Motion control synchronization
Inside Machines: Simpler, more advanced, cost-effective motion control techniques hone a competitive advantage in new machine designs for Sunnen, a precision original equipment manufacturer.
Using market insight coupled with new technology, Sunnen has been able to grow in a downward economy. The company expanded its platform of high-production, high-precision bore sizing and finishing systems to include maintenance and repair operations honing machines. This 85-year-old original equipment manufacturer’s (OEM’s) success includes simpler, yet more advanced and cost-effective motion control.
It was an evolutionary decision, says Carl Mik, product design engineer for Sunnen. Traditionally, the company’s bore sizing and finishing systems have been customized, high-end designs. Having identified a new market segment opportunity, the immediate problem was system cost versus market willingness to pay. But the larger and longer-term problem was how to evolve the company’s technology platform while maintaining its competitive advantages in systems design, manufacturing, and service efficiency.
“When we went into this, the costs were not in line with the envisioned spec,” Mik said. “The stroker would be an ac motor and the spindle would be an ac motor. We wanted some sort of encoder on the ac motor for the stroker to hold relative position; and then we wanted a touchscreen display. The costs were becoming prohibitive.”
An early breakthrough came when Sunnen learned that a basic-performance servomotor with resolver feedback was available for the price of an ac motor. But Sunnen still faced the challenge of developing an all-new system design for low-cost honing that would be consistent with the company’s established product platform, supported by the existing multi-axis high-performance drive line and automation.
This need for platform consistency is an industry-wide challenge, as OEMs and end-customers evaluate the cost-performance advantages of emerging motion control solutions versus traditional hydraulic, mechanical, and electromechanical machine system designs. For Sunnen, this evaluation has been facilitated by the automation supplier’s mutual interest in the possibilities of new servo-based systems design.
“I have been on the motion control side from the beginning,” said Mike Nikrant, Sunnen product engineer. “Back in 2002-2003, we did a lot of research on different communication bus structures and what people had to offer. We chose Profibus [industrial network protocol] because of component availability and cost, along with its high acceptance in the market.” Drives were selected because they were the most flexible and configurable for the Sunnen KGM product line, which “required extreme accuracy for all axes of motion when finishing cylinders. Then, we used a lot of the same components when we introduced our SV vertical honing machines.”
Sunnen’s product platform evolution soon fell into step with evolution of the drives technology platform, Nikrant recalled.
“When we first started the SV vertical honing line, we were attempting to use ball screws. At the time there was only one company that had a motor that could handle the load we were doing, because of the reciprocation.”
Nikrant then found a motor design “that fit our application requirements and assisted us in our initial synchronization and tuning. We established a common dc bus drive structure” with the drive platform, which made it possible to have all the same drives in the system for servo or vector applications. “It is a very clean and proficient design because there are no mixes and matches of drive types. Everything just flowed a lot better with that solution, and our customers like this common approach and service efficiency.”
Advanced, simple positioning
As Sunnen’s attention moved last year to the development of a basic large-bore horizontal honing system called the HTA, both Nikrant and Mik agreed about product platform evolution. Joining them were other engineering team members, including Russ Jacobsmeyer, the company’s chief technology officer, who oversees technology adoption in support of global company growth.
Jacobsmeyer sought global support capability, increasingly important to company growth strategy. Beyond meeting a spec, there’s a need to explore system performance.
The automation supplier provides a partnership with ability to understand Sunnen products, make suggestions, help solve problems, and add value for customers.
“Precision bore sizing and finishing is a very niche capability that requires significant engineering content and resultant product performance. Our customers value what we have to offer with our systems and our ability to solve their difficult bore sizing and finishing applications,” Jacobsmeyer said.
The engineering team wanted to develop a new basic bore sizing and finishing system to fill a gap in the Sunnen product line. In regard to control system design, “We didn’t have anything at that point,” Jacobsmeyer says. “We heard from our customers and engineers in the field that there was a need for a basic economical system. However, we were not sure if we could satisfy the product requirements and meet the market price point.”
Mik agreed about the scope of the engineering problem. Mik said that about nine months before production of the basic system, “I started programming and put a prototype system together, and the biggest issue I found was spindle response time, due to delays in signals between the display, PLC, and a servo and general purpose drive. We had 300 milliseconds altogether, which may be acceptable from the standpoint of introducing a basic system at a basic system cost, but it was unacceptable for our application.”
The new system was to include a new basic performance servo drive and new 6-in. touch display, which allows software-based PLC capability with related software. The direct connection between the servo drive and display over Profibus made the system cost effective and responsive. This reduced the number of components and made it possible for Sunnen to stay in line with the migration to one drive platform, using the same software already being used to program controllers on other machines.
According to Mik, the new basic servo positioning package gave Sunnen an unexpected level of performance for basic machine development. “If you think about trying to stop an ac induction motor to do stroking back and forth, it’s pretty difficult. Even when applying dynamic braking and braking resistors, traditionally acceptable reversals on a tube-hone machine are around a quarter-inch repeatability. But our tests show the new system is achieving under 0.015-inch, and this is a low-cost system.”
Mik explained that the key components of the new system are an easily programmable software-based PLC at a low-cost point and a low-cost distributed motion control.
This also accomplished a new level of simplicity for this basic machine because the cable between the drive and motor provides automatic configuration as well as the feedback of the servo system. Related software made the configuration and communication simple and straightforward.
”We have a color TFT display, we are programming everything with ease, and we can even automate the machine. It’s not in the original spec, but we could do this to add even more value to our offering. And spindle response time is down in the 25-millisecond range, instead of 300,” said Mik, unexpected capability for the cost, he added.
Platforms for growth
Mike Nikrant believes alignment between Sunnen and automation product platforms is helping drive Sunnen’s business forward. The decision to develop new, more basic systems was facilitated by the automation products. Performance improvements are under consideration for Sunnen’s next generation of high-end PC-based systems with integrated safety functions.
Nikrant said, “For our high-end PC line, we are trying to come up with a common circuit for multiple machines.” Drives, bus structures, and components use fit because of the way some of the logic can be split in the controllers. The drives are easy to use and highly configurable. The same piece of hardware can be used for multiple functions. Some systems can be configured to use any functionality the user can conceive. On other systems, a simple servo system provides a simple and efficient solution. And control, programming, and communication are all the same. The “platform works well for us, for both the higher and entry level,” Nikrant said.
Jacobsmeyer added that common platforms enable more efficient use of “global resources to engineer, construct, service, and sell product.”
According to Sunnen’s David Moehn, manager of engineered machines and custom systems, the automation vendor stood by Sunnen and helped find solutions. “This relationship continues to improve our market success by getting us to market faster and ahead of competitors.”
Phil Hanna, Sunnen’s global product manager for machines, agreed: “The goal of partnering has been to standardize control systems across all our machine platforms—horizontal, vertical, and tube hones, of which the new HTA machine is the latest edition as an entry-level market machine. This is part of an ongoing effort at Sunnen to produce modular designs that can easily be modified to new configurations. The SV machines are a perfect example of this concept.” The modular columns with integral controls can be easily configured on a custom basis to optimize the customer’s process. One, two, three, etc. columns depend on the customer’s stock removal and geometry requirements. This lends great flexibility to the product line. And, with component standardization and global presence, the machines are much more supportable globally because of vendor technical expertise and resources.
Sunnen machine design upgrade details
When the Sunnen engineering team first looked into developing a new basic bore sizing and finishing system to fill a gap in the Sunnen product line, Siemens was the logical resource. Siemens:
- Provided easily programmable software-based PLC at a low-cost point and a low-cost distributed motion control, using the new Siemens Sinamics S110 drive and 1FK7 servomotor. A Drive-Cliq cable between the Sinamics S110 drive and motor provides automatic configuration and feedback of the servo system. For human-machine interface (HMI), the new MP177 6-in. touch display allows software-based-PLC capability with Siemens WinAC MP software, making configuration and communication simple and straightforward.
- Offered a basic performance servomotor with resolver feedback for the price of an ac motor.
- Included capability with multi-axis high-performance Siemens Sinamics S120 drive line and Simatic automation platform.
- Had mutual interest in the possibilities of new servo-based systems design.
- Provided drives that were the most flexible and configurable for Sunnen’s KGM line, and product development for drive technology paralleled Sunnen platform evolution (See graphic).
- Designed a motor that fit Sunnen application requirements and assisted initial synchronization and tuning. A common dc bus drive structure with the Siemens drive platform made it possible to have the same drives in the system for servo or vector applications.
- Built a partnership with Sunnen and understands Sunnen products requirements, making suggestions and adding value.
- Provided heads-up to Sunnen about new product development, reducing the number of components, and making it possible to stay in line with migration to one platform on the Sinamics family of drives, using the same Step 7 software already being used to program other machines.
- Matched Sunnen goals of developing new, more basic systems with similar motion control ideas.
- Included flexible drives, bus structures, and components that can split some of the logic among controllers; Sinamics drives are easy to use and highly configurable, working well on entry- and higher-level Sunnen products.
- Provides stable and high-performance products with global support, enabling Sunnen to more efficiently engineer, construct, service, and sell products.
- Worked with Sunnen, helping to find machine design solutions.
- Helped Sunnen standardize control systems across all machine platforms. Modular columns with integral Siemens controls easily can be custom configured to optimize Sunnen customers’ processes.
- Bob Davis is global communications manager, Sunnen Products Co., and Craig Nelson is Sinamics S Drives product marketing manager, Siemens Industry Inc., Drives Technologies, Motion Control. Edited by Mark T. Hoske, Control Engineering, CFE Media. www.controleng.com
CNC advice http://bit.ly/mQFpE1