A CNC grinding is an exact process that uses an abrasive tooling system to remove small sections of unwanted material on the workpiece.
To achieve this process successfully, you must choose the right type of CNC grinding machine. Each machine offers unique machining finishing on various sections, from outer to inner surfaces. Let’s look at some of the most common machines.
Types of CNC Grinding Machines
1. Surface Grinding Machines
You can use surface grinding CNC machines to finish plain and flat surfaces horizontally or vertically. There are two main types of surface grinding machines based on the orientation of the spindle:
- Horizontal spindle surface grinding machines
- Vertical spindle surface grinding machines
In horizontal surface grinding machines, the grinding operation is performed by the periphery of the wheel with the table, where the workpiece is mounted and reciprocated.
Vertical spindle grinding machines use the face and sides of the grinding wheel for grinding. Due to the large area of contact, a lot of material can be removed in a single pass. However, they leave a crisscross pattern on the surface of the workpiece.
Horizontal spindle type is widely used due to its superior quality surface finish.
2. Cylindrical Grinding Machines
You can use these machines to grind cylindrical workpieces where the workpiece rotates and is fed past a grinding wheel.
In most cases, cylindrical CNC grinding machines are suitable for workpieces that can be fitted on a central rotation axis. You can use them to machine external diameters of shafts, spindles and rods. The construction resembles that of a lathe machine.
During setup, you will put the workpiece between the headstock and wheel head. Usually, you will rotate the workpiece in the opposite direction of the grinding wheel.
Unfortunately, cylindrical CNC grinding wheels are limited to circular and symmetrical workpieces.
3. Internal Grinding Machines
Internal CNC grinding machines are used to grind internal diameters of cylindrical workpieces, which maybe straight, tapered, grooved or profiled. They are extensively used in aerospace, automobile, and mold manufacturing industries where strict tolerancing and surface finishing requirements need to be met.
When grinding using these machines, the workpiece is held by the chuck on the headstock. Then, you will mount the saddle, which has the feed mechanism that feeds the grinding wheel into the workpiece.
It is important to note that this is a versatile machining process, which you can use to process a wide range of parts, including dies and molds. They are also used in finishing complex and delicate internal profiles.
Their application is often limited by the size of the grinding wheel and the general machine setup. Usually, this can prevent certain movements in machining small features, such as pinholes or components with underturns.
4. Centerless Grinding Machines
You can use centerless CNC grinding machines mainly for cylindrical workpieces. They however, use a work rest to support the workpiece instead of centers like in cylindrical grinding machines. External cylindrical grinders have a regulating wheel that applies pressure to the wheel and guides it across the face of the grinding wheel.
Furthermore, the regulating wheel head is mounted on the top slide and can therefore be moved towards the grinding wheel. The movement in turn moves the workpiece, providing the feed.
Internal cylindrical grinders have two extra wheels: the pressure roll and the supporting roll. These two wheels offer additional support to the workpiece as the grinding wheel works on the inner diameter.
You can use these CNC grinding machines for high-volume production.
The best part, these machines have a shorter setup time as compared to cylindrical grinders. Additionally, they are also more accurate as there is no deflection of the workpiece.
5. Universal Grinding Machines
These are versatile grinding machines capable of performing internal, external and face grinding. Its headstock can swivel to grind tapered and angled workpieces.
Furthermore, the wheel head, which carries the grinding wheel, can also be swiveled to allow for internal and external grinding. More importantly, the work table can be traversed longitudinally providing flexibility for different grinding operations.
Its main advantage is the ability to perform various grinding operations with a single set up greatly saving time and improving accuracy.
Even as you choose these machines, it is critical to note that it has a number of challenges, like the high cost of maintenance. This is mainly attributed to the fact that it has many moving parts. Usually, this also contributes to high initial costs and the need for high-skilled operators.
Machines Designed for Specialized Applications
Specialized CNC grinding machines include:
6. Gear Grinding Machine
They are used for finishing gear teeth profiles after they have been turn. The grinding wheel in the form of a worm tooth and the gear blank rotate in a synchronized and continuous motion.
The gear blank moves against the grinding, which simultaneously grinds its profile. This machine ensures reduced noise and vibrations by reducing meshing errors.
They are preferred for high-pressure applications as opposed to general gear manufacturing due to their low production volume.
7. Jig Grinding Machine
If you want to finish holes, contours and complex patterns, then jig grinding machine is perfect for your machining operations.
The grinding head has three main components:
- Main spindle housing allows for the vertical movement of the grinding wheel assembly.
- High-speed air spindle rotates the grinding wheel.
- Outfeed mechanism allows for the spindle to be offset from its center, thus making it possible to grind the diameter of a hole.
The workpiece is stationary on the worktable. Jig grinders are an indispensable tool in the workshop due to their ability to grind complex contours. It is also due to their accuracy in finishing hardened materials.
But more importantly, you should note that these CNC grinding machines are quite expensive and also have a slow material removal rate.
8. Thread Grinding Machines
They are used for finishing threads. They are particularly useful when correcting defects brought about by the material having been hardened.
Here, the workpiece is held between centers or by a chuck and tailstock like in turning on a lathe machine. A grinding wheel that has been dressed to match the thread profile is fed against the workpiece. Finally, the wheel moves along the length of the workpiece.
These machines are essential in the medical and aerospace industry because of their ability to grind hardened materials to high accuracy. Their operation is however slow due to their slow material removal rate. They also tend to produce a lot of noise and dust.
How to Choose CNC Grinding Machines
The choice of a CNC grinding machine is greatly dependent on your manufacturing needs. Since grinding is a finishing operation that greatly defines the quality and precision of the manufactured product, the selection process must be rigorous. These are the key factors to consider when buying a CNC grinding machine:
- Machine application:
- Workpiece specification such as size, shape, material and weight
- Desired precision
- Production volume
- Cost which includes the initial cost and the operational cost of the machine
Conclusion
The importance of CNC grinding machines in the workshop cannot be overstated. These machines ensure that you can achieve tight tolerances, superior surface finishes, consistent output and faster cycle times. By acquiring CNC grinding machines, you will always stay ahead of the curve in this competitive and demanding industry.
FAQs
What Are the Advantages of CNC Grinding Machines
CNC grinding machines offer numerous advantages over conventional grinding machines. These include:
- High-dimensional accuracy and precision
- Good quality surface finishing
- Offer high efficiency and large production volume
- They are versatile
- They offer a reduced labour and operational dependency
- Increased safety with the presence of machine enclosure and automation
What Is the Average CNC Grinding Machine Price
The average cost of a CNC grinding machine depends on the machine type, specifications, dimensions, number of axes, and capacity (the maximum workload the machine can handle). Grinding machine prices vary by model and configuration, so please contact us for a complete quote.
