Interface solutions for the Machine-Tool Industry

Aug. 22, 2001
Modular designs simplify transport, speed setup, and permit expansion of a machine or system.

Jim Gibson
Weidmuller Inc.
Richmond, Va.

Today's machinetool applications demand power supplies that not only provide the desired power level, but are also engineered to fit within smaller spaces while offering more functions.

Weidmuller's Sensor/Actuator Integrator joins distributed field peripherals to the control network by simply inserting the plug and turning two screws.

Cable interfaces with prewired terminal blocks virtually eliminate PLC wiring errors while substantially reducing assembly time.

The Micro-series relay package from Weidmuller allows for plug-in replacement without disturbing field or control wiring, which speeds installation and maintenance.

The U.S. machine-tool industry is in transition. In the face of competitive threats from Europe, Japan, and Taiwan, North American machine-tool OEMs are working to retake the U.S. domestic market while continuing the recent growth in exports. Software and hardware technology improvements are the drivers to a user market that may be positioned to make productivityenhancing investments as the manufacturing segment emerges from recession.

To increase productivity and overall value to the end-user, machine-tool manufacturers are demanding much more from their supply chain. It is no longer acceptable for a component manufacturer to offer a simple product to fit an application. Today, suppliers must offer solutions to the OEM that reduce overall costs and increase functionality. This certainly holds true for industrial-interface suppliers, whose goal is to offer the machine builder packaged innovations that include product, supply, and service flexibility.

Interface trends
Machine-tool performance has greatly improved over the years with the advent of new systems and technologies that increase overall production rates. However, increased production rate is but one of several ways in which the machine OEM can effectively position their product to the end user.

Other trends within machine design, such as modularity, networked communications, and reduced space requirements, are helping machine manufacturers build smaller and smarter machines that are easier to transport and set up. Innovations from system component manufacturers play a key role within this competitive market segment.

System modularity
Increased modularity is one significant trend. Modularity simplifies system transport, speeds set-up and operation, and permits expansion of the machine or system. The ability for a machine-tool OEM to quickly and easily disassemble a large machine for transport and reassemble at the customer site is critical. In addition, it is imperative that ancillary options, such as automatic toolchangers, easily connect to the machine.

At the component level, enclosureless connectivity, such as the Weidmuller Sensor/Actuator Integrator, joins distributed field peripherals to the control network. The design allows machine-tool manufacturers to simply disconnect the control-wiring plug and ship the block on one machine section, while the cable goes with another section during transport. Replacing the plug and turning two screws easily reconnects the system.

In discrete parallel wiring applications, the task of connecting rack-mounted I/O to field peripherals can be time consuming and expensive. Wire preparation and landing each signal wire — from PLC to one or two subfunctions within the panel and out to the field device — reduces productivity and can inflate installation costs particularly when testing and troubleshooting time is added.

OEMs can minimize installed costs through prewired cable-interface solutions. With a cable interface, front panel adapters with prewired cables extend to simple DIN-mounted breakout terminals, replacing PLC swing-arms. The connection to the breakout module is made via IDC connector, virtually eliminating any chance of PLC wiring error while substantially reducing installation time. Cable interface modules with onboard relays, fusing, LED indication, or other functions can be used to integrate panel subfunctions to a single rail, saving space within the panel and further reducing installation time. The modular nature of this system allows for easy connectivity to field sensors and actuators.

Reducing panel space
The cost of panel space is at a premium. Thus, it is no wonder that another trend involves more functions being pushed out of the panel, along with common voltages used in power conversion. The demand is for power supplies that not only provide the desired power level, but are also engineered to fit within smaller spaces while offering more functions. Many manufacturers have begun to design power supplies to match the small, shallow panels associated with distributed control/fieldbus architectures. Designs incorporating low height and shallow profiles fit more easily within these cabinets but gobble up space along the rail.

For larger control cabinets, these designs only take up space, adding to material costs and possibly reducing functions within the panel due to space limitations. Power supplies need to offer the machine builder overall cost savings through easy serviceability, space savings, multiple input voltages, and output power to meet most every need.

Eliminating front-end power conversion step-down transformers, by using a power supply capable of operating from three-phase mains, can also render component and space savings. Often, a machine's large inductive loads cause today's power supplies to recycle power due to their internal circuit protection. High-quality supplies can handle up to 200% of rated output for one full second, depending on the power supply type. This again ties into space savings whereby power supplies that had to be oversized to accommodate inductive load surges can now be sized according to real power demand.

Ease of maintenance
It is important for machine OEMs to offer their customers systems that not only perform to expectation, but also are easy to operate and maintain. This holds especially true for interface products found inside the machine control panel. Let's look at relays as an example. Why, for instance, do many OEM's prefer pluggable relay packages to those that contain fixed, or soldered, relays? The answer is ease of maintenance. A service technician will spend much more time disconnecting and reconnecting control and field wiring on a fixed relay package during replacement than simply pulling out the worn relay and plugging in a new one.

As an example, the new Micro-series relay package from Weidmuller addresses the maintenance issue in several ways. Easy access to the relay within the panel allows for simple plug-in replacement without disturbing field or control wiring. The comb-style bridging system simplifies the task of joining common or potential distribution and will not loosen in high-vibration environments common in machine applications.

Interface products should offer features that appeal to the OEM, as well as to their customers, so that cost savings can be passed on to the enduser. Interface component manufacturers need to be aware that the most effective way to sell products into this industry segment is to better understand the OEM's challenges in a global market. Up-front material cost is one of many issues facing the machine manufacturer. The key is to offer solutions that reduce installed costs for the OEM and maintained costs for the end user while increasing overall performance and function. By doing so, component manufacturers offer not only product solutions, but also the opportunity for strategic partnerships which ultimately benefit both the OEM and the vendor.

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