Project Description

WHAT ARE POT MAGNETS?

Pot magnets are made from permanent magnets in a custom durable metal shell. Magnets and hardware are secured with glue (326). Here the permanent magnets can be extremely strong neodymium magnet or high temperature SmCo and alnico magnet, or economical ferrite. The role of the steel housing in such magnetic assemblies is to increase the magnetic force on the working surface and also to protect the magnets.

Cup magnet assemblies are not only the perfect alternative to single magnets, but they can also meet some special requirements that cannot be met by a single magnet. Sometimes even the cost will be lower than a single magnet.

Permanent magnets are known to be hard magnets and they are very fragile.

The inclusion of metal hardware solves the disadvantage that permanent magnets cannot be drilled with threaded holes and provides more options for fixing magnets to other non-ferromagnetic objects, whether it is standard hardware (nuts and bolts) or various hooks. This is why cup magnets are so popular, both in production and in everyday life.

Pot magnet with different holes
pot magnets with different extension accessories

TYPES OF CUP MAGNETS

Although these extension accessories add additional functions to the pot magnet, its core working principle remains unchanged, so we refer to these magnetic assemblies as pot magnets. In addition, due to different accessories or specific uses, the cup magnets are subdivided into more types. For example, cup magnets are mostly round and are mainly used as lamp holders for vehicle signs or light bars. They are also known as round base magnets. Generally, the pot magnets used in daily life have a hook for hanging items and are therefore called hook magnets. The magnets used for latching purposes are usually square in shape and are called rectangular pot magnets.

custom neodymium pot magnet

cost-effective
strongest magnetic force
surface treatment required
working Temp.: 80-200 ℃

high temperature smco pot magnet

expensive
strong magnetic force
good anti-oxidation
working Temp.: 250- 350℃

ferrite/ceramic pot magnets

cheap
less magnetic force
good anti-oxidation
working Temp.: 250℃

AlNiCo deep pot magnets

ALNICO DEEP POT MAGNETS

cheap
weakest magnetic force
good anti-oxidation
working Temp.: 550℃

block pot magnets

BLOCK NEO POT MAGNET

rectangular
good closure systems
strong neodymium magnets
durable stainless steel housing

rubber coated pot magnets

friction
rust-proof
waterproof
scratch protection

HOW TO CHOOSE A POT MAGNET?

As with how to choose permanent magnets, the first thing is to choose what kind of magnetic material, which mainly involves the working temperature. Secondly, we need to know the shape and size, and also the plating is important. Finally, although we don’t need to know the exact material properties (e.g., N35 or N42 or N52), you have to tell us what the required pulling force is in kg/lb.

We can design and manufacture various pot magnets according to your specific requirements. Need a quote, or want to know more about custom service, you are always welcome to contact us!

FEATURE OF POT/CUP MOUNTING MAGNETS

Compact & Powerful

The iron shell changes the original magnetic circuit of the magnet so that most of the magnetic energy is concentrated at the edge of the metal cup, resulting in a strong pull force on one side. Thus, a very small pot magnet can have a stronger holding force.

Durable

Hard magnets are brittle and if they accidentally slam into each other or hit the steel surface they will chip or break. The iron shell is the first layer of protection, while we will also design different methods to prevent the magnet from breaking according to the situation.

Extremely Useful

Our pot/cup magnets are available with countersunk holes, screw holes or through holes to make installation work easier. The additional metal or plastic accessories such as thread bush, clips, and hooks etc. make it possible to use in more workplaces.

APPLICATIONS OF POT MAGNETS

Pot magnet can be widely used to position/hold/mount devices and tools. When you want to hold something in place excellently, pot magnets can easily help you to do so. China Magnetic Source can provide a wide range of cup magnets, including different sizes, forces, and fitted with different accessories to meet your application requirements as closely as possible.

Great tools always helpful, try POT magnet in your product!

  • Plant construction
  • Metal construction
  • Booth and store construction
  • School, training & studies
  • Hobby & leisure

WHY CHOOSE US FOR YOUR POT MAGNET SOURCE?

  • Rich experience in design and production
  • Custom sample available and volume production
  • Wide range pull force: a few kilograms to several tons
  • Manual assembly combined with automated assembly
  • Professional technical assistance: higher force or lower cost
  • Fast action: custom design + production + worldwide delivery
  • Happy Customer from big scientist machine to small startups around the world
  • Here is the size list for standard pot magnet, contact us for custom size

STRUCTURAL OPTIMIZATION OF POT MAGNET

Sometimes, customers will find the magnet information they need directly from online store and ask us to quote and make sample. For example, this German customer wrote in an email:

Thank you very much for sending the quotation. Please tell us the cost to produce 5 pcs pot magnet samples in NdFeB N42 according to standard magnet technical specification attached.

specification of D16 pot magnets

The customer gave us the most complete information and it was reasonable that our samples should be fine, but we were told that:

We have tested the magnets. But it lacks 50% of the power which is needed of us.
Can you make new sample, that the magnet in the same size, but has more power?
We want to test these magnets: with magnet material N50, 5 PCS with H = 4,5 mm & 5 PCS with H = 5 mm, cost these samples like the last time?

So, we started making magnet prototypes again according to the N50 grade. But the second feedback was still a failure. In the end the customer sent us a sample with enough power they want, but with larger size.

Is it possible to make the magnet without changing the measurements with a stronger force?
We need the power of the sample we send you and the measurements of the samples you have send us.
Please make us new samples.

After receiving the customer’s sample, we measured it and found that the size was D20 and that the vertical pulling force was up to 16 kg. Given the large difference in pulling force, we confirmed some more information with the customer.

What is the grade of magnet for sample D20x6mm you sent us?
Can you accept changing d2 from 7.22 to 5.22mm or 6.22mm?
There will be no gap between magnet and steel cover, is this okay?

We started working on a new design after receiving the response that no grade information, fixed D2, and no gap is ok.

Due to the limited size, we optimized the interior design of the pot magnet, removed the gap between the magnet and the iron shell, and used magnets with different properties. After continuous professional simulation calculations, finally, the new sample achieved the pulling force of the D20 prototype while retaining the original dimensions D16.

D20 & D16 countersunk pot magnets

This time the customer was finally satisfied with the sample’s pull force. But they also raised a new question:

The sample arrived us. Thank you very much. It looks like good and the improved design and stronger force are okay for us. Is it possible to make a little radius on the outer ring of the magnets. We have marked the point on the attached picture. It would be useful for us to have a radius 1.0 mm (chamfer) . Please speak with your people.

Pot magnet chamfer

By calculations, we found that R1 will reduce some magnetic force. We think small chamfer ((0.3-0.5)x45°) can minimize impact on magnetic force as much as possible.

Kindly find the impact data of chamfer on magnetic force (analog computation) in attachment. It’s okay between 0.3 – 0.5×45°. Please confirm this.

Simulation of the effect of chamfering on magnetic force

The customer finally accepted our proposal and chose the third chamfer size 0.5 x 45°.

Thank you for your effort in this case.
The magnets arrived us and we had proofed magnets during the incoming goods inspection.
They are good. The Quality of the magnets which you delivered us is perfect.
Next Time I will send you a new order about the magnets.

MORE ABOUT CUP MAGNET: THE PRODUCTION OF STEEL SHELLS

The material used for the iron shell hardware is mainly A3 steel (Q235A), with a choice of ZnNi alloy, NiCuNi alloy or epoxy plating to reduce corrosion and provide a smooth finish. If there are special coating and salt spray test requirements, it can be specified in advance. We can choose more corrosion-resistant hardware to suit your requirements.

There are two main machining processes for iron shells: stamping technology and turning technology.

Stamping is a production technology that uses the force of stamping equipment to deform the sheet metal parts directly in the mold to make product parts with a certain shape, size and performance. Sheet metal, molds and equipment are the three main elements of the stamping process.

Turning, i.e., lathe machining, is a part of mechanical machining. Lathe machining mainly uses a turning tool to turn a rotating workpiece. Drills, reamers, reamers, taps, plates and knurling tools can also be used on the lathe for corresponding machining.

The Difference Between Stamping and Turning Technology

The lathe has a very wide range of machining, easy handling and fast clamping for turning, while stamping requires tooling, so turning can be better adapted to the requirements of flexible production in small batches; in the case of high-volume machining of high precision parts, a CNC machine with good rigidity, high positioning accuracy and repeatability is required.

In general, the iron shells used for pot magnet do not require high precision, and large quantities are produced through the stamping process, which is also low cost.

In contrast, prototypes are generally produced quickly by means of a turning process. So don’t be surprised if you find a difference in appearance between the prototype and the large batch (as shown in the picture below), this is a production method determined by the machining process and production costs.

The exception is when the customer has strict requirements for accuracy and can accept higher production costs. Sometimes a professional customer will state directly that this part can be made by machining or stamping. Most cost-effective method is preferred.

Comparison of the appearance of turned and stamped parts

THE MOST FREQUENTLY ASKED QUESTIONS ABOUT CUP MAGNETS

  • What these pot magnets can hold?

Pot magnets are very flexible and removable fixing tools and they are easily to hold everything from key to display screen.

  • Do these magnets have a north and a south? Can they repel each other? Do you sell the opposite polarity?

All magnets will contain the South and North poles. It is only the iron shell that hides one pole, so it looks as if there is only one pole. Sometimes they are also called monopole magnets.

The pot magnets have a very strong pull force and are not magnetized in pairs. Usually, the working surface of all pot magnets is the N pole. Therefore, they will repel each other. If you have a need for paired magnetization, you will need to specify this when placing your order.

  • How to remove the magnet from the metal plate?

Small or weak cup magnets can be pulled straight out. But big or strong cup magnets need to be slid to separate them.

  • Will the magnet rust in water? Are they waterproof?

Salt water is not good for NdFeB magnets and metal cup as the Ni or Zn plating will corrode (24-48 hrs). If a longer time is required, epoxy plating or other material is recommended.

  • Can they be used outdoors?

For long-term outdoor use, it is best to choose pot magnet with a rubber cover.

  • The hole in the middle is smaller so the bolts I already have don’t fit.

We can supply not only magnets, but also high-quality matching screws.

  • Can these magnets be used on toys?

These cup magnets are too strong to be recommended for any toys. Toddlers wouldn’t be able to pull them apart. And when they can pull away and suck up again, they may pinch their fingers and get hurt. So never for kids!

  • Why the pulling force is not as strong as described?

In addition to the performance and construction parameters of the magnet, the pull force of a pot magnet is directly influenced by the material, composition and size of the test object.

We have professional tensile testers for magnet corresponding to a wide range of sizes and suction forces. Our test results (holding/gripping force) are based on the holding force of a magnet against direct pull force when attracted to a clean, flat mild steel surface with a minimum thickness of 6 mm. And the painted, unground or thin metal surfaces will reduce this force considerably.

In practice, the attractive force also decreases with the increase of the air gap, and even a small air gap can have a significant impact on the attractive force. And the contact way between the pot magnet and the object may cause the air gap to be ignored at the same time.

But tensile test conditions are based on ideal conditions. The test result may therefore differ from the suction force in practice. If you really care about the pull force used on your product, we can provide you the cup magnet sample for test.

  • The neodymium magnets in the steel casing are very strong, but they are also easily broken. How to solve this problem?

Different pot magnets with different solutions. If pot magnet has a hole in the middle, we would advise our customers don’t tighten screw to hard or it will crack magnet. For small magnets without a hole in the middle, we will seal the working surface with epoxy. For example, mini pot magnets for pick-up.

If you are struggling with this problem, please feel free to contact us. We will provide perfect solutions according to your actual situation.

small pot magnet sealed by epoxy to prevent the magnet from breaking during use

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