CNC Machine Tool Selection Guide

1. Typical workpieces processed by CNC machine tools

1. Horizontal machining center:

Box parts: Process the bottom surface on a vertical machining center → Process the surrounding surfaces on a horizontal machining center.

2. Vertical machining center:

Plate parts: Process flat surfaces on a vertical or gantry milling machine → Process various holes on a vertical machining center or tapping machine;

Cavity mold parts: Process the shape and base surface on a conventional machine → Process the profile on a CNC milling machine → Finish on a high-speed CNC milling or engraving machine → Polish or electro-etch the profile;

3. Turning machining center:

Shaft parts: Mill the end face and drill the center hole → CNC lathe (rough machining) → CNC grinder (finishing);

Flanges and disc parts: CNC lathe (rough machining) → Turning center (finishing);

4. For simple box types, irregular shapes, and cavity mold workpieces, if the machining allowance is large (rough machining) and mainly involves profile machining with less tool change, CNC milling machines are generally selected.

5. For box types, irregular shapes, and cavity mold workpieces, if the machining allowance is small (finishing) and mainly involves single-sided hole systems requiring frequent tool changes, vertical machining centers are generally selected.

6. For box types, irregular shapes, and cavity mold workpieces, if the machining allowance is small (finishing) and mainly involves multi-sided hole systems requiring frequent tool changes, horizontal machining centers or vertical machining centers with rotary tables are generally selected.

7. For complex multi-axis curved surfaces, spatial multi-angle surfaces, or hole parts, four-axis, five-axis machines, or turning-milling composite machining centers are generally selected.

2. Differences and similarities among various CNC machine tools

1. CNC milling and machining centers

Used for processing workpieces with a large milling volume, requiring moderate speed from the CNC system, with spindle speeds around 0-8000 RPM. Sometimes low-speed high torque is needed, requiring spindle reduction to increase torque, focusing on metal removal rate. The rigidity requirement for the base part is very high, and the rigidity requirement for the moving part is also very high.

Advantages: Capable of heavy cutting, suitable for processing parts with concentrated processes; Disadvantages: Due to the high rigidity of the moving parts and relatively heavy mass, the machine's rapid response capability is moderate, and it is ineffective for small tool processing and rapid feed displacements.

2. CNC engraving and milling machine

Used for processing smaller milling volumes or soft metals. Requires a high-speed CNC system, with spindle speeds around 3000-30000 RPM. The rigidity requirement for non-moving parts is high, while the moving parts mainly consider rapid response capability, aiming to be as light as possible while maintaining certain rigidity.

Advantages: Capable of relatively fine processing with high processing accuracy. Can perform high-speed processing for soft metals; Disadvantages: Due to poor rigidity, heavy cutting is not possible.

3. High-speed cutting machine tools

Used for processing medium milling volumes and reducing the grinding volume after milling. Requires a high-speed CNC system and good servo motor characteristics, with spindle speeds around 1500-30000 RPM. The rigidity requirement for the base part is very high, and the rigidity requirement for the moving part is relatively high, while also aiming to improve response speed as much as possible.

Advantages: Capable of medium and small cutting, suitable for processes that separate semi-fine and fine machining parts; when used correctly, it can achieve low costs and reduce grinding volume. Disadvantages: High requirements for tools, operators, and manufacturers, and significant losses can occur due to operator errors.

3. Choosing CNC machine tool specifications

1. The machine tool's worktable area should be larger than the typical part size to facilitate the installation of fixtures or clamps, generally at least 100mm larger;

2. The machine tool's travel should be greater than the typical part processing range to facilitate tool entry and exit, generally at least 150mm larger;

3. The machine tool's worktable load capacity should be greater than the weight of the parts and fixtures.