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When comparing the advantages and disadvantages of rapid prototyping (RP) and numerical control (CNC) machining, proponents often have many different opinions.
There is no doubt that CNC machining offers outstanding accuracy. However, RP machining also provides some advantages that CNC cannot match.
As technology advances, rapid prototyping has seen significant improvements in precision, material properties, and surface quality.
Let’s explore five key reasons why RP machining is becoming the preferred choice for more and more manufacturers.
Table: RP machining vs CNC machining: pros, cons
Part Complexity
RP machining stands out for its ability to easily produce complex parts. Modeling a complex prototype in design software has little effect on time and cost.
RP machining can quickly and economically manufacture these complex parts, which greatly increases efficiency.
In contrast, CNC machining requires handling each feature of a complex part individually. This increases machining time and costs.
As complexity rises, the number of setups and tool changes increases as well.
For some features, such as high aspect ratio parts, deep holes, slots, and square corners, CNC machining can become challenging.
Feature Details
RP machining excels at creating features that are difficult to achieve with traditional machining.
For example, RP can produce sharp inside corners, deep and narrow channels, tall and thin walls, ribs, and columns with high aspect ratios.
In contrast, traditional machining is better suited for smooth fusions, sharp edges, and clean chamfers.
However, traditional machining is less effective at generating complex details compared to RP machining.
Skilled Labor
RP machining requires a less skilled workforce than CNC technology. The process has been optimized to rely less on the operator’s skill, making production more straightforward.
In contrast, CNC machining requires operators with extensive technical knowledge and creative thinking.
Technicians must design tool paths, select machining strategies, and operate and monitor the cutting process. This level of expertise is necessary for efficient CNC machining.
Staffing
RP machining typically requires fewer personnel. Apart from a few minor operations (like bench machining), RP machining is simple and quick.
Production files can be ready, and parts can be in production within minutes.
CNC machining, on the other hand, still requires considerable manual intervention despite improvements in CAM software.
Machine setup, operation, and monitoring all need experienced machinists. This increases both the complexity of operations and the costs.
Delivery Time
The efficiency of RP machining directly impacts delivery time.
RP machining reduces both physical build time and the lead time of the entire production process due to its lower labor requirements and simplified processing steps.
Overall, RP machining saves time and reduces personnel costs for most parts.
CNC machining, however, involves multiple steps (labor, tool paths, machine time, fixtures, and materials), leading to longer lead times and a more complex overall machining cycle.
To summarize
In many cases, RP machining outperforms CNC machining when it comes to fast delivery, handling complex designs, and reducing costs.
As technology advances, the precision and material options for RP machining continue to improve.
This makes RP machining the preferred choice for most manufacturers in rapid prototyping and low-volume production.