This section describes the formats and parameters to control the output for the fourth and fifth axes.
These are the basic four axis machine tools:
A rotary table in either the YZ or ZX planes.
A tilting table in either the YZ or ZX planes (this is treated the same as a rotary table.)
A swiveling head in either the YZ or ZX plane.
These are the basic five axis machine tools:
A rotary table mounted on another rotary table. These can be any combination of XY, YZ, or ZX planes.
A rotary table or a tilting table in either the XY, YZ, or ZX planes and a swiveling head in one of the planes.
Two swiveling heads in any combination of XY, YZ, or ZX planes.
The Independent table (or 4th axis) is the rotary axis that does not change its orientation or plane of rotation when the other rotary axis moves. When one axis is a swiveling head and the other is a rotary table, the swiveling head is the independent axis and the rotary table is the dependent axis.
The Dependent (or 5th axis) is the rotary axis that does change its orientation or plane of rotation when the other rotary axis is rotated. By definition there must be a 4th axis in order to have a 5th axis.
When you select the 4th or 5th axis option you have the following choices:
Minimum Angle Increment Degrees - This is the smallest amount of delta rotation possible. For example, if a rotary axis has 360,000 positions the minimum increment is .001. Likewise if it is a 72 position table the minimum increment is 5 degrees.
Enter the number which represents the minimum angle increment for the rotation.
Direction Of Rotation Determined By - This determines how the postprocessor forces either clockwise or counterclockwise rotation. You have the following options:
Sign Of Angle, Plus Is CLW, Minus Is CCLW - For this type of rotary axis -90 will cause a counterclockwise rotation of 90 degrees and 90 will cause a clockwise rotation of 90 degrees. The sign is used only to determine direction of rotation.
Table Rotates CLW To A Large Angle, CCLW To A Smaller Angle - (this is the most common choice) For this type of rotary axis the sign is used to determine the absolute angle. For instance 90 degrees and -90 degrees are different positions, -90 and 270 are exactly one rotation or 360 degrees apart. The rotary axis will rotate clockwise from -100 degrees to -50 degrees and counterclockwise from 100 degrees to 50 degrees.
M Codes Force Direction Of Rotation - The user at this point selects the two M codes, one for clockwise and one for counterclockwise. The menu is shown after this definitions list.
Enter the number which represent the M code to force the table rotation in a clockwise direction.
Enter the number which represent the M code to force the table rotation in a counter clockwise direction.
The user is then asked if the M codes for direction are modal or not.
Rotation Is Always CLW - The postprocessor cannot control direction of rotation for this type.
Rotation Is Always CCLW - The postprocessor cannot control direction of rotation for this type.
Rotation Is Always Shortest Distance - The postprocessor cannot control direction of rotation for this type.
Sign Of Angle, Minus Is CLW, Plus Is CCLW - For this type of rotary axis 90 will cause a counterclockwise rotation of 90 degrees and -90 will cause a clockwise rotation of 90 degrees. The sign is used only to determine direction of rotation.
Rotary Axis Rotates CCLW To A Larger Angle And CLW To A Smaller Angle - For this type of rotary axis the sign is used to determine the absolute angle. For instance 90 degrees and -90 degrees are different positions, -90 and 270 are exactly one rotation or 360 degrees apart. The rotary axis will rotate counterclockwise from -100 degrees to -50 degrees and clockwise from 100 degrees to 50 degrees.
Maximum or Minimum Programmable Angle - This is maximum or minimum allowable rotary position measured clockwise from the minimum allowable rotary position. The valid programmable rotary positions are those that measure clockwise from the minimum position to the maximum position.
The GPM uses the Maximum or Minimum Programmable Angle to determine if rotary positions, derived from the tool axis, exceeds these limits.
Maximum or Minimum Degrees Per Minute - Enter the number which represents the maximum or minimum number of degrees that the 4th axis can turn per minute.
Plane Of Rotary Axis (XY, YZ, ZX) - This defines in which of the three cartesian planes that the rotary axis lies. To determine the plane of the 5th axis, the 4th axis should be at its 0 degrees position. Generally the A axis is in the YZ plane, the B axis in the ZX plane and C axis is in the XY plane. Not all machine tools follow these conventions. The MDFG allows you to assign both the axis letter and the axis plane of rotation. The selection toggles between the three axis planes.
Rotary Axis Type - This option defines what transformations are needed to map the part coordinates to the machine coordinates. The part coordinates are not mapped to reflect the rotation if the rotary axis is not contouring.
There are four types of rotary axis:
Index Or Positioning Table - This type of table is not capable of contouring mode. If the 4th axis is selected you must set other options that will later determine what kind of indexing table is needed. Your options are:
Word Address, Rapid G Code Output With Angle - This table uses Word Address formats to position the table and a G code is output by the GPM.
Word Address, No Rapid G Code Output With Angle - This table uses Word Address formats to position the table and no G code is output by the GPM.
Hyperdex Table - This index table will output a series of three M codes for every ROTATE command. For example ROTATE/TABLE, 270,CCLW will cause M92, M97, M90 in three consecutive blocks.
You can then enter the M Code value output for clockwise and counter-clockwise rotate of the table base.
One M Code Per Stop - Enter the number which represents the number of table positions, that represents the M Code for table indexing (the default is 15), and indicate the angular positions of the corresponding table positions.
One Character Code Per Stop - Enter the number of table positions controlled by a single character Word Address, the character, and the angular value for each of the table positions you specified.
M Code Defines Position - Enter the number of table positions, the angular value for each of the table positions you specified in Option 1, and the M code to define each of the table positions you specified.
Contouring Rotary Or Tilting Table - This type of rotary axis causes no movement of the tool when the table rotates. It can consist of either a rotary axis or tilting table. The tilting table is treated geometrically exactly like a rotary table except that plane of rotation is not the plane of the table. It is the plane that is perpendicular to the axis of the tilting table.
Contouring Swiveling Head - This type of rotary axis causes motion only in the tool.
Index Or Positioning Head - This type of rotary axis is for positioning only.
Conversion Factor Degrees To Rev Or Inches - This option allows you to define the rotary output in something other than degrees. For example, some controls require revolutions and not degrees. The user would enter .002777778 to make this conversion. This option is 1.0 for most controls.
Rotation Of (A,B or C) Axis About (X,Y or Z) Axis Is Standard (or Reverse) Cartesian
This parameter controls how the GPM will translate the i,j,k tool axis information into rotary positions. Most NC machines are Standard, that is, they rotate or swivel clockwise to larger angle. When in doubt use the Standard convention unless the data is incorrect for your machine tool. The following guidelines can be used.
In the XY plane looking down the Z axis from positive to negative rotation clockwise to a larger angle is Standard.
In the ZX plane looking down the Y axis from positive to negative, rotation clockwise to a larger angle is Standard.
In the YZ plane looking down the X axis from negative to position, rotation clockwise to a larger angle is Standard.
Radius From Center Of Rotation To Tool Tip - When you choose to Out Put To Tape, you must indicate the Format for The Radius Parameter.
Distance From Pivot Point To Spindle Gage Line - This option is available when you select Index Or Positioning Swivel Head under the option Rotary Axis Type. Enter the number which represents the distance from the pivot point to the spindle gage point.
Reset Rotary Table - This option allows you to set the parameters for resetting the rotary table.
Retract Before Resetting Table - Toggles between YES and NO. If set to YES, the following menu options become available allowing you to set parameters for retracting from and reengaging the rotary table. For a detailed description of these options, please refer to the discussion under Travel Limit Violations beginning on page .
Clearance Distance to Center Of Rotation -
Reengage Distance Above The Part -
Reengage Feedrate Expressed in Units Per Minute -
Text String Before Retracting Out Of Part -
Text String After Positioning Back To Reengage Point -
Entry Complete -When you select Entry Complete the Reset Rotary Table menu is displayed.
Reset Block - Allows you to set the parameters for setting the reset block.
Rotary Axis Only - Allows you to define how the GPM will respond when the desired rotary motion violates the machine's axis limits.
Output G92 To Reset Previous Rotary Position To Maintain Current Desired Or Shortest Rotation -
Output Valid Rotary Position Closest To Previous Position -
Unwind Code Only - Allows you to enter a text string of up to 66 characters to specify the unwind code.
Unwind Code and Rotary Axis - Allows you to enter a text string of up to 66 characters to specify the unwind code, then displays the Rotary Axis Only menu options, allowing you to define how the GPM will respond when the desired rotary motion violates the machine's axis limits.
4th or 5th Axis Maximum Allowable Error In Edge Rounding - Reports an error when the rotary values are rounded beyond the specified allowable round ing maximum value.
Entry Complete - When you select Entry Complete the Index Or Positioning Table Parameters And Limits menu is displayed.
Entry Complete - When you select Entry Complete the Word Address Character menu is displayed.
Next, you can enter the number of degrees (if any) of angular offset between the rotary component 0 degree position and the expected 0 degree position. The expected 0 degree position is straight down (negative along) the Z axis (i.e., when the tool axis is 0, 0, 1.)
The angular offset value is the rotary axis value when the MCS tool axis is 0,0,1. For example, the Sundstrand OM4 A axis 0 position is with the spindle pointing down the machine Y axis. Since a 0,0,1 tool axis produces an A axis reading of 90_ the angular offset value is 90_.
Several manufacturers use a position 90 degrees CCLW (i.e., looking positive along the X axis) from the expected position. Next one of two menus appear:
Using the Machine Zero To Center Of Forth Axis menu, you can indicate that machine tool's zero position is not at the center of the rotary table. In order for the post to correctly map the part coordinate system to the machine coordinate system, this number must be correct. Enter the number which represents the X, Y, and Z delta distance. This should be entered in machine coordinates from machine zero to the center of the fourth axis.
Using the Center Of Fourth Axis To Center Of Fifth Axis menu (which actually means the center of the fifth axis to the center of the fourth axis), you can indicate that the 5th axis of rotation axis does not intersect the 4th axis of rotation. To derive this vector, both axis should be at zero degrees and it involves at most two coordinates but usually one. This perpendicular vector is measured in the plane of the 4th axis from the axis of rotation of the 5th axis to the axis of rotation of the 4th axis. You are prompted to specify whether a RESET code (G92) is output when the axis limits are violated.
Inclination Of B Axis To C Axis - (special option) The initial implementation is for two swiveling heads, one in the XY plane, the other is inclined, but the 0 position lies in the ZX plane. To utilize this configuration, you must make these selections under ROTATE: Both heads must be contouring swiveling heads. The 4th axis must be in the ZX plane and the 5th axis must be in the XY plane.
If the above conditions exist, the MDFG will ask if the B axis is inclined to the C axis at other than 90 degrees. B refers to the ZX plane and C refers to the XY plane. The actual letter addresses used is not significant, but the planes must be ZX for the 4th axis and XY for the 5th axis. If the axes are inclined, you will be asked to enter the number of degrees. GPM will resolve the B and C angles to align with the tool axis vector in the CLF file.
If you are using a five axis machine tool with a rotary or tilting table and a pivoting head, the pivoting head is always the fourth axis.
If a pivoting head is mounted to a rotary fifth axis, then you must define both the fourth and fifth axes as swiveling heads.
A tilting table is always a fourth axis - never a fifth - and is defined as a tilting or rotary table. It can require the reverse cartesian option.
The C axis (XY plane) is never a fourth axis.
Program the machine coordinate system at the center of the fifth axis rotary table for all pivot head/rotary table machine combinations when the rotary table is in the machine bed. Examples are the Sundstrand OM3, OM4, M60, and M80. This also applies to tilting/rotary table machines such as the 5 axis K&T and all double rotary table combinations.
For incremental rotary output to cross quadrants correctly, the limits must be set to +- 99999.99.
NOTE: You might find it beneficial to build a simple test.cls that repeatedly uses GOTO 0,0,0 with i, j, k vectors to test all reasonable rotary combinations and axis limits. You can easily set up a part file that represents your machine tool with the pivot points defined. Then rotate that geometry about the pivot points and verify the positions using the option Verify Points. The GPM output points should equal the WCS values.
Use this command to allow (or prevent) the machine operator to override the programmed speeds and feeds.
Enter the M code for SAFETY/OFF (allowing operator override) and for SAFETY/ON (preventing operator override.)
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Description: |
This command will output code to control the feed rate and spindle speed overrides.
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Parameter Definitions: |
1. "OFF" will output code to prevent the operator from overriding the programmed spindle speeds and feed rates. 2. "ON" will output code to allow the operator to override spindle speeds and feed rates. |
None
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Description: |
This command defines which head is to be used for merging.
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Parameter Definitions: |
FRONT", "REAR", "RIGHT", "LEFT", "SIDE", "SADDLE", and "OTHER" define the head that is to be referenced.
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Considerations: |
See OP/ command |