3-axis and 4-axis machine tools are more commonly used than 5-axis ones. The core reasons lie in the comprehensive influence of factors such as cost, complexity, and the matching degree with applicable scenarios. The key to choosing between 3-axis, 4-axis, or 5-axis machine tools is to match the structural characteristics and precision of the parts.

1. Main Reasons for the Relatively Lower Application Frequency of 5-Axis Machine Tools

1.1 Cost Factors

• Low Initial Investment: 3-axis and 4-axis machine tools have simple structures, and their manufacturing and maintenance costs are significantly lower than those of 5-axis machine tools (the price difference may be several times).
• Low Operating Costs: 5-axis machine tools require more complex programming, operators with higher skills, and more expensive tools and fixtures.

1.2 Matching Degree with Applicable Scenarios

In industrial production, more than 80% of parts can be processed by 3-axis or 4-axis machine tools without the complex functions of 5-axis ones.

• 3-axis machine tools: Suitable for parts with planes, steps, hole systems, and simple curved surfaces (like cylindrical surfaces), such as face milling, drilling of mechanical parts, and outer circle processing of lathes. They cover basic parts like mold plates, shafts, and boxes.
• 4-axis machine tools: After adding a rotating axis, they can process circumferentially distributed holes, grooves (such as radial holes of flanges), spiral surfaces (such as screws), etc. They are suitable for mass production of parts with angular features (such as blade blanks and valve cores).
• 5-axis machine tools: Only target parts with complex spatial curved surfaces or polyhedrons (such as aero-engine blades, impellers, and mold cavities). Such parts account for a low proportion in the entire manufacturing industry (about 10% - 15%) and are mostly concentrated in high-end fields (aerospace, precision molds, etc.).

1.3 Programming and Operation Complexity

• Simple Programming for 3/4-axis: CAM software programming for 3-axis or 4-axis is more intuitive, and the training period for engineers is short.
• Professional Support Required for 5-axis: 5-axis linkage programming needs to deal with issues such as tool interference, and post-processing is complex, requiring high skills from operators.

2. Selection Criteria for 3, 4, and 5-Axis Machine Tools

2.1 Geometric Characteristics of Parts

The geometric characteristics of the parts (especially the distribution of curved surfaces, angles, and hole positions) are the key to determining the number of axes of the machine tool.

2.1.1 Applicable Scenarios for 3-axis Machine Tools

• Simple Geometry: Plane milling, drilling, tapping, contour processing (such as plate and box parts).
• Single-side Processing: All features need to be completed from one direction (vertical or horizontal).
• Low-cost Demand: Limited budget, or processing tasks do not require complex angle adjustments.

2.1.2 Applicable Scenarios for 4-axis Machine Tools

• Cylindrical Surface Features: Processing that needs to rotate around a single axis (such as gears, cams, cylindrical carving).
• Indexing Processing: Positioning through the rotation axis indexing to reduce clamping times (such as multi-face milling, uniformly distributed holes).
• Medium Complexity: More flexible than 3-axis, but no need for 5-axis linkage.

图

2.1.3 Applicable Scenarios for 5-axis Machine Tools

• Complex Curved Surfaces: Parts that require continuous multi-angle processing (such as impellers, aerospace structures, medical implants).
• High Precision Requirements: Avoid error accumulation caused by multiple clampings.
• Single Clamping Forming: Improve the processing efficiency of high-value parts.

2.2 Precision and Batch Requirements

2.2.1 Precision Requirements

• Ordinary Precision (±0.01mm): 3-axis and 4-axis are sufficient (auto parts, general machinery)
• High Precision (±0.005mm): Complex parts require 5-axis (to reduce clamping errors)

2.2.2 Production Batch

• Small Batch/Complex Parts: 5-axis improves efficiency (single clamping)
• Mass Production/Simple Parts: 3-axis/4-axis are more economical