Maintenance concepts Flashcards
What is a maintenance concept?
- Overall model for how to plan, control, and
improve maintenance
– Basically “how to do maintenance” - Why do we only focus on three in this course?
– Received most attention in academia
– Most commonly used in industry
❑ TPM = holistic model of equipment management
❑ RCM = maintenance planning method
❑ CBM = maintenance action executed based on condition
What is TPM?
Total Productive Maintenance
Productive = The most economic maintenance
that raises equipment productivity
Total = the entire company is involved
What are the 8 pillars of TPM? Describe the pillars as well.
Autonomous maintenance
* Operator maintenance
* Fostering operator ownership
* Cleaning, inspection and lubricating
(CIL)
Focused Maintenance
* Elimination of equipment losses
* Improve system efficiency
* Improve OEE
* Collaboration with other functions
Planned Maintenance
* Plan PM (TBM, CBM etc.)
* Improve MTBF
(Mean Time Between Failure)
* Improve MTTR
(Mean Time To Repair)
Quality Maintenance
* Zero defects
* Track equipment problems and root
causes
Education & Training
* Technical, quality,
interpersonal skills
* Multi-skilled employees
SHE (Saftey, health & enviornment)
* Ensure safe working
environment
* Eliminate accidents and injuries
* Standard operating procedures
Office TPM
* Reduce cost-related issues
* 5S in office
* Improve collaboration
between functions
Development Management
* Maintenance Prevention
* Early Equipment Management
* Maintenance in design phase
Very important, often neglected!
What is RCM?
Reliability-Centered Maintenance (RCM)
History:
* Completely questioned why and how
maintenance should be done
Shift in approach:
Avoid failures => Avoid failure consequences
Reduce unnecessary maintenance, do only what is needed.
What are the 4 basic features of RCM?
Four basic features of RCM:
1. Preserve functions
2. Identify failure modes that can defeat the function
3. Prioritize function need
4. Select applicable and effective PM tasks for high priority
failure modes
Applicable = if the task is performed, it will accomplish one of three reasons for
preventive maintenance (prevent or mitigate failure, detect onset of a failure, discover
hidden failure)
Effective = we are willing to spend the resources to do it
What is CBM?
Condition-Based Maintenance (CBM)
Monitor system performance, system health, and root causes of
failures, forecasting remaining useful life.
CBM utilizes Condition Monitoring, e.g. in production equipment:
* Vibration (any moving component)
* Thermography (temperature)
* Oil analysis (e.g. viscosity)
* Ultrasonic (high frequency sound)
* CBM is not only about sensors
– Five senses is a very cheap version of CBM!
Describe some of the predictive techniques, their application and problem detection.
What do we mean by diagnostics?
Diagnostics = finding the fault after occurring, or in the process
of the fault occurring (fault not equal to failure)
What do we mean by prognostics?
Prognostics = predicting future failures by analysing current
and previous history
Why is there a gap between data collection and data-driven decision making?
– Potential to collect huge amounts of data – information overload!
– What parameters to monitor? What parameters are critical?
– How to collect data?
– What data to analyse?
– How to manage levels? E.g. components, machines, systems
– Which type of algorithm should be used?
– How can we trust the data? (data quality)
What is a PF curve?
PF curve – the heart of CBM
– Describes equipment failure behaviour
How do TPM, RCM and CBM support each other?
TPM: holistic approach to equipment management
RCM: determine the overall maintenance plan
CBM: monitor specific equipment
What do we mean by dependability?
A collective term used to describe the availability
performance and its influencing factors: reliability
performance, maintainability performance and
maintenance support performance
Reliability
Maintainability
Maintenance support
Describe reliability.
Reliability is the ability of an item to
perform a required function under given
conditions for a given time interval
Reliability may also be defined as a
probability that an equipment will
perform its intended function without
failure for a specific time under defined
conditions
Describe Maintainability.
Maintainability is the ability of an item under given
conditions of use, to be retained in, or restored to, a
State in which it can perform a required function, when
maintenance is performed under given conditions
and using stated procedures and resources
Note 1: The maintainability is also used as a measure of
maintainability performance
Note 2: The time characteristic of maintainability is the
active maintenance time
What is a bathtub curve?
What do we mean by infant mortality failure period?
In its early life, an item population exhibits a high failure rate, due to manufacturing weakness, including:
-Poor joints and connections
-Damaged components
-Chemical impurities
-Dirt and contamination
-Assembly errors
What is Weibull distribution?
Most useful lifetime in reliability analysis.
* Development, production and service.
* Quality control and design deficiencies.
* Maintenance planning and replacement strategies.
* Spare parts forecasting.
* Warranty analysis.
* Natural disasters (lightning strikes, storms, high winds, heavy snow, etc.).
2 parameters: shape = β, scale = η
β<1 decreasing hazard function
β>1 increasing hazard function
β=1 constant hazard function
