MAGNETIC WHEELS
Ships and cargo vessels are the most cost effective way of transporting people and bulk goods around the world. Structural failure is a major cause of the wreckage of ships, resulting in loss of life and pollution of seas and coastal waters. For this reason, ships must be inspected regularly for any signs that structural failure may be imminent.
These inspections are currently carried out manually in "dry docks" by operators working in hazardous conditions. However, automated systems are currently being developed. These will be housed inside a robotic crawler, as shown in the concept drawing below:
HSMAG has recently developed magnetic wheels which enable these crawlers to be adhered to the metal surface which is to be inspected.
This assembly usually consists of a Neodymium Iron Boron magnet array with steel pole pieces to concentrate the flux. However, in marine environments, the salt quickly corrodes the iron content of the magnet. This can be overcome by using 400 grade stainless steel pole pieces and samarium cobalt magnets, both of which are completely corrosion resistant. The pictured assembly also includes knurled pole pieces for added grip.
Although these systems are commonly used for ship hull inspection, they can also be used to inspect oil and gas pipelines, large metal storage tanks and a variety of other metal structrures.
Magnetic wheels Neodymium-iron-boron (NdFeB)
Magnetic wheels with multi-pole magnetization, NdFeB, bore with fitting tolerance H7 and groove
Article No. D mm d mm B mm b mm H mm Force* N Temperature °C Optimal sheet thickness¹ mm
HSMWW-25 25+0.1/-0.1 10 15+0.5/-0.5 3 10.6 25 100 < 0.5
HSMWW-32 32+0.1/-0.1 10 15+0.5/-0.5 4 11.1 45 100 < 0.5
HSMWW-40 40+0.1/-0.1 12 27+0.5/-0.5 4 13.1 70 100 < 1.0
HSMWW-50 50+0.1/-0.1 12 27+0.5/-0.5 4 13.1 90 100 < 1.0
HSMWW-63 63+0.15/-0.15 16 39+0.5/-0.5 5 17.3 100 100 < 1.0
HSMWW-80 80+0.15/-0.15 20 39+0.5/-0.5 6 21.7 140 100 < 1.5
HSMWW-100 100+0.2/-0.2 25 51+0.5/-0.5 8 26.7 290 100 < 1.5
HSMWW-125 125+0.2/-0.2 30 63+0.5/-0.5 8 31.7 340 100 < 2.0
HSMWW-160 160+0.25/-0.25 40 75+0.5/-0.5 12 42.1 440 100 < 2.0
¹ This value indicates at which sheet thickness the multi-pole magnetic wheel offers greater holding power compared with a two-pole magnetic wheel (for the same diameter D).