Both machined parts and molded parts are essential methods for producing components. However, when it comes to choosing the most suitable option for your project, machined parts often offer several compelling advantages over molded ones. If you’re deciding between these two options, it’s crucial to understand why machined parts could be the better choice for your needs.
At BOYI TECHNOLOGY, we specialize in providing high-quality machined parts and prototypes with rapid lead times and competitive pricing. Here, we will outline the top six reasons why CNC machining might be the better option compared to molding and help you determine why machining could be the best fit for your project.
What Are Machined Parts?
Before diving into the reasons why machined parts are advantageous, it’s essential to understand what they are. Machined parts are components produced through subtractive manufacturing techniques, such as CNC milling, CNC turning, CNC grinding, or even manual machining. The process involves removing material from a solid block (or blank) of metal, plastic, or other materials to create the desired part.
Machined parts are widely used in both low- and high-volume production runs, as well as in rapid prototyping. They are often compared to other types of manufactured parts, such as:
- Molded Parts: Created using injection or compression molding.
- Cast Parts: Made by pouring molten metal into a mold.
- Forged Parts: Produced through heating and shaping metal under pressure.
- Extruded Parts: Created by forcing material through a die to create specific shapes.
- 3D Printed Parts: Made by building layers of material based on a digital model.
In some cases, parts may combine techniques—for instance, a cast part may have machined features added afterward.
Key Differences Between Machined and Molded Parts
Machined parts are often compared to molded, cast, forged, extruded, and 3D-printed parts, all of which have their own distinct manufacturing processes. Molded parts, specifically those made using injection molding, require specialized molds to create the desired shape, making them more suited for large production runs.
In contrast, machining allows for more flexibility, greater precision, and the ability to create a wide range of shapes and designs without the need for tooling.
6 Advantages of Machined Parts Over Molded Parts
Now, let’s explore why machined parts are often the better choice.
1. No Minimum Order Quantity (MOQ)
One of the most significant benefits of choosing machined parts is the absence of minimum order quantity (MOQ). For molded parts, manufacturers need to create metal injection tooling, a process that requires a substantial upfront investment of both time and money. The tooling cost can run into tens of thousands of dollars, making it less feasible for small orders.
With CNC machining, there is no need for expensive tooling, which allows you to order parts in small quantities or even one-off prototypes. This is particularly beneficial for:
- Small businesses
- Prototyping needs
- Custom orders
In contrast, if you’re dealing with larger production volumes, injection molding may still be the best choice. However, machining offers a unique advantage for those requiring low volumes and more flexibility.
| Feature | Machined Parts | Molded Parts |
|---|---|---|
| Minimum Order Quantity | No MOQ, even for single parts | Requires large batch orders |
| Tooling Costs | No tooling required | High tooling costs |
| Flexibility | Ideal for prototypes, small runs | More suited for mass production |
2. Affordable and Fast Prototyping
When it comes to rapid prototyping, machined parts offer a significant advantage. Molding requires tooling and setup, making it prohibitively expensive for prototype runs. Since machined parts are made directly from raw material, they can be fabricated quickly and affordably without the need for molds.
Here are some reasons why machining is a better choice for prototyping:
- Quick turnaround times for prototypes
- Ability to iterate designs and make rapid adjustments
- Test parts in different materials for performance evaluation
For example, if you’re testing a product in different alloys or composite plastics, machining allows you to experiment with a variety of materials without committing to an expensive mold.
| Feature | Machined Parts | Molded Parts |
|---|---|---|
| Prototyping Cost | Low cost, no tooling required | High cost, requires molds |
| Speed of Prototyping | Fast production of prototypes | Slow due to tooling preparation |
| Material Variety | Multiple material options available | Limited to molding-compatible materials |
3. Greater Design Freedom
Machining allows for greater design flexibility compared to molding. CNC machines can create parts with intricate shapes and fine details, making it possible to produce:
- Complex geometries
- Thicker parts with higher durability
- Tighter tolerances for more precise fitting
In contrast, molded parts often have design constraints due to the nature of the molding process, such as the need for thin walls and uniformity. This is especially problematic when dealing with more complex features that cannot be easily achieved with molding techniques.
3D printing offers a lot of design freedom too, but it often requires support structures for overhangs, and post-processing is needed to remove them. In comparison, machining doesn’t have such limitations, making it an ideal choice for custom, detailed parts.
| Feature | Machined Parts | Molded Parts |
|---|---|---|
| Design Flexibility | High freedom for complex shapes | Restricted by mold geometry |
| Wall Thickness | Can handle both thick and thin walls | Typically requires thin walls |
| Detail and Features | High detail and intricate features | Limited to basic design features |
4. Superior Quality and Precision
When quality and precision are paramount, machined parts shine. CNC machines are capable of producing parts with tight tolerances, ensuring that your components meet exact specifications. This level of control makes machining the ideal choice for high-performance parts in industries like aerospace, automotive, and medical devices.
Advantages of machining quality:
- Tighter tolerances (typically ±0.01mm or better)
- Consistent surface finishes
- No material flow injection molding defects (such as flow lines or jetting) that are common in molded parts
Additionally, since machining doesn’t rely on molds, each part produced can be as accurate and well-finished as the first, unlike molded parts where quality may degrade as the mold wears.
5. Shorter Lead Times
Machining is an efficient process that typically leads to faster production times, especially for low-volume or prototype runs. The absence of complex tooling and the ability to create parts directly from digital CAD files make CNC machining much faster compared to molding processes.
Factors contributing to shorter lead times in CNC machining:
- No tooling or setup required
- Faster iteration and adjustments to designs
- Quick material removal and machining steps
If you’re on a tight timeline or need to get your parts to market quickly, CNC machining is often the best option.
6. Easy to Modify and Alter Designs
Another significant advantage of machined parts over molded parts is the ease of modification. Because CNC machines work directly from a digital CAD file, making changes to the design is straightforward and doesn’t require the costly creation of new molds.
Benefits of design flexibility in machining:
- Make real-time adjustments without costly delays
- Rework designs quickly, even during production
- Minimize waste by catching design issues before full production
In contrast, molding requires new tooling if changes need to be made, leading to delays and increased costs.
When is Injection Molding the Better Option?
While CNC machining offers numerous advantages, injection molding is still a highly effective process for large production volumes. If you need to produce thousands or even millions of identical parts, injection molding may be the more cost-efficient choice. The initial tooling costs for molding are high, but the cost per part drops significantly as production scales up.
However, if you’re working with limited quantities, prototyping, or need design flexibility, CNC machining provides several benefits that molding cannot match.
Conclusion: Machined Parts vs. Molded Parts
When deciding between machined parts and molded parts, it’s essential to consider factors such as:
- Production volume
- Design complexity
- Speed and cost efficiency
Machining offers significant advantages for low-volume production, custom parts, fast prototyping, and high-quality precision. If your project requires any of these factors, CNC machining is likely the best solution.
At BOYI TECHNOLOGY, we specialize in CNC machining services, providing affordable, high-quality, and quick-turnaround solutions for your manufacturing needs. Whether you’re looking for prototypes, custom parts, or small production runs, we can help bring your designs to life.
Ready to order your machined parts? Contact us today for a quote and start your project with confidence.
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FAQ
Machined parts are created using subtractive manufacturing methods such as CNC milling, turning, and grinding. These processes remove material from a solid workpiece to achieve the final part shape.
Machined parts are typically more expensive than molded parts for large quantities due to the cost per unit being higher in machining. However, for small production runs, prototypes, and customized parts, machining is often more cost-effective than injection molding, which requires expensive tooling.
Machining is ideal for low- to medium-volume production but is not typically used for mass production in the same way as injection molding. If you need thousands or millions of identical parts, molding may be more cost-effective.
This article was written by engineers from the BOYI team. Fuquan Chen is a professional engineer and technical expert with 20 years of experience in rapid prototyping, mold manufacturing, and plastic injection molding.
