More than 80% of all metals we use have ferromagnetic properties, these are mostly different steel alloys. That is why practically everywhere we are using a lot of magnetic lifting, handling and transport devices.
Magnetic handling is the most simple, convenient and effective way of handling steel parts, assemblies and devices. For about 200 years we are successfully using magnetic handling in all machine building, shipbuilding, metallurgical, transport, military, separation, and many other applications.
Electromagnetic Handling Devices (EHD)
Immediately after invention of the first electromagnet in 1825, several handling electromagnets were patented and since that time EDH are still the most popular.
Main advantages of EHD are: simplicity, comparatively low costs, rigid constructions and comparatively deep magnetic field penetration into the object to be handled.
EHD disadvantages are: low efficiency due to high level of heat generation and dependance on the external energy supply, which cal lead to unsafe situations.
Last years DVM together with several partners and within performing of several International Investigation Projects has created, produced and supplied the following advanced EHD:
- EHD for high temperature applications: up to 700 degrees C;
- EHD for special high capacity scrap handling applications with up to 3.500mm electromagnet diameter;
- EHD equipped with: highest capacity back-up batteries with up to 60 minutes back-up time; special radio remote control; continuous monitoring systems of coils heat generation and batteries charge level;
- EHD based on: recalculated magnetic circuits from steel with high magnetic permeability; compact band coils from new alloys with highest current conductivity; new compounds with highest heat conductivity;
- EHD with special properties for scientific, underwater, radioactive, space and some other specific applications.
Permanent Magnetic Handling Devices (PHD)
In the beginning of 50-th first magnetic handling devices with permanent magnets (PHD) appeared on the market. These were mostly hand switchable devices, using ferrite magnets. Later both permanent magnets and switching systems were changed and improved.
Main advantage of PHD is independence of external energy supply. Even if we do need external energy source for switching PHD -on and -off, this can not lead to unsafe situations, since during handling the device is using only magnetic flux generated by permanent magnets.
Disadvantages of PHD are connected with different properties and costs of permanent magnets they are using. Some permanent magnets are not able to withstand high temperatures or humidity, other permanent magnets do not have enough mechanical strength or chemical stability, high energy permanent magnets are as a rule extremely expensive…
At the end of 90-th DVM has established a production of special high energy permanent magnets. The aim was creating initial alloys and production technology of high energy rare-earth magnets with special properties for magnetic equipment created and produced by DVM.
Last years DVM together with several partners and within performing of several International Investigation Projects has created, produced and supplied the following advanced PHD, using special high energy magnets from our production:
- Series of advanced hand switchable PHD with safe capacity from 100 till 5000 kg, world lowest weight/capacity ratio and world highest safety (x4);
- Series of advanced PHD with automated mechanical switching for heavy handling applications with safe capacity up to 40 t;
- PHD with special properties: for high temperature (up to 400 degrees C); for movements with high friction; for scientific, underwater, radioactive, space, dangerous (acid) environment and some other specific applications.
Electro-Permanent Magnetic Handling Devices (EPHD)
In the beginning of 70-th new magnetic devices were patented where permanent magnets were controlled (switched -on and -off) by electrical coils, placed around permanent magnets.
EPHD are combining main advantages of EHD and PHD: no heat generation, no dependance on the external energy source within handling, possibility of remote control… Several scientists have predicted that due to all above advantages EPHD will soon become the main type of magnetic handling devices. But after more than 40 years we still have all above mentioned magnetic handling devices together with EPHD on the market. This has to do with several disadvantages of EPHD.
Main disadvantages of EPHD are: different properties and costs of permanent magnets they are using (see disadvantages of PHD); necessity of complicated powerful electronic switching system; crystal structure of some electrically switchable permanent magnets is not able to withstand continuous changing of magnetizing direction, which leads to low longevity for most of such systems.
In 2005 DVM together with several partners, within performance the International Investigation Project, has developed and started production of special high energy initial alloys and permanent magnets with improved crystal structure, which is able to withstand up to 20 millions electrical switchings.
Last years DVM together with several partners and within performing of several International Investigation Projects has created, produced and supplied the following energy saving EPHD, using special high energy magnets from our production:
- EPHD for steel plates and tubes up to 20m long with safe capacity up to 60t, including systems for handling plates in vertical position;
- EPHD for unloading plasma and laser cutting tables up to 15m long with selective radio control, allowing separate handling of parts 100x100mm;
- EPHD for high temperature applications: up to 600 degrees C;
- EPHD powered by highest capacity batteries with up to 6 months safe application time without recharging; with original radio remote control; equipped with continuous monitoring systems of magnets magnetizing level and batteries charge level. Safe lifting capacity up to 10t;
- Special deep field EPHD for scrap handling, bundles handling, thin plates handling, coils handling and several other applications;
- EPHD with special properties for scientific, underwater, radioactive, space and some other specific applications.