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Top Tips by Injection Moulding Suppliers to Reduce Cost Per Unit

2020-06-30 hqt

Injection Moulding Suppliers: Effective Tips to Reduce Cost

Injection molding is an excellent way to create cost-effective parts or components, provided you do mass production. The Injection Moulding Suppliers provide some tips that would help your stretch your budget further.

Everyone would like to have the same product at a cheaper price. This holds true in the molding industry as well. If you are really interested in reducing the overall cost of your molding manufacturing, you have come to the right place.

In this article, we are going to talk about some design recommendations that would reduce the cost of the entire molding process significantly. So, without any further delay, let us get started!

Also, have a look at the Injection Moulding Fields of Application in the Industry.

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Injection Moulding Suppliers – Design Tips to Reduce Cost

The obvious way to reduce the price per unit is to increase the production quantity in injection moulding. After all, it is the upfront cost that is high, but once the machines are in place, everything is inexpensive. Higher the number of production units, the lesser the cost per unit would be.

But what if your product does not require more than a handful of components or parts. Let’s say, you just need 25 pieces. Getting this manufactured would cost your hundreds if not thousands of dollars. So, do you think to pay that much for just 25 pieces is worth it?

We don’t! Therefore, we suggest opting for cost-effective molds for small production quality.

How much would Injection Molding Cost?

There are several factors that affect the cost of the injection molding technique. The amount of time that it would take to produce a tool, is the main determinant of the molding cost. In simple words, we can say that if a part is complex, it would take more time to create it, thus the cost would be higher.

Simple parts that do not require advance surface finishes or undercuts, would be most inexpensive.

Note: Undercuts have the ability to complicate things. In some cases, they would even prevent part ejection. Therefore, it is best to eliminate them.

You also need to pay heed to the material that you are planning to use. It is going to have a direct impact on the per-unit price. There are some plastics that are easier to mold in comparison to others. Likewise, some plastics overlap in functionality and strength.

A good choice is to go with a material that is easy to mold as it would bring down the cost of every part.

So, here are the different injection moulding design considerations that will help in stretching the manufacturing price.

  • Eliminate Undercuts
  • Remove Unnecessary Features
  • Incorporate Core Cavity Approach
  • Reduce Cosmetic appearances
  • Design Parts (Self-mating)
  • Change and Reuse Molds
  • DFM analysis
  • Part Size
  • Overmoulding


Undercuts can lead to the prevention of part ejection as well as it complicates the features. Therefore, avoiding them can reduce the complexity along with the price per unit. We do understand that in some cases it might not be possible.

But, always search for alternatives before you incorporate undercuts. For instance, if you require a side action, pick out, or a sliding shutoff, what are you to do? Try using different alternatives. You can choose the pass-through cores and the sliding shutoffs.

You can also change the draft angels as well as the parting lines to ensure smoother mold building. These are small, yet important design changes. They would have a significant impact on the price per unit as they would decrease the machine cycle time.

NOTE: A cost-effective technique for ribbed surfaces and molding tall walls is using the core cavity.

Injection Moulding Suppliers Suggest Removing Unnecessary Features

There is no denying that company logos, molded part number and textured surfaces look smart. However, they also increase the price dramatically. If it is not a necessity, you should not have it, especially with low volume production.

Eliminate all non-mission critical features. In case, you really need to have the permanent part number, try using the mill-friendly font. For example, go with Verdana, Arial, etc. You can ask your injection moulding suppliers as to which font do, they prefer.

Incorporate Core Cavity Approach

If you require box-shaped parts such as the common home electronics, you have two options. Either can you use bring the aluminum material down around the core and then mold the required part around it. Or, you have the option of sinking the wall cavities into the mould base.

The former approach is the core cavity approach. It is inexpensive to the other approach. In addition, the core cavity approach ensures adequate venting, smoother surfaces, and improved ejection.

Reduce Cosmetic Appearance

Pretty Parts look good, but they would add more to the cost. The EDM, bead blasting, or the high molding polish would no doubt make the parts look smart, but they would drive up the tooling cost. If you need anything above the machine finish (PM-F0) it would require hand finish.

Thus, additional labor costs, as well as machine time. It is also important to let the suppliers know whether you want half, full, or a certain area of the mold polished. If you polish only the required area, it would cut down the cost.

Self-Mating Parts

If you require a design that snaps-together, it is better to go with one mating part instead of two. Try building mating parts that have the ability to fit each other from either direction. These parts are generally called the Universal parts.

Doing this would eliminate the need for an additional mold. You would need one mould to create the entire product. Thus, saving you the upfront productional expense.

Molds Mods

Taking out metal from the exiting metal mold is easy. However, working with metal would be extremely difficult with rapid injection molding. Therefore, you can go with plastic. Do remember, you can add plastic, but it is not possible to take it away.

So, design while keeping this in your mind. Some of the injection moulding parts would go through several iterations before you finalize the design. Opting for a new mold every time is not a cost-effective solution.

Therefore, you need to design smartly. You should be able to use the mold over and over again. A good idea is to start with the basic part design mold. Then once you go on, add re0machine the mould to incorporate additional features.

DFM analysis

Good injection moulding suppliers would accompany every injection mould part’s quote with a design for manufacturing analysis. It would high the possible problematic areas as well as the ways via which you can improve your design.

Few examples where you need to improve your part design include impossible geometries, un-machinable features, etc. Pay close heed to the suggestions as they will not only improve the design quality but also reduce the overall cost per unit.

Part Size

You need to pay close attention to the part extents. It basically means the size of your part and who well will it fit the mold. Would it allow for ejector pins, runners, sprues, and other similar considerations that are required for the mold to be operational?

You should ask the injection moulding suppliers for more details on the part sizes. They would provide you with their maximum and minimum part size requirements.


Overmoulding is another aspect that can help you reduce production per unit cost. However, do bear in mind that it would cost you more upfront. For instance, you want to have a gasket on top of your part.

If you don’t add gasket upfront, the moulding would cost you less. However, when you have someone else to install it individually, it would cost you more. So, the better idea is to pay the upfront cost of the gasket by incorporating it into the moulding process.

For more effective result, learn about the 10 important steps of moulding.

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Take Away

Injection Moulding is an effective and cost-efficient way to produce parts and components, especially for mass production. However, incorporate some effective tips, it is possible to reduce the overall production cost of a limited number of pieces.

For more information, please free to contact our engineers.