SURALAC 9000

SURALAC® 9000
SURALAC® 9000 is a new bonding coating introduced by Cogent Power to bond stamped
laminations using heat and pressure. The coating has a good lubricating effect and prolongs
the life of the stamping tools used. Compared to cores made with other methods, like
welding or interlocking, cores made with SURALAC® 9000 have.
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better magnetic properties
good mechanical strength
optimal thermal conductivity
reduced noise
no “breathing” at temperature changes
The coating on the delivered strips/sheets is similar to SURALAC® 1000 and other C-3 type
coatings. But it is still reactive if heated and thus stacked laminations can be bonded
together. After the bonding the coating is passive and cannot again be made reactive.
Properties of the “as-supplied” coating before bonding
Designation
Type
Standard thickness per side
Colour
SURALAC® 9000
Organic epoxy based
4.5 µm (180 µinch)
Clear
2
Franklin ASTM A717: Typical value per lamination >200 Ωcm
Typical pencil hardness
5-7H
The parameters for bonding should be optimized for each case. As a guideline 3 minutes to
1 hour at 220°C (430°F) or 1 – 24 hours at 150°C (300°F) are suitable combinations of time
and temperature at a pressure of 300 N/cm2 (435 psi). Bigger cores need longer time to
reach uniform temperature.
The bonding strength depends on a number of factors. A roller peel test may show bonding
strengths between 2 and 10 N/mm (11 – 60 lbf/inch) depending on e.g. the steel grade of the
laminations and the bonding conditions.
SURALAC® 9000 is harder than earlier versions of bonding coatings in order to minimize the
“squeeze-out” during the bonding operation. Thus the dimensional tolerances of the bonded
stacks are improved and the high insulation resistance between laminations is maintained.
Bonding coatings have some limitations the user needs to be aware of. The use of lubricants during
stamping is not recommended since they may have a negative influence on the bonding strength. But
the coating itself has a good lubricating effect on the tools. The bonding strength is reduced with
increased operating temperature. Up to about 60°C (140°F) the influence is minimal and at about
125°C (260°F) the bonding strength is 50% of that at room temperature, but the strength is regained
when the temperature is lowered. However there is a degradation of the bonding strength with time
and temperature. After 20 000 hours at about 170°C (335°F) the room temperature bonding strength
is reduced by 50%. A long time between the coating operation performed by the steel manufacturer
and the bonding operation can also influence the result. This effect can be seen after six months
between the coil coating and bonding operations.
For further information please see www.sura.se for contact details.
The information and data on this data sheet is accurate to the best of Cogent’s knowledge, but are intended for general information only.
Cogent and its subsidiaries accept no liability thereof.

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