The Value of Machine Troubleshooting

Troubleshooters are highly skilled workers but are becoming an increasingly rare breed in the workforce. Managers from large manufacturers often have problems finding qualified troubleshooters. In the past, training courses only taught the basics, while the real troubleshooting skills were learned on the job over a long period of time from shadowing experienced maintenance personnel. Unfortunately, the majority of these skilled workers are now leaving the workforce for a well-deserved retirement, while an insufficient number of new maintenance workers possess this valuable skill set.

The real issue is that troubleshooting is essential for any manufacturer to stay competitive in today's tough markets. Quick and effective machine troubleshooting is vital to keep paper-thin profit margins from slipping into the red. This places a huge responsibility on technical instructors to prepare workers to hit the ground running. Long gone are the days of a machine sitting idle for long periods of time while troubleshooters substitute one component after another based on their personal experiences or conjecture.  

Since it is not feasible to allow promising young troubleshooters to take years to acquire troubleshooting skills on the job, teaching these skills in a classroom environment is key. Future technicians and operators must gain real-world troubleshooting experience before they reach the production floor. Therefore, institutions such as community colleges and company training centers must be able to create equipment issues in many combinations to build troubleshooting expertise. Use of training equipment with the ability to insert a wide range of realistic faults into a system is critical so that workers can gain hands-on experience diagnosing and fixing the broad range of problems seen in the real world. To ensure proper procedures are being taught, a troubleshooting training program should use an industry-vetted curriculum that ensures the outcomes for every worker is consistent.

Community colleges and industrial training centers are stepping up to meet this challenge with programs geared specifically toward teaching troubleshooting skills. While these programs may vary in teaching methods, effective troubleshooting, regardless of the specific technology, follows five basic steps: identify the symptoms, isolate the problem to a particular component, test the suspected component, repair or replace the component and test the system.

Identifying a malfunctioning machine's symptoms is critical because it can shorten the troubleshooting process by placing the focus on only those components capable of causing those particular problems. Teaching future troubleshooters to first ask the operator to identify any observed symptoms in a malfunctioning machine is essential. No matter how well a troubleshooter is trained, the operator who daily runs and monitors that particular machine is much more familiar with its operation than anyone else, and his or her input is quite valuable at this stage. Too often inexperienced troubleshooters assume they know the answer when they truly don't understand the question. When training troubleshooters, it is important to teach them not to overlook this crucial resource. Once the operator has identified the machine's specific symptoms, it is much simpler to draw useful conclusions concerning the fault that is causing the problem.

Categorizing the probable fault based on the symptoms focuses a troubleshooter's efforts to a significantly smaller area, which saves valuable time and money. A well-trained troubleshooter should be able to quickly categorize the problem into machine sequence, machine performance or system-related issues. Machine sequence relates to the order in which events occur, including actuator movements, pressure changes or speed changes. Machine performance refers to the characteristics of an actuator's motion or output, such as speed or force output. System-related issues involve the overall system characteristics, including vibration, fluid temperature, overall system pressure, fluid leaks, etc.

For instance, let's consider a fluid power system to see how categorizing the fault is helpful. Machine sequence faults indicate problems with components that control movement, such as sensors, directional control valves or a PLC controller. Conversely, machine performance faults are commonly caused by output components or components that affect output like pressure-reducing valves, relief valves or pumps. Symptoms that fall into these two categories can quickly narrow troubleshooting efforts to specific machine areas and parts. When system-related faults such as leaks are reported, these point to issues likely to cause machine failure. In some cases, system-related faults accompany a sequence or performance fault and are helpful indicators of what may be causing the problem. This systematic approach quickly focuses the troubleshooter on the problem.

Once the problem is categorized, a testing methodology should be used to properly identify the failed component.

Shotgun

Every component or connection in the affected area is tested until the problem is located.

Half-Split

This method continually tests a point halfway between a known good test point and a known bad test point until the problem is identified.

Output-Back

The output-back approach starts testing the system outputs and systematically works back toward the inputs until the problem is detected.

Symptom and Cause

This technique isolates the problem according to whether the component could cause the observed symptoms.

Many highly skilled troubleshooters recommend the symptom and cause method as the most effective. Teaching troubleshooters to focus only on those components that are capable of causing the observed symptoms saves time, which is why proper identification of a machine's symptoms is critical. For this method to be effective, troubleshooters must not only understand a component's function but also how it operates internally to achieve that function.

Once the faulty component is identified through in-circuit testing, it should be tested out of circuit to verify its failure. Out-of-circuit testing isolates the component from the rest of the system and can prevent time wasted in replacing the wrong component. One parts manufacturer stated that nearly 70 percent of its returned parts were not defective.

Once the problem is "fixed," testing the system's operation is the last step before signing off on the job ticket and walking away from the machine repair. The following example illustrates the importance of this step.

After a hydraulic system's main relief valve was replaced, the system started to show leakage. However, once the maintenance personnel left, the machine operator attempted to adjust the valve to the proper system pressure only to discover that this could not be done because the wrong replacement valve had been installed. This resulted in yet more downtime and almost double the labor cost to fix it.

Industry needs more troubleshooters. As manufacturers strive to create quality products in less time, they are facing a desperate lack of these skilled workers. While community colleges and training centers are teaching these skills today, they are needed in a much greater capacity than is currently available.