
M 6053 M
rev 16 – 03/2021
Page 20/96
GB
www.tractel.com
INFLUENTIAL FACTORS ON LIFTING CAPACITY
Air-gap
It corresponds to the space between the magnet lifter active poles and the load due to surface
roughness, oxidation, paper or painting on the load, flashings, etc.
A rusted hot laminated plate presents an air-gap between 0.1 to 0.3 mm. Surface roughness on a
piece in wrought iron can reach 0.5 mm.
Permanent magnet lifter capacity is reduced when the air-gap increases (see table in following
paragraph).
Dimensions of the load (see table in following paragraph)
Thickness and contact surface : a load too thin or a contact which doesn’t cover all the active
poles surface, doesn’t allow a good closing of the magnetic circuit and reduces the magnetic
force on the load.
IMPORTANT : presence of holes with large dimensions also limits the magnet lifter capacity.
Length: bending of the load due to its long length produces an air-gap.
Load horizontality
To achieve the maximum capacity of a magnet lifter, loads must be perpendicular to the active
poles surface. That is why it is necessary to find out, with a good positioning of the magnet lifter,
the best horizontal position of the load before lifting.
Kind of load
WLL (kg)
Steel type *
%
**
magfor II
100
magfor II
300
magfor II
500
magfor II
1000
magfor II
2000
magfor II
3000
magfor II
5000
Low carbon content (E24-2,
S235)
100 %
100
300
500
1 000
2 000
3 000
5 000
St 52 (A50-2)
96 %
96
288
480
960
1 920
2 880
4 800
Stainless steel 430F
50 %
50
150
250
500
1 000
1 500
2 500
Fonte
45 %
45
135
225
450
900
1 350
2 250
Nickel
10 %
10
30
50
100
200
300
500
Stainless steel 304
0 %
0
0
0
0
0
0
0
WLL: working load limit
* non exhaustive list
** % regarding maximum working load limit of magnet lifter with steel with low carbon content
(like S235 steel) with a surface roughness
≤
0,1 mm (smooth and clean manufactured surface)
and for loads dimensions which are within the parameters given the « practical tables for capacity
reduction ».
The same reduction % apply to WLL of magfor not listed in this table