CAPTCHA protection
A few months ago, a client contacted us urgently.
The issue:
The project was already underway. The first parts had been produced.
But it was already too late to easily switch manufacturing processes.
The result:
At EC International Group, this type of situation is far from uncommon.
In most industrial projects, we observe the same pattern: the wrong process is chosen… at the wrong time.
The real challenge is not simply choosing between CNC machining and plastic injection.
It’s about selecting the right manufacturing process at the right stage of the project, based on production volumes, product maturity, and industrial constraints.
CNC machining and injection molding are two major industrial processes, but they rely on fundamentally different approaches.
This is a subtractive process. It starts from a solid block of material (metal or plastic), and material is removed using cutting tools (milling, turning, drilling).
CNC machining offers extremely high precision, tight tolerances, maximum flexibility, and rapid adaptation to design changes. It is ideal for prototypes and low volume production runs.
In contrast, it is a manufacturing process based on molding. Plastic material is heated and injected into a mold to form the final part.
It is a solution suited for fast production in series, with a very low unit cost… but a high initial investment.
| Criteria | CNC Machining | Injection Molding |
| Lead time | 6 business days to 3 weeks, including transport | 3 to 5 weeks (depending on mold complexity + iterations), including transport |
| Initial cost | Low | High: tooling + industrialization (mold cost + (unit cost × quantity)) |
| Unit cost | High | Very low |
| Ideal volume | 1 to 500 parts | Simple mold: 300+ parts Complex mold: 500 to 2000+ parts (depending on project) |
| Flexibility | Maximum | Low |
| Precision | ±0.005 mm | NFT 58000 standard - reduced class (depending on material, geometry, and molding conditions) |
| Repeatability | Good | Excellent in mass production |
| Surface finish | Controlled Ra directly in machining, wide range of finishes without specific tooling | Directly dependent on mold quality, may require additional finishing processes |
| Design constraints (DFM) | High design freedom, few geometric constraints | Strongly dependent on Design for Manufacturing (DFM): draft angles, uniform wall thickness, ejection constraints |
Design approaches for CNC machining and plastic injection are fundamentally different and directly impact feasibility, costs, and industrialization timelines.
In CNC machining, parts are produced by material removal, offering high geometric freedom. The main constraints relate to tool accessibility, internal radii, and optimizing machining strategies to control costs and lead times.
Conversely, in plastic injection, design is entirely driven by Design for Manufacturing (DFM) principles. Every design detail affects the mold, part quality, and repeatability in mass production.
Key design considerations for injection:
In practice, a part designed for CNC machining cannot be directly industrialized for injection without DFM redesign.
Integrating DFM early in the design phase helps reduce mold iterations, secure production, and optimize overall costs, especially in industrial-scale or high-volume production contexts.
In real-world industrial projects, nothing stays fixed:
This is exactly where CNC machining becomes essential.
Thanks to its high flexibility, it allows for the rapid production of technical parts, making it easy to test, adjust, and improve without requiring heavy investment in tooling.
This is why it is very often the first key step in the industrialization of a product, before potentially moving to plastic injection.
Fast Production
Ultra Precision
Advanced CNC Technologies
Multi-Process Approach
High-Speed Machining (HSM)
Total flexibility to support your projects, from functional prototypes to small industrial series.
Context
An industrial pump manufacturer faced alignment issues on a high-precision motor flange.
This caused premature wear and reduced equipment lifespan.
Our Approach
Results
Beyond performance, the client secured a robust and scalable production process.
Many industrial companies assume injection molding is the fastest and cheapest option from the start.
In reality:
Result: premature tooling decisions can lead to expensive mold modifications and delays.
Controlled and Fast Production
Industrial Quality
Custom Tooling
Injection molding becomes ideal for mass production, with significantly reduced unit costs once the mold is amortized.
Context
A client developed a complex industrial housing with strict requirements: sealing, assembly, resistance.
After validating the design with CNC machining, we identified the right moment to switch to injection molding.
Recommendation
Transition to injection molding once the product was stable and industrial-ready.
Results
A fully controlled project with no costly tooling rework.
It’s not about cost per part. It’s about total project cost.
A client wants to reduce costs → launches a mold
But:
Result:
Plastic injection becomes cost-effective once the tooling cost is amortized over the production volume.
This threshold varies significantly depending on part complexity and material.
| Volume | Recommended approach |
| 1 – 100 parts | CNC machining (almost systematic) |
| 100 – 500 parts | CNC machining or preparation for injection (DFM, design optimization) |
| 500 – 2000 parts | Profitability threshold analysis (tooling cost, complexity, material) |
| 2000+ parts | Injection becomes relevant if the design is stabilized and volumes are recurring |
In industry, time is often more valuable than cost.
A delay can cost more than the manufacturing process itself.
These mistakes often cost tens of thousands of euros.
There is no single path in industrialization.
The choice depends on:
In practice, a hybrid and progressive approach is often the most effective.
Possible processes:
CNC machining remains the reference for high-precision prototypes.
Once the product is validated, low-volume industrial production requires finding the right balance between cost, lead time, and quality.
At EC International Group, the most commonly used solutions for manufacturing plastic parts are:
At this stage, the choice between CNC machining and plastic injection becomes strategic:
CNC machining = adaptability and responsiveness
Injection molding = reduction of unit cost (if volumes are sufficient)
Plastic injection becomes particularly relevant when:
Launching a mold too early can be very costly.
The best strategy is to adapt the process to the project stage.
This allows:
Choosing a partner is not just about manufacturing.
We act as a key industrial partner from the earliest stages.
Our value: helping you make the right technical and economic decisions.
Consulting Approach
We guide you toward the most relevant process.
Ability to Challenge
We identify risks early:
Global Vision
We integrate:
Multi-Process Expertise
This allows us to adapt solutions at every stage of your product lifecycle.
| Situation | Recommended Solution |
| Urgent prototype | CNC machining |
| Evolving design / under optimization | CNC machining |
| High-risk project / technical uncertainties | CNC machining |
| Low volume production | CNC machining (in most cases) |
| Low-volume production (recurring volumes) | CNC machining or plastic injection (profitability threshold analysis) |
| Complex geometry not suitable for molding (sharp angles, undercuts, non-uniform wall thickness) | CNC machining or redesign for injection |
| Stabilized product | Plastic injection (if volumes and constraints are compatible) |
| Cost reduction at scale | Injection molding (if volumes are sufficient) |
What industries do you support for CNC machining and plastic injection projects?
EC International Group supports industrial companies in the manufacturing of technical parts, from prototyping to mass production, adapting to the specific requirements of each industry.
We work in particular with:
Thanks to our expertise in CNC machining and plastic injection, we help our clients:
Our multi-process approach allows us to get involved early in the design phase to optimize both technical performance and industrial profitability.
What is the difference between cnc machining and injection molding?
CNC machining consists of removing material from a solid block (metal or plastic) to produce a precise part, whereas plastic injection involves molding molten material into a mold to form the final shape.
In practical terms:
At EC International Group, we often use both processes in a complementary way to optimize cost and lead times.
Which process is more cost-effective: cnc machining or injection molding?
It mainly depends on the production volume.
The unit cost of plastic injection is very low once the mold is amortized, despite a higher initial investment.
The key factor remains the initial tooling cost, which can be significant and must be spread over the total production volume.
At what volume does plastic injection become cost-effective?
In practice, the break-even point for plastic injection is typically:
This threshold depends on several factors:
For example, a complex mold will require a higher production volume to be amortized.
At EC International Group, we systematically analyze these parameters to avoid premature investment.
What are the lead times for cnc machining and injection molding?
Lead times differ significantly:
If your project is urgent or in the testing phase, CNC machining is often the best option.
Which process offers the highest precision?
Both processes offer excellent precision, but with important differences depending on the application.
CNC machining:
Plastic injection:
In practice, the choice depends on the required level of dimensional accuracy and the function of the part.
Can you switch from cnc machining to injection molding?
Yes, and it is actually a very common and recommended strategy.
At EC International Group, the typical approach is:
This approach secures the project before investing in tooling.
What materials can be used in cnc machining and injection molding?
Cnc machining:
Injection molding:
Material selection depends on:
Is injection molding suitable for small production runs?
Not always.
Injection molding becomes relevant only if:
For small runs (typically under 300 to 500 parts), cnc machining is often more flexible and cost-effective.
What are the risks of choosing the wrong process?
A poor decision can have significant consequences:
This is exactly why we support our clients from the early stages of their project.
How can you be sure to choose the right process?
You need to analyze four key factors:
If one of these elements is uncertain, it is generally safer to start with cnc machining.
