Injection Mold Design – A Comprehensive Guide

Injection mold tooling can only be carried out properly if the injection mold is designed as per product requirements. Any compromise on the design of the injection mold can lead to a great loss to your injection molding business in China. If you are not an experienced mould designer then you can hold on to this article. GO4 Mould will look at the requirements and guidelines for a good injection mould design below.

What is Injection Molding?

Injection Molding

Injection Molding

Understanding the process of injection molding is necessary along with the injection mold design. Injection molding die is the new technique in the market that is used to turn plastic into useful products by melting it. 

Usually, injection molding die is performed in the following steps.

Melting: The very first step is to melt the plastic material you choose to do injection molding with. It is a delicate process because maintaining the temperature is difficult. Be certain of the point where the plastic melts because you don’t have to over-boil it. 

Casting: Casting means injecting the heated plastic into the injection mold. The injection cycle timer starts at this point when mold is closed after pouring mold material.

Cooling: After the injection, the mold is set to cool for as long as it is possible because cooling enhances the finishing quality of the mold.

Ejecting:  At this part, the molded product is ready and gets ejected from the mold. Mold gates and screws are used to open and close the molds. 

Packaging: Runners are also used in the manufacturing of mold product. If a little amount of runner is left in the mold, it is removed and used for recycling. The ejected mold product is collected and packed after it is manufactured. 

Moving on to the next section which is about the injection mold design. 

What is Injection Mold Design?

Injection Mould design

Injection Mould Design

Every machine or product needs a proper draft for its manufacturing. It is highly crucial in executing the product formation and we call it a design. Like all other products, injection molds also require a fine design so that the injection molding takes place with ease. 

Injection mold design is related to the field of engineering and companies hire expert engineers to make their mould designs. These designs are analysed and tested to ensure their accuracy and precision. Go4 Mould also trains its mould designers to make the best quality and authentic injection mold designs.

For making a mould design, you’ll need to know the basics and important considerations which are discussed further. 

Basics for Making Plastic Injection Moulds

The Basics for making plastic moulds are as under.

  • Be precise with the temperature and pressure 
  • Choose the right material 
  • Use CNC machines and other digital technology to make moulds 
  • Keep the environment clean 
  • Concisely make the design of the mould 
  • Stick to your budget 
  • Select the valuable manufacturer 
  • Uses imported technology 
  • Sterilize the mould tools 

Important Parameters for Injection Mold Design

Making a reliable and high-strength moulding tool can take a long time and demands a high level of precision. The quality of an injection mould determines its success and precision. Molds are also one of the most expensive capital investments in a project, thus it’s is important that the mould tooling is manufactured with utmost care. It is especially recommended in high-volume injection moulding applications, where moulds can be quite complicated.

You should make moulds based on the following parameters. 

  • Excellent engineering and design
  • You should manufacture them with cutting-edge machinery that allows for precision machining.
  • The mould manufacturing machines must be sterilized and of high quality and high technology
  • They should have high-tolerance and environmental resistance 
  • Mold bases and cavities should be made of high-quality stainless steel for maximum performance and durability
  • They must be tested before delivering to the client 
  • There must be a thick and corrosion-resistant layer above the mould cavity.
  • Due to the complex cavity designs, the total cost of cutting and manufacturing increases for the high-production orders. So, to keep up with the quality, the cutting and processing should be outclassed.
  • To avoid risks in the massive orders of plastic injection moulding, use pre-hardened steel moulds. They’ll enhance the production quality of the product.

You’ll find the injection moulds fulfilling the above-mentioned mould parameters at Go4 Mould. 

Materials Used to Make Injection Moulds

Selecting the right material for making injection moulds is very necessary. The materials used in plastic injection moulds are typically medium and alloys of steel and carbon. Designing the cavities of an injection mould is easier than manufacturing them. They are complex and are significant for the dimensional accuracy and surface roughness of the mould.  These seemingly little requirements enhance the quality of 

  • Mould steel
  • Mirror polishing performance
  • Heat treatment deformation
  • And dimensional stability with other things.

Following materials are used at a larger scale to design injection molds.

Aluminum: When it comes to the manufacturing of a high-quality mould, aluminum is the best choice. Combination of aluminum with a well-equipped CNC machine, you would not only get a good mould but it would have a high tolerance, mirror finishing, and other sets of impeccable properties. 

Injection mold designers should also make their mould drafts based on easy removal of the mould part. This technique saves time and the monthly yield of the mould parts increases by 20 sets.

Stainless Steel: It is also a great material to make injection moulds for your plastic products. Its corrosion-free and high tolerance against temperature and pressure add to the durability of the molds. Resultantly, you get a very smooth and fine-looking plastic product out of injection mold. 

Hardened/Pre-hardened steel: The majority of the injection moulds are designed with hardened or pre-hardened steel. Hardened steel has a better resistance against environmental conditions and lasts longer than pre-hardened steel. Steel moulds are more expensive than aluminum moulds. Yet, steel moulds can handle massive productions.

Advantages of a Good Injection Mould Design

No matter how perfect are the machines and tools to make the injection mould, if your designs lack accuracy and precision, that mould is of no use. A good plastic mould design costs you a one-time investment and you can pursue it for years. Your flawless mould design offers you the following advantages.

  • It avoids the risk of malfunctioning of the mold 
  • A good injection mold design excels production and efficacy of the mould
  • It reduces labor cost
  • You can tackle with both low and high mould part orders
  • The complex parts can be easily manufactured with a good injection mold design
  • It leaves little room for scrap or wastage of the part material
  • You don’t need to work on the mould parts after they are injected molded with a good design mould. This is because it provides good surface finishing

You see by going concisely with a single step, you can have advantages greater than your investment. 

Effect of Mold Shape and Design on the Final Product

Impact of Mould design

Impact of Mould Design

The shape and the design of the injection mould affect the final products in both positive and negative ways. We’ll discuss both sides below. 

  • Positive impacts 

The list of positive effects on the mould is long. 

Tolerance: First of all, a good mold shape and design will deal with the shrinkage of the resin material. Some plastic resins are prone to shrink or relax during injection molding. If the injection mold design is good, it’ll accommodate the changes.

Fewer Defects: Secondly, a good injecton mould design and shape reduce the possible number of defects. If the complexity of the mould cavity is perfectly maintained through a good design, the final product will be the exact replicate of the design you want to have. 

No Material Limitation: There are no limitations to the mould part material if the design and shape of the injection mould are up to the mark. You can use any kind of plastic material and resins you want. There’ll be no risk and fear of breakage or false outcomes. 

  • Negative Impacts

The faulty shape and design of your mould increases the odd of 

  • Reduced production 
  • Rough surface 
  • Increased cost 
  • Defects in the injection molding operation 
  • The downfall of your business 
  • Disappointed client

Considerations for Injection Mold Designing

Injection Mold design requirements

Injection Mold Design Requirements

When designing and producing a plastic moulding tool, it is important to think about the design of the part. It is recommended to check through certain points that may contribute in process of the injection mold design.

Mold draft:

Creating a mold draft is the first and foremost process of injection mold design. It is important to stimulate your mind with certain ideas which can prove valuable later in the injection mold design. Start by making a rough draft and take it towards perfection by observing minute troublesome details. 


Just like the buildings need pillars to support and increase their strength, similarly, the injection molds need ribs to enhance their efficiency. Note that the rib design must not be greater than the wall thickness of the mold otherwise it may create designing issues. The key to smartness is to look for convenient locations to lace the mold ribs.

Wall thickness: 

Choose the wall thickness according to the mold part material. The wall thickness is specific to the specific mold materials. For instance, the wall thickness for polycarbonates ranges from 0.040 to 0.150. Similarly, it differs for different plastic and metals alloys.

Location of the Gates:

gates are the very openers of the injection moulds. Keep the design of the gates greater than the mouth of the mould so that the part material flows in easily. Screws are attached with the gates for the opening and closing of the mould. 


It is the area where we take off the mould part. In automatic mould injection moulding, the mould part is collected in the bin while in a manual process, we take off the moulds with the help of vacuum pumps and other similar tools. 


Undercuts guard the mold material to slide away from the molds.  But avid too much undercut as they’ll only increase the cost.


Cavities or cores are the unmatched features of the injection moulds. Cavities reduce the material waste and keep the material intact. 

Mold material: 

While designing, opt for the most suitable mould material possible. Make sure that it doesn’t affect the quality of the mold material because materials of low quality can intermix with the mold part and resultantly create chemical reactions.

Parting lines:

Defining the parting lines is so crucial because they determine not only the areas to be covered by the mold part but also the angles and other technical information. 


A proper radius adds to the degree of a good mould design. Maintain a proper radius between the edges and the centre. Also, avoid making sharp edges of the mould as it hinders the mold ejection. 

Choosing the Right Partner for your Injection Molding Business

The second important thing after designing the injection mould is choosing the right partner. Although we have provided you with a checklist for the designing of injection moulds it doesn’t mean that any layperson can design them. You need authentic and reputed manufacturers and designers to go along with your project. 

We find Go4 Mould as your most trusted and reliable business partner for the services it provides. 

Cost of Injection Mold Design

The cost of the mould designs depends upon the companies you give your project to. If the company uses highly skilled and knowledgeable designers then the costs will be high. Local designers, on the other hand, may offer you a considerate price.


Whether you are designing a new injection mould or changing an existing one, design is always an important part of the process. If you don’t stimulate the design of your injection mould before you hit the drafts, you are more likely to increase the price and time of production.

We have explained every possible thing regarding injection mold design and hope that you’ll be able to implement the knowledge in your business. If you are to start a new business of injection molding then do consider Go4 Mould for the designing services. We have a huge network of injection mold design supplies and a lot of on-field experience. You’ll get remarkable products and services while collaborating with Go4 Mould.

Scroll to Top