Improving PLC Compatibility and flexibility in aseptic blow/fill/seal machines

Upgrading components in manufacturing equipment is something that plant engineers take very seriously and think through carefully. Equipment-upgrade options are inspected and tested empirically before a selection is made. The newly modified machine must operate flawlessly to fulfill the requirements of the facility and must integrate smoothly with other designated equipment within the plant.

11/01/2007


Upgrading components in manufacturing equipment is something that plant engineers take very seriously and think through carefully. Equipment-upgrade options are inspected and tested empirically before a selection is made. The newly modified machine must operate flawlessly to fulfill the requirements of the facility and must integrate smoothly with other designated equipment within the plant. However, too often, engineers end up settling for less capability from their new components solely because of compatibility issues with their control systems. Such issues can bring the upgrade project to a standstill.

It’s important for original-equipment manufacturers to make component changes to their production machines. OEMs must consider the machine’s operating variables for the wide spectrum of clients’ plant applications and integration of various equipment options that will interface with the machine. Weiler Engineering Inc. ( www.engineering.com ), an original-equipment manufacturer of aseptic blow/fill/seal machines, confronted programmable-logic-controller compatibility issues when its original controls supplier changed its product offering.

Weiler Engineering provides aseptic custom- packaging machinery for pharmaceutical and healthcare applications; its machines are distributed worldwide. Based in Elgin, IL, and founded in 1959, Weiler’s proprietary blow/fill/seal system is based on 40 years of innovation in machine design and sterile-process development, producing a highly advanced aseptic-liquid packaging system. Weiler’s Asep-Tech blow/fill/seal technology integrates blow molding, sterile filling, and hermetic sealing in a continuous operation to produce aseptically manufactured products.

The company uses the latest technological advances in equipment design and systems to ensure the highest level of quality in the production of sterile-liquid products. Products must meet corporate, scientific, regulatory and end-user requirements. These application challenges are met by specific container and closure designs available with its systems. Weiler offers several machine models designed to manufacture containers ranging in size from 0.2 to 1000mL at production rates of up to 15,000 units/hr, depending on container configuration.

“We have been using PLCs on our machines for 25 years, and a specific controller for a long time,” says Robert Mazur, manager of electrical engineering manager for Weiler. “Problems came when the company that was providing our PLCs decided to make the product line we were using obsolete. That company’s new, second-generation PLCs were not up to our standards. Another PLC manufacturer was brought in to help us, but it was unsuccessful. They could not provide a completely functional controller for our machines. We were quite concerned, but it was not the manufacturer’s PLCs that failed, it was the integration of its PLCs with our equipment that was the problem.” After a number of unsuccessful attempts to resolve the PLC difficulty, the company asked Siemens Energy & Automation Inc. ( www.sea.siemens.com ) to “look at our product line and tell us what we needed,” Mazur says. Siemens recommended its Simatic S7-300 line of PLCs.

Weiler’s Asep-Tech equipment continuously extrudes 5 to 16 parisons (round tubes of plastic) per cycle. The machine carriage, which holds a mold, retracts and while the tubes are open, the mold closes on the tubes. The parisons are then cut, and the carriage moves forward, while plastic continues to extrude for the next cut. The machine, which has five to 60 fill-nozzles, then fills the containers, which are formed inside the mold, with a liquid. The nozzles then retract from the molds, and a die seals the containers. The formed containers are conveyed out of the machine to a remote station, where excess plastic is removed and the finished product is conveyed to final packaging.

When Weiler began developing an all-electric machine, its PLC and drive manufacturer differed, creating integration challenges. Siemens engineered a resolution to the PLC-drive compatibility problem and provided engineering for debug time. Weiler uses the Siemens Simatic S7-300 series PLC and touch screens on its all-electric equipment, said to provide flexibility in machine control and systems integration.

Mazur says Siemens “backed us up with its engineering staff and helped us to develop a well-documented and well-structured software program that did the communications, so we could run our machines.” Mazur says that level of support was “something extra” brought to the table.

The Simatic S7-300 is a modular PLC platform said to be optimized for high-performance machine and factory automation, facilitating integrated and economical system solutions in centralized and distributed architectures. Central processing units integrate input/output (I/O), technological functions, and communications and provide efficient processing speed for short machine-cycle times. The modules are hung on a DIN rail (Deutsches Institut für Normung eV, the German Institute for Standardization) and screwed on to form a rugged, electromagnetically compatible configuration. The backplane bus is already integrated into the modules; the bus connectors can be plugged in. With the varied range of modules for the Simatic S7-300, centralized expansions and simple distributed structures can be configured.

The new PLC “gives us the capability of doing on-line changes and flexibility that allows our customers to see what is happening in the machine,” Mazur says. “From a programming-code method, there are advantages, in that our customers can see the code, they can troubleshoot it, yet we can lock-in certain functions, like code calculations, that we don’t want them to change.” Ethernet or Profibus communications can provide alerts, Mazur explains. Each I/O card and each of the drops used is self diagnostic, he says. “If anything should go wrong, such as shorts or a bad connection on a particular card, it will indicate on the card that it has a problem and internally set alarm bits that are trapped onto a diagnostic screen. It immediately gives the maintenance people at our customer’s site a very fast way of finding the card that is the problem.”

More options for touch-screen graphics are available beyond what Weiler had been using. Weiler still has the 15 or so basic screens that most of its customers are used to for basic operations, and adds about 65 more, including all screens used for troubleshooting and diagnostics. The system works with Siemens’ products and third-party products that are Profibus registered. Weiler can just connect the wires and control them.

“We bring very industry-specific experience to our OEM clients,” says Michael Cizmar, Siemens’ account manager; technicians have experience in the industry and equipment used.


More information is available:

Siemens Energy & Automation Inc. , 770/871-3993. www.sea.siemens.com .

Weiler Engineering , 847/697-4900. www.weilerengeneering.com .





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