Hardware Comparison: Allen Bradley Servo Motor Selection Guide
Today’s motion control systems require motors that do many different things, such as precise positioning or controlled torque. Servo motors allow for better control of these conditions by allowing a high rpm spin at low torque yet slowing down and increasing torque as states require.
With position sensors, encoders, and gearing, microcontrollers can sense the actual versus the desired position and correct it to allow rotors to turn to the machine gear or wheel to the precise position required.
These DC motors can be either positional, where precise rotor control is needed, or continuous, turning clockwise or counterclockwise at different programmed speeds. Servo motors are available in numerous sizes, and torque ranges and cost-effective to achieve control in high torque situations. They are best suited for speeds over 2000 rpm where high torque is needed. However, they are limited in positional rotation to 180 degrees.
Allen Bradley Servo Motors
Allen-Bradley has a long history of quality, durable, and robust servo motors for a wide variety of applications across many industries. Today, this includes both the Kinetix family of servo motors and the LDL and LDC linear servo motors.
As part of the Kinetix Motion Control group of products, Kinetix servo motors allow many options. They can be included in motion systems to build an integrated approach utilizing Kinetix linear actuators, servo drives, Logix 5000 motion modules, and other motion control devices in an entire ecosystem called Kinetix Integrated Motion.
And, as part of Rockwell Automation’s Integrated Architecture, designers can use the Motion Analyzer within the Connected Component platform to configure a system for the proper torque, speed, position, and performance for almost any industry application.
Allen-Bradley also offers the specialty Kinetix LDC and LDL series linear servo motor group when precise positioning is required at the payload point. These specialty servo motors impart smoother motion and cost-effective options for industries that need high-speed motion and fast directional change.
Selecting an Allen-Bradley Servo Motor
The VP series of servo motors are designed for both multi and single-turn use with absolute position encoders. The series also offers a 24V DC brake and can be either keyed or keyless. The series provides several variants depending on duty cycle and application:
The Kinetix VPC servo motor is designed for continuous use applications where high speed and high torque are required. In applications where speed and torque are consistent and known for the specific end-use, the design offers several benefits that improve performance and reduce the current needed to drive the motor. These benefits include:
- Bearing Size: Larger bearings that last up to 60% longer.
- Installation: Single cables can be used for both power and feedback reducing both build and setup time.
- Increase Torque: The VPC has both a cooling fan and fins to help manage thermal output. The fan helps deliver increases in both torque and power output. The VPC can produce continuous stall torque ranging from 17.6…191 Nm.
- Power: VPC servo motors come in 19 frame sizes from 200V…400V.
- Speed: The Kinetix VPC series can range from 1000-3000 RPMs depending on the model.
Kinetix VPL Low Inertia:
The Kinetix VPL is a low inertia motor for applications requiring high reciprocating motion. Based on Allen-Bradley’s MP technology, the VPL is ideal for high volume production environments and includes features such as:
- Improved Winding: The VPL uses Kinetix’s innovative winding based on the MP series technology. It provides much greater torque compared to other servo motors.
- Rare Earth Magnets: With rare earth magnets, VPL servo motors can increase speed more quickly than other motors.
- Installation: Like the VPC and all Kinetix servo motors, the VPL uses a single cable for both power and feedback to reduce installation and setup time.
- Power: The VPL is available in 26 frame sizes for 200V power and 38 frame sizes for 400V power.
- Torque: The VPL delivers continuous stall torque ranging from 0.46…33 Nm.
- Speed: The VPL RPM speed ranges from 3000-8000 depending on the version.
The food industry operates across many different material types, processes, and regulatory environments. Because of this, Allen-Bradley offers the Kinetix VPF, a servo motor explicitly designed for food-grade applications. Like the VPC and VPL, the VPF has both single and multi-turn absolute encoder capability. But it offers 24V power with both a braked and brakeless option. Features include:
- Configurable Options: Because different food manufacturing environments require different setups, winding, braking, and encoder feedback are all configurable.
- Coating: VPF servo motors are constructed with a food-grade epoxy to coat the outside and protect against harsh cleaning environments and continuous exposure to moisture.
- Installation: The VPF also uses a single cable for both power and feedback to reduce installation and setup time.
- Torque: The VPF delivers continuous stall torque ranging from 0.93…19 Nm.
- Seals: Because of the nature of food environments, the VPF uses food-grade shaft seals to protect the motor’s internal parts.
- Frame Sizes: The VPF comes in three frame sizes, 63-, 75- and 165-mm options.
- Speed: Speed in RPMs for the VPF ranges from 1000-8000 RPMs.
Kinetix VPN Hygienic:
The Kinetix VPN servo motor was designed for hygienic uses. These may include food production with high washdown environments such as poultry, dairy, meat processing, and other food and beverage environments. It is frequently in pharmaceutical environments. The features for the VPN are like those for the VPL food-grade servo motor but with the following exceptions/additions:
- Extended Cables: The VPN uses the same single cable configuration as other VP series motors. However, it can also allow a cable extender on the motor to raise the cabling with flying leads to protect during washdown.
- More robust Seals: The VPN also uses a shaft seal rated for up to 1200 psi washdowns.
- Torque: The VPN delivers continuous stall torque ranging from 0.8…19 Nm.
- Frame sizes: The VPH comes in six frame sizes, 63,75,100, 115, 130, 165 mm.
- Speed: The VPN is rated to run between 2300-8000 RPMs.
Kinetix VPS Stainless Steel:
Again, similar to the VPF and VPN, the Kinetix VPS is built for even harsher applications within the same industries as the VPN. The VPS was explicitly designed for highly caustic and high-pressure washdowns as required by some segments of those industries. The features of the VPS are like those of the VPN with the following exceptions/additions:
- Stainless Steel Housing: The VPS is built with a 300-series stainless steel housing for protection against caustic chemicals.
- Cable Connectors: The cable extension for the VPS is only 16 ft compared to 49 ft on the VPN.
- More robust Seals: The VPS also uses a 1200 psi shaft seal but also includes a slinger.
- Torque: The VPS has a more robust continuous stall torque, delivering from 8.1…21.0 Nm.
- Speed: Speed on the VPS is a static 3000 RPMs.
- Feedback Differences: The VPS only allows multi-turn, high-resolution absolute positioning, whereas all other VP model family members allow both single and multi-turn.
MPM Medium Inertia:
The Kinetix MPM series servo motors are medium inertia motors used in printing, web handling, converting, and the automotive industry. The MPM is like the MPL in most features. However, the MPM’s most significant difference compared to the MPL is in its increased torque. It has a higher peak torque than the MPL and a much larger continuous torque of 2.18 to 62.8 Nm. Other differences/additions include:
- Feedback: The MPM uses multi and single-turn high-resolution absolute positioning and allows for a resolver. Unlike the MPL, it does not allow the use of incremental encoders.
- Speed: Depending on frame size, the MPM speed ranges from 1000-7000 RPMs.
- Windings: The MPM comes in 230 and 460V windings and has other winding speed options available compared to the MPL.
The MPF is used within the food industry in the same way that the VPF is used, such as the food-grade epoxy coating and shaft seal with a food-grade grease. The most significant difference is in the footprint size. The biggest distinction between the MPF and the MPL and MPM is that, like the VPF, the MPF has configurable winding, braking, and encoder options. Other differences/additions include:
- Magnets: Unlike the MPL and MPM, the MPF does not utilize rare earth magnets for improved acceleration.
- Torque: The MPF delivers a range of 1.6…19.4 Nm of continuous torque.
- Speed: The MPF has a speed range in RPMs of 1000-5000.
- Feedback: The MPF only utilizes single and multi-turn high-resolution absolute positioning.
The MPS stainless steel servo motor has build and functionality like the VPS. It is used in the same industrial applications offering features for caustic washdown environments such as stainless steel housing, a more robust shaft seal rated at 1200. Like the MPL and MPF, it is a low inertia servo motor. Other Differences/additions compared to the MPL include:
- Magnets: Unlike the MPL and MPM, the MPS does not utilize rare earth magnets for improved acceleration.
- Torque: The MPS delivers a range of 3.6…21.5 Nm of continuous torque.
- Speed: The MPS has a speed range in RPMs of 3000-5000.
- Feedback: Like the MPF, the MPS only utilizes single and multi-turn high-resolution absolute positioning.
Linear Servo Motors
Linear servo motors improve machine performance by placing the motor nearest the payload. Linear servo motors can be iron core or ironless, depending on the machine and load requirements. They have high acceleration speeds and are very responsive with low or slow wear parts.
Allen Bradley’s Kinetix line includes two series of linear servo motors.
- The LDC servo motor has a high thrust force-to-cost ratio. This lowers the overall cost for control design. It also has a low cogging torque and is available in both 200 and 460V AC. LDC servo motors have a max velocity of 10m/s and are used in large routers, large format printers, machining, material handling applications, packaging machines, and cutting machines. Other features include:
- Motor Type: Iron core coil and magnet
- Continuous Force: 74…2882 N
- Maintenance: No or low wear parts
- Connectivity: LDC servo motors can connect to other Kinetix motion system components.
servo motor’s chief difference compared to the LDC is that the LDL has an ironless core. Because the core and magnet have no magnetic connection, the LDL can utilize more miniature and more cost-effective bearings. It also has a zero cogging technology compared to the LDC that does have some cogging. Like the VP and MP series, the LDL can utilize the Motion Analyzer software to size the motor to each application correctly. It is used in plate printing, solar and flat-panel scribing, wafer cutting, and others. Other features include:
- Motor Type: Ironless core and magnet
- Continuous Force: The LDL has a lower continuous force of 63…596 N than the LDC.
- Maintenance: Low or no wear parts
- Connectivity: LDL servo motors can connect to other Kinetix motion system components.
Other Allen Bradley Kinetix Servo Motors
Not all control system needs are the same, and Allen-Bradley’s Kinetix line has offerings for compact and specialized applications. These include:
- TL Series Servo Motors: Consisting of the TL and TLY, these servo motors are the compact line for Kinetix, suited for smaller applications such as robotics, light packaging, lab equipment, and similar end-uses. Continuous torque is low compared to the VP and MP series, and the TL series only comes in 230V models. Continuous torque is also much lower given the size and application of these motors. Features include:
- Windings: Like the MPL, MPM, PVL, and PVC servo motors, the TL and TLY use rare earth magnets for fast acceleration.
- Torque: Both versions have a continuous torque of 0.086…5.42 Nm.
- Speed: TL and TLY come in speeds of 3500, 5000, and 6000 RPM.
- Feedback: The TL and TLY also use multi-turn high-resolution absolute position and incremental up to 2000 counts. They do not utilize a single turn.
- TLP Series Servo Motors: The TLP servo motor was designed as a multi-purpose motor intended as a consolidated standalone unit. The TLP works with a Kinetix 5100 drive and cable and acts as a standalone system with no controller. This offers designers a cost-effective way to leverage Allen-Bradley’s Kinetix quality and features to power single machines. This combination is valuable to OEMs seeking to integrate a simple solution within a piece of equipment. One can be integrated into a more extensive control system once deployed in automotive, robotics, lab equipment, packaging, and converting. Features of the TLP servo motor include:
- Torque: The TLP has a high torque to size ratio with a continuous torque ranging from 0.160…95.4 Nm.
- Speed: The TLP can reach speeds of up to 3000 RPMs
- Feedback: 24 Bit single and multi-turn high-resolution feedback.
- Windings: The TLP is available in both 200 and 400V windings.
- 6000M Servo Motors: Like the TLP, the 6000M is a combined servomotor and servo drive. It utilizes an MP series food-grade servo motor combined with a Kinetix 6000 servo drive to provide a compact, low inertia solution. It is small and compact and can also be used in OEM equipment applications. It is used in packaging, fill and seal, food and can even be combined with the MP series stainless steel servo. It features the same food-grade coating and seals as the MPF and has a continuous torque of 3.0…7.25 Nm. The system is available at speeds of 3000, 3500, and 5000 RPM.
- Kinetix RDD Series: This servo motor is a direct-drive motor that eliminates the need for gearboxes, belts, and pulleys. By direct-coupling, the motor delivers greater efficiency for situations where the load is bearing housed or supported on its own by bearings. It is only available in 400V windings and has a continuous torque of 32.7 to 426 Nm. It is also slower than other Kinetix servo motors with a speed range of only 177…1836 RPM. It allows both single and multi-turn absolute feedback and can be configured for multiple winding speeds.
- HPK Series: The Kinetix HPK series is the only asynchronous servo motor in the Kinetix line. It is designed for high-power applications and those requiring large load inertia. It has a continuous torque of 96…955 Nm and speeds ranging from 1500…3000 RPMs. The HPK is a heavy-duty motor that utilizes the power of an induction motor to power applications such as high-speed packaging, repeated winding and unwinding, sheeting, and converting.
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