Nowadays, product features are often what differentiate one component from another. Diagnostics and maintenance feedback functions are a major way to add value to your design, by providing a way to run processes more efficiently or produce a higher quality product. They can report output, predict the upper limits of a new design, and make maintenance more effective. “Whether new or for the retrofit market, the paybacks are huge when diagnostics are provided, employed, and used correctly,” says Don Kosnik, product manager at Avtron Manufacturing Inc., Cleveland. Diagnostics also assist in the detection of suboptimal equipment conditions. “So if a system is not monitored, then reliability and maintenance personnel have no opportunity to know the condition of the equipment,” says Howard W. Penrose, Ph.D., CMRP, president of Success by Design Reliability Services, Saybrook, Conn.

Because diagnostics is based on data processing, accurate input information is paramount to these systems. The quality of data depends heavily on the caliber of both data collection and system connectivity. Open standards such as Ethernet itself, open industrial protocols on Ethernet, OPC, HTML, ACTIVE-X, and XML have improved industrial communications in recent years. “And diagnostic information in real-time is also vitally important,” says Kosnik. It's nearly impossible to diagnose systems with information fed slowly relative to the process; timely information about a system's status provides a real picture of subtle motion workings, and allows users to make corrections more quickly. “Productivity increases with direct process control using immediate feedback,” agrees Ralph Brillhart of Advanced Test Group, San Diego.

Diagnostics can be optimized for a new system in a couple ways. “Data from existing systems and historical information can be used directly to define the environment that exists for a new system,” says Brillhart. This translates into more efficient new designs by preventing overdesign and ensuring proper parameters from the start. Too, new designs can incorporate the ability to make measurements that allow for future diagnostics — improving the new design's life, and validating design criteria — in turn, feeding improvements for future designs.

Without diagnostics, prototyping and assembly are especially inefficient. Diagnostics improve assembly by adding calibration functionalities for visibility in production and process quality, machine downtime, and synchronizing multiple production and logistics schedules. “This calibration must be frequent, consistent, and comply with process quality standards, but slow the process as little as possible,” says Jacques Hoffmann, president of InterTech Development Co., Skokie, Ill. “When systems are calibrated ineffectively, they don't reveal problems in underlying system design and functioning. So then phenomena such as leak test fixtures, for example, can allow creep that makes it impossible to differentiate good parts from defective, or system design flaws resulting in inadequate signal-to-noise ratios during electrical testing.”

On lines that run continuously, especially on critical, costly systems, regular diagnostics is the most effective way to foresee potential breakdowns. Now, in many cases, diagnostics are being built directly into new systems, right off the assembly line. “Investing in new equipment with this capability is expensive, but it promotes more effective and consistent routine maintenance,” says Rick Brooks, manager of reliability services, The Timken Co., Canton, Ohio. Systems can automatically perform diagnostics checks at scheduled intervals to report back to an online maintenance program, drastically reducing unplanned downtime for repairs. “In this way, a plant can operate on the offense rather than the defense. Otherwise, if systems do not have these diagnostics preinstalled, consistent screenings can be achieved with effort and a little diligence,” Brooks adds.

Newly installed equipment should be tested to establish baselines for future monitoring, and (by acceptance testing) to identify any faulty new equipment.

“Another benefit of consistent diagnostics testing: Improved efficiency from exposing root-cause problems, enabling engineers to correct it during design,” says Brooks.

Sometimes the final decision to include diagnostics is made by management. “Even when infrared windows and diagnostics test points are specified in the initial RFQ, they are often sacrificed to lower initial purchase cost. But in fact, this can increase safety and reliability costs over the long run,” laments Penrose. This is why the relationship between management goals and engineering realities must be clear.