Search Results for Bearing journals

This chapter details the vibration limits for gearboxes. It focuses on critical speed and peak load. The chapter presents vibration measurement and analysis, which provides a quick and relatively inexpensive way to detect and identify mechanical problems before they become more serious and costly.

Gearbox vibrations can often be dealt with in the field by modifying, replacing, and repositioning components and adjusting operating conditions and control parameters. Every gearbox design, however, eventually reaches a point where problems due to vibration are not so easily addressed. This chapter discusses such a case, that of an epicyclic reducer plagued by subsynchronous vibration, and explains how the gearbox was redesigned, improving lifetime as well as efficiency.

This chapter discusses many aspects of extrusion die and tooling, including the terminology and function of extrusion die and tooling, the types of dies, the fundamentals of die design, manufacturing, correction, material, and the surface treatments of die bearings and tribology in extrusion dies. It then presents the fundamentals and function of finite-element modeling simulation. The chapter describes the role of tribology and thermodynamics in the die bearing to control the flow and dimensional stability of extrusion exiting the die.

Induction heat treating is used in a wide range of applications. Typical uses, as described in this chapter, include the surface hardening of many types of shafts as well as gears and sprockets and the through-hardening of gripping teeth, cutting edges, and impact zones incorporated into various types of tools and track pins manufactured for off-highway equipment.

This chapter discusses the effect of friction in the context of design. It explains how friction coefficients are determined and how they are used to make sizing and selection decisions. It covers practical issues associated with rolling friction, the use of lubricants, and the tribology of metal, ceramic, and polymer surfaces in contact. It also discusses the nature of rolling friction and provides helpful design guidelines.

In the case of gearboxes, vibration is the primary mode of failure even at the mid-range of operating speeds. Avoiding such failures requires an understanding of gearbox design, vibration theory, and material properties. This chapter details sources and types of gearbox vibrations; characteristics of gearbox vibrations; fundamentals of periodic vibrations; and vibration theory. It provides housing design for single-stage offset parallel gearboxes, high-speed gearboxes, and epicyclic gearboxes. The chapter then provides an analysis and selection of design factors for vibration reduction. It presents five types of gear tooth geometry errors. The chapter also focuses on gear quality inspection and on bearing-induced vibrations.

This chapter covers the tribological properties of different types of oil, greases, solid lubricants, and metalworking and traction fluids. It explains how lubricants are made, how they work, and how they are applied and tested. It also discusses the fundamentals of lubrication and friction control, the relationship between viscosity and breakaway friction, and the factors that affect load-carrying capacity and service life.

Gaseous ferritic nitrocarburizing, like salt bath nitrocarburizing, involves the introduction of carbon and nitrogen into steel in order to produce a thin layer of iron carbonitride and nitrides, the "white layer" or compound layer, with an underlying diffusion zone containing dissolved nitrogen and iron (or alloy) nitrides. This chapter first presents the development and principles of the process. It then discusses the properties of gaseous ferritic nitrocarburized components. The chapter also presents the applications for the ferritic nitrocarburizing process. It provides an overview of the safety considerations.

This chapter provides a brief review of the scientific and technological developments leading to the widespread use of induction heat treating and its many applications in industry.

Many companies conduct only metallurgical evaluations in the wake of failures, discovering nothing more than the physical mechanism by which the failure occurred. The origin of failures, however, is often complex, involving not only physical mechanisms, but also human behavior and latent factors. Failures may also involve multiple parts, entire machines, or processes of any size and shape. The chapter examines the unique aspects of many failures and explains how they can sometimes be traced to systemic issues. It also covers the reasons why products fail, including improper service or operation, improper maintenance, improper testing, assembly errors, fabrication or manufacturing errors, and design errors. The case of the Tacoma Narrows Bridge collapse is presented to illustrate the consequence of overlooked factors, in this case, wind dynamics, and the importance of identifying root causes to prevent repeat failures.

Induction heating, in most applications, is used to selectively heat only a portion of the workpiece that requires treatment. This chapter covers the basic principles, features, and metallurgical aspects of induction heating. The discussion includes the conditions required for induction heating and quenching, the use of magnetic flux concentrators to improve the efficiency of surface heating, and the quenching systems used for induction hardening. The discussion also provides information on time-temperature dependence in induction heating, workpiece distortion in induction surface hardening, residual stresses after induction surface hardening and finish grinding, and input and output control of steel for induction surface hardening of gears.

This article discusses the composition, properties, and behaviors of copper and its alloys. It begins with an overview of the characteristics, applications, and commercial grades of wrought and cast copper. It then discusses the role of alloying, explaining how zinc, tin, aluminum, silicon, and nickel affect the physical and mechanical properties of coppers and high-copper alloys as well as brasses, bronzes, copper-nickels, and nickel silvers. It also explains how alloying affects electrical conductivity, corrosion resistance, stress-corrosion cracking, and processing characteristics.

This chapter discusses the processes and procedures involved in tribotesting, the significance of test parameters and conditions, and practical considerations including test metrics and measurements and the interpretation of wear damage. It also describes the different types of erosion tests in use and common approaches for adhesive wear and abrasion testing.

This chapter provides information on the biennial International Wear of Materials Conference, which is the inspiration for this book. It reviews the fundamentals of tribology, tribosystems, and related terminology. The glossary at the end of this chapter is intended to familiarize readers with some of the fundamental tribology terms that will be repeated throughout this book.

This chapter discusses the design and operation of electromechanical servo-drive presses. It begins by comparing the operating flexibility of servo-press drives with that of their conventional counterparts. It then explains the difference between direct-drive and belt and screw-driven servo presses and describes some of the innovations and improvements made possible with high-torque servo motors. The chapter provides examples of how servo presses are used in blanking, warm forming, and other applications and compares the operating characteristics of two 1100-ton presses, one driven by servo motors, the other by a mechanical crank.

Molybdenum thermal spray coatings are used in aerospace and other industries for wear resistance applications. Metallographic sample preparation of molybdenum coatings presents unique challenges. The purpose of the investigation described in this article is to determine Accepted Practices for sample preparation to better understand the process related microstructures of thermal spray molybdenum powders. The committee followed a round robin approach to assess metallographic sample preparation by a variety of laboratories. The article summarizes the results of the committee’s work.