Keith Fitzsimmons
LMO- Lathe Maintenance Ontology
IE 500 – Ontological Engineering
IE 500
INTRODUCTION
Lathe Maintenance Ontology has been compiled to help document, with the hope of eventually
compiling for all models of metal machining lathes, the necessary manufacturers preventative
maintenance requirements. The Lathe Maintenance Ontology (LMO) at this time has initially been
focused on computer numeric controlled metal machining lathes. Though; it is hoped that eventually
this ontology can be expanded to encompass all type of metal machining lathes and potentially other
machinery which needs time based preventative maintenance as required by the original equipment
manufacturer.
Equipment manufacturers outline the necessary maintenance needed to keep a machine
operating at its peak performance levels on a time based interval. In many cases these maintenance
requirements can impact whether or not the machines warranty will be honored if a failure should occur
during the warranty period. The current limitation which this ontology hopes to solve is that of the
availability of reliable maintenance requirements of any metal machining lathes, especially those which
may no longer be supported by an original equipment manufacturer.
The limitations that exist at this time are that no central databases for information on metal
machining lathes preventative maintenance requirements exists and in many cases the requirements for
older machinery does not exist on the internet for easy searching. An ontology outlining the time based
requirements for machinery maintenance would allow for maintenance technicians to have access to
the knowledge they need to complete their jobs in the correct and timely fashion. This information can
also be used by those setting up maintenance programs and original equipment manufacturers in
different ways.
EXISTING DATABASES
In the world of manufacturing the current systems available for the tracking and the prescription of
maintenance tasks employ the use of a conventional database system. Currently there exists
commercially available programs which are able to track the work that is compiled into the Lathe
Maintenance Ontology, however they are strictly for the tracking of the maintenance and require that
the time periods, tasks and materials which Lathe Maintenance Ontology prescribes to be input every
time a new system is setup and do not offer any value with regards to maintenance procedures for
machinery which the organization purchasing the software may own. The drawbacks to this type of
program is that they are company or site specific setups which leads to the inability to transpose data
freely between themselves even if the information needed is available as part of the preventative
maintenance program the organization has setup at another site. Thus in even a single company they
are unable to freely share their machinery maintenance requirements between different sites in an easy
manner.
EXISTING ONTOLOGIES
Overview
The existing ontologies that were reviewed during the formation of Lathe Maintenance
Ontology (LMO) were the Manufacturing Descriptive Language (MSDL) and the Industrial Maintenance
Management Ontology (IMAMO). While both of these ontologies offered insight into the world of
manufacturing with regards to the formation of ontology they do lack the necessary components to
define an original equipment manufacturers preventative maintenance schedules for machinery in a
manufacturing environment. Manufacturing Descriptive Language (MSDL) does not encompass the
maintenance aspect of the manufacturing process when it looks at the machinery used in the
manufacturing process. While it is felt that the Lathe Maintenance Ontology could potentially be related
to the Industrial Maintenance Management Ontology there are components lacking in the Industrial
Maintenance Management Ontology(IMAMO) hierarchy that preclude the data in Lathe Maintenance
Ontology from being easily combined. Below is an in depth analysis of the limitations of both ontologies
have in relation to preventative maintenance schedules.
Manufacturing Descriptive Language (MSDL)
The Manufacturing Descriptive Language’s compatibility model, figure 1, shows the entire
process of manufacturing for an entity as viewed by the Manufacturing Descriptive Language (MSDL). It
deals with all aspects of manufacturing but omits the maintenance of the machine used in the process.
While the machine is looked at in this process we are only looking at how much work it can complete,
the working envelope, the time to complete a piece, the time of setup and the number of axises
involved. While these are all important parts of the manufacturing process the maintenance aspect
needed to keep the machinery running is omitted. Based on ISO and other quality standards
maintenance is an important aspect of the manufacturing process.
It can be assumed that the maintenance is part of the process but the nature in which it would
be incorporated and what this model is looking at does not allow for the maintenance requirements in
the process to be seen as part of this ontology. This model may make the assumption that maintenance
is being completed but does not look at the requirements of maintenance for a machine.
Figure 1 - Manufacturing Descriptive Language
Industrial Maintenance Management Ontology (IMAMO)
Industrial Maintenance Management Ontology has roots in the same area as Lathe Maintenance
Ontology (LMO) but is still lacking in that it looks at the process of maintenance management as
opposed to the actual time based maintenance needs of the machinery. Certain aspects of this ontology
can be incorporated into the Lathe Maintenance Ontology conceptually but they are approached in a
different manner by Industrial Maintenance Management Ontology (IMAMO). This ontology has the
components needed to setup and maintain a maintenance management program for a facility. Looking
at figure 2 below we can see what goes into the maintenance process but not the maintenance
requirements for the machinery that need to be completed as part of the maintenance process. This
ontology would give you the maintenance program while Lathe Maintenance Ontology (LMO) will give
you the maintenance tasks and preventative maintenance schedule to build the maintenance program.
In this ontology it might be possible to insert the materials encompassed by Lathe Maintenance
Ontology (LMO).Though where Lathe Maintenance Ontology (LMO) looks at the actual tasks necessary
to comply with the original equipment manufacturers preventative maintenance requirements
Industrial Maintenance Ontology (IMAMO) only looks at the parts necessary to complete a maintenance
schedule.
Figure 2 – Industrial Maintenance Management Ontology
Lathe Maintenance Ontology – LMO
Overview
To solve the problems discussed with the existing ontologies above the author of this ontology
has devised an ontology which relates the original equipment manufacturers required preventative
maintenance tasks for a machine to the machine based on time period for which the maintenance must
be performed. By doing this we are no longer limited by the single site terminology and data. Now any
lathes preventative maintenance requirement using the structure of this ontology.
Basic Formal Ontology (BFO) creates a good base for the building of our ontology. By putting the
lathe terms into this type of higher level ontology the ability to use this at a later time to incorporate
Lathe Maintenance Ontology (LMO) into a larger machinery preventative maintenance ontology, or
another ontology for machine maintenance that uses Basic Formal Ontology (BFO) is now possible.
Lathe Maintenance Ontology (LMO) looks at the preventative maintenance required by the
original equipment manufacturer for a lathe; something that no other ontology that was found is
organized to accomplish. It relates the maintenance tasks needed to maintain the lathe, and the
materials required for those tasks, back to a maintenance regimen which has been prescribed by a
preventative maintenance requirement for a specific lathe.
Definitions
The definitions in Lathe Maintenance Ontology (LMO) are important due to the variations that
exist between different machines. Many machines may use the same basic terminology for a
maintenance task or the objects used as part of the task but the actual object or task will vary due to the
differences of the machinery. These differences exist due to design by the original equipment
manufacturer, machine usage, or the machines upper level class within the ontology. Because of this we
must be sure to define each part of the ontology in a manner which gives a general definition of the
component part relatable to the other similar component parts yet still allows for the definition to be
specific enough to ensure that no parts or tasks can be used in the wrong manner as this could cause
issues when the preventative maintenance is completed by the technician who is using this data as a
resource.
Continuants
The components which are used as part of the preventative maintenance process, or those
components which will have the process completed on them are known as continuants. In the case seen
below the machinery, the computer numeric controlled lathe, has requirements for maintenance to be
performed on it. The preventative maintenance schedule, which is also a continuant, is given by the
manufacturer as a process that should be completed to keep the machine operating at its optimum
performance level.
The preventative maintenance schedule is almost always a time based schedule which is
provided to the machine owner by the original equipment manufacturer. This schedule has tasks which
are to be completed as part of the maintenance process to ensure the full life of the machine.
We also have here the metal machining lathe, a machine which turns material at a varying speed
allowing it to be cut by a tool. In Lathe Maintenance Ontology (LMO), at this time, we are only looking at
computer numeric controlled lathes but eventually it is to that it will be able to encompass both
computer numeric controlled lathes and manual lathes used to machine metals.
The continuants of Lathe Maintenance Ontology (LMO) also include the objects used as parts in
the prescribed preventative maintenance schedule. These objects are the parts and materials used to
complete the original equipment manufacturers preventative maintenance schedules tasks. The objects
in Lathe Maintenance Ontology (LMO) are oils, filters, and other materials which are required to keep
the machines in running order and satisfy the original equipment manufacturers preventative
maintenance schedule.
Figure 3 - Continuants
Occurents
The process that completes the preventative maintenance schedule is the occurent’s in this
ontology. The Preventative maintenance schedule, a continuant, which is prescribed by the original
equipment manufacturer demands that a maintenance regimen is completed. This maintenance
regimen is specific to each machine and includes a maintenance task on some process profile. The
maintenance tasks and process profiles are ambiguous and can be applied to many different
maintenance regimens, as can the objects required to complete these tasks, to meet the manufacturer
recommended preventative maintenance schedule. The objects used however, though of a similar top
level name, may change based on the machinery requirements of a different grade of fluid or model
filter is prescribed by the original equipment manufacturer.
Maintenance tasks are the actual actions as prescribed by the original equipment manufacturer
that need to occur to accomplish the preventative maintenance schedule. There are many different
tasks that can occur and some machines require the same tasks to occur at the same or different time
periods. These tasks are part of the maintenance process and are dependent on the materials, objects,
that they use as they are completed and the time period, process profile, in which they need to occur.
The process profile gives the time periods in which the preventative maintenance must occur.
As with the tasks being variable between machines the process profile can also vary. The maintenance
tasks and process profile are always related to create the maintenance regimen for the given machine.
Figure 4 – Occurents
Object Properties
The object properties in this ontology are used to relate the actions that are necessary to
complete the preventative maintenance schedule as prescribed by the original equipment
manufacturer. Not many object properties are needed at this level of the ontology as many of the
relationships, no matter which style or model of lathe is being describled, are similar. These properties
create relationships that outline the maintenance profile of the machine. While the ontology has broken
the prescribed maintenance of the lathe down into subcomponents and organized them based on the
upper hierarchy of Basic Formal Ontology (BFO) we can related all of the parts using these properties
below.
Figure 5 –Properties
The “has_process_part” and “has_process_profile”, figure 6, are important to this ontology as
they are used to create the maintenance regimen, which is prescribed by the original equipment
manufacturers preventative maintenance schedule. The process parts allow for the description of the
maintenance task that needs to be completed for a specific machine as part of the maintenance
regimen. The process profile allows for the designation of the time period in which this task must be
completed
Figure 6 – Use of Object Properties
Data Properties
This ontology only requires a single data property, seen in figure 7, to fully define the period in
which the maintenance needs to take place. By relating this period to a process profile from figure 5, as
a value, we can designate how often the required maintenance tasks defined for the machine must take
place. This property can be used to define any maintenance period that can be thought of and is
designated by the number of days in that period. There are limitless possibilities for the use of the
property as there are limitless possibilities for the period in which a manufacturer will prescribe
maintenance be required.
Figure 7 – Data Properties
Inputs and Outputs
In this ontology the information that is input will be output as reference material for managers,
technicians and any others who may have use for a machine preventive maintenance needs. The data
that is input is tied to a specific machine and by completing a sparql query you would be able to locate
the necessary data for completing time based preventative maintenance of the machine. This data will
be directly related to the original equipment manufacturers prescribed maintenance for the machine
which maintenance technicians or maintenance managers will be interested in.
The hope is that one day you would be able to search for a specific machine, or style of machine,
and a time period and be able to find the necessary maintenance requirements. The inputs will be set by
those who populate the ontology and then maintenance personnel will be able to find the output, the
maintenance requirements, as needed for their projects or maintenance programs.
Application
Preventative Maintenance
Lathe Maintenance Ontology (LMO) is expected to be used during preventative maintenance to
ensure that machinery is undergoing the proper preventative maintenance schedule as prescribed by
the original equipment manufacturer. In this scenario it can be used as a reference by those who will be
conducting the maintenance on the machinery to ensure that they are completing the necessary tasks at
the designated time period. This can be important in organizations where many different people can
work on the same machine or similarly an organization which has one person primarily working on the
machinery and in their absence another person who may not be familiar with the day to day operations
will be tasked with filling in and fulfilling the preventative maintenance requirements.
Machine Maintenance Programs
In many organizations preventative maintenance is part of a larger machine or facility
maintenance program. Lathe Maintenance Ontology (LMO) can be used as a resource by those creating
or updating these programs to ensure that all the necessary preventative maintenance is being
conducted at the correct time interval for the machinery included in their program. Once this ontology is
compiled and made available to any persons in the field of maintenance management and engineering it
will become a resource for them in the planning and construction of a preventative maintenance
program. These programs can be small or large depending on the company and with the larger the
company becomes the higher the possibility of a large age range for the equipment, or large diversity in
equipment model and type, increases. The potential for different machinery across many organization
locations can also create a problem with machinery maintenance which may be controlled from one
central location. References like Lathe Maintenance Ontology (LMO) would allow these organizations
access to the necessary maintenance requirements for all their machinery.
Original Equipment Manufacturers
Lathe Maintenance Ontology would also be useful to the original equipment manufacturers as it
would give them a tool to evaluate what their competitors are doing with their machinery in regards to
preventative maintenance. This would allow them to alter their designs to match a competitor who
offers an easier, more cost effective, maintenance schedule while still allowing for optimal performance
of the machine. It would also allow them to evaluate what a competitor may require in their prescribed
maintenance which could reduce issues that may be occurring in their own equipment.
This ontology would also allow for the manufacturers to go back in time if it were necessary to
support a customer with older machinery. This ontology would offer a source for machinery
maintenance requirements which would allow for original equipment manufacturers to offer support
longer as the training necessary for personnel and the space needed for the storage of documentation
would become non-existent with this.
Second Owner Equipment
With the multitude of different manufacturers and ever changing machine models being
introduced into the machining market it is often not long before older machinery is sold second hand to
a smaller machine shop or machining enthusiast. In many cases at this time the materials which outline
the necessary maintenance are lost in transition. This ontology would allow those who are buying
equipment second hand to continue the proper preventative maintenance schedule by knowing what
the schedule is; hence keeping the machinery operating optimally through its entire lifespan.
Conclusion
Lathe Maintenance Ontology (LMO) creates a comprehensive source for lathe maintenance
requirements. While this ontology is only limited to lathes at the moment it could very well be
expanded, if it’s found acceptable for the use, with other types of machinery which require preventative
maintenance on a time based schedule as required by the original equipment manufacturer.
The potential resources this creates open a new means for people in different fields who require
access to the requirements for the preventative maintenance of machinery. With so many different
machines out there a singular source for the requirements will decrease the time needed to search for a
machines preventative maintenance requirements; cutting costs for company of all sizes or freeing up
the time of those who are tasked with looking for the preventative maintenance requirements for a
company’s machinery to complete other tasks.
References
[1] Ameri, Farhad, Colin Urbanovsky, and Christian McArthur. "A Systematic Approach to
Developing Ontologies for Manufacturing Service Modeling."
[2] Mohamed Hedi Karray, Brigitte Chebel-Morello, Noureddine Zerhouni. A Formal Ontology
for Industrial Maintenance. Terminology & Ontology : Theories and applications, TOTh
Conference 2011., May 2011, Annecy, France. sur CD ROM, pp.1-20. <hal-00602182>