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Machined Parts vs. Molded Parts: Six Reasons to Choose CNC Machining

Author: YiNuo Zhang
Published on: 2023-07-27

In the world of manufacturing, the choice between machined parts and molded parts often presents a dilemma. While each method has its merits, there are specific applications where one might be preferred over the other. However, recent advancements in CNC machining technology have tilted the balance in its favor for many reasons. In this article, we delve into six compelling reasons to choose machined parts over molded ones, highlighting the inherent benefits of CNC machining.

This article will discuss six compelling reasons to choose CNC machined parts over-molded parts, showcasing the unique benefits offered by Prolean’s CNC Machining Services.


Reason 1: Superior Precision and Accuracy

High-Speed Precision Machining

When it comes to the precision and accuracy of finished parts, CNC machining stands head and shoulders above the molding. CNC machining is a subtractive process where a block of material is whittled down to the desired shape, based on the instructions provided by a digital file. This precise control allows for highly accurate, complex parts with tight tolerances.

1. Accuracy in Complex Geometries

CNC machines have the ability to move along multiple axes, enabling them to create parts with complex geometries that would be challenging or impossible to achieve through molding. The precision of CNC machining is typically measured in microns, with some machines capable of maintaining tolerances as tight as +/- 0.001 inches.

2. Consistency in Production

CNC machines follow the exact same process for every part, ensuring remarkable consistency in production. This is particularly valuable for large production runs where maintaining the same level of precision across all parts is critical.

Table 1: CNC Machining vs. Molding – Precision and Accuracy

Aspect CNC Machining Molding
Complexity of Geometries High Limited
Precision +/- 0.001 inches Varies
Consistency High Can vary


Reason 2: Material Versatility

Another compelling reason to choose CNC machined parts over molded ones lies in the versatility of materials that can be used.

1. Broad Range of Materials

CNC machining is a versatile technology that can handle a broad range of materials. These materials include various metals such as aluminum, steel, and titanium. Additionally, CNC machining can also process plastics like ABS, Nylon, and PEEK. This versatility is essential when it comes to creating parts with specific physical properties that are crucial for their function, such as strength, thermal resistance, conductivity, etc.

2. Challenges of Hard Material Processing

Molding certain hard materials can be incredibly challenging, particularly when intricate designs are involved. However, CNC machining provides a solution to this problem, as it can effortlessly process these materials. This results in high-precision parts that would have been difficult to create otherwise. It is for this reason that CNC machining is a preferred choice for processing hard materials with intricate designs.

Table 2: CNC Machining vs. Molding – Material Versatility

Aspect CNC Machining Molding
Range of Materials Extensive Limited
Processing of Hard Materials Possible Limited

Note: The tables provided here offer a high-level comparison between CNC machining and molding in terms of precision and accuracy, and material versatility.


Reason 3: Shorter Production Time

Speed is often a critical factor in product development and manufacturing, and this is another area where CNC machining has an edge over molding.

1. No Need for Mold Creation

Injection molding process

In molding processes, the creation of the mold itself can be time-consuming and costly, particularly for complex parts. CNC machining, on the other hand, bypasses this step entirely. The digital designs are fed directly into the machine, which can begin producing parts almost immediately.

2. Rapid Prototyping

CNC machining is ideal for rapid prototyping, where design iterations and testing are common. Changes can be made to the digital design and implemented immediately, whereas, in molding, a new mold would need to be created for each design change.

Table 3: CNC Machining vs. Molding – Production Time

Aspect CNC Machining Molding
Time Required for Setup Short Long
Flexibility for Prototyping High Low


Reason 4: Lower Costs for Short Runs

While molding can be more cost-effective for high-volume production runs due to the initial cost of mold creation, CNC machining can be more cost effective for short runs and prototypes.

1. No Mold Costs

One of the biggest advantages of CNC machining is that it eliminates the need for expensive mold costs, which can be a major obstacle for small production runs. Without the upfront investment required for mold creation, CNC machining is a much more affordable option for those looking to produce short runs or custom pieces. This can be especially beneficial for businesses or individuals who are just starting out and may not have the financial resources to invest in expensive mold creation.

2. Streamlined Design Changes

In addition to cost savings, CNC machining makes it easy to make design changes without the need for expensive mold modifications. With a simple update to the digital file, design changes can be implemented quickly and efficiently, with no need to create a new mold. This can be a major advantage for projects where design iterations are anticipated, as it allows for flexibility in the production process and can help to minimize both time and costs.

Table 4: CNC Machining vs. Molding – Costs

Aspect CNC Machining Molding
Upfront Costs Low High
Cost-effectiveness for Short Runs High Low

The above considerations indicate that, while both CNC machining and molding have their strengths, CNC machining offers numerous advantages that make it a highly attractive option for many manufacturing needs. Be it precision, material versatility, speed, or cost-effectiveness for short runs – CNC machining delivers.


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Reason 5: High Degree of Consistency

Another crucial advantage of CNC machining over molding lies in its ability to maintain a high degree of consistency in the production of parts.

1. Precision Manufacturing

Due to the computerized nature of CNC machines, they can reproduce designs with extreme accuracy over and over again. This means you can expect virtually identical parts from the first to the last, even in large production runs.

2. Minimized Human Error

With less manual intervention involved in the process, the potential for human error is significantly reduced in CNC machining. In molding, factors like uneven pouring or cooling can result in inconsistencies across different parts.


Reason 6: Environmentally Friendly Process

In today’s manufacturing landscape, sustainability and environmental impact are increasingly important considerations. Here, too, CNC machining stands out.

1. Waste Reduction

CNC machining is a manufacturing process that has a lower environmental impact compared to other production methods. This is because CNC machining is a subtractive process, which means it carves out the desired part from a larger block of material. This technique allows for more precise control over material usage, leading to less waste compared to molding. Additionally, CNC machines can produce products with high accuracy and quality, which reduces the need for post-processing and further minimizes waste.

2. Reusable Scraps

Furthermore, the metal or plastic shavings produced during CNC machining can often be collected and recycled, further reducing the environmental impact of the process. These scraps can be melted down and reused, reducing the amount of material waste generated during the CNC machining process. Not only does this reduce the carbon footprint of the production process, but it also decreases the amount of raw materials needed for future production.



In a nutshell, CNC machining has proven to be a versatile and efficient process that offers numerous advantages over molding. Its superiority in precision, flexibility, speed, consistency, cost-effectiveness, and environmental friendliness make it a preferred choice for many manufacturers. For these reasons and more, CNC machining continues to play a pivotal role in industries ranging from aerospace to automotive, healthcare, and beyond. At Prolean, we are proud to offer exceptional CNC machining services, providing high-quality machined parts that meet and exceed our client’s expectations.



1. Can CNC machining work with all types of materials?

CNC machining can work with a wide range of materials, including metal, plastic, wood, foam, and composite materials. The choice of material often depends on the specifics of the project and the desired properties of the finished part.

2. Why is CNC machining considered more precise than molding?

CNC machining is a computer-controlled process, allowing for highly accurate reproduction of designs. The precise control offered by CNC machines often leads to higher accuracy compared to molding processes.

3. Is CNC machining environmentally friendly?

Yes, CNC machining is considered more environmentally friendly than many other manufacturing processes. This is due to the ability to precisely control material usage, resulting in less waste, and the fact that many of the byproducts (like metal or plastic shavings) can often be recycled.

4. How does CNC machining ensure consistent quality in large production runs?A: The

computerized nature of CNC machines means they can replicate the same design over and over with minimal variation, ensuring consistency across large production runs. Additionally, the reduced manual intervention reduces the risk of human error.

5. Can I use CNC machining for complex designs?

Absolutely! One of the strengths of CNC machining is its ability to handle complex geometries and intricate designs, which might be challenging or even impossible with other manufacturing methods.


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