Design for Reliability (12) & Design for Maintainability (13) Group 6 -Sudarmono -Irwan Setyaji -Pitarsono Yulihartanto -Subur Priyono

Only as a probability that the system or product will run smoothly according to satisfaction in a satisfying manner. Inherent in this definition is the probability or more specifically the systemic operational requirements. 1. The main element of reliability is expressed as a quantitative term as a probabilistic representative. 2. The second element of this reliability is satisfactory performance to meet customer needs. 3. The third element of reliability is the most important because it is a measure of the operational performance of the system without failure DEFINITION AND EXPLANATION OF RELIABILITY

1.Reliability Function/Survival Function (Rt)  Probability that a system (or product) will be successful for at least some specified time t  where F(t) is the probability that the system will fail by time t Measure of Reliability

2.The Failure Rate  The rate at which failures occur in a specified time interval 3. Component Relationships  After defining the basic reliability function and some of the measures associated with system failures, it is appropriate to consider their application in design : Measure of Reliability

Reliability in Life Cycle System - Define reliability requirement - Plan reliability program - Predict reliability - Estimating reliability cost - Eveluate prototype reliability - Recommend change prior mas production - Reliability test and analysis - Corrective action - Reliability improvement study

Requisiteness of Reliability of Product 1.Company Reputation 2.Customer Requirement and Satisfaction 3.Warranty Costs 4.Competitive advantage 5.Increasing Profit

Ways to improve Reliability by design 1.Derating  Set maximum operating conditions lower than inital design values. 2.Redundancy  Critical component are duplicated in parallel to perform the same function 3.Durability  The material selection should resistant to degradation 4.Ease of inspection  Initial damaged should be possible to perform various visual methods 5.Simplicity  Reduces the chances for failure and errors 6.Replacement  Ease of replacement of critical component.

Reliability Analysis Method 1.Failure Mode Effect and Criticality Analyis (FMECA)  Method to identify and investigate potential system (product or process) weaknesses. DESIGN Identify Failure Modes Establish Failure Effect Determine Criticality Improve Design System Overview

Reliability Analysis Method 2.Fault Tree Analysis (FTA)  Top-down deductive failure analysis in which an undesired state of a system is analyzed using logic gate. 3. list as many causes as possible in boxes below the related fault. 1. Select a top level event for analysis 2. Identify faults that could lead to the top level event AND gate OR gate

3. list as many causes as possible in boxes below the related fault 1. Select a top level event for analysis 2. Identify faults that could lead to the top level event AND gate OR gate Reliability Analysis Method 2.Fault Tree Analysis (FTA)  Top-down deductive failure analysis in which an undesired state of a system is analyzed using logic gate.

Reliability Test and Evaluation  Test reliability refers to the degree to which a test is consistent and stable in measuring what it is intended to measure.  Most simply put, a test is reliable if it is consistent within itself and across time.

 The ability of a system to be maintained, whereas maintenance constitutes a series of actions to be taken to restore or retain a system in an effective operational state.  Maintainability  a design-dependent parameter  a result of design  the counterpart of reliability DESIGN FOR MAINTAINABILITY

Maintainability, as characteristic of design, can be expressed in terms of maintenance frequency factors, maintenance labor hours, and maintenance cost Explanation of Maintainability. Maintainability requirements must be specified not only for the prime mission-related elements of a system but for the various elements of logistics and maintenance support infrastructure as well

Maintenance can be broken down into the following categories; 1.Corrective Maintenance 2.Preventive Maintenance Measures of Maintainability. Several additional categories that are often used; 1.Adaptive Maintenance 2.Perfective Maintenance

The Elapsed-Time category includes: 1.Active Corrective and Preventive maintenance 2.Administrative delay time 3.Logistics delay time 4.Total maintenance downtime Maintenance Elapsed-Time Factor. 1. Active Maintenance Time (M): The elapsed time required to perform scheduled (preventive) maintenance and unscheduled (corrective) maintenance. 2. Administrative Delay Time (ADT), refers to that portion of downtime during which maintenance is delayed for reason of an administrative nature.

Maintenance Elapsed-Time Factor. 3. Logistics Delay Time (LDT), LDT refers to that maintenance downtime that is expended as a result of waiting for a spare part to become available, waiting for the availability of an item of test equipment to perform maintenance, waiting for transportation, etc. 4. Maintenance Downtime (MDT) Maintenance downtime constitute the total elapsed time required (when the system is not operational) to repair and restore a system to full operating status, or to retain the system in that condition.

Measures of Maintainability. 1. Maintenance Labor Hour Factors Although elapsed times are extremely important in the performance of maintenance, one must also consider the maintenance labor hours expended in the process. When considering measures of maintainability, it is not only address to MDT, but also necessary to consider the Labor-time element. 2. Maintenance Frequency Factors Maintainability deals with the characteristics in system design pertaining to minimizing the corrective maintenance requirements for the system when it assumes operational status. Maintainability also deals with the characteristics of design that minimize preventive maintenance requirements. Hence, an objective of maintainability is to provide the proper balance between corrective maintenance and preventive maintenance at least overall cost

Measures of Maintainability. 3. Maintenance Cost Factors For many systems/products, maintenance cost constitutes a major segment of total life-cycle cost. Maintainability is directly concerned with the characteristics of system design that will ultimately result in the accomplishment of maintenance at minimum overall cost. Thus, it is essential that total life- cycle cost be considered as a major design parameter. 4. Related Maintenance Factors There are several additional factors that are closely related to and highly dependent on the maintainability measures described, includes various logistic factors. Maintainability is closely related to the area of system support since the results of maintainability directly affect maintenance requirements.

Measures of Maintainability.

Availability And Effectiveness Measures. Availability May be expressed and defined in three ways; 1.Inherent Availability 2.Achieved Availability 3.Operational Availability

Availability And Effectiveness Measures. System Effectiveness (SE), may be defined as “the probability that a system can successfully meet an overall operation demand within a given time when operated under specified condition” or “the ability of a system to do the job for which it was intended.” Cost Effectiveness (CE), relates to the measure of a system in terms of mission fulfillment (system effectiveness) and total life-cycle cost and can be expressed in various ways, depending on the specific mission or system parameters that one wishes to evaluate.

Maintainability in The System Life Cycle  Every system is developed in response to a need or to fulfill some anticipated function.  In essence, maintainability constitute a major factor in determining the usefulness of the system  Maintainability requirements for a system are defined as part of the overall system operational requirements and the maintenance concepts. System Requirements

Maintainability in The System Life Cycle Specific objective may include the following:  Select standardized components and material where possible.  For repairable items, select those that incorporate built-in self-test features.  Select items that can be repaired using common and standard tools and test equipment.  Avoid the selection of short-life components  Incorporate the proper amount of labeling and identification of components in repairable items to aid the technician in completing tasks in an effective and efficient manner. Component Selection and Application

Maintainability in The System Life Cycle Review of the extent to which maintainability is incorporated in system design is accomplished as an inherent part of the process. In accomplishing a maintainability review, a checklist may be developed to facilitate the review process. Some of the example of the question checklists are below;  Have the maintainability quantitative and qualitative requirements for the system been adequately defined and specified?  Are the maintainability requirements compatible with other system requirements? Are they realistic?  Has the proper level of accessibility been provided in the design to allow for the easy accomplishment of repair or item replacement? Are access requirements compatible with the frequency of maintenance? Accessibility for items requiring frequent maintenance should be greater than that for items requiring infrequent maintenance.  etc Design Review and Evaluation

Maintainability Analysis Method Reliability And Maintainability Trade Off Evaluation Maintainability Prediction Reliability-Centered Maintenance (RCM) Level of Repair Analysis (LORA) Maintenance Task Analysis (MTA) Total Productive Maintenance (TPM) Maintainability Analysis Methods

Design Review and Evaluation Reliability And Maintainability Trade Off Evaluation The objective is to compare and select the best configuration in terms of system availability, reliability, and maintainability requirements in the basis of the least cost Maintainability Prediction Involves an early assessment of the maintainability characteristics in system design and is accomplished periodically at different stages in the design process. Maintainability Analysis Methods

Reliability-Centered Maintenance (RCM) A systematic approach to developing a focused, effective, and cost efficient preventive maintenance program and control plan for a system or product. Level of Repair Analysis (LORA) In expanding the maintenance concept to establish criteria for system design, it is necessary to determine whether it is economically feasible to repair certain assemblies or to discard them when failures occur. Maintainability Analysis Methods Design Review and Evaluation

Maintenance Task Analysis (MTA) The MTA is process of evaluating a given system configuration with objectives:  Identify the resources required for sustaining maintenance and support of the system throughout its planned life cycle  Provide an assessment of the configuration relative to the incorporation of maintainability characteristics in design, both in the design of the prime mission-related elements of the system and in the design of the maintenance and support infrastructure. Maintainability Analysis Methods Design Review and Evaluation

Total Productive Maintenance (TPM) Represents an “integrated life-cycle approach to the maintenance and support of a manufacturing plant”. TPM is an approach for improving the overall effectiveness and efficiency of a manufacturing plant. The objectives are to:  Maximize the overall effectiveness of manufacturing equipment and processes.  Establish a life-cycle approach in the accomplishment of preventive maintenance.  Involve all operating departments/groups within a manufacturing plant organization in the planning for and subsequent implementation of a maintenance program.  Involve employees from the plant manager to the workers on the floor.  Initiate a program based on the promotion of maintenance Maintainability Analysis Methods Design Review and Evaluation

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