Bicycle Helmet  Possible Materials We will only introduce the most common materials that are presently used for these applications. The bicycle wheel, frame, and components materials to be considered are Steel alloys, Aluminum alloys, Titanium alloys, and Composites. Possible Materials  The Helmet materials lie in a separate material category:
Lubricating Oils Based On Synthetic Hydrocarbon Oils Synthetic hydrocarbons are similar to mineral hydrocarbons in their chemical structure.
They have nearly identical properties relating to their compatibility with sealing materials, disposal, reprocessing and miscibility with mineral oils. The main advantage is their excellent low temperature behavior.
It is possible to manufacture food-grade lubricants for the food processing and pharmaceutical industries with SHC base oils using special additives. Lubricating Oils Based On Polyglycols These lubricants ensure especially low friction coefficients, which makes them suitable for gears with a high sliding percentage worm and hypoid gears.
In gear systems, higher polarity polyglycols allow greater interaction on the metal gear surface. This gives polyglycols mild extreme pressure performance even without additives. Polyglycol oils may Material selection in gear a negative impact on sealing materials and may dissolve some paints.
Before using PAG oils in production applications, it is advisable to test compatibility with paints, seals and sight glass materials. Miscibility with mineral oils is limited; mixtures should therefore be avoided.
Polyglycols are neutral toward ferrous metals and almost all nonferrous metals. If the application has a loaded contact with one component consisting of aluminum or aluminum alloys rolling bearing cages containing aluminumthere may be increased wear under dynamic load sliding movement and high load.
In such cases, compatibility tests should be conducted. If a worm gear is made of an aluminum bronze alloy, polyglycols should not be used because the reaction in the load zone could result in increased wear. Lubricating Oils Based On Ester Oils Ester oils are the result of a reaction of acids and alcohols with water splitting off.
There are many types of esters, all of them having an impact on the chemical and physical properties of lubricants. In the past, these lubricating oils were mainly used in aviation technology for the lubrication of aircraft engines and gas turbines as well as gear systems in pumps, starters, etc.
Ester oils have a high thermal resistance and excellent low temperature behavior. In industrial applications, rapidly biodegradable ester oils will gain importance because it seems possible to achieve the same efficiency as with polyglycol oils by selecting an appropriate ester base oil.
Certain ester oils may exhibit low hydrolytic stability. Hydrolysis is the cleavage of the ester into an alcohol and an acid in the presence of water.
Ester lubricants need to be hydrolytically stable because they are often exposed to humidity in use. In practice, hydrolysis may be a less serious problem than commonly reported. The hydrolytic stability of an ester depends on: It may be up to 30 percent lower than if a regular mineral gear oil with EP additives was used.
The efficiency of gears with a high sliding percentage, worm and hypoid gears, for instance, may increase up to 15 percent if a synthetic oil is used instead of a mineral oil. Even in the case of spur, helical and bevel gears which have a naturally high gear efficiencyit is possible to increase gear efficiency of up to one percent by using a synthetic gear oil.
This may not seem like much at first, but it may result in considerable cost savings depending on the nominal output of the gear unit, especially in the case where several gears are deployed.Selection of Gear Materials.
Presented By: Ric (Mr. if your nasty) Jackson Peter Cannon. Introduction. Selection Factors BHN and Carbon Content Typical Applications Conclusion. Strength Durability Toughness. Wear resistance Finish Fatigue. Selection Factors. What Are the Materials Used for Spur Gears? A spur gear is the most basic type of gear available.
It consists of nothing more than a cylinder or disk with radially projecting teeth aligned parallel to the rotational axis.
Because they are used often, spur gears must be built of materials, like plastics and metals, that are easily. Scribd is the world's largest social reading and publishing site.
Material selection is the key issue in optimal design of any manufactured product. Nowadays, many materials are being replaced by newer materials in order to meet the demands of cost reduction and better performance.
Selecting gear materials for different machining operations is a relatively common and difficult task due to the presence of . Materials. Worm gear sets are usually used to reduce speed and increase torque. Since the worm drive undergoes more contact stress cycles than the worm gear, the worm drive is usually of a stronger material.
This criteria of gear selection is used in countries which have adopted the metric system and is intended to standardize gear selection. GEAR MATERIAL SELECTION MODELS Optimal design of gears requires the consideration of the two type parameters: Material and geometrical parameters.
The choice of stronger material parameters may allow the choice of finer geometrical parameters and vice versa.