Fixture comprising magnetic means for holding rotary symmetric workpieces

Abstract

A method for using a fixture system and a fixture system for holding workpieces or parts to be treated by a plasma assisted vacuum process, the fixture system including magnetic means which generate a magnetic field with a magnetic force which is high enough for holding the workpiece or part. The magnetic means of the fixture system are designed and arranged in such a manner that magnetic field lines of the generated magnetic field are largely confined to the space including the fixture system and the body of the workpiece or part, so that a generation of unintended plasma inhomogeneities caused by the magnetic field lines is avoided.

1 . A fixture system comprising a holding part for holding a workpiece comprising ferromagnetic substances, said workpiece comprising a body with two ends and exhibiting along a rotary axis a symmetric shape with a radial dimension and with surfaces to be treated by means of a plasma assisted vacuum treatment process, said holding part comprising a magnetic means which generates a magnetic field with a magnetic force in the rotatory axis direction which is high enough for holding the workpiece if the workpiece is placed on a holding surface of the holding part in such a manner that one end of the workpiece is in contact with the holding surface of the holding part, the holding part further comprising:
 a fixture base, a magnet yoke comprising an opening, an outer diameter and an inner diameter, said magnet yoke being placed between a surface of the fixture base and the holding surface of the holding part in a manner that said opening is positioned in the opposite side to the fixture base, at least one magnet placed inside the magnet yoke in a manner that the at least one magnet is kept circumferentially at equal distance from the magnet yoke by a non-magnetic spacer; and   the magnetic means of the holding part are designed and arranged in such a manner that the magnetic field lines of the generated magnetic field are at least largely confined to the space occupied with parts of the fixture system or body of the workpiece, so that a generation of side plasmas caused by the magnetic field lines during the execution of a plasma treatment is avoided.   
     
     
         2 . A fixture system according to  claim 1 , wherein the outer radius regarding the outer diameter of the magnet yoke is in the range of 100% to 50% of the radial dimension of the workpiece body. 
     
     
         3 . A fixture system according  claim 1 , wherein the holding part comprises a non-magnetic cover comprising stainless steel which is used as holding surface. 
     
     
         4 . A fixture system according to  claim 1 , wherein one or more magnets comprised in the holding part are permanent magnets which are made of hard magnetic material. 
     
     
         5 . A fixture system according to  claim 4 , wherein the hard magnetic material has a Curie-Temperature of above 450° C. 
     
     
         6 . A fixture system comprising a holding part for holding a workpiece comprising ferromagnetic substances, said workpiece comprising a body with two ends and exhibiting along a rotary axis a symmetric shape with a radial dimension and with surfaces to be treated by means of a plasma assisted vacuum treatment process, said holding part comprising a magnetic means which generates a magnetic field with a magnetic force in the rotatory axis direction which is high enough for holding the workpiece if the workpiece is placed on a holding surface of the holding part in such a manner that one end of the workpiece is in contact with the holding surface of the holding part, the holding part further comprising:
 a fixture base, a magnet link plate placed between a surface of the fixture base and the holding surface of the holding part, and at least one pair of magnets placed between the magnet link plate and the holding surface of the holding part in a manner that each magnet of said at least one pair of magnets is positioned next to each other with opposite polarities and forming an outer diameter; and   the magnetic means of the holding part are designed and arranged in such a manner that the magnetic field lines of the generated magnetic field are at least largely confined to the space occupied with parts of the fixture system or body of the workpiece, so that a generation of side plasmas caused by the magnetic field lines during the execution of a plasma treatment is avoided.   
     
     
         7 . A fixture system according to  claim 6 , wherein the outer radius regarding the outer diameter formed by the pair of magnets is in the range of 100% to 50% of the radial dimension of the workpiece body. 
     
     
         8 . A fixture system according  claim 6 , wherein the holding part comprises a non-magnetic cover comprising stainless steel which is used as holding surface. 
     
     
         9 . A fixture system according to  claim 6 , wherein one or more magnets comprised in the holding part are permanent magnets which are made of hard magnetic material. 
     
     
         10 . A fixture system according to  claim 9 , wherein the hard magnetic material has a Curie-Temperature of above 450° C.