Effective Maintenance Management. V. Narayan
We discussed how we compute the value of work, using production costs or competitive market prices. We noted that there are some sources of error in arriving at the value of work.
Thereafter, we saw how manufacturing and service industries add value. Manufacturing productivity has grown dramatically, due to cheap and plentiful electro-mechanical power and, more recently,computing power. A beneficial cycle of increased productivity—raising the buying power of consumers—results in increased demand. This has lowered prices further, encouraging rapid growth of manufacturing and services industries.
Manufacturing and service industries similar processes. The systems approach helps us to understand these, and how to control them.We illustrated this similarity with a number of examples.
Thereafter, we examined the impact of efficiency on the use of resources. We noted that cost is a measure of efficiency, but recognize that all costs are not visible; hence distortions can occur. With this understanding, we saw how to use costs to monitor efficiency. A brief discussion of the role played by maintenance in managing safety, availability and costs sets the stage for a more detailed examination later. We will address the questions why, what and when in regard to maintenance as we go through the book.
REFERENCES
1.Original Baker report is at http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/SP/STAGING/local_assets/assets/pdfs/Baker_panel_report.pdf
2.UK HSE report. http://www.hse.gov.uk/leadership/bakerreport.pdf
The term process describes the flow of materials and information. In order to achieve our business objectives, we use energy and knowledge to carry out the process.
The purpose of running a business is to produce or distribute goods (or services) efficiently. A business uses its mission statement to explain its objectives to its customers and staff. This is a top-down approach and enables us to see how to fulfill the mission, and what may cause mission-failure. We call this a functional approach, because it explains the purpose, or function, of the business. We can judge the success or failure of the business by seeing if it has fulfilled its function, as described in the mission statement. A high-level function can be broken down into sub-functions. These, in turn, can be dissected further, all the while retaining their relationship to the high-level function.
After reading this chapter, readers who are unfamiliar with this approach should have acquired an understanding of the method—this is the mission or function of this chapter. The main elements of the method are as follows:
•The functional approach, methodology, and communication;
•Identification of functional failure, use of Failure Modes and Effects Analysis, and consequences of failures;
•Reduction of frequency and mitigation of the consequences of failures;
•Cost of reducing risks;
•Damage limitation and its value.
The U.S. Air Force initiated a program called Integrated Computer Aided Manufacturing (ICAM) in the 1970s. They developed a simple tool to communicate this program to technical and non-technical staff, named ICAM-DEFinition or IDEF methodology1,2. With IDEF, we use a graphical representation of a system using activity boxes to show what is expected of the system. Lines leading to and from these boxes show the inputs, outputs, controls, and equipment.
As an illustration, consider a simple pencil. What do we expect from it?
Let us use a few sentences to describe our expectations.
A.To be able to draw lines on plain paper.
B.To be able to renew the writing tip when it gets worn.
C.To be able to hold it in your hand comfortably while writing.
D.To be able to erase its markings with a suitable device (eraser).
E.To be light and portable, and to fit in your shirt pocket.
The item must fulfill these functional requirements or you, the customer, will not be satisfied. If any of the requirements are not met, it has failed. Figure 2.1 illustrates a functional block diagram (FBD) of how we represent the second function in a block diagram.
Figure 2.1 FBD of pencil system.
Note that we state our requirements in the most general way possible. Thus, pencil does not have to be a graphite core held in a wooden stock. Pencil can easily be a metal holder, and still meet our requirements. The second function is met whether we have a retractable core or if we have to shave the wood around the core.It could have a hexagonal or circular section, but must be comfortable to hold. The writing medium cannot be ink, as it has to be erasable. Finally, its dimensions and weight are limited by the need for comfort and size of your shirt pocket!
Every production or distribution process has several systems, each with its own function, as illustrated by the following examples.
•A steam power-generation plant has a steam-raising system, a power generation system, a water treatment system, a cooling system, a control and monitoring system, and a fire protection system.
•A courier service has a collection and delivery system, a storage and handling system, a transport system, a recording and tracking system, and an invoicing system.
•An offshore oil and gas production platform has a hydrocarbon production system, an export system, a power generation system, a communication system, a fire and gas protection system, a relief and blow-down system, an emergency shutdown system, and a personnel evacuation system.
•A pizza business with a home delivery service has a purchasing system, a food preparation system, a communication system, and a delivery system. Sometimes, all these systems may involve just one person, who is the owner-cook-buyer-delivery agent!
We can use functional descriptions at any level in an organization. For example, we can define the function of a single item of equipment. Jones3 illustrates how this works, using the example of a bicycle, which has the following sub-systems:
•Support structure, e.g., the seat and frame;
•Power transmission, e.g., pedals, sprockets, and drive chain;
•Traction, e.g., wheels and tires;
•Steering, e.g., handles and steering column;
•Braking, e.g., brakes, brake levers, and cables;
•Lighting, e.g., dynamo, front and back lights, and cables.
We can define the function of each sub-system. For example, the power transmission system has the following functions:
•Transfer forces applied by rider to drive-sprocket;
•Apply forces on chain;
•Transmit the force to driven-sprocket to produce torque on rear wheel.
Similarly, we can examine the other sub-systems and define their functions. The functional failure is then easy to define, being the opposite of the function description; in this case, fails to transfer force.