Influential Factors On Lifting Capacity - Tractel magfor100 Manual De Empleo En El Interior

5. 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, flashes, etc.
A rusted hot laminated plate presents an air-gap between 0.1 to 0.3 mm. Surface
roughness of a piece in wrought iron can reach 0.5 mm.
Permanent magnet lifter capacity is reduced when the air-gap increases (see tables
in following paragraph).

Dimensions of the load (see tables 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 important 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
Steel type *
Low carbon content
(E24-2, S235)
St 52 (A50-2) 96 %
Stainless steel 430F 50 %
Fonte 45 %
Nickel 10 %
Stainless steel 304
* non exhaustive list
** % regarding maximum working load limit of magnet lifter with steel with low
carbon content (like S235 steel) with a surface quality which warrants a surface
roughness ≤ 0,1 mm (smooth and clean manufactured surface) and for loads
dimensions which respect characteristics given the « practical tables for capacity
reduction ».
magfor magfor
%**
100 300
100
100 300
%
96 288
50 150
45 135
10 30
0 % 0 0
WLL (kg)
magfor magfor magfor
500 1000 2000
500 1000 2000
480 960 1920
250 500 1000
225 450 900
50 100 200
0 0 0
WLL: working load limit
magfor magfor
3000 5000
3000 5000
2880 4800
1500 2500
1350 2250
300 500
0 0
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