In addition to the cylindrical grinder, there is another common grinding machine – the surface grinder. To get the best manufacturing practices, here we’ll break down the surface grinding machine working principle, benefits, purposes, applications, process, types, parts, diagram, and comparison between surface grinders and milling machines.
What Is Surface Grinding?
Surface grinding is used to produce a smooth finish on flat surfaces for the metalworking and other industries. According to the standard DIN 8589-11, it is a face-peripheral-longitudinal grinding process, which is used for removing materials from the workpiece in the form of chips with the help of a spinning grinding wheel with rough particles. The grinding wheel may be offset on its peripherally (face-peripheral-longitudinal grinding) or centrally (face-peripheral-plunge grinding). Surface grinding can achieve the desired surface finish with high accuracy.
What are the applications of surface grinding?
Surface grinding has numerous industrial applications. In the aerospace industry, accuracy in parts such as turbines is essential as they operate under strict tolerance limits. Thus, their exact engineering is necessary for efficient functioning. In the automotive sector, parts like crankshafts and engine blocks go through surface grinding due to the need for high precision and quality finishing during mass production. In the manufacturing of medical devices, hernia mesh and surgical tools require high precision as well as smooth and flawless surfaces for the safety of the patients. Furthermore, it is very important in the tool and die making industry for making punches and molds, which need to be highly precise.
Differences between surface grinding and cylindrical grinding
The primary difference between these two grinding processes is the shape of the workpiece and the grinding methods employed. An abrasive wheel is positioned above a stationary workpiece during surface grinding, which is often secured onto a magnetic chuck. This approach is dominant in the automotive as well as aerospace industries when high tolerances are needed during flat surface machining. While performing cylindrical grinding, the focus is on grinding the workpiece’s outer and internal diameters. In this case, both the grinding wheel and workpiece rotate. The workpiece is commonly mounted in a chuck or between centers, which enables rotational movement while the grinding wheel traverses the workpiece’s length.
| Feature | Surface Grinding | Cylindrical Grinding |
|---|---|---|
| Workpiece Geometry | Flat surfaces on non-cylindrical parts | External/internal cylindrical surfaces |
| Applications | Automotive components, aerospace plates | Shafts, rollers, bearings, internal bores |
| Machine Configuration | Workpiece clamped on a magnetic chuck; horizontal wheel on vertical spindle | Workpiece held in a chuck; rotating workpiece with vertical/horizontal wheel |
| Grinding Wheel Types | Flat or cup-shaped wheels | Straight or profiled wheels (external), cup-shaped (internal) |
| Key Outcomes | High flatness, parallelism, and surface finish | Precise diameters, roundness, and concentricity |
| Setup and Fixture | Magnetic chucks or clamps; stationary workpiece | Workpiece rotates; requires alignment for concentricity |
| Typical Operations | Finishing large, flat surfaces with shallow cuts | Processing cylindrical parts with deeper cuts |
What Is a Surface Grinding Machine and How Does It Work?
Surface grinding machines are one of the most commonly used grinding equipment and have a similar construction to milling machines. A general surface grinder has a grinding wheel selectively turned around to grind the surface of a workpiece mounted on a magnetic plate. Initially, the operator positions the workpiece over the bed and secures it there using a clamp. The machine provides numerous adjusting knobs, which can easily adjust the workpiece horizontally(the left or right) and vertically (up or down). The rotating wheel is lowered towards the workpiece, which is also rotating in a predetermined direction. As the wheel rolls over the surface, the bed can rock back and forth to create a consistent finish. The surface grinding wheel is harder than the material of the bench grinders.
What is the primary purpose of a surface grinder is to produce?
Surface grinders can be manually operated or have CNC controls and can also be used to create or apply special surface finishes to components. This type of grinder can produce parts with tight tolerances, exact dimensions, and great flatness. Besides shaping, grinding is employed with a good surface finish. Furthermore, these machines are highly efficient in machining parallel edges; this would be difficult to obtain using other machining techniques.
What are the benefits of a surface grinder?
- Smooth and flat surfaces
- High precision and professional surface finish
- A wide range of materials can be handled
- Maintain and sharpen cutting tools
Surface Grinder vs Milling Machine: What Are the Differences?
| Feature | Surface Grinder | Milling Machine |
|---|---|---|
| Working Principle | High-speed grinding wheel removes material via friction; worktable moves beneath wheel. | Rotating cutter shapes workpiece; cuts intermittently to produce chips. |
| Cutting Tools | Grinding wheels (silicon carbide/aluminum oxide); die/angle grinders for specific tasks. | Milling cutters (end mills, face mills, slotting cutters) are tailored for diverse operations. |
| Material Removal Rate | Low (ideal for finishing, tight tolerances, delicate surfaces). | High (fast material removal for rough machining of metallic parts). |
| Cut Features | Continuous cuts; stable action with minimal interruptions. | Interrupted cuts may cause vibrations affecting surface quality. |
| Heat Generation | High heat from friction; coolants are mandatory to prevent damage. | Less heat is generated; dry machining is possible for some applications. |
| Accuracy | Superior precision and tight tolerances for small/flat surfaces. | Good precision but less fine-tuning for intricate details. |
| Applications | Precision grinding of flat surfaces, grooves, and slots in toolmaking. | Complex shapes in metals, wood, and plastics (gears, molds, engine parts). |
| Draft Sensitivity | No draft impact; wheel covers full surface area. | Requires draft awareness for casting depths and clamping. |
| Coolant Use | Coolants are essential for abrasive machining and chip removal. | Optional for softer materials; fluids are needed for high-speed/hard materials. |
| Entry/Exit Angles | Full/line contact; no critical entry/exit angles. | Gradual entry/exit required to avoid tool damage. |
| Clamping | Magnetic chucks handle most iron castings; minimal deflection risk. | Secure clamping is critical for malleable/nodular iron castings. |
| Vibration | Less prone to chatter on rigid setups with light feeds. | Chatter risk in thin-walled castings may damage tools. |
Types of Surface Grinders
According to the spindle orientation, surface grinding machines can be categorized into horizontal spindle (peripheral) and vertical spindle (wheel-face) types.
| Feature | Horizontal Spindle Reciprocating Table | Horizontal Spindle Rotary Table | Vertical Spindle Reciprocating Table | Vertical Spindle Rotary Table |
|---|---|---|---|---|
| Spindle Orientation | Horizontal | Horizontal | Vertical | Vertical |
| Table Movement | Reciprocates (longitudinal) | Rotary (circular) | Reciprocates (back and forth) | Rotary (circular) |
| Grinding Wheel | Cup, segmental, or straight wheel | Cup or segmental wheel | Large segmented or disk-type wheel | Segmented or cup wheel |
| Cross-Feed | Wheelhead moves perpendicular | Wheelhead moves radially | Limited transverse movement | Wheelhead adjusts radially |
| Down-Feed | Manual or automatic | Vertical adjustment | Vertical feed | Vertical feed |
| Applications | Flat surfaces, slots | Large circular workpieces, gears | Heavy-duty grinding of large surfaces | High-production grinding of round workpieces |
There are also single and double-disc surface grinding machines. A single-disc grinder is quipped with a single abrasive wheel; it has a relatively large contact area and is primarily used for deburring because of faster and more efficient material removal. The double-disc grinder features two grinding wheels arranged to grind in opposite directions. The workpiece is sandwiched between the two abrasive wheels, both sides can be ground simultaneously.
Main Parts of Surface Grinding Machines
- Grinding Wheel: The main cutting tool used to remove material from the workpiece using abrasive particles.
- Base: The machine base holds all of the parts together and also acts as a device to control machine vibration during use.
- Work Table: The table on which the workpiece is rested during grinding and offers support and stability.
- Saddle: The part that links the base and the working table and enables horizontal movement.
- Hand Traversing Wheel: The wheel head can be moved along the table to enhance the grinding process to allow the grinding of large-sized workpieces.
- Cross Slide Hand Wheel: The work table can be moved crosswise (to the grinding wheel), and can carry out automatic feed for grinding.
- Magnetic Table: A device that magnetizes and secures the workpiece while grinding.
- Splash Guards: Barriers that prevent sparks and metal chips from hitting the grinder’s user.
- Column: The column of the grinder, which acts as the main driving structure and supports the head.
- Head: The head houses the grinding wheel and is the vertically moving part. This is used to compensate for the depth of cut.
- Wheel Guard: A cover over the grinding wheel that limits the contact an individual can make with the wheel to reduce the likelihood of injury.
- Vertical Feed Hand Wheel: For raising and lowering the grinding wheel head, and advancing the depth of cut.
- Coolant Pipe: A tube to deliver coolant to the grinding area to prevent overheating and increase the grinding efficiency.
Surface Grinding Machine Diagram
Process of Surface Grinding – How to Use a Surface Grinder
1. Clamp Workpiece
Fix the workpiece on the surface grinding machine table. A magnetic chuck works well for magnetizable materials, while mechanical clamps work best for non-magnetic materials. Clamp the workpiece as accurately as possible helps avoid moving and helps achieve accuracy and safety. Clamping force should not be too great, as it may damage the workpiece.
2. Select a Grinding Wheel
Select a grinding wheel according to the workpiece material and the required surface finish. The most common abrasives are aluminum oxide for steels and alloys, silicon carbide for cast iron and nonferrous metals, and diamond or cubic boron nitride for hard materials like ceramics. Other considerations include grain size, hardness of the wheel, and bonding agent; finer grains lead to better surface finish while harder wheels suit softer materials. High-efficiency grinding wheels are either resin bonded or vitrified.
3. Dress the Grinding Wheel
The performance of the grinding wheel changes when it is dull or not round. As such, it must be dressed. Dishing restores a wheel’s sharp edges and contours, enhancing the even distribution of abrasives. Diamond tools are commonly used, but certain conditions, like depth of cut and feed rate, must be maintained for skills to yield the best results.
4. Adjust the Position of the Grinding Wheel
Balance the distance of the grinding wheel from the workpiece to avoid both collision and grazing. Uniform contact of the wheel with the workpiece surface requires its height to be set accurately.
5. Start the Grinding Wheel
Permit the motor for the grinding wheel to be on and allow it to reach its set speed. Effective and safe grinding is achieved by waiting for the wheel to stabilize before the feed begins.
6. Feed the Workpiece
In gradual stages, move the workpiece underneath the rotating grinding wheel. Both manual and automatic feeding are appropriate. Through control of the feed rate, damage to the wheel and workpiece from excessive material removal is avoided.
7. Material Removal and Surface Finish
Improved surface finish and flatness occur as the rotating grinding wheel interacts with the workpiece, which is fed into the wheel. The abrasive grains embed themselves into the grinding wheel, and fine chips are produced. Apply cutting fluid to the sharpening zone to cool it while also reducing friction, getting rid of debris, and maintaining the effectiveness of the wheel and the quality of the surface.
8. Inspect the Workpiece
Check the workpiece after its surface is ground to ensure that all features like flatness, parallelism, roughness of the surface, and others are within the specified limits. For high-precision components, evaluation of the workpiece can be done with special devices such as optical interferometers.
9. Clean the Workpiece
Like parts used in machines, the workpiece must be scrubbed to remove all swarf produced during grinding as well as cutting oils to aid in the prevention of corrosion. Cleaning may be performed ultrasonically or chemically, or by compressed air, depending on the material.
10. Maintenance of Grinding Wheel
During and after use, grinding wheels should always be cleaned to remove constructed material, and always be stored in dry and ventilated areas to avoid moisture damage. Shattered or heavily worn wheels should always be replaced immediately for safety and consistency in further grinding results.
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