This article will take an in-depth look at 5 axis CNC machining.
The article will bring more detail on topics such as:
This chapter will explore 5-axis CNC machining, including its construction, operation, and functionality.
Standard CNC machines operate along three axes: X, Y, and Z. However, 5-axis CNC machines include two additional axes, A and B. These extra axes enable the machining of more complex and intricate parts with greater precision. The increased adoption of 5-axis machines is largely due to their ability to significantly reduce production time.
The use of spinning cutting tools in CNC machines enables rapid achievement of the desired part geometries. By positioning and rotating the table across all five axes, the stress on the cutting tools is minimized, which helps extend the lifespan of the CNC machine. The diagram below illustrates a 5-axis CNC machine.
5-axis machining is a specific type of CNC machining that enhances the traditional 3-axis approach. This electromechanical process controls tools across five axes with high accuracy and precision to cut away excess material and produce components and parts. The starting design is created using CAD software and then converted into CNC codes, which provide programmed instructions for the CNC machine's tools.
CNC machining delivers high-quality results for turned parts across a wide range of applications that involve both horizontal and vertical machining.
The multitasking capability of CNC machines allows for the efficient and precise completion of parts or components in a single operation. CNC machines are used for various applications, including the production of collars, bushings, fittings, fasteners, inserts, washers, pins, spacers, nuts, spindles, drive shafts, standoffs, and splined shafts, among others.
The setup of a 5-axis CNC machine includes the following:
Diamond tools, commonly used in high-precision applications, feature cutting surfaces embedded with diamond particles. Figure 1.3 illustrates the machine table equipped with a spindle for carving gemstones and shows the motion directions of the diamond tool during machining. Although diamond particles are distributed across the tool's surface, these tools are specifically designed for cutting edges.
The selection of tool size depends on the cut width and the desired surface quality after machining. The diameter of the diamond particles coated on the tool is proportional to the tool head diameter. The main tool operates along the three axes: Z, X, and Y. In the design of the T-shaped diamond tool, as shown in Figure 1.3a, the Y-axis represents the depth of cut direction. The rotation of the B and A axes influences the carving of curves and arcs on the workpiece.
Materials used for jewelry, such as sapphire, marble, and quartz, are highly brittle. The dimensions of the processed product are typically limited to 60x60x60 mm³. Given the high hardness of these materials, the process follows abrasive machining principles, requiring the diamond tool to operate at high rotational speeds, generally between 8,000 and 12,000 RPM. Due to the tool's unique shape and the high spindle speed, the tool holder is oriented horizontally, parallel to the rotation plane. The requirements for machinery design parameters are outlined below.
| X, Y, Z linear motion Material size | 100 mm |
|---|---|
| Rotation angle of A axis | 180 degrees |
| Rotation angle of B axis | 360 degrees |
| Spindle Speed | 0 to 18 000 RPM |
| Cutting tool size | Φ(3 – 6)mm by 60mm |
| Material size | 60 by 60 by 60 cubic mm |
Based on the design parameters outlined above, the main parts and components are selected initially. The manufacturing of CNC machines starts with choosing the primary components and existing parts and systems, followed by developing new systems to meet specific usage requirements. The selection of these primary components is detailed below.
The machine design encompasses both the electrical and mechanical systems. In the mechanical system, the component assembly must be structured to ensure stability and effective transmission within defined limits. The machine frame supports the shaft and other components to provide flexible, precise, and coherent movement between the drives, resulting in a complete system.
The movement and spindle of the axes are configured in the correct directions. Inventor software is employed to design, analyze, and simulate the mechanical system components. The 3-dimensional CAD model of the CNC machinery is depicted in the image above. In this design, the Z, X, and Y axes are driven by stepper motors via ball screws, while the B and A axes are driven by stepper motors through timing belts. The initial design utilized commercially available parts, with other components repurposed to fulfill specific functions. Calculations for the B and A axes ensure strong connections and operational efficiency. Selecting durable machining materials, using timing belts to reduce motor torque, and determining dimensions and transmission ratios are crucial steps. The full assembly of the CNC machine is completed using 3-dimensional CAD simulations, including axis movement simulations, component resizing, and machining.
The electrical system is designed and installed to support the CNC machine's operation. It uses a DC power supply with three distinct voltage levels: 5VDC for input to controllers and signals, 24VDC for operating the stepper motors, and a variable range of 12 to 100VDC for controlling spindle speed. The electrical system of the CNC machine is depicted in Figure 1.5 below.
CNC machining employs subtractive technology to shape components using cutting tools that remove material to achieve the desired form. The shape is initially defined by a CAD (Computer-Aided Design) file. A program is then created in G-Code, which provides the CNC machine with precise instructions.
While most CNC milling machines operate with three axes—Z, X, and Y—5-axis CNC machines utilize additional axes to enable cutting from multiple angles, allowing for more complex and intricate designs. In a 5-axis CNC machine, axes A, B, and C are introduced to enhance flexibility in the cutting operation.
The cutting tool on a 5-axis CNC machine can access the workpiece from any of the five axes. It moves along the Z, X, and Y linear axes and rotates on the A, B, or C axes. The following are the corresponding axes and their motions:
In a 5-axis cutting machine, the Z, X, and Y axes work in rotational angles to enable the creation of complex designs with high-quality finishes. The A, B, and C axes rotate freely around the Z, X, and Y axes. The specific configuration of the CAD design or machine determines which two of the three additional rotational axes are used. This 5-axis setup incurs higher costs due to the advanced calibration and automation technology required for precise operation and command execution.
When selecting a 5-axis CNC machining approach, consider the following factors:
The CNC control must have sufficient processing power to calculate, control, and manage the simultaneous operation of all utilized axes.
The look-ahead function for a four-plus-one (4+1) axis machine should be at least 200 blocks. For more complex 4-axis sequences, 400 blocks is preferable. For full five-axis simultaneous machining, a CNC control with a look-ahead function of 1000 blocks or more is required to achieve extremely high calculation speeds.
Sufficient rigidity and power of the machine spindle are crucial factors that are sometimes overlooked. A powerful spindle requires a robust mechanical design to support it effectively. To ensure smooth and error-free cutting, the spindle, which is central to the five-axis CNC machining center, must not only handle the loads and stresses but also have adequate reserve capacity. For some machining tasks, a spindle with 11kW to 15kW of power and a maximum torque of less than 100 Nm may limit the machine's capabilities. While such spindles may be cost-effective initially, they may not be as economical in the long term.
It is essential to verify that the tool-holding systems used are either HSK or BBT to minimize vibration. These systems must ensure optimal attachment between the tool holder and spindle, regardless of machining conditions or time.
Depending on machining requirements, it may be necessary to either maintain a consistent cutting feed rate or adjust it for varying cutting conditions. Therefore, a machine capable of effectively managing these variations to optimize the cutting feed rate is essential.
To ensure the machine tool provides high durability, careful consideration of its design and construction is essential to meet tolerance requirements.
This process typically involves two stages:
5-axis CNC machines provide significant benefits, including fewer errors and enhanced productivity over traditional machining techniques. In any industrial process, inspection is vital, and 5-axis CNC machining is no exception. Quality control is embedded throughout every phase of the CNC process, with quality assurance also addressing documentation and procedural standards.
Quality inspection for 5-axis CNC machining comprises three essential levels: tool accuracy, part testing, and process monitoring and control.
Despite the high accuracy and reliability of 5-axis CNC machining, inspection remains crucial to ensure the final product aligns with the customer's vision and requirements. While 5-axis CNC is a highly advanced production method, it still demands careful oversight, control, and monitoring.
Monitoring heat control in the frame and spindle is critical for any CNC machinery, especially for 5-axis CNC machines. Effective heat management not only extends the lifespan of these key components but also enhances the accuracy and quality of the machined parts. To prevent spindle overheating, it is essential to ensure that both the spindle housing and spindle nose are adequately cooled. Proper heat prevention is crucial during demanding machining tasks to manage and reduce heat generated by bearings and motors during high speeds and extended machining cycles.
In a built-in spindle, the motor operates within the spindle housing. Therefore, it is important to ensure that the spindle housing and spindle nose are cooled effectively in sections.
5-axis CNC machines are uniquely engineered to deliver precision and versatility. Below, we present some of the leading manufacturers and their top 5-axis CNC models available in the United States and Canada.
The UMC-750SS by Haas Automation is a versatile 5-axis machining center known for its robust construction, which ensures both stability and accuracy. It offers simultaneous 5-axis machining, enabling the production of complex and intricate parts. This model is equipped with a high-speed, direct-drive spindle for rapid and precise cutting.
The DMU 50 from DMG MORI is a compact 5-axis machining center designed for a wide range of applications. It features a swivel rotary table and a swiveling milling head for multi-sided machining, along with a high-performance spindle that provides substantial torque for efficient and accurate cutting. Advanced control systems and software further enhance its machining capabilities.
The VARIAXIS i-800 by Mazak is a high-performance 5-axis machining center that combines versatility with productivity. It includes a tilting rotary table and a sturdy spindle for simultaneous 5-axis machining of complex parts. This machine is equipped with Mazak's SmoothX CNC control for advanced programming and monitoring, along with automatic tool changers and tool length measurement systems to boost efficiency.
The MU-4000V-L by Okuma is a vertical 5-axis machining center renowned for its high rigidity and precision. It offers a spacious work envelope and a tilting trunnion table for versatile machining of various part sizes. This model features Okuma's thermo-friendly technology to minimize thermal deformation and ensure consistent accuracy, along with advanced spindle technology and tooling systems for improved productivity.
The Robodrill α-D21MiB5 by FANUC is a compact, high-speed 5-axis machining center known for its efficiency and precision.
It features a built-in motor spindle and a simultaneous 5-axis drive system, which allows for rapid and accurate machining. Additionally, it is equipped with FANUC's CNC control system, offering user-friendly programming and advanced optimization capabilities. The machine also includes a tool magazine with automatic tool changing, which helps to reduce setup times and enhance productivity.
Please be aware that manufacturers may offer various models with different specifications and features within their product lines. For the most accurate and current information on specific models, it is recommended to consult directly with the manufacturers or their authorized distributors.
The primary difference between types of 5-axis CNC machines lies in the location of their rotational axes. In some 5-axis CNC machines, the rotation occurs by moving the table, thereby rotating the workpiece. In others, the rotation is achieved by spinning the tool head while the material remains fixed. Swivel head machines can handle larger and heavier materials since the workpiece does not need to be moved. In contrast, spinning table machines provide greater speed and stability for lighter objects.
This machine features a B-axis with a 360-degree rotary table positioned underneath the workpiece. It provides a workspace with a diameter of 50 inches and a height of 50 inches.
This machine is ideally suited for components with angled holes, such as turbine housings. These holes are positioned at various points around the outer diameter (OD) of the component. With this machine's design, transitioning from one hole to another requires movement in just one axis. In contrast, other types of 5-axis CNC machines would need to move in two or more axes to reach the next hole on a cylindrical component. However, with a pivoting head and rotary table machine, the apparatus only needs to be angled once to the correct position, and the spindle head must be oriented in the Z, X, and Y axes only once. Drilling a series of holes thus becomes a matter of retracting, feeding in, and indexing in the B axis to reach the next hole.
This approach results in a more repeatable process. Using additional axes for positioning increases the potential for positional errors. Another advantage of this machine design is its suitability for larger materials. With fewer rotational axes moving the material, the machine can more effectively handle large parts. Although the material is rotated around the B axis, this limited movement allows the machine to work efficiently with tall materials. In contrast, 5-axis CNC machines with both pivots on the table often have constraints related to material size due to their linear movement limitations. This design allows the machine to operate effectively on very tall cylindrical materials, as the material remains more fixed in place.
This CNC machine features a primary table so large that the A-axis unit can be oriented across a wide range of positions, offering increased flexibility. Efficient programming requires the programmer to precisely know the A-axis table face's position relative to the B-axis pivot. This often means the code is written with the assumption of a specific A-axis position, leaving the operator with the task of aligning the A-axis unit accurately to match these requirements. This alignment process can be time-consuming and requires careful configuration.
This CNC machine is ideal for components that require machining around the outer diameter (OD) of a cylindrical material, particularly when the component features holes or rings that need to be aligned with the spindle.
The machine is open, which can pose challenges for handling large parts if the axis components are not properly positioned. While it is equipped for 5-axis CNC machining, it has limitations on material size. When the A-axis component is in place, the material's volume is restricted by both the swinging around the A-axis and the practical size limits of the material that can be supported by the horizontal table surface.
Nevertheless, the extensive XYZ movement capabilities of the smaller 5-axis unit make this machine particularly well-suited for using long extensions or tools, especially when working at unusual angles.
The trunnion setup, also known as a Table-Table configuration, features both rotary axes integrated into the trunnion table, with the machining head remaining stationary. This configuration is familiar to many programmers and operators because it builds on the principles of standard three-axis CNC machining. The two rotary axes are often used to position the material precisely, making it straightforward to visualize the machine’s behavior and positioning during the machining process.
The trunnion table machine often provides superior undercut capabilities compared to other setups because the table can tilt further in one direction than a swivel head design. Additionally, the trunnion setup offers a larger effective work envelope. The table's ability to tilt and lock into position allows the X, Y, and Z axes to have their full range of motion. In contrast, a swivel head machine may require some of the work envelope to accommodate the tool length as the head tilts, which can be a limitation, especially when using long tools that significantly impact the work envelope.
The trunnion configuration is also advantageous for heavy metal removal. Since the head remains stationary, it allows for the use of belt-driven or geared spindles, which typically provide more torque at low RPMs. This stationary head design also reduces the risk of the head moving out of alignment during machining.
This type of machine can be configured in one of two ways: a head-head setup, where all rotational movements are performed by the head while the table remains fixed, or a head-table setup, which features a rotating table and a tilting head. Generally, these head-table and head-head configurations allow for the machining of heavier materials compared to the trunnion setup.
In this configuration, the table remains stationary, so the entire weight of the material is transferred directly through the CNC machine base to the ground. This makes the setup highly stable for handling larger parts. Additionally, compared to the trunnion design, the table's construction allows for accommodating larger materials overall, regardless of their weight. The rotating head also facilitates the use of shorter or average-length tools since all tool rotations occur above the material.
This chapter will explore the applications and advantages of 5-axis CNC machining.
Originally, 5-axis CNC machines were primarily used in the aerospace industry, but they are now widely adopted across various sectors. A 5-axis CNC machine can replace a 3-axis CNC machine, offering smoother finishes and greater efficiency. It reduces cycle times and minimizes the need for manual tool changes or component repositioning. In a 3-axis CNC machine, repositioning the component is necessary to machine all its faces, which can introduce alignment issues and human error. A 5-axis CNC machine eliminates these challenges by providing easy access to all faces of the component.
CAM and CAD software for 5-axis CNC machines can be highly advanced, offering numerous programming options. These tools often include collision avoidance features and post-processors for seamless machine integration. With the right setup, these programs can even facilitate "lights-out" CNC machining, where the machine operates unattended. 5-axis CNC machining is particularly useful for creating complex 3D shapes and performing traditional machining on angled or irregular surfaces. Some common industries that benefit from 5-axis CNC machining include:
Aerospace Applications: In the aerospace industry, 5-axis CNC machining is valued for its ability to produce contoured edges and smooth surfaces. Aerospace components are often geometrically complex, and the precision of a 5-axis CNC machine is crucial for achieving intricate details and interior cuts. Additionally, the machine's capability to complete a component in a single pass without repositioning enhances accuracy and efficiency.
Medical Device Manufacturing: In the medical field, 5-axis CNC machining offers significant advantages for manufacturers of implants, devices, and other precision parts. The high precision of 5-axis CNC machines meets the stringent standards of healthcare production. These machines are capable of efficiently producing small, intricately detailed components, saving both time and money through improved accuracy and streamlined processes.
Military Applications: 5-axis CNC machines are frequently used to manufacture precision parts for military devices. In addition to their aerospace applications, they produce components for submarines, compressor blades, turbines, smart weapons, sensors, high-performance engine parts, stealth technology, and even nuclear weapons. While not all components are military-related, nearly half of all 5-axis CNC machines are purchased for projects or contracts involving the American government.
Energy Equipment: 5-axis CNC machines are well-suited for producing specific and detailed parts required by the energy sector. When working with particularly tough or abrasive materials, these machines provide stability, making it easier to shape and cut the material. They also enhance process efficiency and reduce tool wear.
Additional industries that benefit from 5-axis CNC machining include pharmaceuticals and food processing.
Five-axis CNC machining facilitates the cost-effective production of intricate designs. The advantages of adopting five-axis CNC machining include:
With a five-axis CNC machine, you can access all surfaces of a component, except for the bottom and clamping areas. Unlike a three-axis CNC machine, which requires multiple setups and manual rotations to achieve complex geometries, a five-axis CNC machine completes the task in a single setup. This reduces the number of setups needed and saves time.
The additional movements provided by five-axis CNC machining allow for the creation of intricate designs and shapes. This capability enables machining of arcs and angles that previously required multiple setups and special fixtures. With five-axis CNC technology, complex fixtures are no longer necessary, as the part is held in place and rotated during a single process to achieve the desired geometry.
Every time a component is removed from a machine, precise alignment is often lost, impacting quality. Unlike three-axis CNC machining, five-axis CNC machining improves accuracy by allowing the entire job to be completed in a single setup. This method maintains precision and quality while producing complex shapes without compromising on the required accuracy.
In five-axis CNC machining, the cutting tool remains tangential to the cutting surface, which allows for shorter cycle times. This approach helps in removing more material with each pass of the tool, leading to increased efficiency and reduced machining time.
The additional fourth and fifth axes in five-axis CNC machining improve orientation and bring the component closer to the cutting tool. This allows for the use of shorter tools, which are less prone to vibrations at high cutting speeds, resulting in superior surface finishes. Additionally, this setup reduces machining time compared to a three-axis CNC machine, where smaller cuts are often necessary to achieve a good surface finish, leading to longer lead times.
While 5-axis CNC machining offers numerous benefits, it also has some drawbacks, including:
5-axis CNC machines and their associated software often require a higher initial investment compared to standard 3-axis machines. The overall cost of acquisition and maintenance can be significantly higher, with maintenance sometimes being more complex.
5-axis CNC machining involves two additional rotational movements beyond the three linear axes, making it more complex than 3-axis machining. Coordinating the movement of all axes to avoid collisions and ensure precise interpolation can be challenging. Complex programming is required to achieve optimal surface quality and machining precision, which may necessitate the expertise of a skilled programmer.
Operating a 5-axis CNC machine requires advanced skills for setup, programming, and operation. Skilled technicians are essential to manage the complexity of the technology effectively.
Despite these challenges, the advantages of 5-axis CNC machining generally outweigh the drawbacks. However, it is important to carefully consider the various challenges associated with adopting this advanced technology.
Travels and Available Capacity
Spindle Machining using CNC
Tool changer
Feed rates
5 Axis Size
5 Axis CNC Machining Electrical
Some considerations when maintaining 5 axis CNC machines are:
The primary advantage of 5-axis machining is its capability to produce intricate and complex parts with high precision. This efficiency significantly reduces production time from start to finish. By allowing the cutting tool or work table to rotate, 5-axis machining minimizes the risk of collisions and efficiently handles various part geometries without the need for reprogramming or additional machining.
Most CNC machine centers are based on the traditional 3-axis configuration, consisting of the X, Y, and Z axes. The 5-axis configuration expands on this by incorporating two additional axes, enhancing the tool's movement and flexibility.
5-axis machines typically include the following five-axis configurations:
Double Swivel Head Form - With the double swivel head form, two rotation coordinates control the direction of the cutter axis directly.
Droop Swivel Head Form - The droop swivel head form has the two coordinate axes at the top of the cutter with the rotational axis not perpendicular to the linear axis.
Double Swivel Table Form - In the double swivel table form, the two rotation coordinates control the space rotation, directly.
Droop Table Form - With the droop table form, the two axes are on the table, while the axis of rotation is not perpendicular to the axis.
One Swing, One Rotate Form - The one swing, one rotate form has two rotation coordinates with one on the cutter and one on the workpiece.
A 5-Axis CNC machine offers industries the chance to undertake jobs that they were formerly unable to complete. For manufacturers who presently use 3-Axis CNC machining, the advancement to a 4+1 or even full 5-axis CNC machine is the next logical step in their investment and production planning. Due to the price of such machines, nevertheless, it is advised that customers fully understand which procedures best meet the specific production requirements. There is also a need to pick the right CNC machine tool to realize the profitability and efficiency of production completely.
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