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ما هى أنواع الشحوم والزيوت المستخدمة فى الصناعة

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  1. [1]
    ahmedbayomy
    ahmedbayomy غير متواجد حالياً

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    ما هى أنواع الشحوم والزيوت المستخدمة فى الصناعة


  2. [2]
    nicetalk
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    Types of Lubricants
    It’s important to make yourself familiar with the various kinds of lubricants, so , that you can recognize them and use the correct type for each application. In some applications, using the wrong type of lubricant will quickly destroy the machinery. The two major groups of lubricants are oils and greases.
    Oils
    Oils are fluid lubricants and are classified according to source:
    Mineral oils are refined from crude petroleum - the sort that is extracted from underground oil fields. They are still the most common type and are produced for a wide range of applications.
    Biodegradable oils are made from vegetable sources like castor oil and rapeseed oil, or from synthetic 'esters' (an ester is a kind of organic chemical). They are used when there could be a danger to the environment - for instance the water supply .
    Synthetic oils are manufactured by chemical processes. Examples are polyalkylene glycols, poly-alpha-olefins and silicones. Their use is growing, because synthetic oils can have unusual properties. For instance, they can function in extremes of temperature with no appreciable change in their normal lubricating properties.
    Oils are described as light or heavy, according to how easily they flow.



    Greases
    Greases are usually made by combining an oil with a thickener. The oil provides the lubricating film, while the thickener holds the oil in place and keeps it from flowing away from parts that need lubrication. The most common thickeners are soaps of various kinds. Clays and other non-soap thickeners are also sometimes used. Greases are described as soft or hard, according to how stiff they are.
    1.3 Other types of lubricants
    There are three other groups of lubricant, all of them less common than oils and greases ..
    Solid lubricants are made from minerals such as mica~ talc, graphite, and soapstone. They are characterized by a plate-like structure right down to microscopic level. These lubricants work because the plates slide easily over each other when subjected to shear stress at an angle. Solid lubricants can be used alone or mixed with fluid lubricants or greases. They are frequently used in the machine-tool industry.
    Fire-resistant oils are used in situations such as foundries, coal mines and steel works where combustible materials (including most ordinary oils) would cause a hazard. The water glycols and invert emulsions are examples of fire-resistant oils.
    Dry, spray-on lubricants are used in some applications.






    1.4 Types of lubrication
    Lubricants work by creating special conditions between the surfaces in contact. There are three main types of lubricant film conditions that can exist.

    a) Boundary Lubrication
    In this condition, a thin layer of lubricant is present, but significant metal-to-metal contact still exists. Hence part of the load is taken by the lubricant but most is still taken by the surface high spots. This condition, when used to combat heavy loading, is known as extreme pressure lubrication.

    b) Mixed-film lubrication
    This is an intermediate condition between boundary and full-film lubrication in which the lubricant layer is thicker than the boundary lubrication but some metal-to-metal contact still exists.

    c) Full-film lubrication
    This is the condition in which the moving surfaces are completely separated by lubricant film. This can occur in two different ways:

    Hydrostatic:
    When the lubricant is supplied under pressure from an outside source, e.g. a pump or gravity feed.

    Hydrodynamic:
    In which the pressure develops due to the resistance of the lubricant itself. This is the type of lubrication that occurs in a plain bearing and can best be understood by examining how the lubricant film is formed in that situation. Fig.(1.2) shows the stages involved. While at rest the journal sits on the bottom of the bearing, fig.(1.2-a), on start-up it climbs up the side of the bearing and establishes a lubricant film which, as it develops, forces the journal over to the other side of the bearing where it rides on a wedge of lubricant, fig.(1.2-b). As the lubricant is drawn into the wedge by the action of the journal, it is compressed, and the pressure developed keeps the metal surfaces apart.

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  3. [3]
    محمد وصيف الشناوى
    محمد وصيف الشناوى غير متواجد حالياً
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    شكرا يا اخى ولكنى اريد اسماء الشركات والبدائل لها

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  4. [4]
    محمد علي مكي
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    السلام عليكم اخي العزيز واليك نبده عن اهميه الزيوت والشحوم
    تستدعي الحمولات الكبيره المطبقه على مختلف القطع الاساسيه في المحركات ضروره تامين وصول الزيت الى اماكن الاحتكاك حيت ان وجود هده الطبقه الزيتيه تودي الى خفض قيمه الاستطاعات في التغلب علىمقومات الاحتكاك كما ان الزيت يقلل من التاكل ويحمي المحركات وصناديق التروس هدا علاوه على المهمه الاساسيه للزيت فانه يقوم بسحب قسط من الحراره المتولده نتيجيه لاحتكاك السطوح المتلامسه ويستفاد من الزيت كجسم وسيط في بعض اجهزه التحكم وهناك عده شركات تنتج عده انواع من الزيوت المختلفه على سبيل المتال ( caltex&sheil&BP&agip&castrol&mobil oil &texaco)

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  5. [5]
    محمد علي مكي
    محمد علي مكي غير متواجد حالياً
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    زيوت التنظيف والعزل

    زيوت التنظيف والعزل

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    الملفات المرفقة

  6. [6]
    إلى فلسطين
    إلى فلسطين غير متواجد حالياً
    عضو فعال
    الصورة الرمزية إلى فلسطين


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    مشكور الاخ محمد علي مكي

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  7. [7]
    وائل عبده
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    عضو متميز


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    جزيت خيرا و اكلت طيرا و تزوجت بكرا

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  8. [8]
    AHMAD-1976
    AHMAD-1976 غير متواجد حالياً
    عضو فعال جداً


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    مشكور الاخ محمد علي مكي مشكور معلومات مهمة

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  9. [9]
    ياسر بركة
    ياسر بركة غير متواجد حالياً
    جديد


    تاريخ التسجيل: Jul 2007
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    جزاك الله خير الجزاء

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  10. [10]
    fadi kabes
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    عضو فعال جداً


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    مشكورين جدا

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    أجمل هندسة في العالم مد جسر الأمل فوق بحر من اليأس

  
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