Why You Need Design for Manufacturing in Injection Molding Design

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Why You Need Design for Manufacturing in Injection Molding Design

In every manufacturing process, it is essential to ensure that every stage is foolproof and executed appropriately. From material selection all the way to the actual manufacturing, it is essential to find a balance between cost and quality. In the injection molding process, the injection molding design for manufacturing/manufacturability (also known as DfM) is the process which ensures all the above is adhered to.

Injection molding design for manufacturing basically has to do with the improvement and enhancement of your part design. It ensures that your part is economically fit for production, easy to produce, and fulfills its functional duties. However, DfM doesn’t only deal with the injection molding design. It also covers selecting the suitable materials, the injection molding mold design, evaluating product lead time, quality, hazard associated with use, and so on.

This article will explain the importance and benefits of using design for manufacturing and factors to consider during plastic part design for manufacturing. You’ll also find an easy and reliable way to evaluate injection molding design for manufacturing on this page.

Importance of DfM in Injection Molding

As a client, you definitely want to minimize the cost of production as much as possible. Hence, you might see the injection molding design for manufacturing process as an unnecessary step. However, this would only lead to subsequent problems and possibly higher maintenance and repair costs than needed.

Here are a few other reasons why the plastic part DfM process is essential in any injection molding production:

1. Guarantee of Manufacturing Feasibility

At the beginning of every plastic design and manufacturing process, the probability of the designed part being suitable for manufacturing is relatively unknown. Without the design for manufacturing check, many manufacturing processes will have to reach the actual production stage before determining if the production is possible or not.

However, with the injection molding design for manufacturing process, it is possible to determine the feasibility of the manufacturing process right from the start. Manufacturers will be able to ascertain if they encounter manufacturing difficulties such as parts stuck in molds or collapsing 3D prints. This will help save time and capital, making the product affordable and the time scale of production shorter.

2. Prevention of Part Failure

The worst thing that could happen during a plastic design and manufacturing process is for the finished part to fail to execute its intended functions. This could be due to physical defects on the part or some other mechanical dysfunction.

an example of a part defect injection molding dfm could prevent
An example of an injection molded defect

These defects could lead to the client having to incur double the costs of producing the part. As a result, there will be an increase in production costs The production process might even become unprofitable for the client.

3. Determination of the Complexities of Manufacturing

After making the injection molding design for a part, the various intricacies that the machinists will have to use for easy manufacturing are quite unknown. However, after evaluating the injection molding design for manufacturing, the engineers can determine various complexities such as the use of undercuts and draft angles. This ensures fewer uncertainties are heading into the production stage.

Also, the injection molding mold design will benefit from this factor. Understanding the complexities involved right from the injection mold design stage gives more clarity to the structure and shape of the mold. Also, this will help in the production of prototypes.

Apart from these options, some other issues plastic parts design for manufacturing can help prevent include:

  • Using costly parts for simple designs.
  • Simplifying a quite complex part or injection mold design, etc.

As important as the injection molding design for the manufacturing process is, some manufacturers tend to leave it out when manufacturing a product. In most cases, it might be due to the lack of personnel or the necessary software required for this process. This is common among smaller, local contract manufacturers.

However, at RapidDirect, we offer premium quality injection molding services accompanied by injection molding design for manufacturing. We have a team of injection molding professionals and all the latest software to evaluate your part production for irregularities and improvement.

Upload your files and get started with RapidDirect today!

Factors to Consider During DFM in Injection Molding Processes

To optimize any injection molding process for manufacturing, designers consider many factors before clearing the design to move into the next stage. These factors consider many sections of production, from material selections and tool considerations to the machining method itself. Examples of such factors include:

1. Material Selection

Selection of plastic material is one of the preliminary processes that are quite important in plastic design and manufacturing. It could determine if a part will be able to function in its intended environment or not. When manufacturers attempt to select, they consider many properties such as:

  • Material Shrinkage Rate

Shrinkage is the change in dimension of the molded part as it cools after the injection process. All materials possess different shrink rates. The shrinkage rate depends on many factors, such as the family of the plastic, the melt flow index, and the processing conditions (such as injection pressure). The shrink rate of a part can affect its performance and geometry.

  • Assembly

Machinists also consider the ability of a plastic material to handle assembly processes such as mechanical fastening, welding, and bonding during material selection. This factor comes into play whenever the part in consideration is part of a larger contraption.

  • Cost

While the desirable attributes of the plastic material are important, it is also important to consider the cost. This is an important factor that many machinists have to consider alongside the other attributes the plastic must possess. However, the designers do not only consider the cost of purchasing plastic. They also consider other factors such as the cost of finishing, machining, and maintenance of the plastic. This will help to minimize the cost of production as much as possible.  

2. Draft

The draft of a part is the degree of narrowness or taper on the vertical walls of a plastic part. The angle of a part is an important factor machinists consider in plastic parts design for manufacturing. The reason is that the draft on a plastic part is essential for easy ejection of the finished part from the mold. In the injection molding design for manufacturing process, the designers evaluate if the draft angle is in the direction of the mold. This is important as it ensures clearance for the easy ejection of the part as the mold begins to open.

a way injection molding design for manufacturing
How to optimize draft angles

Generally, the angle of the draft varies between one and two degrees depending on the part dimensions. Also, it is advisable to design all the part drafts in a parallel direction to the movement of the mold when separating. This helps to avoid the creation of thick walls.

3. Uniformity of Wall Thickness

In the injection molding design for manufacturing, the designers thoroughly check the uniformity of the part wall’s thickness. This is because consistency in the thickness of the part walls helps prevent many defects in the finished part. This is because inconsistency in thickness could lead to an uneven flow of the plastic when it flows.

In some cases of parts with uneven wall thickness, the material usually flows into the thicker areas. This could lead to inadequate filling of the thinner areas. However, this order of flow depends on the location of the gates on the part. Also, uneven thickness could cause deformation in shape. This is because the thicker areas tend to cool more slowly; hence, the uneven cooling might cause physical defects to the part.

However, if any section of the part requires varying thicknesses, the designer should make the transition as smooth as possible. This will cause minimum disturbance to the flow of the resin.

4. Location of Gates

image showing where gates are in an injection molder
Location of gates in plastic mold design

Gates are the areas of passage between the molded part and the runner system. They are essential in the flow of resin into the mold. They serve as a directional guide to the resin flow from the runners to various areas of the part. In the injection molding design for manufacturing process, the designers inspect the gates to ensure that they are large enough to prevent impeding the resin flow. However, they must not be too large, so the machinist can easily separate the runner from the part.

5. Use of Ribs

One of the reasons why manufacturers use thicker walls in parts is to increase the part’s strength. However, this is not so advisable as it could lead to part deformation, voiding, and other defects. However, with ribs, it is possible to increase the strength of the part without increasing the thickness of the walls.

a feature of injection molded parts injection molding dfm improves
Ribs in plastic parts

The thickness of the rib should range between 50 – 70 percent of the relative part thickness. This way, the part will be devoid of stretch marks.

6. Adding Extra Radii to Edges and Corners

corners and edges of plastic parts
Poor and ideal corners and edges

The radius of the edges and corners is another factor that designers consider in the injection molding mold design. Using sharp edges and corners could lead to a buildup of stress at such junctions. However, with the addition of ample radii, the designers eliminate the concentration of stress. It also enables the resin materials to flow better. Doing this also improves the parts’ strength and manufacturing ease.

7. Undercuts

a feature of injection molded parts
An example of an undercut in a plastic part

Undercuts are cavities or projections included in the injection mold design of various plastic parts. Designers usually include them in parts intended for assembly to a larger contraption. However, these cavities or projections tend to hinder the ejection of parts from molds. Also, their addition raises the cost and complexity of the injection mold design and manufacture. Hence, in parts where they seem unavoidable, a better option is to place the part’s features in a perpendicular direction to the draw line.

Why You Should Allow RapidDirect Handle Your Plastic Parts DFM

Either simple or complex, every part requires the use of the injection molding design for manufacturing process. With the plastic part design for manufacturing feature, you can always find ways to optimize stages of part production. However, a DfM study isn’t a job to assign to just any industry. It would be best to have an experienced team of injection molders handle this to ensure the best results.

rapiddirect quoting platform
RapidDirect Quoting Platform

This is why you need to outsource your injection molding job to us at RapidDirect. With a dedicated team of designers, manufacturing engineers, machinists, and tooling engineers, we give you the best design for manufacturability suggestions to make your production cost-effective and as easy as possible.

Can you perform your injection molding design for manufacturing and do not have time? Or do you not even have any idea of how to handle the process? RapidDirect is here to help.

Upload your files and get started with RapidDirect today!

The Benefits of Plastic Parts DFM Analysis

The benefits of plastic parts design for manufacturing analysis are quite numerous as it affects various stages of part production. Examples of the benefits include:

1. Quicker Lead Time

With injection molding design for manufacturing, the team of injection molders will come up with optimum suggestions to improve the manufacturing process. This will help make the manufacturing process quite easier and faster, hence improving the product’s lead time.

2. Quicker Time to Market

 Due to the quick lead time from the optimized production processes, the product owners can bring their products to the market within a short period. It will give the owner products an edge over their competitors for products meant for a highly competitive market.

3. Reduction of Production Cost

There’s nothing more pleasing than ways to reduce production costs as a client and still get quality parts produced. This is exactly what the injection molding design for manufacturing process offers. With this evaluation process, you can find ways to reduce costs while still making quality parts.

4. Higher Quality of Parts

No one wants a part that can’t fulfill its functions. With the plastic part DfM, you can certainly predict the feasibility of the part functioning optimally in its environment.

5. Reduces Wastage

If injection molding design for manufacturing processes is not carried out, it could lead to a lot of wastage of time and resources. This is because the manufactured parts could fail to perform their intended function, leading to a need to repeat the manufacturing process. With plastic parts design for manufacturing, these scenarios can be easily prevented.


The process of part production is not complete without the injection molding design for manufacturing processes. This is because this DfM process helps optimize the production process, thereby saving up on material used and time spent. To get the best injection molding design for manufacturing processes, reach out to RapidDirect today!

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