The Path From CNC- to PLC-Controlled Gantries

Breaking with the industry tradition of CNC-controlled gantries, Harry Major Machine devises a new approach to industrial gantry control with help from Siemens.

Though the Detroit area still struggles with its economically blighted perception, the reality is that industry in the area continues to forge ahead with new ideas—not only to maintain existing operations, but as part of a larger effort to help rebuild Detroit’s industries and communities.

During a recent visit to attend the annual Manufacturing in America event, hosted by Siemens and Electro-matic, I had the opportunity to visit Harry Major Machine in Clinton, Mich., less than 30 miles from downtown Detroit.

In the company’s 100,000 square foot facility, Harry Major Machine builds conveyor systems, assembly and test systems, laser marking systems and multiple types of industrial washers, as well as dry cleaning and cooling products. The company also develops cableless and robotic gantry systems for pick-and-place and handling/sorting/loading applications.

“Most work we do here is systems integration,” said Curt Major, who has been president of the company (founded in 1962) since 1989. “Most manufacturing sites are set up around cells, and we develop and integrate those cells here with minimal integration required on site, though we also do that too,” he added.

One of Harry Major Machines’ new systems highlighted by Curt during my visit was a new PLC-controlled robotic gantry. The motion control systems of most gantries are CNC-based (as CNC controlled gantries were recognized as being faster than PLC/servo-driven gantries), but Harry Major Machine become interested in a PLC approach to address the high engineering and maintenance support requirements of CNC-controlled gantries. Major noted that these new PLC-controlled gantries can operate at speeds of “up to 4 meters per second.”

Beyond expanding and enhancing gantry control possibilities, Major knew this new PLC-controlled gantry also needed to address specific customer needs for unique performance specifications—ranging from speed, uptime and cost requirements to individual plant layout specifications.

With these goals in mind, Harry Major Machine set out to design a PLC-based linear, XYZ-type gantry that is user-friendly, easy to maintain, and able to multitask without major logic changes. The company now offers five models of PLC-based gantries, with the model numbers representing each system’s lifting capacity in kilograms: MGL-30, MGL-50, MGL-150, MGL-250 and MGL-500.

Creating the new gantry
Explaining the development process behind the creation of this new gantry series, Frank Loria, vice president of Harry Major Machine, pointed out that “Siemens came to us with advanced and relevant technologies [for use on the series] including total integrated diagnostics and safety.”

Siemens products used in this new series of PLC-controlled gantries include:

  • Simatic S71516F controller, which is part of the Siemens advanced S7-1500 range of failsafe CPUs. Specific features of this controller that led Harry Major Machine to select it for the new gantry series are: integration with Siemens TIA (Totally Integrated Automation) Portal for quick software development and deployment, consistent data storage, and its smart library concept to simplify use of universal functions. These fail-safe controllers also feature integrated diagnostics with fault analysis and troubleshooting to reduce commissioning and downtime. Embedded diagnostics was a critical feature for Harry Major Machine, as it enables the gantries’ servo motors, PLC, HMI and I/O devices to talk to one another.
  • Simatic TP1500 HMI with a 15.4-inch wide screen, a high-resolution TFT display and touch screen controls.
  • Sinamics S120 drive from Siemens was chosen for its range of coordinated components and functions in single-axis drives and coordinated multiple-axis applications. The drives also feature vector and servo functionalities for motion control.
  • Simatic MP277 mobile panel—a mobile HMI device with TFT (thin film transistor) display, 64k colors and 18 function keys with LED. It is operable via touch screens and membrane keyboards. It connects to Profibus, Profinet and Ethernet. Safety functions of the system architecture are available on the mobile panel—including a button that stops the machine in critical situations.

These features, as well as the overall system architecture and digital communication options across the devices, allowed for implementation of the customized drive solutions that Harry Major Machine wanted this line of gantries to have for flexibility and increased productivity.

New gantry benefits
According to Harry Major Machine, some of the benefits the company is able to deliver to its customers with these new PLC-controlled gantries compared to CNC-controlled models include:

  • A 25 percent increase in uptime;
  • Fault recovery times improved by 35 percent;
  • Compatibility with a variety of robot technologies, including automation systems and industrial parts washers offered by Harry Major Machine;
  • The ability to feed multiple machines; and
  • Configurability into “I” or “H” arrangements.
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