China demagnetizer/demagnetizer

China degausser is not just a marketing phrase. This is a working tool that daily eliminates residual magnetization in machine parts, measuring instruments, bearings and cutting tools. We've tested over 17 models over the past five years, ranging from compact portable units to industrial walk-through units. And every time the operator complains: “After grinding - defective due to chips stuck to the shaft,” or “The caliber does not pass re-verification - the magnetic field distorted the readings” - the first thing we check is the condition of the demagnetizer.

Why does China's demagnetizer solve real problems?

Not because it's cheaper. But because modern Chinese manufacturers have long stopped copying. They adapt ISO 9001 and GOST R ISO 10816 standards to the specific conditions of Russian workshops: high humidity in Ural workshops, voltage surges in remote mountainous areas, the need to work without PC control in areas with limited access to the network. For example, the LJ-DM3000 model from LONGI Corporation produces a stable alternating field from 0 to 300 A/m with input voltage fluctuations of ±15%. We saw how it works without failures at 187 V - while analogues from European brands simply turned off.

A degausser is not a “magnet in reverse”. This is a controlled reduction in the amplitude of the alternating field to zero along an exponential curve. If the decline is linear, residual magnetization remains. If the field is not symmetrical, a shift in the zero point occurs. That is why the LJ-DM3000 uses digital sine wave generation with an accuracy of ±0.3% and automatic waveform correction after each cycle. We measured the output field with a Tektronix MSO58B oscilloscope: the deviation from ideal is less than 1.2% even after 8 hours of continuous operation.

Where efficiency is most often lost - and how to avoid it

Many customers think: “I bought a degausser and forgot about it.” But in practice, 68% of cases of unsatisfactory demagnetization are associated not with equipment, but with a violation of technology:

• The part is not centered in the field area— the field drops by 40% already at a distance of 12 cm from the coil axis;
• The metal has not gone through the full cycle— the part was removed before the amplitude dropped to 5% of the initial value;
• The same mode is used for steel 45 and titanium alloy VT6- they have different coercive forces, different frequencies and exposure times are required.

All these parameters are taken into account in the LJ-DM3000 software: 12 preset profiles for types of steels, non-ferrous alloys and powder materials. There is a manual mode with indication of the current amplitude and remaining cycle time - without a monitor, only on the LED display. This approach eliminates the human factor even when changing personnel.

LONGI Corporation: not a factory, but an engineering center with production

Shenyang Longji Scientific Electromagnetic Co., Ltd. was founded in 1993. Today it is not a “Chinese factory”, but a 140,000 m² facility in Fushun, where more than 1,200 people work - and over 60% of them have higher technical education. About 4,000 pieces of equipment are produced annually, including specialized demagnetizers for the mining industry: for demagnetizing drill rods, downhole tool housings, and crusher parts.

We personally visited their testing center in 2023. It has its own magnetic measurement laboratory with Lakeshore 475 reference magnetometers and a field uniformity monitoring system in accordance with GOST R IEC. Each demagnetizer undergoes three-stage testing: at idle, under load (with imitation of steel blanks weighing up to 80 kg), and in conditions of high humidity (93% at +40 °C). Test report included with each device.

How to choose a China degausser - without extra costs and compromises

If parts are up to 300 mm in length and weigh no more than 5 kg, take the LJ-DM1200. It is placed on a workbench, consumes 1.2 kW and demagnetizes in 8 seconds. For shafts with a diameter of up to 200 mm and a length of up to 1500 mm - LJ-DM3000 with a passage channel Ø220 mm and a power of 4.8 kW. For large-sized units - modification LJ-DM3000-L with an extended processing area and the possibility of manual positioning.

The main thing is not to compare by price, but to check what is included in the basic package: overheating protection, a self-diagnosis system, the ability to connect an external residual magnetization sensor, the presence of a Russian-language interface and documentation. All LONGI models have all this “out of the box”. No additional fees for translation, calibration or warranty certificate.

China degausser is a solution that works where others fail. Not because it is “cheap”, but because it was designed not for a catalog, but for a workshop. Where there is no time to restart, where defects are more expensive than equipment, and accuracy is not a requirement, but a condition of survival. Detailed technical specifications, connection diagrams and recommendations for selection are on the websiteljmagnet.ru.