It All Starts With Design: A Detailed Guideline on Insert Molding Design Guide

It All Starts With Design- A Detailed Guideline on Insert Molding Design Guide-

Of the various injection molding techniques, insert molding is one of the most sought after, and all for the good reasons.

As a method, insert molding is very beneficial for various industries since it is a proven technique in the fast and cost-efficient production of parts that are not just functional but with product value.

To make sure that the benefits of insert molding are achieved, parts designers as well as engineers incorporate an insert molding design guide.

In general, insert molding design guides are beneficial since multi-material analysis and combination are done to make sure that only functional parts are produced through insert molding.

In this post, a detailed guideline, including factors to consider, methods involved, and other considerations in insert molding design shall be laid down.

Hence, if you are one of those who are on the lookout for these, read on.

How Insert Molding Capability is Reinforced

Insert molding is a go-to technique for both plastic and metal products. Generally, insert molding has built-in molding threads which specializes and strengthens the functionality of the molded products.

The following processes efficiently reinforce insert molding capabilities:

Machine Preparation:

Note that inject molding requires high-end, automated machinery to ensure the uniformity of the products. As such, all machines involved in the process strictly follow injection molding design guidelines to ensure accuracy in the production.

To this end, machine preparation requires the engineering and design team to prepare the needed machinery by setting the required modes according to product specifications.

Position Molds for Insert Molding:

Position Molds for Insert Molding

The necessity of following injection molding design guidelines is very manifest in the loading molds. Design guidelines incorporate features such as better adhesion and surface threading.

These two design features of molding machines make stronger products and more gripped materials while in the mold.

Positioning molds in the machine usually makes use of automation and robotics. It can also be done manually.

Nevertheless, automated processes are now more considered in insert molding capability for purposes of accuracy, and better capacity to withstand high heat.


Once everything is prepared and in place, the last phase is molding. In this phase, the needed temperature is sustained so that the parts will be solidified uniformly.

The plastic is now molten and shall enter the mold cavities. The molten plastic shall now mold into the inserts. Mold time and solidification depends on the size of the product and the material used.

Factors to Consider Before Finalizing Insert Molding Design

Factors to Consider Before Finalizing Insert Molding Design

As we have argued, it all starts with the insert molding design. The design of the mold determines the price, the complexity of the aesthetics, and the general production capability of manufacturers.

In this respect, you must know the factors to consider before finalizing your insert molding design.

Part Dimension:

When it comes to part dimension, you must majorly consider the size and depth of the molds to be used. Essentially, part dimension shall give you a hint as to the length of time needed for the product to be molded.

It is also beneficial in knowing which materials and equipment to be used and the overall cost of production.



Knowing beforehand the production volume allows you to identify the right production method to be used. If you are working with 1,000 units and below, manual molding may be a more cost-efficient production method.

But if you are working on high volume and complex designs, then an automated production would be better for such production volume.



Note that insert molding products are used in a variety of fields and applications. In this factor, choice of material is key.

There are different material specifications for various molded products. It is best if you have access to a wide range of materials so that you can meet various demands for various applications.

Cost or Budget:

Cost or Budget

Budget, as a factor, zeroes in the entire cost of the production. Thus, you do not only consider materials, but also operations cost, labor costs, and maintenance costs if you are dependent on automation.

You must also know that inserts are subjected to sudden price increases, depending on the type. Hence, before engaging in insert molding, be sure that you have inventoried all things needed for costing.

Surely, there are other significant factors to be considered before finalizing your insert molding design. Nonetheless, the above mentioned are the most upfront and indispensable when it comes to strategizing for your insert molding design.

Design Must-Knows for Insert Molding

Design Must-Knows for Insert Molding

Now that we have covered the basics in insert molding design, it is time to break down some of the most important design guidelines for insert molding. The following tips shall significantly upend your insert molding design if done right.

Veer Away From the Sharp Corners:

Sharp corners are a big hassle in insert molding design. Aside from it adds to the cost of production due to the need for machine work, the complexity of the mold to be used also makes it expensive.

Most importantly, it is a make or break in the molding process. If not molded right, the sharp corners bring about warping or shrinking to the product itself.

Observe Draft Angle Height:

Observe Draft Angle Height

Draft angles are essential because they allow the faster removal of the mold components should visible shrinking occur during the molding.

However, according to Rapid Direct, when the draft angle is too high, drag marks may become imprinted, hence, lessening the aesthetic value of the product.

To avoid drag marks and to make use of the function of the draft angle, make sure that it is lower. You may optimize and adjust draft angles with the use of CAD.

Design Inserts:

The insert molding design guide, as per Fast Radius, decrees that insert molding designers must produce molds that are smaller in size relative to the plastics that shall be embedded in them.

Rapid Direct provides the rule of thumb as to the depth of the inserts for you to get the right measurement as to produce an accurate product without sink marks.

Suitable Boss Diameter:

A boss is a common feature among parts which need to be assembled after molding. An example of a product with a boss is receptacles. The suitable diameter for molds is at least one and a half bigger than the insert’s diameter.

Consider Durable Resins:

Consider Durable Resins

Always consider the resins to cover the mold. One of the common defects in molded parts is the cracking around the metal inserts due to the damaged plastic resins.

This happens after solidification and the resins are already removed to get the final product. As is the case, use durable resins for this purpose.

Metal Bonding is a Gamble:

While metal bonding is perfect in reinforcing the layers in between the materials, it is not always applicable to different materials.

Note that not all metals chemically bond with plastics or even other metals. As such, you must understand which materials have the chemical bond for reinforcing. Otherwise, it is a gamble.

Mold’s Wall Thickness:

Mold’s Wall Thickness

According to Protolabs, the wall thickness of molds dramatically affect the production costs, aesthetics, and functionality of the product.

For example, too thin walls shall need constant pressure, or else, too much air will be trapped in the plastic material.On the contrary, too thick walls shall require more pressing and cycle time, hence, more expensive.

What Materials Are Used for Insert Molding?


Remember that insert molding is a go-to production method because it is compatible with various materials.

If you are wondering about the types of plastics and other materials which you can use for insert molding, this section lays them down for your reference.


The most common thermoplastics used for insert molding are nylon, polyethylene, and polystyrene. The upside of using these materials in insert molding is that they are eco-friendly since they can be recycled and used many times.

They also have a commendable chemical resistance which is beneficial in creating variance in the molding process itself.


Another common plastic material used in insert molding are elastomers. Of elastomers, the most popular are polyurethane and natural rubber. Elastomers are popular among engineers and chemists because of their elasticity.

Aside from this, elastomers are also known for their recyclability. Because of these two characteristics, elastomers are used in insert molding to produce products for the automotive industry. Examples of which are cables, caps, and gears.


Thermosets like epoxy and phenolic are like thermoplastics. The only downside is that thermosets cannot be reused.

Although a common material for insert molding, they are not considered much these days by engineers and producers because they are not that eco-friendly. Most of all, they are expensive.

Of course, there are other plastic materials out there used in insert molding. However, insofar as insert molding is concerned, these three ranges of materials are the most used for the method.

Threaded Inserts: Why Choose the Most Suitable Ones?

Threaded Inserts- Why Choose the Most Suitable Ones

The reason why insert molding can create even the most complex mold designs is because of threaded inserts. This is so because inserts of insert molding come with threaded fasteners.

Due to the reinforcement given by threaded fasteners in terms of adhesion, complex products can be manufactured.

Some of the products which benefit from threaded inserts are terminal boards, electronics parts, aerospace and communication products, and automotive parts, to name a few.

As a benefit, threaded inserts enhance the mechanical attributes of metals and plastic components. It also contributes to faster lead time, and greater precision.

However, you must choose the most suitable threaded inserts. Your choice is imperative in making sure that your inserts can be durable even in heavy materials load.

Getting Thorough With the Test Program

By test program we mean rigorous end-use testing and validating. This is very important in insert molding because all the rough patches become visible. This gives you enough time to rectify what can be rectified, assess the functionality of the product, or redo it if need be.

In making a valid test program, you must set checklists or parameters. For instance, did you use the right temperature range? Was the solidification uniform? Was the cycle time too fast or too slow?

Why Switch to Insert Molding?

Why Switch to Insert Molding

There are a lot of reasons as to why you should switch to insert molding if you are a producer. If you are wondering about the most significant benefits you can get from this production technique, the following are the reasons as to why you should highly consider insert molding.

Flexible and Reliable Designs:

Whatever your design preference or configuration, you can depend on insert molding to deliver. For example, you can infuse a multi-material approach to your molds so that you can produce more reinforced products.

Most importantly, the presence of threaded surfaces prevents misalignment, shrinks, and warping.

Cost-Efficient Assembly:

Note that insert molding is a single shot, single cycle method. Aside from this, insert molding no longer requires post-assembly and parts installation.

All things considered, you get lesser production wastes, faster cycle times, and other manufacturing costs through insert molding.



As have been mentioned, insert molding no longer needs consumables and fasteners as it already has threaded surface. From this alone, production wastes are dramatically lessened.

Aside from this, the materials used in insert molding are reusable.All of these and more make insert molding a more eco-friendly production technique.

Size and Weight Reduction:

Since there is lesser wastes and consumables included in insert molding, the parts to be molded come lightweight and in smaller sizes.

Without fasteners, cables, and adhesives, the final product has reduced size and weight. As such, insert molding products find their applicability in automotive, medical field, and aeronautics, among others.

Create Strong Insert Molded Prototyping and Parts

Create Strong Insert Molded Prototyping and Parts

With everything that we have covered here so far, you should now get the idea as to how you should consider insert molding for production. It might look complex at first, but the insert molding process can be upfront when you get familiar with it.

Just know that everything starts with a good and functional mold design. Using the insert molding design guide, you can create strong insert molded prototyping and parts.

But if you would opt for more convenience, know that there are reliable manufacturers who will do the work for you. Get some of the most extensive insert molding applications with reputable manufacturers like Kemal Manufacturing.

Kemal: The Best Choice for Quality Plastic Injection Molding Services

Kemal- The Best Choice for Quality Plastic Injection Molding Services

If you are looking for the best choice for quality plastic injection molding, you can check out Kemal Manufacturing. Kemal offers a wide range of injection molding services, design and consultation, and other production services for your needs.

Kemal has an expert pool of designers and engineers who are equipped with the knowledge of known and trusted insert molding design guides for quality plastic injection molding services. Check the services of Kemal in their main website.


As have been covered here, it all starts with the design. A good mold design sets everything into motion. The mold design determines the type of material to be used, the machine and tools needed for production, the size, depth, of the product to be manufactured and the overall manufacturing costs.

As is the case, you should be wary of the insert molding design guide in insert molding. Parameters as to design, material, application, insert molding capability and other factors to zero in before the insert molding process should be taken into consideration.

The reason for this is for you to reap the benefits of insert molding in your production.

With all things considered, insert molding remains to be a sought-after production method because of its reliability, flexibility, cost-efficiency, and positive environmental impact, among others.

So, what are you waiting for? Explore insert molding and discover reputable insert molding manufacturers like Kemal.


Put your parts into production today

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