Surface & Cylindrical Grinding

Surface grinding is an invaluable finishing process using a spinning wheel with an abrasive surface to create an impeccably smooth finish. This method excels at achieving exceptional surface finishes while adhering to remarkably tight tolerances—think precision down to plus or minus 0.0001 inches or about 0.002 mm.

The process starts with a rotating grinding wheel, which is embedded with abrasive particles like aluminium oxide or silicon carbide, all bound together by a durable binder.

This wheel spins at a high velocity, passing over the workpiece with the depth of each cut carefully controlled by how far the wheel descends. Surface grinding typically involves several passes over the material, with each pass delicately removing layers of material to incrementally improve the finish.

But it’s not just about making things smoother. Depending on the desired outcome, various specific techniques can also be deployed.

Rough grinding

Think of this as the heavy lifter. It’s all about quickly removing substantial amounts of material, naturally resulting in a rougher surface texture.

Precision grinding

This is where finesse comes into play. For tasks that demand extreme accuracy and a polished finish, this method uses a finer-grit wheel to gently shave off just microns at a time.

Creep-feed grinding

This technique is tailored for more intensive removal. It takes off larger quantities of material in just one pass, using a slow, steady feed rate that allows for deeper cuts.

Cylindrical grinding meticulously shapes the external surface of an object, which is carefully positioned on a central axis. An abrasive wheel then methodically removes the surplus metal, similar to how surface grinding operates. This technique is particularly valued for producing components that require not just a smooth surface but also precise dimensions.

What’s so special about cylindrical grinding?

Well, it’s remarkably precise, making it the go-to method for sensitive parts, such as those you’d find in the automotive industry.

The process can refine either the inner or outer surface of a cylindrical workpiece, and it’s even adept at shaping intricate threads. The magic happens as an abrasive grinding wheel whittles away material from the workpiece, sculpting it to the desired dimensions and surface texture.

Here’s how it typically goes

The workpiece gets clamped between centres or held in a chuck. It then spins while the grinding wheel moves back and forth along its entire length, shaving off material as needed. The depth of cut depends largely on how forcefully the wheel presses against the workpiece, which keeps spinning at a steady pace.

And the final touches? They depend on the finish you’re after. Here are a few techniques.

Rough grinding

This is all about speed. It quickly removes a lot of material, leaving behind a rough surface texture.

Finish grinding

For those who need precision and a polished finish, this method uses a finer-grit wheel and lightly skims the surface, removing just a few microns of material at a time.

Plunge grinding

Perfect for creating specific shapes or profiles, like a groove. This involves driving the grinding wheel straight into the workpiece at a precise angle and depth.

Each technique brings its own flair to the table, transforming rough cylindrical blanks into finely crafted parts with impressive accuracy and surface quality.

Steel

Stainless Steel

Aluminium

Titanium

Horizontal Surface Grinding Machine

These have a magnetic horizontal bed or table that holds down the components or vice. The bed moves back and forth underneath the machine’s grinding wheel. The table is adjusted vertically to control the depth of cut.

Cylindrical Grinding Machines

1. Plain Cylindrical Grinding Machine

This type of machine has a single grinding wheel mounted on a horizontal spindle which traverses along the area of the workpiece to be machined. The workpiece can be mounted between centres, in a chuck or on a magnetic plate.

2. Universal Cylindrical Grinding Machine

These are similar to the Plain Cylindrical Grinder but have a swivelling work head adjustable to grind angles and tapers on the workpiece.

3. Centreless Grinding Machine

As the name suggests, these don’t use centres or a chuck to hold the workpiece. Instead, they use a regulating wheel that feeds the workpiece between the grinding wheel and a support blade. The grinding wheel removes material from the workpiece while the support blade controls its position.

Surface Roughness

Surface roughness can influence a component’s performance, impacting its wear, friction, and fatigue resistance. Several techniques are typically used to measure and monitor this parameter.

• Stylus Profilometry
• Optical Profilometry
• Atomic Force Microscopy (AFM)

Roundness

Ensuring roundness is crucial for the fit and function of cylindrical components. Measurement techniques include.

• Roundness Tester
• Coordinate Measuring Machines (CMM)

Dimensional Accuracy

Maintaining dimensional accuracy is vital for the component’s fit and functionality, processes and tools include.

• Traditional Tools – Micrometres, calipers, and gauge blocks.
• CMMs
• In-process Gauging

Process Control and Monitoring

Controlling the grinding process itself is as important as measuring the final product. Monitoring parameters such as wheel wear, coolant flow, temperature, vibration, and grinding forces allows operators to optimize the grinding process. By keeping a close watch on these variables, it’s possible to reduce defects, maintain consistency, and uphold a high standard of quality throughout production.