Intro to Grinding Methods, Machines and Tools

April 16, 2021 11:00 am

Grinding is a widely used abrasive finishing process. Did you know grinding machines have been around for centuries? Well, not the electric ones but the ones that are powered via a pedal. 

Oftentimes grinding operations are compartmentalized by machinists and considered separate from typical cutting processes used in  machine shops. This is most likely for a couple reasons, one being that grinding operations are quite often mistaken as a rubbing process and not a cutting one. Also, grinding is a cutting process that actually creates a smooth finish, unlike the other processes in the category that create unsmooth surfaces. 

There are a variety of machines and tools that perform grinding operations. Read on to learn more about the different methods that are used to get the job done along with some books to check out if you’re interested in deepening your grinding knowledge.

How grinding works 

Grinding is used to finish workpieces so that they meet the required surface finish quality. It rids unwanted material from the workpiece, like any rough texture that remains from previous machining applications. 

Grinding machines or tools use an abrasive wheel to remove metal from the workpiece. When the wheel rotates, it cuts material off the workpiece by cutting. The amount of material removal is dependent on factors like abrasive material and grit selection. The video below explains how to select the right abrasive. 

 

Grinding is a pretty diverse segment of machining, as the amount of material removal varies. Depending on the grinding attachment and project, both miniscule and larger amounts of material can be removed. For example, grinding can be used to either produce fine finishes or work in larger production environments to rough out large volumes of metal. Grinders can also be used to sharpen tools as seen in the video below. 

 

 

Grinding methods

There are different ways to accomplish your grinding operations. Several factors to consider are workpiece size, shape and features along with the production quantity. Machine tools are a larger investment whereas handheld tools are more affordable. 

Grinding machine tools 

Belt grinders are versatile and used for different applications like finishing, deburring and stock removal.
Bench grinders are connected to a workbench or some type of floor stand. Depending on the type of wheel, a bench grinder can be used for all sorts of finishing applications.
Cylindrical grinders are great for achieving superior surface finishes. They are able to remove the finest pieces of material. They can also be used to shape the outside of an object. These grinders are most frequently used when manufacturing a cam or crankshaft.
Surface grinders are considered the most common grinding method. They are very precise tools that use a rotating wheel held in place by a vise. The vise then moves back and forth under the abrasive wheel.
Tool and cutter grinders are very versatile tools that can host a variety of different grinding operations, like surfaces and other complex shapes. 

Grinding hand tools

A die grinder is a high-speed rotary tool that is typically powered by compressed air. The tool has a small-diameter abrasive bit that rotates to get the job done. Check out Choosing the Right Air Die Grinder for more information and some recommended models.
Angle grinders are also abrasive hand tools. Unlike die grinders, however, they run electrically. Learn more about angle grinders and some recommended models in our article Top 5 Angle Grinders Recommended by the Practical Machinist Community

There are also more specialized grinding tools, for example gear grinders which are specific to gear manufacturing, or jig grinders, which have a variety of uses but are most commonly used for jigs, dies, and fixtures. 

Coolant use when grinding

Whether or not coolant is necessary for your grinding application will depend on how much heat is generated. For example, high precision grinding machines like cylindrical and surface grinders generate so little heat that using coolant isn’t necessary. 

Grinding fluid can even increase the material removal rate without subjecting the workpiece to damage. The best fluids to use in this case are water-soluble chemical fluids and oils, synthetic oils and petroleum oils. 

Check out our article How to Select and Maintain Machine Coolant for more information about cutting fluids to make sure you are selecting the correct one. 

Learn more about grinding operations

Grinding technology has come a long way and the industry has a growing need for qualified professionals. But how do you learn about grinding? And where can you learn more about it? Check out some of these handpicked books to either get you started or deepen your knowledge. 

If you’re interested in a broader resource that have some sections on grinding topics, check out 5 Machining Books to Keep on Hand and 15 Timeless Books Every Machinist Should Have.

Handbook of Machining with Grinding Wheels

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Handbook of Machining with Grinding Wheels highlights important industry developments that can improve part quality, higher productivity, and lower costs. The book is divided into two parts, beginning with an explanation of grinding behavior and ending with a focus on new and emerging industrial applications.

American Machinist Grinding Book: Modern Machines and Appliances, Methods and Results

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This text is a classic. It was inspired by the columns from the original magazine American Machinist. It provides a thorough description of all the different types of grinding machines and how to take care of them.

Tribology of Abrasive Machining Processes

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Tribology is “the study of friction, wear, lubrication, and the design of bearings; the science of interacting surfaces in relative motion” (Oxford Languages). This book uses the science of tribology to understand, predict and improve abrasive machining processes. In this book, you will find solutions to the most commonly experienced industrial abrasive machining problems such as poor surface quality, rapid wheel wear, vibrations, high process costs and more. 

Turning and Mechanical Manipulation: Abrasive and Other Processes Not Accomplished With Cutting Tools

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This book covers a wide selection of different finishing processes. You will find information about the production of cylindrical, spherical, conical and plane surfaces by abrasion and surface grinding. 

Eco-efficiency of Grinding Processes and Systems

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Eco-efficiency is a term related to sustained growth and development. If you’re interested in how to further optimize your grinding systems and processes, checkout the research in this book. Various combinations of grinding process parameters and system configurations can be evaluated based on the eco-efficiency and this book will assist you in analyzing those economic and environmental impactors.

 

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1 Comment

  • sparky says:

    As a Mold Maker/ Grinder Specialist with over 40 years experience it would take all day to talk about what I have done on the grinder! The surface grinder is a primary machine in the mold shop, but probably only about 10% of my work has been flat work on a surface grinder which you would think is primarily a flat work machine! Diameters, elliptical shapes mixed with multiple angles are just some of the “fancy” stuff we do in the typical plastic injection mold tool shop! I would be happy to answer any questions someone might have about grinding!

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