Helix Approach Macro in Circular Milling Concepts

Helix approach macros is used in Circular Milling operations.

This page discusses:

Helix Motion Options
Tool Path for Different Combinations of Selected Helix Parameters

Helix Motion Options

When you select the Standard Machining mode in a Circular Milling operation, the Approach macro and Return between levels Approach macro have an additional predefined motion.

The following parameters are available and editable:
- Helix Radius. The default value is 5mm.
- Helix Ramping Angle. The default value is 5 deg.
while the following parameters are not editable and are computed by the operation.
- Helix Height: it is computed by the operation based on the hole depth and the Number of levels as specified.
- Helix axis: it is the same as the tool axis. The helix is at the center of the hole.
- Arc radius of the arc joining the final circular motion: This values is not editable and is the same as the Helix Radius specified.

Helix Radius Constraint

If the radius of the helix is the same as that of the final circle, the helix motion of the tool is followed by circular motion. The image below shows Number of paths=1 and Number of levels=1.


	Radial Outward Movement (1) Helical Movement (2) Circular movement (3) Circular Arc inward movement (4) Radial inward return movement (5) Axial upward movement (6)
D R r H	Hole Depth Radius of Circle Radius of Helix =R Helix height =D

Note: Similar logic works for multiple pass and when the Number of levels is more than 1.

If the helix radius given is greater than the final circle radius for that particular part, a warning message is displayed and the radius of helix is set to the maximum possible (i.e. hole radius) by the operation.

Note: The radius of Helical motions in the macros used is greater than the smallest radius of the computed tool path. To avoid collisions, the macro radius has been set equal to the smallest tool path radius.

Helix Radius Value

You can provide the helix radius:

as the Absolute Helix Radius: the helix radius value is the same as that provided on the radius manipulator.
or as Radius difference vs next path: the helix radius is internally computed and a difference with the next path radius is given to the helix radius.

Note: Click the label to switch from one option to the other.

For example, the path radius (radius of the circular motion) is 5mm. You set the helix radius to 3mm and select Absolute Helix Radius. The radius of the helix motion is 3mm, i.e. the absolute value you have provided.

If, for the same values as mentioned above, you select Radius difference vs next path, the helix radius is computed and it is the difference between the radius of the circular motion and the radius value provided by you in the macro tool box. So in this case, the helix radius is 5mm - 3mm = 2mm.

Tool Path for Different Combinations of Selected Helix Parameters

The following sections shows the tool path for different combinations of selected helix parameter.

To summarize the entire tool path motion, the multiple pass is applied to the circular motion only and the helix motion is performed only once when the Number of levels is 1.

Based on the Number of levels, the helix motion is repeated with an intermediate circular motion before starting the next helical motion.

Notes:

All these motions are applicable only for Standard Machining mode and Predefined-Helix mode.
The Number of paths and the Number of levels are editable in the Stepover tab.

Number of paths=1 and Number of levels=1

When the Number of paths and Number of levels are both1, the motion of the tool path consists of 8 sub -motions as follows:

The helix and the final circular motion are concentric.
There is a straight line parallel to the hole bottom plane after the helix (See number 3 below) and a circular arc (See number 4 below) that join the helix to the final finishing circle.


	Radial Outward Movement (1) Helical Movement (2) Linear movement in a plane parallel to the hole bottom plane (3) Angular Arc movement tangent to the final circle (4) Circular movement (5) Circular Arc inward movement (6) Radial inward return movement (7) Axial upward movement (8)
D R r H	Hole Depth Radius of Circle Radius of Helix Helix height =D

Number of paths=2 or More and Number of levels=1

When the Number of paths=2 or greater and Number of levels=1, tool path is as follows.

The Number of paths (or multiple pass) applies only to the finishing circular motion.
The helix approach is performed only once and the circular motion is performed according to the Number of paths.

In short, when the Number of paths is more than 1:

There is a Return in a Level Approach macro ( line + arc) joining the new circular tool path. (See 8 and 9 in image below).
The return again is standard retract (arc + line)(See 11 and 12 in the image below).
The last level is a Retract.
Intermediate levels are Return in a Level Retract.

Notes:

Circular motion is the only machining motion.
Multiple pass applies to circular motion only.
Helical motion being a part of the Approach and Return between levels Approach motion, it does not participate in the multiple pass.


	Radial Outward Movement (1) Helical Movement (2) Linear movement in a plane parallel to the hole bottom plane (3) Angular Arc movement tangent to the final circle (4) Circular movement (5, 10) Circular Arc inward movement (6, 11) Radial inward return movement (7,12) Radial Outward movement (8) Circular arc movement (9) Axial upward movement (13)
D R r H	Hole Depth Radius of Circle Radius of Helix Helix height = D

Number of paths=1 and Number of levels=2 or More

The Number of levels is used to compute the tool path. When the Number of levels is more than 1, the tool path of scenario Number of paths=1 and Number of levels=1 above is repeated for the Number of levels as specified.

In the image below, the Number of levels is 2.

The hole depth is divided into two equal halves.
Note: The hole depth for each level is altered based on the Number of levels, example, if the Number of levels is 4, the hole depth is split into four equal lengths totaling to the total hole depth and the tool path is computed for those many levels
As shown below, motion 6 and 7 are Return between levels Retract motions.
After this motion is done, the Return between levels Approach motions are performed. If you selected a Predefined-Helix mode for Return between levels Approach too, then after motion 7, the same motions from 1 to 7 are performed at a lower level.
For the last level, the axial upward motion (8 in image below) is performed.


	Radial Outward Movement (1) Helical Movement (2) Linear movement in a plane parallel to the hole bottom plane (3) Angular Arc movement tangent to the final circle (4) Circular movement (5) Circular Arc inward movement (6) Radial inward return movement (7) Axial upward movement (8)
D R r H	Hole Depth Radius of Circle Radius of Helix Helix height = D/2 = distance between levels

Number of paths=2 or More and Number of levels=2 or More

In this scenario, the motions of the Number of paths=2 or More and Number of levels=1 scenario 2 is repeated as many times as the Number of levels input given by you.

From the first level onwards (except for the last level), the Retract is replaced by Return between levels Retract
From the second level onwards, Approach is replaced by Return between levels Approach.

The image below shows the tool path motions for Number of paths=2 and Number of levels=2.


	Radial Outward Movement (1) Helical Movement (2) Linear movement in a plane parallel to the hole bottom plane (3) Angular Arc movement tangent to the final circle (4) Circular movement (5, 10) Circular Arc inward movement (6, 11) Radial inward return movement (7,12) Radial Outward movement (8) Circular arc movement (9) Axial upward movement (13)
D R r H	Hole Depth Radius of Circle Radius of Helix Helix height = D/2 = distance between levels