Classic Universal Small Precision M250 Cylindrical Grinding Machine

Core Characteristics of the M250 Small Grinding Machine

The M250 is a very classic universal, small, precision cylindrical grinding machine. Known for its compact structure, high precision, and wide applicability, it is widely used in tool rooms, maintenance workshops, laboratories, and small-batch production.

Core Features of the M250 Small Grinding Machine

I. Structural Layout and Rigidity Characteristics

1. Compact Design and Small Footprint

   • As a small grinding machine, it has a compact structure and typically occupies less than 2 square meters, making it ideal for installation in workshops or laboratories with limited space.

2. High Rigidity Bed

   • Despite its small size, the bed is usually made of high-quality cast iron with a rational structure, providing good rigidity and vibration damping characteristics, forming a stable foundation for precision grinding.

3. Precision Guideway System

   • The table and wheelhead typically use manually or hydraulically driven precision sliding guideways (V-and-flat type). These guideways offer good rigidity, smooth movement, and strong vibration resistance, representing the classic choice for traditional precision grinding machines.

II. Performance and Configuration Characteristics

1. Grinding Wheel Spindle System

   • High-Precision Spindle: Utilizes hydrodynamic sliding bearings or precision rolling bearings to ensure high rotational accuracy and stability of the spindle at high speeds, which is key to achieving high roundness and low surface roughness.

   • Grinding Wheel Size: Typically equipped with a grinding wheel with a diameter of around 250mm to 300mm, which is also the origin of its model name "M250".

2. Workhead and Tailstock

   • Workhead: The spindle is supported by precision bearings and can achieve variable speed (mechanical or inverter-controlled) to adapt to workpieces of different materials and diameters.

   • Centers: Both the workhead and tailstock are equipped with Morris tapers (e.g., Morse Taper #4) for accurate positioning and easy clamping.

   • Tailstock: The quill moves flexibly, and the spring pressure is adjustable, ensuring a stable clamping force on the workpiece during grinding.

3. Feed System

   • Cross Feed (Infeed): The wheelhead cross feed usually employs a manual fine-pitch lead screw equipped with a dial or DRO, enabling precise micron-level infeed to control the grinding depth.

   • Longitudinal Feed: The table longitudinal movement can be manual or hydraulic, ensuring smooth motion without creep.

III. Technical Advantages and Application Characteristics

1. High-Precision Machining Capability

   • With correct operation and maintenance, the M250 can consistently achieve:

     • High Roundness: ≤ 0.002 mm

     • High Cylindricity: ≤ 0.005 mm

     • Low Surface Roughness: Ra ≤ 0.4 μm or even lower

2. Operational Flexibility and High Versatility

   • Ideal for small-batch, high-mix part processing, offering easy setup and quick changeover between different products.

   • Capable of performing various grinding operations by equipping different attachments and fixtures.

3. Wide Machining Range

   • Primarily used for grinding cylindrical and conical external surfaces and shaft shoulders.

   • Typical applications include:

     • Precision shaft parts like transmission shafts, motor shafts, and spindles.

     • Precision measuring tools like plug gauges and snap gauges.

     • Special small parts for scientific research and experiments.

4. Cost-Effectiveness and Ease of Maintenance

    

   

   Specification data

    

    

   • As a basic model, it has a relatively low acquisition cost. Its simple structure and mature, reliable mechanical components make it easy to maintain, and it is relatively user-friendly for operators.

   Table size (length x width)			mm	500×250
   Workbench front and rear travel			mm	260
   Workbench left and right travel			mm	560
   Workbench left and right moving speed (stepless)			m/min	3 20
   Worktable front and rear feed	Continuous (stepless speed regulation)		mm/min	50-500
   	Intermittent (stepless speed regulation)		mm	1 20
   Workbench T-slot (number of slots × slot width)			mm	1×14
   grinding head	Distance from grinding wheel spindle centerline to work table		mm	470
   	Vertical feed handwheel feed amount	Handwheel per turn	mm	2
   		Handwheel per grid	mm	0.01
   	Transverse feed handwheel feed amount	Handwheel per turn	mm	4
   		Handwheel per grid	mm	0.02
   	Grinding wheel spindle speed		r/min	2850
   	Grinding wheel size (outer diameter × width × inner diameter)		mm	Φ200×16×Φ31.75
   hydraulic system	spindle motor		kw	1.5
   	Work pressure		Mpa	3
   	Fuel tank capacity		L	60
   Working accuracy	Parallelism of the machined surface to the base surface		mm	300∶0.01
   	surface roughness		μm	Ra0.32
   Machine weight	net weight		kg	1100
   	Gross weight		kg	1200
   Total motor power			kw	2.79
   Grinding head motor power			kw	1.1
   frequency			w	50
   Overall dimensions (length × width × height)			mm	1700×1300×1800
   Packing box dimensions (length × width × height)			mm	1400×1200×1900

The M250 Small Grinding Machine is the "classic workbench" in the field of precision machining. It does not pursue extreme efficiency like large, fully automatic grinders, but instead achieves a perfect balance between precision, flexibility, and cost-effectiveness for small workpieces.

For users involved in part rework, tool manufacturing, prototype development, or small-batch production of precision shafts, the M250 is a reliable, practical, and cost-effective piece of fundamental precision equipment. It represents the reliability and essence of traditional mechanical grinding machines.