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CITIZEN SEIMITSU (THAILAND) CO., LTD.

1. What is Machining?
Machining refers to techniques for shaping and sizing materials such as metals and plastics using methods like cutting and grinding. With the advancement of automation through CNC (Computer Numerical Control), high precision and high efficiency are now essential in modern manufacturing. The choice of machining method has become a critical factor in both quality and cost. Among these, the three primary machining methods are turning, milling, and drilling.

2. Characteristics and Applications of Turning
Turning is a process in which the workpiece rotates while a stationary cutting tool (bit) removes material. This method, using a lathe, is particularly suitable for machining cylindrical shapes like shafts.

Main Applications:
- Finishing outer and inner diameters
- Face machining
- Step or taper processing on cylindrical parts

Features:
- High concentricity for symmetrical shapes
- High machining efficiency, suitable for mass production
- Continuous machining of outer diameter, inner diameter, and face

Points to Note:
- Not suitable for non-rotational symmetrical shapes
- Attention needed for tool wear and thermal deformation

3. Characteristics and Applications of Milling
Milling involves fixing the workpiece while the rotating milling cutter performs the cutting. This versatile method is not only suitable for flat surfaces but also for grooves and contour shaping.

Main Applications:
- Surface finishing
- Keyway and T-slot cutting
- Machining of parts with irregular shapes or steps

Features:
- Capable of complex shapes with multi-axis control (especially with machining centers)
- High efficiency achievable through optimized cutting conditions
- Good chip evacuation helps extend tool life

Points to Note:
- Setup can become complex
- Tool selection and cutting conditions greatly influence machining quality

4. Characteristics and Applications of Drilling
Drilling is one of the most basic machining methods, involving the vertical penetration of a drill bit into the workpiece. It is widely used for pre-holes and mounting holes.

Main Applications:
- Through-holes for bolts and pins
- Pre-holes for reaming
- Creation of center holes

Features:
- Simple structure and efficient
- Low machining cost and wide variety of tools
- Easy to automate

Points to Note:
- Limited accuracy in depth and diameter of holes
- For deep holes, chip removal and center deviation require caution
- Precision holes may require post-processing like reaming or boring

5. Choosing Machining Methods and Process Planning
Selecting a machining method should not be based solely on shape or size. It's important to consider the balance of the entire process. In most cases, multiple methods are combined to complete a part, with the following considerations being crucial:

- Choose the method that suits the material and shape of the workpiece
- Set process sequences based on required precision and tolerances
- Understand the capabilities of available equipment (lathe, machining center, drill press, etc.)
- Plan with an eye on reducing steps and improving yield

For example, a common process flow might involve turning to machine the outer diameter, followed by milling for side features, and finally drilling to create threaded holes. This approach helps achieve both stable quality and high productivity.