TonZa Making | What is the process design of intelligent CNC machining center?

What is the process design of intelligent CNC machining center?

Table of Contents

Complex parts typically feature intricate structures, cumbersome manufacturing processes, and stringent precision requirements, making traditional process design inadequate to meet these demands.

With the rapid development of technologies such as artificial intelligence, big data, and the Internet of Things (IoT), intelligent technologies have provided new solutions for the manufacturing of complex parts.

Industries are increasingly applying intelligent computer numerical control (CNC) machining centers as advanced production equipment.

By integrating intelligent algorithms, intelligent CNC machining centers can achieve precise processing, shorten production cycles, optimize process flows, and enhance production efficiency.

Optimized processes reduce raw material usage, lower production costs and scrap rates, and improve product quality.

Researching process design for intelligent CNC machining centers in complex part manufacturing enhances product quality and drives the intelligent development of manufacturing.

It promotes industrial upgrading and transformation, boosts a company’s market competitiveness, and helps predict future trends in manufacturing technology.

Together, these efforts provide strong technical support for the manufacturing industry’s development.

Intelligent CNC Machining Centers

Intelligent CNC machining centers integrate automated control and precision machining to function as automated processing equipment.

They precisely control tools and workpieces along predetermined paths.

Using digital control methods, they perform various actions at designated work positions to complete complex machining tasks based on pre-programmed instructions.

Intelligent technology connects CNC machining centers with factory production management systems to generate digital production plans and work instructions.

Real-time monitoring of CNC machining centers allows the intelligent system to automatically adjust processing parameters and tool paths based on current conditions.

This adaptive control identifies and resolves issues during machining, promptly enhancing production efficiency.

Characteristics of Complex Parts and Principles for Process Flow Design

The geometric shapes of complex parts may include multiple surfaces, holes, and slots, and they typically have high requirements for dimensional and geometric tolerances, necessitating precision machining.

Complex parts have intricate structures and may require special materials during machining, such as high-strength alloys or composite materials, making the machining process more challenging.

Therefore, the machining process requires more precise control and must meet higher standards.

During the manufacturing of complex parts, planners must design the processing workflow.

They break the process into multiple steps, arrange the sequence of each step, and develop corresponding processing solutions.

Manufacturers must finely control each stage of the complex parts manufacturing process to ensure that processing parameters and workflow meet requirements.

Case Analysis

A representative complex part—a turbine wheel—was selected as the test subject, which features complex surfaces and strict dimensional tolerance requirements.

We used a 3 mm ball-nose cutter for CNC simulation machining on a five-axis CNC machining center, model ZLCTC7035-25. A visible cone was constructed along the tool path direction on the turbine wheel surface.

The visible cone represents the visible area from the tool to the workpiece surface. We identify potential collision scenarios by analyzing whether the tool axis overlaps with the visible cone at specific points on the surface.

When performing collision detection using tool position points, we determine the minimum angle between the tool axis and the visible cone if the tool axis collides with the workpiece surface.

To prevent collisions, rotate the tool axis and adjust the angle so that it is inside the visible cone, ensuring no collision with the workpiece surface.

Perform a Boolean operation between the rotated tool axis vector and the machine tool’s machinable range. If there is an intersection, it indicates that the tool axis can complete the machining task without causing a collision.

If no intersection occurs, the machine tool cannot meet the machining requirements. Therefore, we must adjust the machine tool’s machinable area accordingly.

  • Automated Drawing Generation

The Solid Edge software development environment uses Component Object Model (COM) technology to access its Application Programming Interface (API).

The system transmits operational instructions to the design software, and Solid Edge extracts the 1:1 part contour.

Develop CNC machining drawing software to achieve paperless data exchange results and flexible workflows, thereby enhancing design and production efficiency. The relevant software workflow is shown in Figure 1.

TonZa Making | What is the process design of intelligent CNC machining center?
Figure 1 Software flow

> Reading the component drawing bill of materials

Extract the information required for drawing CNC machining drawings from the part design data.

The component drawing bill of materials typically includes key information such as the detailed dimensions, materials, and quantities of the parts.

> Determining the Spatial Position and Angular Orientation of the Part Model

Before generating drawings, it is necessary to determine the part’s spatial position, i.e., the elemental reference plane corresponding to the largest surface in the part model, and to determine the relative angle between this plane and the reference plane (e.g., horizontal or vertical plane).

This step helps avoid misunderstandings or errors in subsequent production and machining processes, ensuring the accuracy and readability of the drawings.

> Automatically generate the part drawing

Based on the angular relationships obtained in the previous step, create a new engineering drawing and automatically generate the part drawing (in .dft format).

Using Solid Edge’s automation features, generate drawings compliant with standards based on the part’s actual dimensions and position information.

> Iterative Generation of CNC Machining Drawings

For assemblies comprising multiple parts, the above steps must be iteratively executed to generate corresponding CNC machining drawings for each part.

This process ensures that all parts are processed accurately.

> Batch Conversion Operations

Execute batch conversion operations to convert .dft format documents into .dwg or .dxf format process drawings.

Converting .dft format drawings into the more widely used .dwg or .dxf formats in manufacturing facilitates the use of material cutting programming software (e.g., FastCAM) by staff to perform subsequent process flows, conduct mathematical calculations, and ultimately generate CNC machining programs.

  • Toolpath Optimization

Predict the direct impact of various cutting machine conditions on cutting deviations and adjust processing parameters to meet design tolerance requirements. Predicting deviations can optimize tool posture and reduce shape errors.

Utilize process simulation calculations to determine clamping cutting conditions during various process simulation processes, and provide tool center point (TCP) coordinates and clamping angle coordinates as the angular vector of the clamping fixture in the workpiece coordinate system.

After the calculation, predict the actual shape differences between the modified discrete points for each tool during the simulated process and optimize the tool path design.

First, based on the results of the tool simulation process, calculate the actual shape differences between the series of discrete points for each tool.

Second, based on the calculated shape deviation data, we adjust the TCP. Then, we transform each simulation process according to the position perpendicular to the feed vector and tool vector to minimize graphical offset.

Third, we write the transformed TCP vector position data and the original tool vector information into the numerical control (NC) file for use in subsequent NC machining design processes

Finally, execute the compensated NC tool optimization program using either a direct method or CNC machine control.

Adjust the optimized NC tool path parameters based on the predicted geometric shape deviation values to enhance cutting quality and production efficiency during the machining process.

  • Tool Collision Detection

> Tool Collision Analysis

The visible cone radius of each positioning point on the complex surface must be determined, i.e., the tool’s accessible range.

Perform a Boolean operation between the tool axis vector cone and the visible cone to determine whether interference may occur with the detection object.

If the detection result is an empty set, it indicates potential interference, requiring further calculation to determine the minimum rotation angle needed to adjust the tool path.

Rotate the tool axis vector by the minimum rotation angle to obtain the updated tool axis vector.

Next, perform Boolean operations between this redesigned tool axis vector field and the machine tool’s workspace.

If there is an intersection between the two, it indicates a smoother machining process, and the machine tool CNC program must be adjusted promptly to accommodate the new CNC tool direction better;

If the collision result is still an empty set, it is necessary to re-adjust the tool dimensions or reduce the rotation speed range of the machine tool spindle to ensure that machining can begin.

This process ensures the interaction between the tool and the workpiece, thereby ensuring smooth machining and providing assurance for the production process.

The tool collision result analysis process is shown in Figure 2.

TonZa Making | What is the process design of intelligent CNC machining center?
Fig. 2 Flow of tool collision result analysis

> Tool-to-Tool Collision Conflict Detection

During CNC machining, tool-to-tool collision issues must be addressed.

To ensure machining safety and improve machining accuracy, strict collision detection must be performed before machining.

The implementation steps for tool-to-tool collision conflict detection are as follows:

1) Load the complete point coordinate information of the surface and the pre-generated tool path data.
2) Construct the visible cone and map it to the standard unit sphere.
3) Verify whether the visible cone overlaps with the tool axis vector. If there is no overlap, it indicates no collision has occurred.
4) Successively examine other visible cones.

If they do not meet the previously set conditions, it indicates that tool collisions may occur.

At this point, it is necessary to calculate the minimum rotation angle required to rotate the tool axis into the visible cone range to prevent collisions.

In the workpiece coordinate system, let the tool axis vector be Kt, where Kt = ωAt (0.0.1.0) T.

Where ωAt is the shape generation matrix of the machine tool, describing the geometric transformation process of the tool’s motion trajectory, and (0.0.1.0)T is the initial direction vector of the tool axis.

The angles between the tool axis vector and the four boundary vectors (u1, u2, v1, v2) of the visible cone are Δλui = cos⁻¹(Kt, u1) (i = 1, 2) and Δλvi = cos⁻¹ (Kt · v1) (i = 1, 2), the minimum angle is the minimum rotation angle required to avoid collision.

Δλui is the angle between the tool axis and the upper boundary vector of the visible cone, and Δλvi is the angle between the tool axis and the lower boundary vector of the visible cone.

u1 and u2 are the vectors of the upper and lower boundaries of the visible cone, and u1 and u2 are the vectors of the left and right boundaries of the visible cone.

> Determination of the Feasible Direction of the Tool Axis

Taking an AB-type five-axis CNC machining center as an example, the configuration code of the machine tool is k = W/axz0 yb/T.

Among them, k is the configuration code result, reflecting the combination of scaling and translation parameters of the machine tool;

W is the weighting coefficient;

a is the X-axis scaling coefficient;

x is the X-axis coordinate variable representing the actual position of the workpiece or tool along the X-axis (three-dimensional coordinate system variable);

z0 is the initial offset along the Z-axis, and y is the Y-axis coordinate variable.

b is the Y-axis scaling coefficient;

T is the normalization factor used to perform homogeneous coordinate transformation to calculate the possible rotation angle °rt of the tool axis, defining the machine tool’s operational reachable domain.

» Tool Axis Rotation Capability

According to the definition, the tool axis vector has the ability to rotate around the A-axis and B-axis, with its angle calculated in incremental form, as shown in Formula (1).

TonZa Making | What is the process design of intelligent CNC machining center?
Formula 1

where: TonZa Making | What is the process design of intelligent CNC machining center? is the transformation matrix for rotation around the A-axis, with the exponent indicating the number of times the matrix is applied;

TonZa Making | What is the process design of intelligent CNC machining center? is the transformation matrix for rotation around the X-axis;

TonZa Making | What is the process design of intelligent CNC machining center? is the transformation matrix for rotation around the Z-axis;

TonZa Making | What is the process design of intelligent CNC machining center? is the transformation matrix for rotation around the Y-axis;

TonZa Making | What is the process design of intelligent CNC machining center? is the transformation matrix for rotation around the B-axis by angle β;

TonZa Making | What is the process design of intelligent CNC machining center? is the transformation matrix for rotation around the θ-axis by angle θ;

α is the rotation angle around the A-axis;

β is the rotation angle around the B-axis.

As shown in Equation (1), the tool axis vector of a five-axis machine tool can rotate α degrees around the A-axis and β degrees around the B-axis. The tool axis vector is rt = [sinβsinαcosβsinαcosβ].

The angles are calculated incrementally, and the operable angle range of the tool axis is determined, thereby obtaining the feasible orientation of the tool axis.

  • Experimental Results

To verify the effectiveness of the proposed method in real-world complex part processing, we experimented.

The test used a specific type of impeller as the workpiece and employed a 3 mm diameter ball-nose tool for CNC simulation processing.

During the experiment, we compared the traditional processing method with the method proposed in this paper.

The comparison focused on path length, collision frequency, and runtime. Table 1 presents the results.

TonZa Making | What is the process design of intelligent CNC machining center?
Table 1 Comparison results between conventional processing methods and the method in this paper

As shown in Table 1, the method proposed in this paper outperforms traditional methods in terms of tool path planning, collision detection, and processing efficiency.

During complex part processing, the method proposed in this paper uses intelligent technology to optimize the tool path.

It reduces processing distance and runtime, improves efficiency, and avoids predefined collision scenarios.

In contrast, the traditional method resulted in three collisions.

The experimental results show that applying intelligent CNC machining center process design methods in complex part manufacturing holds significant value.

These methods improve production efficiency and product quality. As a result, they provide strong technical support for the transformation and upgrading of the manufacturing industry.

Conclusion

This study explores how to design processes for intelligent CNC machining centers in complex part manufacturing.

It also analyzes how innovative technology can be applied in the manufacturing industry and what prospects it offers.

By adopting intelligent technology, enterprises improve production process efficiency and enhance product quality.

This advancement strengthens their manufacturing capabilities and drives the transformation and upgrading of the manufacturing industry.

As artificial intelligence, big data, and IoT technologies continue to advance, intelligent CNC machining centers will see broader application in complex part manufacturing.

This trend will drive the sustained development of the manufacturing industry.

FAQ

Intelligent CNC machining centers integrate automation, AI, and digital control technologies. Unlike traditional machines, they offer real-time monitoring, adaptive control, and automatic adjustment of tool paths, enhancing precision and efficiency in complex part manufacturing.

Complex parts have intricate geometries and tight tolerances, requiring precision and multi-axis control. Intelligent CNC machining centers streamline the process by optimizing workflows, reducing errors, and preventing tool collisions through adaptive algorithms.

Intelligent systems use simulation and predictive models to calculate tool deviations, adjust tool center points (TCP), and optimize tool paths. This minimizes graphical offsets, improves surface quality, and ensures machining accuracy.

Key steps include breaking down the machining workflow, optimizing tool paths, designing adaptive process plans, simulating machining behavior, and validating collision-free operation through real-time feedback and simulation tools.

Tool collision detection involves visible cone analysis, Boolean operations between tool vectors and the machine’s workspace, and calculating the minimum tool axis rotation angle to avoid interference. If a collision is predicted, the system adjusts tool orientation or dimensions.

Automated drawing generation uses APIs like Solid Edge COM technology to create precise engineering drawings (.dft, .dwg, or .dxf), enabling paperless workflows and improving communication between design and production.

By optimizing machining paths and process parameters in real-time, intelligent CNC systems reduce unnecessary movements, tool wear, and material usage. This leads to lower scrap rates and reduced production costs.

Five-axis CNC machining centers provide greater flexibility and precision in tool orientation. They allow complex geometries to be machined in fewer setups and reduce the risk of collisions during multi-surface operations.

The method was tested on a turbine impeller using a 3 mm ball-nose cutter. Compared with traditional methods, the intelligent approach reduced collision incidents, shortened tool paths, and improved machining efficiency, as shown in comparative data.

With the continued development of AI, IoT, and big data, intelligent CNC machining centers will expand in application. They will become critical in the transformation and upgrading of the manufacturing industry, especially in high-precision, complex part production.

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