Cylindrical Grinder Guide
What Is a Cylindrical Grinder?
A cylindrical grinder is a specialized form of grinder used to shape the outside of an object. It can work on a variety of shapes, such as cylinders, rods, cams, or crankshafts. Cylindrical grinders can be categorized by their working mechanism, which are traverse grinding and plunge grinding. They can also be classified based on the workholding method. The grinding wheels, coolant, maintenance, and other grinding parameters can all vary depending on the application.
Figure 1. CNC Cylindrical Grinder in action
Although cylindrical grinding is a common operation for bringing finished parts to tolerance, the operator must be familiar with the machine itself. This includes knowing how to utilize different wheels, workholding methods, and coolants to ensure desired result. The basic know-how is crucial for reducing scrap, increasing grinding quality and production rates, as well as lowering cost.
Construction and Main Components
The very basic components of a cylindrical grinder include a base, a headstock, a tailstock, and a wheel head. A cylindrical grinder usually has a rectangular base that connects all the parts together as a machine. There is a bed mounted on the base with a rail or a guide. A headstock is fixed on one end of the bed. The headstock is constructed with a spindle and a chuck so that it can clamp a workpiece and rotate.
A tailstock is mounted onto the other end of the bed; it can travel across the bed via the rail set or the guide. With the linear movement of the tailstock on the bed, a cylindrical grinder can work with objects of different lengths. The movement and positioning of the tailstock can be controlled either manually with a handwheel or automatically by a power system.
The wheel head is mostly positioned on the side of the bed so that it can machine the circumference of a cylindrical workpiece. There is sometimes a second grinding wheel that faces the headstock so that the machine can perform an internal grinding process. That being said, a cylindrical grinding process is typically done all by the main wheel head since most cylindrical grinders have the wheel head equipped with the 3-axis movement capability.
How Does a Cylindrical Grinder Work?
The construction of a cylindrical grinder consists of five main components: the headstock, the tailstock, the grinding wheel, the wheelhead, and the table. Advanced models may be computer controlled (e.g. CNC cylindrical grinders) or have multiple wheels.> The headstock and tailstock are mounted on the table as it moves laterally. The table consists of an upper and a lower layer. The upper table can be adjusted to a small angle to perform conical grinding. The high-speed rotating grinding wheel along with the wheel frame is used for lateral feed movement.
> When putting everything in motion, the workpiece is first supported between the headstock and tailstock, and rotates rapidly between the centers. The grinding wheel, which rotates at various speeds against the workpiece to perform grinding, is attached to the wheelhead. This moves the grinder in either plunge or traverse motions.
> See the below video for an in-depth look at the construction and operation of cylindrical grinders:
Cylindrical Grinding Machine, E-tech
Types of Cylindrical Grinders
There is a wide variety of cylindrical grinders, but can essentially be classified into three groups.
Plunge Cylindrical Grinder
This type of grinder features high productivity. When the part to be ground is less than the grinding wheel in width, the grinding wheel is only required to be fed in the transverse direction, and the workpiece does not have to move relative to the wheel in the axial direction.
Figure 2. CNC Plunge Cylindrical Grinder, Supertec
Angular Cylindrical Grinder
The angular approach is suitable for tight tolerance requirements on angles or tapers, as well as generating the required faces and diameters simultaneously. This type of grinders is fast, quiet, and powerful that excels in high volume production. For certain multi-form plunge applications, this type of machine will do the job, too.
Figure 3. CNC Angular Cylindrical Grinder, Supertec
Universal Cylindrical Grinder
A universal cylindrical grinder is suitable for single piece production in a small to medium volume. It has improved versatility, which can grind the inner hole with a larger taper. The wheel frame is added with an internal grinding attachment. The wheel frame and the head frame can be inclined at an angle around the vertical axis.
Figure 4. Universal Cylindrical Grinder, E-Tech Machinery
CNC Cylindrical Grinding Operations
Outside Diameter Grinding
In this type of grinding, the outside of an object between the centers is worked on. The centers basically act as an end unit that enables the rotation of the object. The cylindrical grinding machine also spins in the same direction as the object contacts the wheel. When the contact is made, the two surfaces move in opposite directions, allowing smoother workflow.
Inside Diameter Grinding
As the name suggests, this type of grinding takes place inside of an object. The width of the grinding wheel is always smaller than that of the hole being ground. A collet, which holds the object in place, also rotates the object. Just like outside diameter grinding, surfaces move in a reverse direction as the object comes into contact.
This is actually a form of outside diameter grinding, but with the key difference that the grinding wheel shapes an object by making contact continuously on a single point of the object rather than traversing the object.
Creep Feed GrindingCreep feed grinding is a type of grinding that removes a cut at a full depth in a single pass of the wheel. When performed properly, creep feed grinding is said to be capable of reducing manufacturing time by at least 50%. But this type of grinder typically needs to be designed for a specific purpose rather than a general-purpose grinder. This is used in both surface and cylindrical grinding.
Applications & Industries
The cylindrical grinder was developed in conjunction with the progression of industry and the relative technologies. In any applications where extremely precise metal working is needed, a cylindrical grinder is able to provide a high level of precision machining. Cylindrical grinders are largely used in the following industries:
Engine case grinding is the most popular cylindrical grinding application. Other automotive parts that are commonly ground with a cylindrical grinder include shock absorbers, crank, and camshafts.
Cylindrical grinding machines are widely used in the textile industry for yarn processing. The operation is often performed in conjunction with other machinery such as a texturing machine, combing machine, thick yarn machine, etc.
Cylindrical grinders are often used in the orthopedic segment for implants such as femoral knees, tibia trays, etc. The machines used are typically equipped with CNC capability with multiple axes.
Cylindrical grinders also take part in other sectors such as military and aerospace. They are often used to manufacture a variety of office and communication equipment as well, such as copiers, printers, face machines, etc.
For users to choose an appropriate cylindrical grinder, the control system is the key. Most cylindrical grinding machines are now controlled by either NC or CNC controllers to eliminate the problems that a conventional grinder would have. Before you look into the spindle, wheel, working table, etc., you need to check the controlling unit first to ensure smooth and coordinated workflow.
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