Inox Cast- Your Two Shot Injection Molding Provider

Are you new to two shot injection molding and you might think it is more expensive, time-consuming, or more complex than other plastic molding methods? That may be true but two shot injection molding also offers reasonable savings and functionality. Inox Cast is here to provide the services you deserve.

When on-time delivery and tolerances are important for your urgent demands, then choose Inox Cast for two shot injection molding parts. Inox Cast is a problem-solvers which means more than a normal manufacturer.

Two shot injection molding, also known as double-shot, dual-shot, overmolding, and multi-shot. This is an exceptional plastic molding method in which 2 types of plastic resins are molded at one in a single machining rotation.

This method is best acknowledged in terms of the assorted layers of colors or material that are produced by the injection molding machine. This can be slowed up or speed up depending on how the polymer is transferred to the mold`s other chamber.

Inox Casting is professional in this two shot injection molding since it offers engineers plenty of flexibility because it can create complex geometries and colors. This will produce more aesthetically satisfying parts and components.

For applications, Inox Cast two shot injection molding is one of the ideal plastic molding methods for multi-color, complex, multi-material plastic products. Inox Cast serves many industries such as agriculture, consumer, garden, appliance, automotive, etc.

Our two shot injection molding is eventually a more economical way of creating a product with multiple parts. Some benefits of Inox Cast two cast injection molding are:

• Improved efficiency,
• Part consolidation,
• Complex moldings, and
• Improved quality

Whenever you`re looking for a partner with wide experience in this field, better choose Inox Cast!

Here, you can rest assured you`re receiving the best quality you desired at competitive costs. Allow our services to solve your two shot injection molding needs! Contact now.

Two Shot Injection Molding: The Ultimate Guide

Before you opt for two shot injection molding, read this guide.

It has all information you are looking for about two shot injection molding process.

So, keep reading to learn more:

1.  What Is Two Shot Injection Molding?

This is a molding method that you will use when producing complex molded components using two different materials.

It will combine two materials or colors into a single plastic part.

Furthermore, you will inject the first material to form a substrate and the other materials will be molded around it.

two shot injection molding

Two shot molding is also known as dual-shot or double-shot molding.

2.  What Are The Benefits Of Two Shot Injection Molding?

There are several advantages to using a two shot injection molding process.

These include the following:

Mechanical Bond

Two shot injection molding products have suitable mechanical properties.

When you use suitable materials, the molding process will form molecular bonds at different levels of the product.

Furthermore, this kind of bond is stronger than the standard molding and assembly processes.

It is also stronger than some advanced techniques like over-molding and insert molding.

Ergonomics

A two shot injection molding process can make perfect ergonomically designed final products.

Besides, you can add or cover the plastic with other materials suitable for human use.

For instance, you can use a soft and rubbery material that is suitable for the human hand to use.

This is because it will offer a good grip with a soft touch.

Aesthetics

Two shot injection molding can make products that look good and also retain the structural features as per the design specifications.

In this process, you will mold the load-bearing part first then conduct the final touches using appealing materials in the second phase.

Cost Per Unit

This is one major advantage of two shot injection molding.

Two shot injection molding will enable you to make several complex products with minimal production phases.

Take for example the conventional injection molding technique.

Here, if the product was to have two different materials, you will mold them separately in two separate molds.

Afterward, you will manually assemble the two separate parts into the final product.

Two shot injection molding enables you to make these two parts in a single mold.

Also, the two parts will fuse thus there is no need for you to conduct an assembly process.

Production Time

The other benefit of two shot injection molding is that it will save you a lot during production.

Since you can add several product levels in this technique, you get rid of any secondary assembly processes.

Two shot injection molding allows you to conduct the whole process in one molding process which is impossible in conventional injection molding processes.

Accuracy

Two shot injection molding offers accurate manufacturing even if you compare it to standard molding processes or insert molding.

This is because there is no need to eliminate the unfinished product from the mold during the different molding phases.

Furthermore, this capability ensures that everything aligns properly during the entire molding process.

The final product can attain the accuracy of the mold if you properly manage the thermal effects via suitable product designs.

Efficient Use Of Materials

Two shot injection molding will enable designers to make the best use of several materials.

When you engineer plastics, they may contain suitable but different features.

For this reason, a designer can combine hard plastic with suitable structural features and softer appealing material.

This enables them to attain a suitable final product with desirable qualities.

3.  What Are The Limitations Of Two Shot Injection Molding?

Besides having several advantages, two shot injection molding has some limitations.

However, this should not deter you from using it in your production line.

Some limitations of two shot injection molding include the following:

Compatibility Of Plastics

Here, you will consider the compatibility between the two plastics you are using in the process.

Different plastic materials have different chemical properties.

This means their compatibility affects the bonding strength which will affect the bonding surface.

Note that not all plastics are compatible with one another.

Shrinkage Rate

Ensure the rate of shrinkage between the plastics you are using is very minimal.

When the shrinkage rate is too large, the bonding strength will get affected and this causes the product to warp.

Shape

The shape of the final product you are manufacturing needs not be very complex.

4.  How Does Two Shot Injection Molding And Overmolding Compare?

As you investigate manufacturing techniques for future products, professionals of injection molding find that two shot and overmolding are alike.

In both these processes, you will conduct molding in several steps using several materials.

Furthermore, both techniques have the same advantages like time and cost-saving on secondary assembly processes.

two shot injection molding

Two shot injection molding needs complicated setups which tend to be more expensive.

Also, two shot injection molding contains rotating platens that will hold the semi-finished products.

Besides the mold design is complicated, it still offers a high manufacturing accuracy.

This is because there is no need to remove and handle the product between the phases.

Furthermore, it will eliminate any machine or human error that might occur during the handling processes.

Overmolding will use a simple mold setup.

overmolding

However, overmolding will not offer the same repetition, accuracy, and a stable process as in two shot injection molding.

Also, the unit cost of two shot injection molding is higher than that of overmolding.

Besides, overmolding offers designers the capacity to conduct molding over metal substances such as scissor blades making them suitable for specific applications.

Besides, it depends on specific situations as to which process is suitable for your product.

Two shot injection molding is a costly process but will offer designers more manufacturing accuracy and suitable mechanical bond.

5.  How Does Two Shot Injection Molding Operate?

Two shot injection molding happens using two injection shots and not one with conventional injection molding.

Here, you will use special molds that will house all the requirements you need for the two shots.

Furthermore, the mold together with the supporting units will conduct both shots without the need to remove the unfinished product between the stages.

Two shot injection molding begins as a normal injection molding process with the molds closing and forming a cavity.

Here, the runner connecting to the first cavity aligns with the sprue of the main base substance.

Concurrently, the runner to the second cavity is shut off.

Thereafter, you will inject and fill the first material into the first cavity.

Once you complete the first phase, the mold will open.

The platen that contains the unfinished product will rotate at 180 degrees via a horizontal axis.

After the rotation, it will align with the sprue of the second phase.

In this phase, the first cavity is completely shut off and will take no injection.

Now the sprue of the second substance aligns with the runners of the second cavity.

The second shot happens to fill the mold of the product that is remaining.

Furthermore, during two shot injection molding, you will not remove, shift, or move the mold.

This makes the final product to be accurate and has no imperfections because of elements like irregular cooling.

6.  What Are The Applications Of Two Shot Injection Molding?

Here are some examples of two shot injection applications:

Toys

Two shot injection molding can make suitable plastic toys since you can use several colors and textures to make the products.

Containers

Two shot injection molding can make plastic storage containers.

Also, you can add various colors together with rubber edges that will seal the lids or soften the surface of the containers.

Gardening Tools

Two shot injection molding operates well in gardening tools because plastic has suitable properties in humid or water environments.

Also, you can combine the hard-wearing bases with soft surface seals.

Electronic Units

Two shot injection molding can make plastic electronic components that contain LED within the design.

Also, you can mold translucent inserts within the design to add color or assist in spreading the light of the LEDs.

Toiletries

Two shot injection molding can make various toiletries such as toothbrushes.

Here, you will use a rigid plastic base with a soft rubbery second sot that enhances grip and adds color.

Medical Devices

Here, you can manufacture medical equipment like bone saws using two shot injection molding.

The rubber grips are vital elements for the proper functioning of this tool.

Also, two shot injection molding will enhance the hygiene of these tools.

This is because it forms minimal crevices where the sub-components interface.

7.  What Aspects Should You Consider When Selecting Materials For Two Shot Injection Molding?

Since plastics are different, they have different properties that affect their compatibility.

For this reason, ensure you select materials that are compatible with one another to make durable products.

Also, make sure the covering materials and the CTE [coefficient of thermal expansion] are similar.

Make sure the covering materials and the rate of shrinkage of the base materials are close are possible.

Ensure the HDT of the main base material is higher.

Finally, avoid combining semi-crystalline and amorphous plastic materials.

8.  What Are Some Of The Design Guidelines For Two Shot Injection Molding?

These include:

Internal Bonding Surface

The cover material and base material bond strength relies on the following:

1. Material compatibility
2. Process temperature
3. Molding sequence
4. Bonding surface design of inner bonding surface mechanical structure interlock

Cosmetic Mating Surface

Ensure the cosmetic mating surface offers ample bonding strength otherwise it might lead to flying and rolled edges, burrs, and flaking.

The common designs of cosmetic mating surfaces are fluted and stepped.

Uniform Wall Thickness

Since two shot injection molding is a version of injection molding, ensure you adhere to uniform wall thickness, even transitions, and smooth corners.

Draft Angle

This angle is vital for double-colored injection molding as it influences the mold part attachment during rotation.

The part needs to attach to the moving mold in the first injection and the ejector side in the second injection.

Also, ensure the plane has a large release slope to avoid any scratching when closing the mold.

Weight Difference

Ensure that the weight difference between the cover and base material is not too big as this affects molding cycles, injection pressure, etc.

9.  What Are Some Important Terminologies To Understand In Two Shot Injection Molding?

These include:

• Boss which is a raised cavity that enhances alignment when assembling
• Flash is materials forming on the parting lines or seams of the cavity
• Knockout pins that remove molded parts from the mold
• Runners are channels in the mold through which molten resin flows to cavity gates from machine sprue
• Shrinkage which is how the plastic contracts during cooling
• Sprue are channels where molten resin flows to mold runners from the machine nozzle
• A short shot is the failure to fill the mold with resin thus leading to melted edges or a missing geometry

10.  What Should You Consider Before You Start Using Two Shot Injection Molding?

Before you start mold construction, conduct a flow simulation analysis that will verify the intentions of the design.

Create structural parts in the first shot.

Identify and eliminate possible defects before making molds.

Ensure you consider the shrinkage of materials you are using.

Sub-gates should allow respective runners not to open during certain phases in two shot injection molding.

two shot injection molding

Check the position of logos to prevent damage from happening in the process.

Make sure injection setup parameters can offer suitable pressure, rate of flow, and cooling capacities.

Ensure the first shot has a structural strength that can support pressure during the second shot.

11.  How Important Is Material Compatibility With Two Shot Injection Molding?

It is very important to understand the chemistry of the materials you are to use.

This is because not all materials will perfectly bond as some can form strong molecular bonds than others.

Also, conduct adhesion tests to verify unknown adhesion combinations before conducting the process.

Add undercuts, grooves, or shoulders to lock parts together in situations where bonding capacity is insufficient.

12.  What Materials Should You Use In Two Shot Injection Molding?

The materials you can use include:

• TPE
• TPU
• PP
• PC/ABS

13.  How Can You Lower Costs In Two Shot Injection Molding?

Some tips include:

• Ensure the design is necessary and uses minimal materials
• Avoid using unnecessary features and finishes
• Make intelligent mold designs
• Design to analyze the manufacturability

14.  How Does Two Shot Injection Molding Compare To Multi-Shot Injection Molding?

In two shot injection molding, you will use two materials to make the final product.

Multi-shot injection molding is an injection molding process where you will use two or more substances.

multi shot injection molding

Also, the whole process happens in similar molding machines and with the same molding technique.

The final result is a molded part that has several materials and substrates.

15.  How Does Two Shot Injection Molding Compare To One Shot Injection Molding?

Two shot injection molding entails injecting two raw plastics when making a product.

One shot injection molding will only inject one material when making a complete product.

More Resources:

Precision Injection Molding

Prototype Injection Molding

Over Moulding

For all your two shot injection molding needs, contact us now.