Search Results for solid-film lubricants

This chapter describes the properties and attributes of various classes of metalworking lubricants, including mineral oils; natural oils, fats, derivatives, and soaps; synthetic fluids (olefins, esters, polyglycols, ionic liquids); compounded lubricants (oils, greases, fats); aqueous lubricants (emulsions, synthetics, solutions); and a wide range of coatings and carriers. It also discusses solid-film lubricants (oxide films, polymer films, layer-lattice compounds) and environmental and safety concerns.

Drawing is a bulk deformation process that involves significant surface generation and high pressures. This chapter provides an overview of the mechanics and tribology of wire, bar, tube, and shape drawing. It presents important equations for calculating stresses, forces, friction, heat, strain, and distortion for different tooling configurations and geometries. It explains how to select and apply lubricants based on drawing speed, die design, and other factors and how to maintain sufficient film thickness for hydrodynamic, mixed, and solid-film lubrication conditions. It also discusses the use of vibrating dies, the influence of surface finish and defects, and lubrication practices for specific materials.

This chapter covers coatings and treatments that are used to improve the friction and wear behaviors of materials. It describes modifications that work by hardening contacting surfaces, including heat treating, vacuum coating, thermal spray, and plating, and those that separate or lubricate surfaces, including solid film, chemical conversion, and vacuum coatings, surface oiling and texturing, and lubricating platings. It compares and contrasts methods based on thickness and depth and their relative effect on friction, erosion, and wear.

This chapter reviews the basic theory of lubrication in the context of metal forming applications. It discusses the rheological properties of fluids and their effect on fluid-film thickness at pressures, temperatures, and loading conditions typical of metal working processes. It describes the three lubrication regimes (boundary, mixed, and hydrodynamic) of a Stribeck curve and the forces that maintain surface separation. It also discusses mixed, elastohydrodynamic, plastohydrodynamic, and solid or semi-solid lubrication, the effects of starvation and frictional instabilities, and the role of elastic deflection and ultrasonic vibration.

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.

This chapter discusses the basic principles of friction and the factors that must be considered when determining its effect on moving bodies in contact. It provides an extensive amount of friction data, including static and kinetic friction coefficients for numerous combinations of engineering materials and coatings. It also describes the causes and effects of the most common forms of wear, the conditions under which they occur, the role of lubrication, and wear testing methods.

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.

This chapter deals with the mechanics and tribology associated with the extrusion of bars, sections, and tubes. It covers direct and indirect extrusion processes in detail and demonstrates the use of important equations, relationships, and measurements for determining pressure, force, material flow, friction, die wear, heat generation, and lubrication requirements. The chapter also provides information on hydrostatic, friction-assisted, and severe plastic deformation extrusion processes, discusses the cause of instabilities and defects, and explains how to select and apply lubricants to minimize friction and die wear when extruding steel, aluminum, copper, and refractory metals.

This chapter reviews the types of friction that are of concern in tribological systems along with their associated causes and effects. It discusses some of the early discoveries that led to the development of friction laws and the understanding that friction is a system effect that can be analyzed based on energy dissipation. It describes the stick-slip behavior observed in wiper blades, the concept of asperities, and the significance of the shape, lay, roughness, and waviness of surfaces in sliding contact. It explains how friction forces are measured and how they are influenced by speed, load, and operating environment. It also covers rolling contact and fluid friction and the effect of lubrication.

Forging is a deformation process achieved through the application of compressive stresses. During the stroke, pressures and velocities are continuously changing and the initial lubricant supply must suffice for the duration of the operation. Lubricant residues and pickup products also change with time, further complicating the analysis of friction and wear. This chapter provides a qualitative and quantitative overview of the mechanics and tribology of forging in all of its forms. It discusses the effects of friction, pressures, forces, and temperature on the deformation and flow of metals in open-die, closed-die, and impression-die forging and in back extrusion and piercing operations. It presents various ways to achieve fluid-film lubrication in upset forging processes and examines the cause of barreling, defect formation, and folding in the upsetting of cylinders, rings, and slabs. It also explains how to evaluate lubricants, friction, and wear under hot, cold, and warm forging conditions and how to extend die life and reduce defects when processing different materials.

This chapter reviews the knowledge of the field of gear tribology and is intended for both gear designers and gear operators. Gear tooth failure modes are discussed with emphasis on lubrication-related failures. The chapter is concerned with gear tooth failures that are influenced by friction, lubrication, and wear. Equations for calculating lubricant film thickness, which determines whether the gears operate in the boundary, elastohydrodynamic, or full-film lubrication range, are given. Also, given is an equation for Blok's flash temperature, which is used for predicting the risk of scuffing. In addition, recommendations for lubricant selection, viscosity, and method of application are discussed. The chapter discusses in greater detail the applications of oil lubricant. Finally, a case history demonstrates how the tribological principles discussed in the chapter can be applied practically to avoid gear failure.

This chapter covers common types of erosion, including droplet, slurry, cavitation, liquid impingement, gas flow, and solid particle erosion, and major types of wear, including abrasive, adhesive, lubricated, rolling, and impact wear. It also covers special cases such as galling, fretting, scuffing, and spalling and introduces the concepts of tribocorrosion and biotribology.

This chapter provides an overview of environmental factors when studying a gear failure. Environmental factors discussed are lubrication, temperature, and mechanical stability.

This chapter covers the mechanics and tribology of sheet metalworking processes, including shearing, bending, spinning, stretching, deep drawing, ironing, and hydroforming. It explains how to determine friction, wear, and lubrication needs based on process forces, temperatures, and strains and the effects of strain hardening on workpiece materials. It presents test methods for evaluating process tribology, describes lubrication and wear control approaches, and discusses the factors, such as surface roughness, lubricant breakdown, and adhesion, that can lead to galling and other forms of wear. It also provides best practices for selecting, evaluating, and applying lubricants for specific materials, including steels, stainless steels, and aluminum and magnesium alloys.

This chapter discusses the factors that must be considered when selecting a lubricant for sheet metal forming operations. It begins with a review of lubrication regimes and friction models. It then describes the selection and use of sheet metal forming lubricants, explaining how they are applied and removed and how their pressure and temperature ranges can be extended by performance enhancing additives. The chapter also explains how sheet metal forming lubricants are evaluated in the laboratory as well as on the production floor and how tribological tests are conducted to simulate stamping, deep drawing, ironing, and blanking operations.

This chapter examines the surface interactions that occur during metal forming operations at both the macroscopic and microscopic scale. It describes the measurement and characterization of surface profiles based on form error, waviness, and roughness. It explains how workpiece surfaces become rougher or smoother due to the effects of deformation, tooling interactions, and lubricant film thickness. It familiarizes readers with the concept of nominal contact, the role of asperities, and the effects of interface pressure, plasticity index, shear stress, and bulk strain rate. It also reviews the two basic friction rules applicable to metal forming and presents advanced friction models that account for the transition between Coulomb and Tresca behavior and the effects of lubrication.

This appendix is a comprehensive collection of selected sources related to corrosion properties of materials and corrosion testing.

This chapter is a detailed account of the general characteristics and effects of and the methods for preventing or reducing different categories of wear failures, namely abrasive (erosive, grinding, and gouging), adhesive, and fretting wear.

This article focuses on friction and wear as they relate to polymeric materials, covering friction and wear applications for polymeric materials. The discussion covers the causes and mechanisms of friction, wear, and lubrication; different test methods developed to simulate friction and wear mechanisms; and friction and wear test data used for polymeric materials.

This chapter provides a practical overview of the tools and techniques used to assess the tribological aspects of metal forming processes. It describes test methods that have been developed to evaluate bulk deformation and sheet metal forming processes along with lubricant rheology, friction forces, and stress and strain distributions. It explains how to measure temperature between tooling and workpiece surfaces as well as surface topography and composition, film thickness, and wear. It also discusses the benefits of reduced-scale and simulation testing and the transfer of results from one process to another.