GD&T in CNC Industry
What is GD&T?
GD&T (Geometric Dimensioning and Tolerancing) हे एक सिस्टम आहे जे ड्रॉइंगवर दिलेले मोजमाप आणि त्यांच्या परवानग्या (tolerances) अचूकपणे परिभाषित करतं. याचा उपयोग CNC, VMC, HMC, CMM अशा मशीनिंग प्रक्रियांमध्ये केला जातो.
Why GD&T is Important?
- Parts ची फंक्शनल अचूकता सुनिश्चित करतो
- Inspection आणि Quality Control सोपं करतो
- Communication between design, machining, and quality teams सुधारतो
Common GD&T Symbols
| Symbol | Name | Description |
|---|---|---|
| ⌀ | Diameter | Cylindrical Feature Indication |
| ⫽ | Flatness | Surface should be flat within tolerance |
| ⌖ | Position | Accurate location of holes/slots |
| ⏥ | Parallelism | Two surfaces should be parallel |
| ⏦ | Perpendicularity | Surface should be at 90° |
| ⌯ | Concentricity | Common center between features |
| ↗ | Angularity | Surface must be at specified angle |
| ⏤ | Symmetry | Equal balance about centerline |
GD&T Applications in CNC / VMC / HMC
| Machine | GD&T Use | Example |
|---|---|---|
| CNC Lathe | Runout / Concentricity | Shaft turning – ensure runout within 0.02mm |
| VMC | True Position | Drilling 4 holes in flange – exact location |
| HMC | Perpendicularity / Flatness | Machining block faces – ensure 90° and flat |
| CMM (Inspection) | All GD&T symbols validation | Checking angularity of side faces of part |
Real-World Example
Component: Flange
GD&T Requirement: True position ⌖ of 4 bolt holes Ø12mm within ⌀0.1mm tolerance from center
Why: So that flange fits exactly with mating part without misalignment