The Wire EDM (Electrical Discharge Machine) manufacturing process consists of passing a straight metal wire through or about a metal work piece. The work piece sits in a bath of oil (or some other liquid), and an electric charge is applied to the metal work piece. In addition, another electric charge is applied to the wire. Material removal results from disintegration of the work piece at the wire contact due to electricity. The liquid bath helps to wash away the disintegrated material and acts as a coolant.
Wire guide holders on top and bottom support the wire. The wire guide is constrained to move in a plane, and the two planes for top and bottom are parallel. The wire is fed from pulleys attached to the wire guide holders. The purpose of this feeding is to constantly supply a fresh wire in order to insure a constant rate of material removal.Wire EDM
The machine tool may be either two or four axis. For the 2 axis type, both the upper and lower wire guides move in tandem creating only vertical walls. For the 4 axis type, the top and bottom guides may be positioned independently to create a taper or conic section. For instance to generate a cone, the top guide can be held fixed while the bottom guide follows a circular path.
There are two ways to create Wire EDM operations. The Create Operation dialog allows you to create individual operations. These operations have the roughing, finishing, cutoffs and backburn functions all contained within a single operation. The Create Geometry dialog allows you to create a sequence of operations. The roughing, finishing, cutoffs and backburn functions are each a separate operation.
In the Create Operation dialog, when you set the type to wire_edm you have the following choices for the subtypes.
External Trim operation
Internal Trim operation
No Core operation
Open Profile operation
In the Create Geometry dialog you can set the type to wire_edm and choose the subtype. This method automatically creates a geometry group with a sequence of operations. You can choose either the External Trim Sequence or the Internal Trim Sequence as subtypes. If you choose the External Trim Sequence, the system creates three operations: External Trim Rough, External Trim Cutoff and External Trim Finish. If you choose the Internal Trim Sequence, the system also creates three operations: Internal Trim Rough, Internal Trim Backburn and Internal Trim Finish.
These three operations use the same geometry. You can arrange them in any order in the Program View. For instance, you may have three pockets you wish to cut. You can have the system do all the roughing first unattended and then do the cutoffs and finish operations while the operator is present.
While specifying the boundary, it is important to keep in mind which type of Wire EDM operation (2 axis or 4 axis) you will be using. While External Trim, Internal Trim and Open Profile can be use with both 2 axis and 4 axis machines, No Core can only be used with a 2 axis machine.
Tool parents are not used for Wire EDM operations. They are always created in the NONE tool group.