Introduction
When it comes to work holding mechanisms, there are a few systems that offer more convenience than magnetic chucks. Magnetic chucks can either have a permanent magnet or coils that can be magnetized by passing electricity through them. While there are different magnetic chucks, one thing is shared between them all. Every magnetic chuck type operates without jaws, locking mechanisms, or screws to secure a workpiece.
Magnetic chucks, in general, are easier to operate and can be used to hold workpieces securely without the risk of falling. Their convenience and safety make them ideal for a wide range of heavy-duty manufacturing applications. However, each type of magnetic chuck has its own distinct properties that set it apart.
If you are choosing a magnetic chuck, then you have to make sure you pick the correct type. While each type of magnetic chuck uses magnetism, the way they work varies from one another. So, the type of chuck you use can have an impact on how you operate it and the features it offers.
This article by GME-Magnet was created to explain all the different types of magnetic chucks. We will also cover the working mechanism of each chuck type and its unique benefits, so keep reading.
2. Why Should You Use a Magnetic Chuck?
Magnetic chucks are gaining popularity across the world among machining facilities. There are many reasons for the large-scale adoption of magnetic chucks across manufacturing facilities. Here are some significant reasons why you should switch to a magnetic chuck:
2.1 Easy access to workpieces: When you choose a magnetic chuck, it allows you easy access to the workpiece from all sides. This benefit comes especially handy if you perform 5-axis machining at your facility. That is because there are no clamps, bolts, or jaws between the machining tool and the workpiece. So the work can be performed faster with higher accuracy.
2.2 Higher Safety: Permanent magnetic chucks have a distinct property that allows them to function without the risk of failure. As the jaws and bolts of a traditional chuck wear out, they pose a risk of slippage and injury for the operator.
Since magnetic chucks don't have any gripping mechanisms and the holding force is constant, they are much safer to operate. As a result, you can get predictable holding power every time. Not to mention, a magnetic chuck keeps the workpiece from falling off, thus preserving expensive workpieces.
2.3 Better Accuracy: A workpiece constantly moving, shaking, or vibrating reduces the accuracy of the machine. Since magnetic chucks use high-powered magnets to stabilize a workpiece, there is no movement in the workpiece as CNC tools make contact with it. This increases the accuracy of the machine and makes sure the output is as per requirements.
2.4 Faster operation: Mounting and dismounting a workpiece from a magnetic chuck is simply a matter of engaging and disengaging the chuck. Since there aren't any complex holding mechanisms to secure and loosen every time you mount a workpiece, it drastically speeds up the operations.
By simply pushing turning a lever, you can secure or remove the workpiece from a magnetic chuck. This feature is handy for workpieces that constantly need to be removed from the CNC machine and moved to a different one.
3. How Can Magnetic Chucks be Categorized?
Magnetic chucks can be categorized based on two criteria. You can differentiate them based on their operating mechanism or their shape.
The shape, as well as the functioning of a magnetic chuck, directly impact its usefulness. We are going to cover the types of magnetic chucks based on the operating mechanism as well as their shapes in the upcoming sections.
4. Types of Magnetic Chucks Based on Operation Mechanism
Most manufacturers think that all magnetic chucks work the same way; however, there can be three different operating mechanisms for a magnetic chuck. Here are the differences between the three major types of magnetic chucks based on their operational mechanism
4.1 Permanent Magnetic Chucks:
As the name suggests, a permanent magnetic chuck is made up of permanent magnets. The magnets present in these types of chucks are constantly active, and there are two sets of magnets with opposite poles that generate a magnetic field. The magnetic field of a permanent magnetic chuck remains available as long as both sets of magnets are aligned with each other. As soon as the opposite poles of two magnets stop facing each other, it deactivates the permanent magnetic chuck.
The two sets of magnets are present in the base and the top plate of the chuck. There is usually a lever present at the base that moves one set of magnets in the correct position to generate a magnetic field.
4.1.1 Advantages:
● A permanent magnetic chuck is the most affordable option out of all the types of magnetic chucks.
● They are easy to install, and most models can be installed on a machine within minutes.
● They don’t require external power sources, so they are more affordable to operate.
● You can quickly transfer a permanent magnetic chuck from one machine to another.
4.1.2 Disadvantages:
● They are small in size and not suitable for large and heavy workpieces.
● Permanent chucks can’t be used automatically with a CNC machine.
● They don’t have a built-in cooling system and, therefore, can’t be used at high temperatures.
4.2 Electromagnetic Chucks:
Electromagnetic chucks don't have permanent magnets like permanent magnetic chucks. An electromagnetic chuck needs an electric current to magnetize its ferromagnetic core, which acts as a powerful magnet. As long as the current is flowing through an electromagnetic chuck, it keeps holding the workpiece. When the current stops flowing through the core, the chuck is no longer magnetic.
Unlike a lever that changes the alignment of two sets of magnets, an electromagnetic chuck has a control unit that allows or stops the flow of current. A more advanced electromagnetic chuck will even allow you to adjust the holding force through the control unit. By turning a dial, you can control how much current flows through the coil and, therefore, adjust the strength of the magnetic field.
While these electromagnetic chucks require a constant flow of electricity, their holding force is higher than that of a permanent magnetic chuck. Not to mention, the ability to adjust the holding force makes these types of chucks a more versatile option.
4.2.1 Advantages:
● Strong holding force and can be used to hold heavier workpieces.
● Comes with a built-in cooling system for high-temperature operations.
● It can be automated by connecting to the CNC machine thanks to a dedicated control unit.
● Magnetic force can be adjusted by controlling the flow of current.
4.2.2 Disadvantages:
● Workpieces can fall off incase of a power outage, so a reliable backup power source is needed.
● Produces a lot of heat due to the constant flow of current through its core.
● Consume a lot of electricity during operation.
4.3 Electro-permanent Chucks:
An electro-permanent chuck is a cross between the two types of magnetic chucks mentioned above. It has both a permanent magnet and an electromagnet. So even when no electricity is being applied to the electromagnet, the electro-permanent chucks use a permanent magnet to hold workpieces in place. However, when the electromagnet is activated by passing current through it, the strength of the chuck increases significantly.
In fact, electro-permanent chucks are the strongest type of magnetic chucks you can buy. In addition, they can be operated directly by the computer system in CNC machines. Unlike electromagnetic chucks, electro-permanent chucks don't need a constant supply of current in order to operate. The current is only needed to activate and deactivate the chuck. Therefore, the risk of the workpiece falling off is eliminated by these chucks.
You can hold larger and heavier workpieces using electro-permanent chucks with great accuracy. However, the cost of these magnetic chucks is high, which means they are only affordable if you have a large machining operation.
4.3.1 Advantages:
● Constant and strong holding force ideal for medium to large workpieces.
● Can be automated and connected to the CNC machines.
● Uses lower amounts of power compared to an electro-magnetic chuck.
● Doesn’t fail in case of a power outage thanks to the presence of permanent magnets.
● Low heat output allows you to use the chuck for prolonged periods
4.3.2 Disadvantages:
● Electro-permanent chucks are the costliest option to buy among all magnetic chuck types.
● Holding force will be reduced if there are gaps between the top plate and workpieces.
● Repairing an electro-permanent chuck can be complex.
5. Types of Magnetic Chucks Based on Shape
The great thing about magnetic chucks is that each of the three types of chucks can be made into different shapes. There is no one shape that can be used for every single machining operation. That is why it is important to understand the different shapes of magnetic chucks and their applications.
Without further ado, here are the different shapes of electromagnetic chucks you can buy:
5.1 Round Magnetic Chucks:Round magnetic chucks are designed specifically for holding smaller workpieces that need to be rotated. Rotary grinder machines, for example, need to turn a workpiece rapidly in order to get the proper finish. Similarly, lathe machines need a round magnetic chuck to rotate workpieces against a tool.
So, if you are looking for a magnetic chuck that can handle rotary movement, then round magnetic chucks are it. You can find round magnetic chucks in permanent, electromagnetic, and electro-permanent variations.
5.2 Rectangular Magnetic Chucks: The second most common shape of magnetic chucks you can buy is rectangular magnetic chucks. These chucks are mostly designed to work with drilling, grinding, milling and other machining machines.
A rectangular magnetic chuck is designed to hold one or multiple workpieces while a tool works on it.
Similar to round magnetic chucks, you can find rectangular magnetic chucks with all three types of operating mechanisms. In addition, rectangular magnetic chucks also come with a square variation.
Rectangular shaped magnetic chucks can be small and large, and they have high holding strength, making them ideal for heavy-duty machining.
6. What are the Different Types of Pole Arrangements in Magnetic Chucks
Magnetic chucks come with different pole arrangements. Here are the most common pole arrangements in magnetic chucks that you may come across:
6.1 Concentric Poles: As the name suggests, concentric pole chucks have poles arranged in a concentric pattern.
The concentric poles are found in round-shaped chucks.
6.2 Radial poles: Radial poles are arranged in straight lines starting from the middle of the round chuck and ending at the edge. There are multiple lines of poles in a magnetic chuck arranged at an equal distance from each other.
The magnetic flux of such magnetic chucks is the strongest in the centre. Therefore, radial poles are ideal for round magnetic chucks that are designed to be used in lather machines.
6.3 Square poles: Square pole design is usually found in rectangular or square chucks, and they are arranged in a checkered formation. These types of chucks have alternating north and south poles with opposite poles facing each other.
7. Top Magnetic Chucks from Each Category
Now that you know the different types of magnetic chucks based on shape and operating mechanism, you might be looking for options to buy. We have compiled a list of the best magnetic chucks from each category to make the choice easier for you:
7.1 Surface Grinder Magnetic Chuck
This Surface Grinder Magnetic Chuck by GME Magnet is one of the best electro-permanent magnetic chucks you can buy. Designed for use in grinding machines, this chuck has a waterproof and highly durable design, making it ideal for industrial applications.
Material: Carbon steel
Type: Electro permanent
Features:
● Minimal electricity requirements
● Easy operation
● Large surface area
7.2 Large Diameter Suction Electromagnet
This Large Diameter Suction Electromagnet is ideal for turning applications. With its compact design, you can use it in lathes and other turning machines.
Offers high accuracy and a reliable holding force. The electromagnetic operation is simple and makes the chuck easy to operate.
Material: Carbon Steel
Type: Electromagnetic
Features:
● Comes with an adjustable holding power mechanism
● Waterproof design
● Solid construction
7.3 Permanent Magnetic Chucks For Milling Machine Chuck
If you are looking for a reliable permanent magnetic chuck, then this product is ideal for you. While it is designed for milling applications, it can also work well for drilling and grinding use. The main advantage of this chuck is that you can adjust it horizontally and vertically, making it a versatile option.
Material: Carbon steel
Types: Permanent magnetic chuck
Features:
● No electricity required
● Can be used to hold both thin and thick workpieces
● Holding force can be set to a low setting if needed
What are Some Common Applications of Magnetic Chucks?
As explained earlier, magnetic chucks offer the versatility to be used in a wide range of manufacturing scenarios. Whether you need a holding mechanism for surface grinding machines, CNC milling, lathe machines, or drilling tools, a magnetic chuck can handle most of the machining applications.
Some common items that can be machined with magnetic chucks include rail wheels, dies, thin sheets, and discs that are difficult to secure on regular chucks.
In short, any application that requires high precision and a reliable hold can use magnetic chucks.
8. Conclusion
With the advancements in magnetic technology, we at GME Magnet are able to manufacture stronger magnetic products. Magnetic chucks are one of our best-selling magnetic products. With different types of magnetic chuck options, it can be difficult to pick a chuck that suits your needs.
This article covers all the key types of magnetic chucks based on various categories. By now, you should be able to tell which type of magnetic chuck is best suited for your usage applications. If you have any additional queries, you can always contact us for assistance.