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CAT40 SK Collet Chuck Tool Holders
What are the differences between SK and ER Collet Systems?
ER collets have an included angle of 16 degrees and most collets have a range of 1mm. Grip is strong and in most applications sufficient. Grip is stronger than SK due to its double angle design.
SK collets have an included angle of 8 degrees and most collets have a range of .5mm. SK collet system is recommended for medium roughing to fine finishing due to slightly better concentricity than ER collets. More of the collet sits in the taper pocket so concentricity is equal or better than ER collets.