Grinding machines come in many types, from light and portable to large and precise. Grinding machines have unique applications, costs, and power ratings.
Manually operated grinding machines are used for low-precision cutting, cleaning, sharpening, and polishing work, while large CNC-operated precision grinders are used to create perfectly flat or cylindrical surfaces that meet tight tolerances. In all cases, grinding is a conventional process that uses mechanical force to slowly cut away material.
Grinding machines can be used to create sharp cutting tools, flat cylinder heads, gear wheels, cutting tools, and much more. The article explores 30 types of grinding machines and examines how they work, how they differ, and how much they might cost you.
Grinding Machines
Machines in which grinding wheels are fitted and grinding is done, such machines are called grinding machines.
On the basis of their function, they can be divided into two parts. Ordinary grinding machines are widely used. These are called rough or snagging grinders. The following types of grinders are included in this category.
Who Invented the Grinding Machine?
The genesis of the modern grinding machine is often credited to a few key figures in history, but the most notable is probably Henry Maudslay, a 19th-century British engineer. His contributions around the early 1800s laid the foundation for subsequent developments in precision grinding.
Grinding Machine History and Developments from Ancient Times to Modern Days The evolution of grinding machines is marked by several key developments:
- Ancient Times: The origins of grinding can be traced back to ancient civilizations where manual grinding stones were used.
- 15th Century: Leonardo da Vinci sketched designs for a basic grinding machine.
- 17th Century: The introduction of the treadle wheel enhanced manual grinding processes.
- 19th Century: The Industrial Revolution catalyzed significant advancements, including the integration of steam power.
- Early 20th Century: Further enhancements saw the introduction of electric motors, enabling greater efficiency and precision.
- Mid-20th Century: The advent of computer numerical control (CNC) technology marked a turning point, leading to the development of high-precision grinding machines.
- Late 20th Century and Beyond: Innovations continued with the introduction of laser-guided and robotic grinding systems, significantly increasing precision and efficiency.
How Does a Grinding Machine Work?
Understanding how a grinding machine operates is crucial for anyone involved in machining or metalworking. Let’s break down the step-by-step process, giving you a clear picture of the intricate workings of a grinding machine.
- Setup: The process begins with setting up the grinding machine. This involves selecting the right grinding wheel based on the material of the workpiece. Factors like wheel diameter, abrasive material, and grit size are critical considerations.
- Securing the Workpiece: The workpiece is then securely mounted on the machine. This could be on a chuck, between centers, or on a rotary table, depending on the type of grinder being used.
- Activating the Machine: Once the setup is complete, the grinding wheel is activated. This wheel, powered typically by an electric motor, rotates at a predetermined speed.
- The Grinding Process: The heart of the operation is the grinding process. The rotating abrasive wheel comes into contact with the workpiece surface, removing material through a combination of crushing and shearing forces. This action can be either a surface grinding or cylindrical grinding, depending on the machine and workpiece configuration.
- Feed Rate and Direction: The workpiece is fed against the grinding wheel at a specific rate and direction. This is controlled either manually or through CNC for precision grinding.
- Coolant Application: Throughout the grinding process, a coolant is applied to minimize heat generation, which can cause thermal damage to both the workpiece and the grinding wheel.
- Finishing: The final stage involves achieving the desired finish and dimensional accuracy. The grinding machine may go through several passes, refining the workpiece to the required specifications.
- Inspection: After grinding, the workpiece is inspected for surface quality, size accuracy, and overall finish.
What are Key Components of a Grinding Machine?
A modern grinding machine is an assembly of multiple critical components, each playing a vital role in its operation. Below is a list of these key components:
- Grinding Wheel: This is the tool that does the actual grinding. It’s made of abrasive grains and bonding material, engineered to cut and shape the workpiece.
- Wheel Head: The wheel head houses the grinding wheel and contains mechanisms for its rotation and positioning.
- Machine Bed: The bed is the framework that supports all parts of the grinder. It is typically robust to absorb vibrations.
- Work Holding Device: This device holds the workpiece in place. It varies based on the machine type, such as a chuck, centers, or a rotary table.
- Table: In surface grinders, the table holds the workpiece and moves it under the grinding wheel.
- Coolant System: This system applies coolant to the grinding area to control heat.
- Control Panel: This includes the controls to operate and adjust the grinding machine, including CNC panels in modern grinders.
- Motor: The electric motor drives the grinding wheel.
- Feed Mechanism: This controls the rate and direction of the workpiece movement.
- Dressing Tool: This tool is used to dress (reshape) the grinding wheel to maintain its sharpness and shape.
Types of Grinding Machines:
The following are the types of grinding machines:
- Bench grinding machine
- Hand grinding machine
- Pedestal grinding machine
- Portable grinding machine
- Flexible grinding machine
- Precision grinding machine
- Cylindrical grinder
- Plunge cut grinder
- Form grinder
- Internal grinder
- Centerless grinder
- Surface grinder
- Universal grinder
- Tools and cutting grinder
#1. Bench Grinder.
These types of grinding machines are fixed on a workbench or table. A gear or pulley is fitted in it. For rotating the big-size gears or pulley, a handle is also fixed.
It contains one or two grinding wheels. Edges of cutting tools can be made with this grinder. Provision can be made to operate these with power also.
#2. Hand Grinder.
This grinder is also fixed on the workbench or table. There is a provision of moving the grinding wheels with a lever as shown in the figure.
#3. Pedestal Grinder.
These types of grinding machines are operated with electric power. This is fitted on a pedestal frame separately on the ground. A grinding wheel is fitted on both sides of the shaft of the electric motor.
Tool rests are also provided with them. These are the most widely used in the workshops. Edges of all types of cutting tools are made with these grinders. Apart from this, molded articles can also be cleaned with it.
#4. Portable Grinder.
This is a small grinder operated with electric power. It can be easily carried anywhere. Grinding can be done by holding it in hand. It is used for cleaning heavy welding jobs.
On one end of the motor shaft, a grinding wheel is fitted, and on the other end, a handle or switch for operating the machine is fixed according to our convenience. It should be used carefully since there is a possibility of getting an electric shock.
#5. Flexible Grinder.
These types of grinding machines are shown in the figure. The electric motor in this grinder is fitted on such a basis that it can be moved in any direction.
A flexible shaft is fitted on the motor shaft with the help of a coupling. On one end of the shaft, a grinding wheel and handle are provided. Large jobs can be easily grinded with this grinder.
#6. Precision Grinder.
In this type of grinder, a movable spindle is fitted in the grinding wheel. This spindle is fitted on a table along with its motor.
With this spindle, the grinding wheel can be turned in forward, backward, left, or right direction in running condition. Jobs of excellent finish and accuracy are grinded with it. These grinders are of the following types:
- Cylindrical grinder
- Plung cut grinder
- Form grinder
- Internal grinder
- Centerless grinder
- Surface grinder
- Universal grinder
- Tool and cutter grinder
#1. Cylindrical Grinder.
The surface which has been made plain by a shaper or plainer are grinded with this grinder. The cylindrical surface is grinded with a machine in which grinding wheel is fitted on the shaft of a free electric motor.
In this type of grinders, the grinding wheel is fitted on the machine’s work table, which can be given crossfade and the entire surface of the job can be grinded. These are of the following three kinds:
a. Plain Cylindrical Grinder
In this type of grinder, the job is rotated in chuck or center and the entire cylindrical surface of the job is grinded. With this grinder finishing of sleeves, pins, rods, taper pins, etc.
b. Roll Grinder
This type of grinder is used in steel mills, printing presses, etc, for grinding heavy rollers.
c. Piston Grinder
Pistons of I.C. engines are required to be grinded not in round shape but in oval and taper shape so that when their size increases due to heat these may not get deposited in the cylinder. This grinder is specifically made for grinding these shapes.
#2. Plunge Cut Grinder.
These grinders are used to grind small shafts. The diameter of the grinder is much more than that of the job. The crankshaft of motor vehicles is a grinder with this grinder.
These are also called crankshaft grinding machines. This type of grinder is also made in a different form for camshaft grinding. In order to save the shaft from becoming flexible, steady rests are used.
#3. Form Grinder.
Grinding wheels of different shapes are made under this type of grinder. These wheels are given feed and accurate grinding is done as per the shape of the grinding wheel on the moving cylindrical surface. Under this category, three types of grinders are included. These are:
a. Ordinary Form Grinder
These grinders are used for grinding jobs of ordinary shape. The principle of an ordinary form grinder is shown in the figure.
b. Thread Grinder
This type of grinder is used to cut accurate threads. Grinding wheels of the size and shape of the thread are used. Its principle has been shown in the figure.
c. Gear Grinder
The principle of the gear grinder is shown in the figure. Grinding wheels of different forms are used in this grinder to cut dents of different sizes and shapes.
#4. Internal Grinder.
These grinders are used for grinding round and hollow jobs whether the internal surface of this job is completely round, ditched round, or is in taper.
Small grinding wheels of 3 cm to 5 cm, are used in such grinders. Sometimes grinding wheels of special shape 0.2 cm to 0.3 cm. These grinders can be divided into two parts.
a. Chucking Grinder
In this type of grinder, the job is held in the chuck. The grinding wheel makes the job accurate through the grinding of its hollow part.
b. Planetary Grinder
In this type of grinder, while the job remains stationary, the grind wheel moves like a planet in eccentric motion in the inner part and grinds the inner surface. Special arrangements are made to move the grinding up and down. its principle has been illustrated in the figure.
#5. Centerless Grinder.
In this type of grinder, for holding the job on the chuck is used. The job is moved through the medium of a grinding wheel and a regulating wheel.
There are four main parts of this grinder: (1) Grinding wheel (2) Work rest (3) Regulating wheel (4) Guide. Their principle has been explained through the figure.
Jobs keeps on touching the work rest blade because of the pressure of the grinding wheel. The regulating wheel forces the job to spin at an equal speed.
In this way, the regulating wheel and the grinding wheel start moving in one direction. The job gets an automatic forward speed.
The rate of movement of the job depends upon the inclination and speed of the regulating wheel. It can be adjusted according to the requirement.
This type of grinder is used in modern workshops for mass production. Jobs of glass, porcelain, wood, rubber, plastic, iron, and steel and alloy are polished and finished with this grinder. The job can be placed in their position.
#6. Surface Grinder.
Flat surfaces are accurately grinded with, this type of grinders. For this grinder, the job is held directly by a magnetic chuck or work table.
The race-protecting table of painting or shaping machines is also used in form of a table. Their classification is done in two ways:
- According to the table, they are of two types
- Rotary table
- Reciprocating table
- According to the spindle, they are of the following types:
- Vertical spindle grinder
- Horizontal spindle grinder
a. Rotary Table Surface Grinder
This type of grinder has been shown in the figure. The work table rotates on its axis and arrangement is also made for feeding this table.
b. Reciprocating Table Surface Grinder
This type of grinder has been shown in the figure. This work table reciprocates like a planer or shaper machine.
c. Vertical Spindle Surface Grinder
In this type of grinder, the grinding wheel is fixed vertically to the machine table or job.
b. Horizontal Spindle Surface Grinder
A horizontal spindle surface grinder is shown in the figure. The spindle of the grinding wheel is fitted in a horizontal direction. The wheel is moved ahead slowly. When one stroke is complete, it is driven back and horizontal grinding is done.
#7. Universal Grinder.
This is a sort of plain cylindrical grinder. Its worktable, headstock, and grinding head are of swivel type. That is why all types of grinding can be done easily with this type of grinders.
#8. Tool and Cutter Grinder.
This is a small grinding machine. Drill, reamer, tap, and the particularly milling cutter are grinded with this grinding machine. The grinding wheels are of soft grade which is of the shape of a straight, flared cup or dish type.
Its wheel head can be turned at any angle. It can be set on the table for various jobs, Tailstock is fitted in its “T” slot on its working table. This complete table can be adjusted anywhere. Job is held in the center between headstock and tailstock at both ends.