Surface grinding is an important manufacturing process used to remove material and create a flat surface. Using the abrasive wheel on a surface grinder, the process also creates very fine surface finishes.
Unlike other popular grinding processes like cylindrical grinding and centerless grinding, surface grinding is not used to shape cylindrical parts, and is instead used to machine flat plane surfaces. It is useful for making very fine finishes, and has some specialist applications such as sharpening machine tools. It is a form of precision machining rather than a pure surface finishing technique.
This article covers the basics of surface grinding, looking at how the surface grinding process works, suitable materials for surface grinding, and common surface grinding applications.
How Does the Surface Grinding Process Work?
Surface grinding is a cutting process that uses tiny ceramic or aluminum oxide grains to remove material from the workpiece. It can therefore be considered a machining process with a geometrically undefined cutting edge: those thousands or millions of tiny abrasive grains function as the cutting tool, rather than a defined edge found on a tool like an end mill.
Like other grinding processes, surface grinding uses an abrasive wheel to remove material. However, unlike some comparable processes, it uses a magnetic or vacuum chuck and a reciprocating table for workholding.
During the surface grinding process, the abrasive wheel of the surface grinder spins at high speed above the workpiece, removing material where it makes contact. With the workpiece held securely in place—usually by magnetic force—the reciprocating table moves the workpiece. After each pass, the wheel moves sideways to allow the spindle to lower a tiny amount for the next pass.
Metal can heat up quickly from the abrasion, so coolant is usually sprayed continuously at the contact point. This prevents temperature-related warping and flushes away small metal particles. However, intermittent dressing of the grinding wheel is required to remove clogged particles and re-expose sharp edges.
Surface grinding machine speeds range from 5,500 to 6,500 fpm (feet per minute) or approximately 28 to 33 m/s (meters per second).
What Materials Can Be Surface Ground?
Surface grinding is typically used for the cutting of ferrous metals. This is partly because of the magnetic workholding of surface grinders, and partly because they are less likely to melt and clog the cutting wheel.
Common surface grinding materials include:
- Cast iron: Common in industrial and automotive applications with good dimensional stability and brittle chips
- Mild/carbon steel: Very easy to machine due to low hardness and do not clog the abrasive wheel
- Tool/hardened steel: Common for the grinding of cutting tools after heat treatment with excellent dimensional stability
- Stainless steel: Less common due to heat generation
- Non-ferrous metals and plastics: Possible but less common due to clogging of abrasive wheel
When it comes to the abrasive wheel of the surface grinding machine, a few different abrasive materials can be used.
The most common abrasive materials are:
- Aluminum oxide: Common and versatile abrasive that suits most ferrous metals
- Silicon carbide: Good for non-ferrous metals due to hardness and sharpness
- Super-abrasives: Materials like diamond and cubic boron nitride for hardened steel grinding
Surface Grinding Capabilities: Accuracy and Surface Finish
Compared to other subtractive manufacturing processes like milling and turning, surface grinding offers a very high level of accuracy and surface finish, as well as the ability to cleanly cut hardened materials.
The table below lists standard and precision surface grinding tolerances and achievable surface finishes.
| Flatness | Surface finish |
| Standard | ±0.013 mm (±0.0005″) | 16–32 Ra |
| Precision | ±0.005 mm (±0.0002″) | 8–16 Ra |
Surface grinding tolerances can be very low because of the millions of tiny cutting edges and low tool pressure of the process, which minimizes deflection. Their precision is roughly an order of magnitude greater than a CNC mill.
Common Surface Grinding Applications in Precision Manufacturing
As a highly accurate cutting process that doubles up as a semi-finishing process, surface grinding is essential to any machine shop. Surface grinders have several uses across industries, though they are less geometrically versatile than some other subtractive manufacturing equipment.
Some of the most important surface grinding applications are listed below.
Tooling
Surface grinding is ideal for shaping dies, molds, and other tooling. This is because it offers a very high level of precision and because it is capable of accurately cutting hardened tool steel.
Tool and Cutter Maintenance
In addition to the production of tooling, surface grinding is often used to sharpen manufacturing tools using specialized fixtures.
Automotive and Aerospace
Surface grinding is regularly used for the machining and finishing of engine components that require very tight dimensional tolerances.
Precision Grinding
In many industries, a surface grinder may be deployed for precision grinding on surfaces that require the tightest tolerances and finest surface finishes.
Other Hard Material Applications
Other surface grinding applications include the cutting of various parts made from ultra-hard metals that would not be processable with a mill or other subtractive equipment.
Surface Grinding Services at 3ERP
Choosing the right surface grinding service provider involves finding a company with experience across industries that can take your design from start to finish.
3ERP and its partner network is well placed to realize your next surface grinding project. We are ISO 9001:2015 certified, and our CNC grinding services can achieve tolerances down to ±0.005 mm and mirror-level surface finishes.
Frequently Asked Questions
When should I use surface grinding vs milling vs cylindrical grinding?
Use surface grinding for flat finishes, tight tolerances, and hardened metals that would damage other cutting tools. Use milling for fast metal shaping and cylindrical grinding for high-precision round parts.
What is surface grinding dressing?
Surface grinder dressing is the process of cleaning and sharpening a grinding wheel surface by passing a diamond-tipped tool across the wheel face to restore its cutting efficiency and performance. It removes metal buildup and exposes fresh, sharp grains.
Is surface grinding only for flat parts?
No. The grinding wheel can be shaped with a specific profile for non-flat applications.
Can surface grinding be used for non-ferrous metals?
Surface grinding is best for ferrous metals because ferrous metals make brittle chips that do not easily clog the pores of the abrasive material on the wheel. Because non-ferrous metals are more gummy, they require shorter passes and lots of lubrication and coolant.
How much does a surface grinder cost?
Surface grinders vary in price depending on their size, quality, and newness. Used entry-level grinders can cost under $10,000, while high-end precision systems from brands like Okamoto and Kent USA cost upward of $50,000.
