IN THIS ISSUE...
- Year in Review... A message from CEO Steve Nylund
- Replacement Option for ControlLogix Motion Modules
- Tech Tip - The Do's and Don'ts of Hydraulic Motion Control System Design
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A message from CEO Steve Nylund:
2023 was a busy year, with many incremental changes. Here are just a few of them:
Regional Sales Managers (RSMs):
Rick Meyerhoefer has retired, and Brad Smith has transitioned to a half-time role. We welcomed Mike Dodds to Delta, who will be responsible for the Northwest US and Western Canada regions. Additionally, Gary Nasca will now oversee the Southwest region and take on Rick's international territories which include Latin America, Africa, and the Middle East.
Business:
Delta Motion is now officially adopted as a trade name (dba). We introduced two new officers, Jacob Paso as President and Wade Nylund as COO, while Steve Nylund continues his role as CEO. It's worth noting that Peter Nachtwey, Delta's former President and motion control expert, is now mostly retired.
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Marketing and Sales:
Delta Motion became a Rockwell Automation Technology Partner. Rockwell suggests that users of the ControlLogix “analog” motion modules consider Delta’s RMC Motion Controllers as an alternative to these modules, which will be EOL in late 2024. Delta participated in a record number of trade shows, including first-ever booths at Hannover Messe in Germany and the Automation Fair. Delta’s updated website went live, featuring improved performance on mobile devices, and better access to content, among other improvements. To see a list of events we're scheduled to attend in 2024, visit: https://deltamotion.com/about/events
Perhaps more important though, are the things that did not change (and will not if I can help it!). For example:
Development:
Strong investment in R&D to keep our products on the leading edge of the curve for the best combination of capability and ease-of-use.
Support:
From pre-sales to long-term—knowledgeable salespeople, 10-day standard lead times, industry-leading technical support and training, service, and repair for the life of your machines. (Our long-standing practice is to not obsolete products as long as there is demand).
What is ahead for 2024 from Delta Motion? Continued incremental improvements, such as a significant update to the Design Guide. And … (insert drum roll here) … a major new product announcement—stay tuned!
In closing, I’d like to thank our customers and distributors for their continued business and to convey my wishes for a wonderful Christmas and a fortunate New Year to all of you.
Steve Nylund, CEO
Delta Computer Systems, Inc. dba Delta Motion
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Replacement Option for ControlLogix Motion Modules
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All three of the Rockwell Automation ControlLogix analog motion modules, 1756-HYD02, 1756-M02AS, and 1756-M02AE, have reached end-of-life and, as of December 2024, will be discontinued and no longer available for sale. Rockwell does not have a replacement option, which leaves a need for a motion solution that Delta Motion is uniquely positioned to fulfill. Rockwell Automation recommends that OEMs and system integrators consider RMC Motion Controllers as a replacement for these modules.
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The Do's and Don'ts of Hydraulic Motion Control System Design
As we transition from 2023 to 2024, it is a fine time to reflect on the constants in life. In this age of AI, it is good to remember that the laws of physics are still in force, and the solid fundamental design of your motion systems will save you a ton of grief. It is true that advanced features of Delta’s RMCs, such as model-based tuning, can wring rather amazing performance out of some rather marginal hydraulic systems, but this sort of “high-tech magic” can only do so much. Delta’s simple list of Do’s and Don’ts has been a popular download for decades. (Now, of course, greatly expanded in the Design Guide).
Fluid power systems are capable of very high-performance motion control. A well-designed closed-loop hydraulic actuator can position heavy loads to accuracies better than 0.0005”. Fast, precise motion requires a controller with specialized fluid power capabilities, such as the easy-to-use RMC family from Delta Motion (deltamotion.com). However, a well-designed hydraulic system is equally important. Here is a concise list of the considerations for high-performance closed-loop hydraulic motion control systems.*
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DOs:
- Use Servo-Quality Valves
Use servo-quality valves or "proportional" valves with zero overlap spools and linear flow per input response. See DON’T #2.
- Place Valves on Cylinders
Mount valves on the end and on top of the cylinders. Keep the trapped volume of oil between the valve and the piston as small as possible.
See DON’T #1.
- Use Accumulators
Use an accumulator, placed as close to the valves as reasonably possible. It should be sized at least 10 times larger than the change in the volume of oil.
- Pre-charge Accumulator
Pre-charge the accumulator to 80% of system pressure. Any oil in the accumulator that is not being used reduces its effectiveness. The nitrogen bubble should be as large as possible as long as there is always some oil in the accumulator.
- Size Pump Correctly
Size the pump to the average oil flow plus 10%. There is no need to size the pump for peak load when using an accumulator.
- Size Cylinders Correctly
Use cylinders with a diameter large enough to get the desired acceleration/deceleration rates.
- Size Hydraulic Lines Correctly
Use adequate pressure and return lines with a minimum number of 45º and 90º joints.
- Size Valves Correctly
Valves should be sized large enough to allow the system to accelerate at the desired rate and the maximum desired speed. Remember that at high flow the pressure drop across the valve will be large and the pressure drop across the piston will drop, reducing the ability to accelerate.
- Use a Suitable Motion Controller
Hydraulic control requires parameters, transducer interfaces, and algorithms not available on motion controllers intended for motor control. Use Delta’s RMC motion controllers for high-performance control of hydraulic and electric systems.
- Use a Precision Position Feedback Transducer
Mount a magnetostrictive linear displacement transducer (MLDT) in the hydraulic cylinder. Cylinders can be ordered so they are “MLDT” ready. Delta recommends MLDT’s with SSI output. Delta does not recommend the older Start/Stop or PWM outputs due to lower resolution and less noise immunity, nor recommends analog outputs due to jitter.
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DON'TS:
- Flexible Hose between Valve and Cylinder
Do not use a flexible hose between the valve and the cylinder. THIS IS VERY IMPORTANT! A flexible hose between the valve and cylinder will result in difficult tuning and poor control. See DO #2.
- Overlapped Spools
Do not use valves with overlapped (closed-center) spools. ALSO VERY IMPORTANT! See DO #1. When an overlapped spool shifts from one side to another to change the direction of the motion, the system will come to a stop with a thud, leading to difficult tuning and poor control around critical zero point. With a zero-lapped spool, the system very smoothly transitions between opposite directions of control. Delta’s RMC’s do have features to control overlapped spool valves smoothly, and may be necessary in some applications due to cost pressures, but they will never perform as well as zero-lapped spools.
- Separate Valve Amplifier
Avoid valves with separate amplifiers unless you are able to set up the amplifier properly. Many valves have electronics built into the valve and are set up by the factory.
- Run Wires in the Same Raceways
Do not run the high current Pulse Width Modulated signal, from the amplifier to the valve, in the same conduit or raceway as the wires from the position feedback transducer. See DON'T #3.
- Go Halfway on Closed-loop Control
Some people are scared of closed-loop motion control, so they put two different valves on their system – one for open-loop control, and one for closed loop control, along with plumbing to switch between the two. This makes a very complicated system, requiring more plumbing, programming, and maintenance than a simple closed-loop system. Closed-loop control is simple and easy. Attend a Delta training course to learn more about hydraulic motion controllers!
- Counter-balance Valves
Do not use counter-balance valves. They counteract the motion controller. If you need to have a safety valve to keep a vertical load from falling, use a blocking valve between the valve and the cylinder. Close the valve when you need the load to be stopped. Open it when you want motion control.
*Click the button below for an in-depth treatment of hydraulic design for high-performance motion control, refer to “Fluid Power Motion Control: A Guide to Practical Design” written by Delta's Peter Nachtwey.
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Delta Computer Systems. Inc. dba Delta Motion
1818 SE 17th Street
Battle Ground, WA 98604
+1 (360)254-8688
Delta Motion Ltd.
5 South Charlotte Street - Edinburgh, EH2 4AN, United Kingdom
(+44) 0131 447 7924
Email us at marketing@deltamotion.com.
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