Differences and Applications of Surface Grinding, Cylindrical Grinding and Internal Grinding

1. Processing Objects

Workpiece morphology is key to distinguishing the three processes, each tailored to specific structural types.

Surface Grinding: Focuses on workpiece planes and planar structures, such as flat plates, templates, machine tool guideways, and box end faces. It also handles irregular planes like grooves, steps, and inclined surfaces, ideal for finishing large-area planes.

Cylindrical Grinding: Specializes in the outer surface of rotating workpieces, including outer cylindrical/conical surfaces, shaft shoulder end faces, and steps. Typical workpieces cover machine tool spindles, gear shafts, piston rods, and bearing outer rings.

Internal Grinding: Targets inner holes and related structures, such as inner cylindrical/conical holes and hole end faces. Common workpieces include bearing inner rings, engine cylinder liners, gear inner holes, and hydraulic valve holes.

2. Equipment Types

Surface Grinding: Uses surface grinders, mainly horizontal and vertical spindle rectangular table types. Core components include grinding wheel, reciprocating workbench, wheel head, bed, and hydraulic drive system. Precision models are equipped with CNC systems for automatic feeding.

Cylindrical Grinding: Adopts cylindrical grinders (universal, ordinary, centerless). Key parts include wheel head, headstock, tailstock, and longitudinal workbench, ensuring stable workpiece rotation and feeding.

Internal Grinding: Relies on internal grinders (ordinary, planetary, centerless). Core devices include wheel head, internal grinding tool bracket, workbench, and centering fixture. Vibration suppression structures are strengthened due to the small-diameter internal grinding wheel.

3. Motion Modes

Surface Grinding: Adopts a composite motion of "grinding wheel rotation + workpiece reciprocation + grinding wheel feed". The grinding wheel rotates at 30-50m/s; the workbench moves longitudinally, and the wheel head feeds vertically and horizontally for layered grinding.

Cylindrical Grinding: Features "double rotation + feed" motion, including longitudinal and plunge grinding. Longitudinal grinding suits shafts with large length-diameter ratios, while plunge grinding is efficient for short shafts and steps.

Internal Grinding: Motion varies by equipment. Ordinary internal grinders use fixed workpieces and longitudinal wheel feed; coordinate grinders add planetary wheel motion for high-precision irregular inner holes.

4. Accuracy and Surface Quality

Surface Grinding: Accuracy reaches IT7-IT8, dimensional tolerance ±0.005mm, and Ra 0.8-0.2μm. Precision grinding achieves IT5-IT6 and Ra 0.1-0.025μm for high-precision planar parts.

Cylindrical Grinding: Offers the highest accuracy (IT5-IT6), with roundness error ≤3μm, cylindricity ≤5μm, and Ra ≤0.4μm (0.1-0.05μm for ultra-precision grinding), ideal for high-precision shafts.

Internal Grinding: Conventional accuracy is IT7-IT8, dimensional tolerance ±0.01mm, and Ra 1.6-0.4μm. Planetary or ultra-precision grinding improves to IT6 and Ra 0.2μm for precision inner holes.

5. Application Scenarios

Surface Grinding: Widely used in machinery, mold, electronics, and aerospace industries for finishing mold planes, machine tool guideways, thin parts, and high-hardness components.

Cylindrical Grinding: Core for finishing shafts and sleeves in precision machinery, automotive, and aerospace industries, processing crankshafts, spindles, and parts made of stainless steel or titanium alloy.

Internal Grinding: Serves precision machinery, automotive, and bearing industries, finishing inner holes of bearing inner rings, cylinder liners, and valve seats, especially after quenching.

6. Summary

The three processes differ comprehensively due to workpiece morphology. Surface grinding is versatile for planes; cylindrical grinding excels in high-precision outer surfaces of rotating workpieces; internal grinding suits inner holes with unique adaptability. Select processes based on workpiece structure, accuracy, batch, and material, or combine them for full-surface precision processing.