For industrial and manufacturing businesses, the cost of assembly and installation errors may be a considerable amount of reported failure and associated repair costs. The problem, as we all know, is that it is not just the cost of repair. That cost also comes from unscheduled production downtime, poor product quality, reduced reliability, and diminished life cycle performance with increased parasitical/frictional forces that consume energy.
Here, we’ll take a look at the common causes of assembly and installation errors, what their ultimate cost is, and how manufacturers can avoid these detrimental delays.
Common Assembly and Installation Errors
While any number of factors can contribute to a manufacturing assembly or installation error, there are a few common culprits.
- Parts errors – Parts that have degraded or rusted due to improper storage or assembly may lead to installation errors.
- Tools and measuring devices – Measurement tools help ensure consistency and accuracy, but can they themselves be rendered inaccurate over time.
- Inspection error – Failure to notice vibration, dents, wear, leakage, or other points of inspection during operator rounds can result in errors in assembly and installation alike.
- Environmental stress – Humidity, extreme cold or heat, improper storeroom asset care, and other ‘outside’ factors can speed up the process of part deterioration.
- Consciousness – When operators are less focused, not really ‘owning’ their equipment, they’re more likely to slip up and make mistakes.
The Real Cost of Assembly and Installation Errors
According to the National Institute of Standards and Technology (NIST), manufacturing rework and scrapping can run between 5 and 30% of their total manufacturing costs. Not only that, but the International Journal of Engineering suggests that human error might account for 80% of quality defects when it comes time to assess the final result.
Defective products, of course, will lead to wasted materials and time at best, and unhappy clients at best.
It’s not just the bottom line that suffers. When a machine breaks down shortly after installation, we refer to it as ‘infant mortality.’
Machine Infant Mortality
Infant mortality is an equipment failure model. It is a metric that shows that the highest probability of failure is when a machine is first started after initial assembly and installation and declines over time. It comes, of course, with an incredibly expensive burden.
Reliability-centered maintenance (RCM) refers to a type of maintenance planning that instills confidence in an operator. That confidence comes from knowing that a given system will do what it is meant to in its current operating context.
The principles of RCM have helped shape the identification and realization of a pattern referred to as “F,” when creating equations to calculate machine infant mortality, as seen in the diagram above.
In simple terms, because of how we repair and operate machinery, the probability of this type of failure is such that no less than 68% of the likelihood of failure is due to “infant mortality. ”
The Need for Reliability in Design
It’s critical to realize that including reliability and life cycle performance in designing new machinery can reduce the associated maintenance costs over the machine’s life by 50%. In most cases, the upfront cost added to the project is less than 3% – that’s not a bad return for a different approach. But let’s now pay attention to what we are addressing in this short note.
Understanding Mechanical Assembly Failures
[[Note for Katie: Is there a study or statistic that generated the figures on this graph? If so, could you link it here? If it was an internal study, that’s fine too, but I want to be able to site a source for this information.]]
When touching on the topic of mechanical failures, the potential for downtime or failure doesn’t rest solely on the shoulders of mechanics or operators. Mechanical failures also happen in the electrical, instrumentation, and production ranks. Wherever a “mechanical” device exists, so does the chance of failure.
The three primary root causes of a piece of manufacturing equipment’s “loss of utility” are usually obsolescence, deterioration, and error. For example, when a machine’s surface degrades, vibration increases, which can lead to misalignment, overheating, and a similar domino effect of issues.
As illustrated in the diagram above, approximately 30% of this type of failure stems from the way machine systems are mechanically assembled. The old adage of “close or good enough” just doesn’t cut it in today’s manufacturing requirements. Profit margins and the need to produce first-pass products are so tight that unrecognized failures can no longer be allowed.
That is why reliability in manufacturing is so critical: when consistency is achieved, operators at every level of the funnel can be confident that the chances of failure in assembly or installation are reduced.
A Simple Example
The summation of eccentricities is where the “art” of assembly begins. When assembling “fitments” to shafts, there is always an accepted allowable roundness, clearance and eccentricity tolerance. Occasionally, in assembly, it may have become a habit to stick parts together without thinking that the final position of these parts may change how the machine was intended to run.
Fitments in their final assembled position actually create vectors of force. How these systems are assembled determines the resulting mechanical force, measured vibration amplitude, machine performance, and life cycle. The diagram below indicates the difference in correct assembly.
Therefore, assembled eccentricity can be added negatively. The net result is that a part’s ‘true’ center can be determined and applied to all system components, ensuring proper alignment.
Without going into detail, how many parts are assembled in a machine and then in connected machine systems? If we do not consider the statements above, we begin to quickly realize the number of failures and the resulting costs from assembly errors. We include these crucial techniques in a Precision Maintenance® and Reliability Roadmap process.
Where to Begin
Assembly and installation are critical to all other processes within the realm of manufacturing. Hands-on exercises should introduce the proper methods and ideologies for these practices. Correct skill set improvement with continuous and sustainable performance is an acquired behavior.
The need for a specific plan for hard skills training with management involvement and field application is paramount to success. Machine failure, downtime, and mechanical infant mortality can be eliminated, mitigated and controlled to an acceptable minimum. Where are you today in reducing your downtime costs? Where are you going to be tomorrow? Reliability Solutions’ is able to effectively, expertly train toward assembly and installation, greatly reducing the chances of failure. Contact us today to learn more about our operator training courses, and start your journey to a better workforce!
