Stock Computing

Initial Stock

The software considers the state of the stock before the application of a cycle.

Cycle

On the application of a cycle, the tool geometry and the toolpath generated are considered together. A swept volume of the tool along the toolpath is generated and this is the material that needs to be removed from the stock.

Final Stock

A Boolean operation is carried out to remove the swept volume from the initial stock and generate the resulting stock.

This process is repeated for each toolpath and can quickly require more processing power for complex topological surfaces.

1 tool movement generates 1 NC code line which produces 1 swept volume object for 1 Boolean operation.

This is the reason why for solid Brep models(Parasolid), the visual stock computation is off by default for shape milling operations, else the computation time to compute all the toolpaths is long and in some cases may fail to compute.

Rapid stock computation is available to compute the stock at a much faster rate with the operation being carried out on a mesh model, but this comes with a trade-off in the precision of the computed stock.

Solid (Brep) modeling

Mesh modeling

Pros

• Result stock is geometrically accurate.

• Works well for simple 3X toolpaths.

• Multiple Boolean operations are less time-consuming.

• Use of multithreading.

• Calculation will always succeed and return a realistic stock model.

Cons

• Calculation time can be really long on complex cycles.

• Not optimized to handle multiple Boolean operations.

• The calculation might fail or return an incorrect stock model.

• Result stock is an approximation of the real geometry.

• Calculation time increases when the precision is reduced.

ORIGINAL STOCK

SOLID

(Cubic, Cylindric, Imported Brep File)

MESH

(Imported STL File/ Designed)

Stock management method

Solid stock

Rapid stock

Solid stock

Rapid stock

Cycle 1

General Mode

Solid

Mesh

N/A

Mesh

Cycle 2

General Mode

Solid

Mesh

N/A

Mesh

Cycle 3

Rapid Mode forced

Mesh

Mesh

N/A

Mesh

Cycle 4

General Mode

Mesh

Mesh

N/A

Mesh

Stock Conversion

The transition from solid to mesh-based (rapid) stock is discussed below:

1. During Initial Stock Definition

Purpose:
To define a mesh stock before creating machining cycles. This defaults all computations to use rapid stock algorithms.

Prerequisites:

• Two distinct components must be available:

  • A mesh model either designed or imported(.stl file format)

  • A solid model (e.g., STEP, Parasolid) or wireframes for the part 

Procedure:

• Open the Stock Creation Dialog (accessed via the machining tree or stock definition menu).

• In the shape selection options:

  • Choose the command ‘From an existing solid’

  • Click on the mesh object to be converted to the stock .

  • Validate the selection.

Expected Behavior:

• The system automatically switches all stock-related computations to rapid stock mode.

• This can be observed by Right-clicking on Stock in the machining tree.

• The user only has the option to use the rapid stock calculation or to deactivate it.

Higher tessellation precision improves accuracy but increases computation time.

2. Stock Management Method

Purpose:
To convert an Existing Solid Stock to Rapid Stock

Prerequisites:

• An already defined solid stock (with or without machining cycles) must exist in the machining tree.

Procedure:

• Navigate to the Machining Tree.

• Right-click on stock and select Solid Stock Calculation and check the Rapid stock option.

All machining cycles computation are immediately switched to rapid stock, regardless of their specific computation mode settings. A key advantage of this method is the ability to revert back to solid stock when required.

3. Hybrid Stock (Individual Cycles computation modes)

Purpose:

Complex parts generally have a mix of 2/2.5 axis machining cycles and shape milling cycles. In this case, simpler cycles are preferred to be computed as solid stocks since the gain in time with rapid stock is negligible. As such the user can define the stock computation mode operation y operation.

Prerequisites:

• An already defined solid stock (with machining cycles) must exist in the machining tree.

• Ensure the stock management method for the Solid Stock Calculation is set to Solid Stock.

Procedure:

• Right-click on the machining cycle and select Solid Stock Calculation and check the Rapid Mode Forced option to switch to the rapid stock computation.

• Check General Mode to keep the computation to the Solid stock.

• Check on Deactivate if ever the user does not want to visualize the stock computation.

Users can also quickly change the stock computation mode for each cycle by accessing the List of Operations (right-click on Machining in the machining tree). They can quickly toggle the computation status for each cycle in the Stock column.

Watch a video on the right demonstrating the 3 stock conversion modes.

The complexity of turning parts is much less compared to milling operations.

In GO2cam, there are 2 stock management for Turning; 2D Stock and 3D stock.

For milling operations of millturn parts, only the 3D stock management engine is used.

2D Stock

3D Stock

For turning operations, the removed material is computed in 2D and subtracted from the 2D stock.

Due to the simplicity of the computation, the 2D material removal form is used to create a 3d volume through revolution which is then subtracted from the 3D stock.

Turning operations are computed on the real stock, which means that all operations take into consideration the material removed from previous operations and generate optimized toolpaths based on that. Further details are provided below.

2D removed material

2D Stock

3D removed material

3D Stock

For turning cycles, rapid stock computation is not necessary because the engine already manages the real stock material removal at a fast rate. Hence the stock management options for each cycles for turning operations is not available.

For milling cycles applied on the axial plane, the stock management options for each cycle is still available and the computation is done exclusively on the 3D stock.

Milling Cycle

3D removed material

3D Stock

In Milling and Wire EDM, the stock is the resulting calculation of the machining toolpaths. Rest Material is not taken into account at any step. For instance, you can program the same pocket operation twice: the toolpaths will be exactly the same. The second pocket does not know that a first similar operation was already made.

3 axis milling is a special case: none of the operations manage the rest material except the roughing/reworking and millyuGO. The stock management is specific for 3 axis milling, please read the dedicated page: Stock Calculation for 3 Axis Milling

In Turning and Swiss Machining, each operation (except rare cases) manages the real stock. Here, the same roughing operation cannot be calculated twice! It means that the ‘shape’ of toolpaths always depends on the previous operation.

When an axial milling cycle is applied on the turning stock shape, it is possible to take it into account for stock computation of next turning operations.

For this, set on ‘Update of turning’ into the solid stock calculation option for each milling operation.

The first half of this option controls whether the computation of the stock on the screen is considered as rapid/solid or not, as explained in the Stock conversion chapter.

The second half controls the adjustment of the turning cycles to that of the milling cycle if ‘Update of turning’ is selected.

In the screenshots, the red area was machined by a milling pocket operation programmed in reference workplane. You can see that facing and reaming operations are shorter due to the remaining stock calculation.

▶️ You can watch a video demonstrating the effect of selecting ' Update of turning':