Time. The word is dear to us all. These days, we never seem to have enough of it. What little time we do have has to be jealously hoarded and used for only the most efficient processes and operations.
This rings true for end users whose processes no longer manufacture the same product day after day. Today the requirement is fast response to customers needs. After all, that customer isn't stocking your product in its warehouse anymore. That customer expects you to provide product on demand--instantly. You can't afford to keep lots of product around waiting for him, nor can you resign yourself to big piles of work-in-process, just waiting to be converted on receipt of the order. You have to be able to change your process over to produce different products, sometimes several times a day. You need a more reactive, flexible process.
Connections in Tight Spaces
Machine-mountable cordsets and remoteI/O connector
boxes let designers make theBest of previously unusable
machine surfaces, while reducing the material and labor costs
of running centralized I/O wiring. (Source: Phoenix Contact)
It also rings true for machine builders, who compete these days by selling the exact solution to those familiar end user dilemmas: machine productivity/uptime, ease-of-use, flexible and fast changeovers, and easy problem solving and diagnosis, as well as on price.
The Edge and How to Find It
So, where do you go to find that competitive edge of supreme flexibility? One place to start is to look at the use of fabricated cordsets, connectors, fieldbus boxes, and sensor modules, etc., instead of traditional wiring schemes for both machines and process equipment. This approach can go a long way towards helping you reconfigure processes and machines quickly--and have you manufacturing product again with minimal delays.
Greg Osbelt is electrical design supervisor for Cambridge, Ontario-based ATS Automation Tooling Systems (www.atsautomation.com), a global leader in the manufacture of advanced factory automation systems, custom and standard automation equipment, and turn-key assembly machinery. His group has been using machine mountable I/O for about four or five years. "We now, almost exclusively, use field-mount, bus-style I/O for all our machine designs," says Osbelt. "We've moved totally away from the problems and cost of pulling all that wire and cabling harnesses, and the massive cabinets that are required."
Other areas most amenable to fast connect/disconnect wiring are those where machine modules are moved in and out of a process depending on the product being made at the time. "Assembly machines, automotive, material handling, machine tool, and printing are industries where I have seen a consistent move to 'connectorize' options on the machines," says Mark Gilliford, PlusCon marketing, Phoenix Contact (www.phoenixcon.com). "Products such as chip conveyors, bar feeders, parts unloaders and loaders, chillers, conveyors, vision cells, and gluing functions are examples. The industry leaders sell the base unit and let their customers add these options as needed. To make it easy to apply the options, they must be pluggable."
Gilliford is not alone in his enthusiasm for the approach, although in some cases, it's still a question of how you view costs. "Sales of our machine-mount IP-67 I/O products are increasing at three times the rate of our standard IP-20 product, for various reasons," says Graham Harris, president, Beckhoff USA (www.beckhoff.com). "Some machinery builders view wire and cable as general overhead, so they do not, or cannot allocate the cost of this material into their actual costs. So, these companies are not going to see the value of IP-67 or even IP-20 distributed I/O until they begin to allocate wiring to their machine costs.
Harris says there should be a call to action for this category of companies, since they are missing a key cost element. "In many studies the total cost of wiring sensors and actuators back to a central control cabinet averaged one dollar per foot," states Harris. "This includes the extra terminations involved in traditional systems plus labor plus material. So, a 100 I/O system with wires running 50 ft. will actually have a total cost around $5,000. This alone has been a major reason for using distributed I/O. Harris argues that many builders will deny this cost, until they do the study themselves. When they do it can be quite a revelation.
The quick connect/disconnect feature of on-machine IP-67 I/O products allow fast and reliable module replacement without tools, an asset when a machine has to be quickly back online.
Another value is that IP-67 I/O can be placed much closer to the sensor/actuator and that makes the associated wiring run as short as possible, which also can improve reliability and reduce signal transmission losses.
Test and Ship
There are instances when a machine or process must be fully assembled, wired, and tested before shipment, then easily disconnected, shipped, and eventually reconnected at the installation site. "End users, working with system integrators and industrial OEMs have made it a requirement to build the equipment, test its functionality, then tear it down, ship anywhere in world, and reconfigure quickly using local labor, says Gilliford. He believes there are three factors that drive this concept:
Some custom assembly builders have seen the value of on-machine IP-67 I/O. "Assembly machines/lines are often modular, so the I/O wiring becomes just a network cable, which is much easier to connect, break, and reconnect than conventional wiring," says Harris. "Assembly machines do not have much space for cabinets and on-machine I/O is easy to bolt onto a structural support." In addition, says Harris, assembly machines are normally customized for a specific customer, so I/O counts will vary from design to design and machine-mount IP-67 I/O provides design flexibility, "since no enclosure or cabinet is needed and wiring can be done on the floor with quick-connect cabling rather than cable harnesses, which need to be pre-designed and manufactured offline."