Rubber density Testing Standard

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Types of Bridge Bearing

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Types of bridge bearing  1. Elastomeric Bearing a.Plain elastomer pads b.Laminated Elastomeric bearings 2.Sliding bearing Mechanism a. PTFE  sliding material b.Alternative sliding material 3.High load multi Rotational building: a.Pot bearing b.Disc bearing c.Spherical bearings 4. Fabricated steel mechanical bearing a.Rocker bearing b.Rocker cum rolling bearing Elastomeric Bearing: It consists of elastomer manufactured from synthetic or natural rubber and can take both translation and rotation movements through elastomer deformation. The ability of elastomer to carry large vertical loads is because of reinforcement provision that prevents lateral bulging of elastomer. There are number of elastomeric bearing pads classified based on types of reinforcements used. For example, steel reinforced, plain, fiberglass reinforced and cotton duck reinforced elastomeric bearing pads Strength and response of each type is different, steel reinf...
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Calendering

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Introduction: Calendering is the process of making thin sheet of rubber and also lamination of such sheet on to other substrate like fabric,cord warp sheet by passing through set if rollers under controlled Conditions. A calendar comprises of a number of rows or bowls held in frame. Rolls rotate in opposite directions either with even speed or with a friction ratio. Types Of Rubber material used Elastomers that can be used include: ·          Neoprene ·          SBR ·          Natural ·          Hypalon ·          Urethane ·          EPDM          Viton           Fluroelastomer         Butyl          Nitrile ...
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Shrinkage rate Calculation

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I n Moulding process the rubber is Cured at high temperature and Pressure, the resulting Moulded parts are smaller in size than the actual. The Difference in the thermal expansion of the mold material result in shrink rate Shrink Rate= ( Cavity dimension- Part Length)/ Cavity dimension) (Typical units in/in) This shrinkage value is applied to the desired finished part size to “scale up” the cavity. The resulting cavity dimension is calculated as: Cavity Dimension= finished part length/ (1- Shrink rate) For example: Shrinkage rate testing was performed on a 70 Shore A Nitrile (Buna-N), Ethylene-Propylene (EP), Fluorosilicone (FVMQ), and 75 Shore A Fluorocarbon (FKM).  The Fluorosilicone and Fluorocarbon materials undergo a secondary vulcanization process called post-curing. During the post-curing process, the molded parts were baked in a ventilated oven at a specific time and temperature recommended by the material manufacturer, or at a temperature g...
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