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Posted

Can anyone explain to me what is the difference in performance, flexibility, or other, of rod blanks with different 'IM' specs? eg: I see advertising for IM-6, IM-7 and IM-8, but what does that mean??

Posted
Can anyone explain to me what is the difference in performance, flexibility, or other, of rod blanks with different 'IM' specs? eg: I see advertising for IM-6, IM-7 and IM-8, but what does that mean??

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I'm no expert, so I may get this wrong. But I think it relates to the modulus of the carbon fibres used in the blank. The higher the modulus, the stiffer the blank, and as a result, it makes for a lighter, thinner blank?

Higher modulus is good for transferring power to the lure when casting, but it can break more easily.

Okay, now maybe somebody else can give the correct answer. :1prop:

Posted

I found this on the www:

IM6 is a 'Grade' of Magnamite, a graphite product of Hercules Inc. BASF makes a similar product, as well as others. The important thing about IM6, IM7, IM8 ratings for fishing applications is the tensile modulus. Most dept. store rods that are graphite composites are around 30-35 million psi tensile modulus. The IM is a shorthand for that tensile rating. IM6 = 40 million IM7 = 41 million IM8 = 45 million Tensile modulus briefly is: (Courtesy Owens-Corning) "When a bar is pulled in tension, it has to get longer. The tensile modulus is used to calculate how much longer it will get when a certain load is applied to it. Units are normally millions of pounds per square inch. Higher numbers indicate materials which will not elongate as much as others when they are being compared under equal tensile loading conditions." That elongation, or elasticity, is what allows the rod to spring and bend back.

So IM6 is a graphite material that is not a stiff as IM8. The significance of this (as I understand it) is that IM6 rods will generally have more material in the blank to compensate for the lower modulus, and so will be generally more resistant to NON-FISHING abuse than higher IM rods. IM (bigger number) rods will be lighter and better-performing for a given weight rod, but will have thinner side walls.

How's that grab ya?

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