You set the width of a Tab on the contour. You can pre-select and color code the Thread Point (in green) and the Start Point (in red) on the contour. With the color code, SURFCAM can automatically select the Thread and Start Points and chain the contour. You will indicate the side of the contour to cut.

SURFCAM creates the toolpath starting with the initial burn from the Thread Point to the entry Retract Point. The initial pass begins with a Straight Line leadin move from the entry Retract Point to an offset from the Start Point on the contour. The initial pass ends with a Straight Line leadout from the offset of the End point on the contour to the exit Retract Point.

There, a Stop command is inserted in the code to allow the operator to apply appropriate clamps on the part. The Tab is then cut with a pass that ends at the entry Retract Point. Another Stop command is inserted so that the waste material can be removed.

Next a number of Skim passes are executed beginning and ending at the entry Retract Point. The Leadin and Leadout moves for Skim passes can be one of three types: Straight Line, Teardrop, or Offset Curve Overlap.

After the final Skim pass the wire can be set to stop at the Retract Point or the Thread Point.

Initial Pass Before Tab is Cut

Skim Passes with Teardrop Lead moves

 

You can also use the 2 Axis XY operation to cut multiple contours. Three strategies are available for the order in which you perform initial passes, Tab cuts, and Skim passes.

Click NC > EDM > 2 Axis XY to display the 2 Axis EDM Contour dialog box. See

Setup Tab, Skim Cut Tab, Cut Control Tab, EDM Options Tab,.

After you click OK on the 2 Axis EDM Contour dialog box, SURFCAM will display the NC > EDM > Select Chain menu.

There are two ways to create the toolpath.

If you have already created and color coded the Thread (green) and Start Points (red), click Auto on the Select Chain menu. Click Visible on the Select menu, then click Done. Click Done on the Select Chain menu.

If you do not select a Start Point, the toolpath starts at the point on the contour nearest the Thread Point.

With the Auto > Visible method, red Start Points must be on the contour, not just near it.

Be sure to consider the width of the Tab when you select a Start Point. Gouges are possible if either a Start Point or an End Point is too close to a sharp corner.

If you did not color code the Thread and Start Points, perform the following steps.

1. Chain the contour(s) to be cut, but do not click Done on the Select Chain menu until you have selected the Thread and Start Points.

2. Click Thread. SURFCAM will display the Select Point menu. Select the Thread point(s) and click Done.

3. Click Start Point. SURFCAM displays the Select Point Menu. Select the Start Point(s) on or near each contour and click Done. Selected points not on the contour will be projected onto the contour as the Start Points.

Click Done on the Select Chain menu.

You will be prompted to select the side to contour. After you click on the correct side of a contour, the 2 Axis XY toolpath appears. Click Accept to keep the operation.

The 2 Axis XY operation is used to program a 2 Axis machine.

For parameters not listed below see Chain Menu.

Thread / Start Point

These buttons are available on the NC > Wire EDM > 2Axis XY > Select Chain menu. Use these buttons to select the thread point for the wire.

Thread

When you click Thread, the Select Point menu appears and the prompt reads "Select thread points, then 'Done'." Select the wire thread point and click Done.

Start Point

The Start Point button is active after you chain the contour. When you click the Start Point button, the Select Point menu is displayed. The prompt reads "Select glue start points on the curve, then 'Done'." Select the glue start point for the cut and click the Done button.

Before you use the 4 Axis operation you must:

Create a top profile. Create a bottom profile. Connect the two profiles with a surface. Edit the surface so that the arrow is (a) attached along the bottom profile; (b) pointed to the outside of the surface; (c) pointing in the direction of the cut. Create a point for the Thread Point. Create a point for the Cut Point (the location where the wire will be cut).

• The Thread and Cut points must be on the side of the surface to be cut. They must be located so that the wire will not gouge the part as it moves from the Thread Point to the Start Point and from the End Point to the Cut Point.

• The Start Point of the cut will be the location on the bottom profile where the surface arrow is attached.

Click 4 Axis on the NC > Wire EDM menu. The prompt reads “Select a surface.”

Select the surface by clicking its surface arrow. (Make sure the arrow is pointed in the right direction. SURFCAM displays the 4 Axis EDM dialog box.

• Since gouge checking is not currently implemented in 4 Axis EDM, it is recommended that you enter a value of 0 for the Wire Diameter parameter on the Setup tab. It is best to use the cutter compensation on the machine controller to control potential gouges in narrow interior angles.

• It is also recommended that you enter a value of 0 for the Curve Tolerance on the Cut Control tab. This will prevent a tool move that is within the allowable chordal deviation from cutting off the tip of a sharp exterior corner.

Click the OK button on the 4 Axis EDM dialog box. SURFCAM displays the Select Point menu and prompts you to select the thread point of the wire. Click on the Thread Point.

The prompt reads “Select cut point.” Click the Cut Point.

SURFCAM creates the 4 Axis toolpath and displays the tool motion on the screen. The Keep Operation dialog box appears. Click Accept to keep the operation.

One application is to trim the edges of a part that has been formed from a relatively thin sheet of material by some process such as vacuum forming or stamping.

The toolpath is directed by a trimming curve that coincides with the final edge of the part. During the 4 Axis UV operation, the outside edge of the tool is tangent to the trimming curve. The center of the tool is offset to one side or the other of the trimming curve. This makes it possible to trim material from the edges of a hole in the interior of a part as well as material from the outer edges. Doing both on the same part requires two separate 4 Axis UV operations. The angle between the top surface of the part and the edge that is cut by the side of the tool is determined by direction lines that you attach to the trimming curve at appropriate locations. The angle at which the direction lines intersect the surface is the angle at which the tool will cut. If a direction line is normal to the surface at a given location, the angle between the surface and the edge will be 90°. The size of the cutting angle, as the tool moves from the location of one direction line to the next, will change in a smooth transition. Direction lines must be attached to the trimming curve at end points of elements that make up that curve. If you must put a direction line between the end points of an element (such as a spline, an arc or a line), you must use the Break 1 command on the Edit > Trim/Break menu to break that element where it intersects the direction line.

A trimming curve Trimming curve with direction lines

 

Views showing tool tilted to follow direction lines

 

To create the 4 Axis UV operation, click 4 Axis UV on the NC > Wire EDM menu.

SURFCAM displays the Select Chain menu and the prompt reads “Select beginning element of trimming curve.”

After you chain the trimming curve, SURFCAM display the EDM 4 Axis UV Trim dialog box.

Click OK on the EDM 4 Axis UV Trim dialog box. SURFCAM displays the Select menu. The prompt reads “Select tool direction lines or vectors.” Select the lines or vectors and click Done.

The prompt reads “Select offset side.” Click on the appropriate side of the trimming curve.

SURFCAM creates the trim toolpath and display the tool motion on the screen. SURFCAM displays the Keep Operation dialog box. Click OK to keep the operation.