EMAG G 250

$600,000 - $850,000 Updated 2026-03-19

Key Specifications

Max Workpiece ⌀

250 mm (10 in)

max workpiece length

550 mm (21.5 in)

max face width

380 mm (15 in)

module range

helix angle

+45° / -45°

grinding wheel diameter

170 / 250 mm (6.5 / 10 in)

Overview

The EMAG G 250 is a CNC gear generating grinding machine designed for high-precision finish grinding of spur and helical gears with workpiece diameters up to 250 mm (10 in) and modules from 0.5 to 7.0 mm. As the mid-range workhorse in EMAG's G-series lineup, the G 250 handles the broadest range of automotive and light industrial gear grinding applications — from passenger car transmission gears to commercial vehicle pinions and industrial reducer gears that require DIN 3-5 quality after heat treatment.

The G 250 features dual work spindles that eliminate non-productive times almost completely, following the same philosophy as the smaller G 160. While one spindle grinds, the other loads and unloads, keeping the grinding wheel cutting for nearly the entire production cycle. The machine accommodates workpiece lengths up to 550 mm (21.5 in) and face widths up to 380 mm (15 in), substantially exceeding the G 160's capacity and enabling grinding of wider-face gears used in commercial vehicle and industrial gearbox applications.

Grinding wheels from 170 mm to 250 mm (6.5 to 10 in) diameter with maximum width of 180 mm (7 in) operate at peripheral speeds up to 80 m/s. The helix angle range of +/-45 degrees covers all standard automotive and industrial helical gear geometries. A dressing tool diameter of 120 mm (4.5 in) enables precision wheel profiling for maintaining gear quality throughout production runs. The overall machine dimensions of 4,120 x 2,200 x 2,700 mm provide a production-friendly footprint.

The Siemens SINUMERIK 840D sl control supports twist-control grinding, superfinishing, and a special shift strategy for low-noise gears. These advanced process capabilities enable the G 250 to produce gears optimized for NVH performance — increasingly critical as electric vehicle drivetrains make gear noise more perceptible without engine masking. For gear manufacturers requiring a versatile generating grinder that spans automotive and light industrial applications, the G 250 delivers the combination of capacity, productivity, and quality capability needed for modern gear production.

Full Specifications

Parameter	Value
Max Workpiece Diameter	250 mm (10 in)
Max Workpiece Length	550 mm (21.5 in)
Max Face Width	380 mm (15 in)
Module Range	mm
Helix Angle	+45° / -45°
Grinding Wheel Diameter	170 / 250 mm (6.5 / 10 in)
Max Grinding Wheel Width	180 mm (7 in)
Grinding Spindle Speed	80 m/s peripheral
Dressing Tool Diameter	120 mm (4.5 in)
Workpiece Spindles	Dual (simultaneous load/grind)
CNC Control	Siemens SINUMERIK 840D sl
Floor Space Required	4,120 x 2,200 x 2,700 mm (162 x 86.5 x 106 in)
Workpiece Dia Max	mmin
Workpiece Length Max	mmin
Face Width Max	mmin
Helix Angle Degree	°
Grinding Wheel Dia	mmin
Grinding Wheel Width Max	mmin
Grinding Spindle Speed Max	m/s
Dressing Tool Dia	mmin
Machine Dimensions L X W X H	mm

Specifications sourced from emag.com — verified 2026-03-28

Strengths & Limitations

Strengths

Dual work spindles eliminate virtually all non-productive loading time, maximizing grinding wheel utilization across the full production shift
250 mm diameter and module 7.0 capacity spans automotive passenger car gears through commercial vehicle and light industrial gearbox applications
380 mm maximum face width accommodates wide-face gears used in heavy-duty transmissions and industrial reducers
Twist-control grinding, superfinishing, and low-noise shift strategies produce NVH-optimized gear flanks for quiet-running drivetrains
80 m/s grinding wheel speed with both conventional and CBN wheel support enables optimized cycle times for different production scenarios
Siemens 840D sl control with integrated gear grinding software provides comprehensive process control and quality management

Limitations

250 mm diameter limit excludes larger industrial and wind energy gears that require the G 400 or dedicated profile grinders
Larger footprint than the G 160 may be a consideration for shops with constrained floor space in existing production lines
Dual-spindle mechanism adds maintenance complexity and cost compared to simpler single-spindle gear grinding machines
Module 7.0 maximum still excludes heavy-industrial and mining gear applications where modules exceed 10 mm

Best For

Automotive transmission manufacturers producing finish-ground gears up to 250 mm diameter for passenger car and light truck gearboxes Commercial vehicle drivetrain suppliers grinding medium-module pinions and gears for truck and bus transmissions Electric vehicle manufacturers requiring NVH-optimized gear grinding with twist-control and superfinishing capability Industrial gearbox builders producing precision-ground gears for reducers, speed increasers, and power transmission applications Gear manufacturers seeking a single machine that bridges automotive and light industrial grinding applications

Frequently Asked Questions

01 What is the difference between the G 250 and G 160?

The G 250 extends maximum workpiece diameter from 160 mm to 250 mm and module range from 4.0 to 7.0 mm. Maximum face width increases from 180 mm to 380 mm, and workpiece length from 300 mm to 550 mm. The G 250 also supports larger grinding wheels (up to 250 mm vs 275 mm diameter). Both share the dual-spindle concept for maximum productivity. The G 250 is the right choice when gear diameter or face width exceeds the G 160's capacity.

02 What is the special shift strategy for low-noise gears?

The low-noise shift strategy is a grinding technique that varies the axial position of the grinding wheel during the generating grinding process to produce a specific micro-geometry on the gear tooth flanks. This controlled micro-geometry reduces meshing noise by distributing contact stress more evenly across the tooth face. The technique is increasingly important for EV drivetrains where gear noise is not masked by engine sound.

03 Can the G 250 perform both generating and profile grinding?

The G 250 is primarily designed for gear generating grinding using threaded grinding wheels. While it supports superfinishing operations, dedicated profile grinding of individual tooth flanks is better handled by EMAG's G 375 H or G 500 H profile grinding machines. Generating grinding is significantly faster than profile grinding for standard involute gear forms.

04 What surface finish quality can the G 250 achieve?

The G 250 achieves gear flank surface finishes of Ra 0.2-0.4 micrometers in standard generating grinding mode. With the superfinishing option, surface finishes of Ra 0.1 micrometers or better are achievable, which is required for high-performance automotive and EV gearing where surface finish directly impacts noise, efficiency, and fatigue life.