Reliability Considerations for Machine Design

In Reliability Considerations for Machine Design , you'll learn ...

• Design Considerations for Reliability of Mechanical Designs
• Why we need reliability considerations for Machine Design
• Definitions and explanation of Probability and Reliability
• Definition of Failure Modes, Factor of Safety and Related Design aspects

Overview

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Credit: 2 PDH

Length: 33 pages

Machine Designers and manufacturers must have a plan and assessment of their equipment before their products are installed in customers’ workshops for actual production. Sometimes, for special machine tools (SPM), this approach will reduce confusion and bones of contention down the line during actual use. The manufacturer and the customer have to come up with this plan together. For mostly used general-purpose CNC machines, the plan for reliability and maintainability is even more important to gain customer confidence in the products.

In any design, uncertainty arises due to variation of material properties, variation of external loadings on the design, manufacturing variabilities and environmental variabilities. Any design is subjected to such variations during its use. Eventually, machine system behavior and longevity also depend on such variabilities and severity of such variations. Actual conditions could vary from design intent variations. Lack of proper knowledge about the loadings and other variables could lead to design failures. The variations could be due to inherent variation of material properties.

The uncertainties in machine performance could be due to unavoidable variations or could be due to lack of knowledge about the variations. Lack of data could be another problem during design.The performance and longevity of any design could also depend on the assumptions for the design. Nevertheless, system behavior is different from its component behavior. System modelling and analysis depend on the assumptions of component and system assumptions. Reliability design is to reduce the risks caused by uncertainties encountered during design and use of the machines. Hence a reliability plan has to be put in place as described below.

A reliability and maintainability plan will help both users and manufacturers reduce the life-cycle cost for the machine, manage and control equipment failures. This will also help both parties design a preventive maintenance program for the machine to reduce machine tool breakdown time and increase uptime during actual use. Machine availability time will be increased as much as possible to get the return on investment as quickly as possible. This will reduce the investment cost for the customer and increase customer satisfaction.The company has to design a plan for this process and has to devise methods to implement it for the equipment. Such a process also helps the manufacturer and user to satisfy the quality programs, such as ISO 14000. The company should have a quality enhancement program for the equipment, and this plan for reliability and maintainability will help the company to maintain and improve the quality programs.

Such a program should outline the goal and objectives of this process. Establishing such a plan will help the manufacturer establish the product among the customer and as a tool to reduce the life-cycle cost for the equipment. This will also help the company and the user define and assess machine tool reliability, failure patterns and rate of failures, cost of operating the machine, mean time to failure (MTBF) and mean time to repair (MTTR), ease of maintenance, machine tool uptime and downtime, effective cost of machining, etc. This plan and process can also help the manufacturer identify the bathtub curve for the equipment and the root cause of failures, such as manufacturing shortcomings, design weaknesses, etc., for the equipment.

The objective of such a plan is to elongate the time for use and reduce the time for infant mortality or failures due to aging. Another primary objective of this process is to establish a standard for the equipment that the purchasing and quality departments can follow as a guideline to procure the equipment from various manufacturers. This process also helps the company during the procurement process and to keep track of equipment performance for machine life. If the life-cycle cost does not match the predicted values, machine tool designers can also determine the cost of deviation and take steps to improve the design to increase the MTTR and MTBF.

Specific Knowledge or Skill Obtained

This course teaches the following specific knowledge and skills:

• Design Considerations for Reliability of Mechanical Designs
• Why we need reliability considerations for Machine Design
• Definitions and explanation of Probability and Reliability
• Definition of Failure Modes, Factor of Safety and Related Design aspects
• Bath Tub Curve
• Probability Distributions such as Binomial, Normal, Exponential, Poisson, Weibull and their effects on the design of machines
• Reliability Management principles for assemblies and components
• Integration of Design Variables and Reliability for customer satisfaction
• Probability, Risk management and Reliability for mechanical design
• Reliability and Cost for any design
• Examples of Reliability Applications for Mechanical Designs

Certificate of Completion

You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 10 questions. PDH credits are not awarded until the course is completed and quiz is passed.