ASSIGNMENT 1

Vikash KumarC-2

7TH SEMME10401206566

Q1. Explain advantages and disadvantages between Block replacement, age replacement and periodic replacement policy.

BLOCK REPLACEMENT

Under a block replacement policy the unit is replaced on failure and at .xed times T; 2T; 3T; :::In practice we have a block or set of components (e.g. lights on a motorway). Two types ofreplacement are carried out:1. units as they fail (in-service failures)2. all units (irrespective of which have failed and been replaced) at the .xed times T; 2T; 3T; :::The former are sometimes termed emergency replacements and the latter are planned replace-ments.Suppose that the unit cost for planned replacement is cpand the unit cost for in-service replacement is cs with cs > cp

Age replacement

Block replacement policy has advantage of ease of administration, since records do not have to be kept of when items are replaced. All items are replaced at times kT irrespective of the length of time in service. However it has the disadvantage that almost new items (those replaced upon failure just before a time kT) are replaced at planned times kT:We may instead replace components either at a predetermined age T or on failure if it occursearlier. The costs are respectively cp, cs with cp < cs:Let the time interval between consecutive replacements (of either type) de.ne a cycle.We .nd T to minimize (T) = Expected replacement cost per cycle Expected cycle length

Q2. Write short notes on all types of maintenance with examples.

REACTIVE MAINTENANCE

Reactive maintenance (also known as corrective maintenance) involves all unscheduled actions performed as a result of system or product failure. Basically, it is an attempt to restore the system/product to a specified condition. The spectrum of activities within this level are (1) failure identification, (2) localization and isolation, (3) disassembly, (4) item removal and replacement or repair in place, (5) reassembly, and (6) checkout and condition verification. This approach is mainly a response to machine breakdowns. Unfortunately, many manufacturers are still in a reactive mode of operation. Their main objective is to ship the product. If their manufacturing equipment breaks down, they fix it as quickly as possible and then run it until it breaks down again. This is an extremely unreliable process and is not the best way to maximize the useful life span of one's assets. It leaves machine tools in a state of poor repair and can cause the production of out-of-tolerance parts and scrap. Because of its unpredictable nature it can easily cause disruptions to the production process.

SCHEDULED MAINTENANCE

Scheduled maintenance utilizes a previously developed maintenance schedule for each machine tool. This is much like an oil change on an automobile that takes place every three months or 3,000 miles, whichever comes first. While this is a broadly practiced technique in many manufacturing organizations, it does possess some distinct disadvantages. The scheduled maintenance may take place too soon, while the machine still operates well (15-20 percent of all components fail after a predictable time), or it may come too late if the machine fails before the scheduled maintenance time. In some cases, the machine may still be running but producing unacceptable parts. Scheduled maintenance can be considered a part of preventive maintenance known as fixed-time maintenance (FTM). Preventive maintenance is discussed later.

PREDICTIVE MAINTENANCE

Predictive maintenance involves performing maintenance on a machine in advance of the time a failure would occur if the maintenance were not performed. Of course, this means that one must calculate when a machine is predicted to fail. In order to do this, the firm must collect data on variables that can be used to indicate an impending failure (vibration, temperature, sound, color, etc.). This data is then analyzed to approximate when a failure will occur and maintenance is then scheduled to take place prior to this time. By seeking the correct level of maintenance required, unplanned downtime is minimized.

PREVENTIVE MAINTENANCE

Preventive maintenance encompasses activities, including adjustments, replacement, and basic cleanliness, that forestall machine breakdowns. Preventive activities are primarily condition based. The condition of a component, measured when the equipment is operating, governs planned/scheduled maintenance. Typical preventive maintenance activities include periodic inspections, condition monitoring, critical item replacements, and calibrations. In order to accomplish this, blocks of time are incorporated into the operations schedule. One can easily see that this is the beginning of a proactive mode rather than a reactive one. The purpose of preventive maintenance is to ensure that production quality is maintained and that delivery schedules are met. In addition, a machine that is well cared for will last longer and cause fewer problems.

Current trends in management philosophy such as just-in-time (JIT) and total quality management (TQM) incorporate preventive maintenance as key factors in their success. JIT requires high machine availability, which in turn requires preventive maintenance. Also, TQM requires equipment that is well maintained in order to meet required process capability.

Preventive maintenance is also seen as a measure of management excellence. It requires a long-term commitment, constant monitoring of new technology, a constant assessment of the financial and organizational tradeoffs in contracting out versus in-house maintenance, and an awareness of the impact of the regulatory and legal environment.

Q3. Explain computerized maintenance and Total Productive Maintenance

Total productive maintenance

One of the main objectives of TPM is to increase the productivity of plant and equipment with a modest investment in maintenance. Total quality management (TQM) and total productive maintenance (TPM) are considered as the key operational activities of the quality management system. In order for TPM to be effective, the full support of the total workforce is required. This should result in accomplishing the goal of TPM: "Enhance the volume of the production, employee morale and job satisfaction."[2]

The Eight Pillars

The eight pillars of TPM are mostly focused on proactive and preventative techniques for improving equipment reliability: Autonomous maintenance, Planned Maintenance, Quality Maintenance, Focused Improvement, Early Equipment Management, Training and Education, Safety Health Environment, TPM in Administration. [3]

Implementation of Total Productive Maintenance

Following are the steps involved by the implementation of TPM in an organization: Initial evaluation of TPM level, Introductory Education and Propaganda (IEP) for TPM, formation of TPM committee, development of master plan for TPM implementation, stage by stage training to the employees and stakeholders on all eight pillars of TPM,

implementation preparation process, establishing the TPM policies and goals and development of a road map for TPM implementation.

According to Nicholas,[4] the steering committee should consist of production managers, maintenance managers, and engineering managers. The committee should formulate TPM policies and strategies and give advice. This committee should be led by a top-level executive. Also a TPM program team must rise, this program team has oversight and coordination of implementation activities. As well, it's lacking some crucial activities, like starting with partial implementation. Choose the first target area as a pilot area, this area will demonstrate the TPM concepts.[4] Lessons learned from early target areas/the pilot area can be applied further in the implementation process.

Objectives of Total productive maintenance[edit]

The main objective of TPM is to increase the Overall Equipment Effectiveness of plant equipment. TPM addresses the causes for accelerated deterioration while creating the correct environment between operators and equipment to create ownership.

OEE has three factors which are multiplied to give one measure called OEEPerformance x Availability x Quality = OEE

Each factor has two associated losses making 6 in total , these 6 losses are as follows:

Performance = (1) running at reduced speed - (2) Minor Stops

Availability = (3) Breakdowns - (4) Product changeover

Quality = (5) Startup rejects - (6) Running rejects

The objective finally is to identify then prioritize and eliminate the causes of the losses. This is done by self managing teams that problem solve. Employing consultants to create this culture is common practice

Q4. Explain all types of Non-destructive testing.

Nondestructive testing or Non-destructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage.[1]

The terms Nondestructive examination (NDE), Nondestructive inspection (NDI), and Nondestructive evaluation (NDE) are also commonly used to describe this technology.[2] Because NDT does not permanently alter the article being inspected, it is a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research. Common NDT methods include

ultrasonic, magnetic-particle, liquid penetrant, radiographic, remote visual inspection (RVI) eddy-current testing,[1]

and low coherence interferometry.

NDT is commonly used in forensic engineering, mechanical engineering, electrical engineering, civil engineering, systems engineering, aeronautical engineering, medicine, and art