantages of Insert Molding?

Despite the many benefits of insert molding, a few disadvantages need to be considered before choosing to use this sub-process.

Multiple Manufacturing Technologies – Insert molding can involve a 2-step manufacturing process. If the inserts are a custom design and not off-the-shelf parts, they will need to be manufactured using a metal forming process like CNC machining. These metal forming techniques are often significantly more expensive per part than similar, fully injection-molded processes. In some cases, the metal parts can be manufactured via die casting or MIM (metal injection molding). This can reduce the overall cost of the metal inserts but cannot eliminate the insert molded unit’s increased cost because parts with metal inserts will typically cost more than a part that is only plastic.

Increased Part Complexity – If a custom-made metal insert is required, the designer must be aware of both technologies’ design for manufacturability (DFM) principles and understand how best to integrate these technologies into a single practical part.

What is Overmolding?

Overmolding is essentially a type of insert molding. However, overmolding vs. insert molding is, as the name suggests, plastic is molded over another molded part. The first component is made inside an injection mold, and it is then placed into a second mold to add the over-molded material. This technique combines multiple plastics for either practical or aesthetic purposes. For example, one might use different durometer plastics to mold a softer plastic over a more rigid one to make a part easier to grip. Using multiple colored plastics in an over molded part can also distinguish the product from other brands. Overmolding is regularly used on the handles of tools like screwdrivers, power drills, or toothbrushes.

Why Choose Overmolding?

Overmolding is a versatile process that has numerous benefits:

Increased Material Flexibility – Overmolding allows designers to leverage the benefits of multiple types of materials to create complex parts with different properties, add visual complexity, or add haptics.

No Adhesives Required – Overmolding allows different materials to be fused in the mold, thus eliminating the need for glues or other permanent bonding methods. This increases the part’s overall durability and reduces assembly costs.

Embedded Seals – Overmolding offers the option of molding soft seals into parts. An example would be an electronics enclosure that needs to be IP rated. Usually, the part will have a groove into which an o-ring can be installed later. However, it is far more cost-efficient and robust to permanently mold the seal as an integral component.

What are the Disadvantages of Overmolding

Despite the many benefits of overmolding, a few disadvantages need to be considered before deciding to use this process.

Multi-Step Process – Overmolded parts are made in a two-step process. This increases part cycle time and is thus more expensive than molding a single part with no overmolding. This also requires two tools or a complex two-shot mold with increased upfront costs. However, when the alternative is to create two separate injection-molded parts and then assemble them after the fact, overmolding becomes a value-added solution.

Debonding – Bonding two different materials together in an injection mold runs the risk of delamination. This typically happens if the temperatures are not in the optimal range for the specific material combination. In some cases, mechanical interlocks may be required when materials cannot be reliably bonded together using heat.

Conclusion: Choosing Between Insert Molding, Overmolding, or Injection Molding

Injection molding, which includes the sub-processes of insert molding and overmolding, is a versatile and low-cost manufacturing production process that is used in the large majority of consumer products. Injection molding often results in the lowest cost per part when compared to other manufacturing techniques like CNC machining and even 3D printing.

Once injection molding is chosen for a specific application, the next step is often whether to use insert molding, overmolding, or just stick with plain injection molding. When trying to weigh the advantages of the processes, it is important to accurately define the product application. Each of these processes has specific use cases that are suited to different product types. It can be difficult to gauge which process will best suit your particular product, so it’s good to get expert advice early on. Contact WIT and We will help steer your design decisions in the right direction so that you can choose between insert molding vs. overmolding or just injection molding.

Gas assisted injection molding is a process for producing big plastic to get rid of complicated designs as well as excellent ornamental surface area coatings. Continue reading to get more information about the advantages of gas assist molds.

Smooth surfaces

 

Gas assist injection molding likewise produces much smoother surface areas to attain the preferred style. After the plastic product has currently been expelled from the machine, it can already be fit for market distribution with really couple of alterations or secondary procedures needed.

With a smoother surface, producers do not need to make changes to the device– i.e. lowering stress, temperature level, and even the place of the gates. This is since gas assisting can already fix many of the problems that may result on the surface of the plastic. Smoother surface areas use a more aesthetically appealing as well as smooth design.

High functionality

 

In the regular injection molding process, there is no gas channel to transmit a low-pressure nitrogen liquid. This suggests that the process may take a lot longer time because there is no element that is quickening the flow of the material into the mold. As a result of the absence of this part, the material can be prone to bending as well as higher inner stress.

With gas-assist, nevertheless, internal stresses are substantially minimized in the resin, leading to a much faster and freer-flowing product. Integrated with properly maintained mold and mildew dental caries, any kind of product resulting from gas-assisted injection molding will conveniently be better compared to the alternative.

Fewer products needed

 

Depending upon the kind of material utilized, injection molding pellets can cost as much as $5 USD per kg. This, along with the expense of purchase and maintaining the elements of the injection molding device are currently costly alone.

Knowing this, makers take advantage of gas assist when they desire a reduced volume of material to be used. This produces cost-beneficial end results for both the maker as well as the end-user.

Using less product can help them save added resin pellets for future usage without giving up the top quality. When a consumer desires a model to be done, on the other hand, they could almost request the much more cost-friendly and also economical gas assist process.

Minimizes fabrication defects

 

There are lots of common sorts of injection molding flaws– from something as minor as circulation lines as well as staining to something as complex as distortion and warping.

To avoid these issues from occurring, injection molding tools operators need to embark on a series of modifications on the device. For instance, they might intend to create another mold and mildew layout, increase/reduce stress and also temperature level, and even utilize various resins entirely.

Gas assist offers a reliable as well as all-around service to these flaws. As claimed before, the low-pressure nitrogen gas is constantly and also uniformly sent to the molten material. It permits the product to be firmly pressed as well as portable itself onto the walls of the mold tooth cavity. The outcome– a high-quality product that’s devoid of stress and takes the intended design and shape of the producer.

 

 

Lighter

 

Plastic has actually been a preferred material for several sectors as a result of its lightweight residential or commercial properties. With the right tools and also maker handy, it’s feasible to come up with acrylic, HDPE, polyethylene, and even polytetrafluoroethylene injection-molded items that are less thick than the typical material yet can still be used in functional applications.

Like the materials over, materials that have undergone gas assist injection molding are far lighter in weight in contrast with the typical injection molding procedure. The main consideration for this is that the procedure uses up much less area and material, leading to a sturdier and also extra long-lasting product that is not also cumbersome.

Critical takeaway

 

Several benefits of gas assist injection molding consist of the following: much better dimensional quality, enhanced efficiency, much less product, lighter product weight, smooth surface areas, and much less warping.

For both manufacturers as well as end-users, the gas assist injection molding strategy uses a number of advantages. Before deciding on whether or not the gas assist procedure is the right one for you, establish your item needs as well as factors to consider such as production as well as procurement expense, parts needed, high quality of the material, and so forth.

Improved sizing quality

 

The procedure of setting up multiple or particular gas channels in a single plastic injection molding equipment is absolutely nothing brand-new. As a matter of fact, gas assist is widely made use of in producing specialty items– specifically those that have special dimension styles and patterns.

Ribbed plastic items, as they’re called, are the result of a finely-tuned gas assist injection molding strategy. This process is one of the most efficient selections for generating these stylized products as a result of the boosted dimensional precision as well as quality that it provides. You’ll frequently locate everyday materials like container caps, water drums, containers, as well as much more.

 

We are a gas assist mold supplier, please feel free to contact us if you need them.