A plain washer is used by placing it between a bolt head or nut and the surface being fastened before tightening the bolt.
Here's a more detailed breakdown:
Purpose of a Plain Washer
Before detailing the "how," it's helpful to understand why you'd use a plain washer. They serve several important functions:
- Distribute Load: They spread the clamping force of the bolt or nut over a larger area, preventing damage to the material being fastened.
- Prevent Galling: They act as a sacrificial layer, reducing friction between the bolt/nut and the surface, preventing galling (damage due to friction).
- Provide a Smooth Surface: They offer a smooth, even surface for the bolt/nut to bear against, ensuring a more accurate and consistent torque application.
- Fill Space: In some instances, washers can be used to fill a small gap.
Steps for Using a Plain Washer:
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Identify the Need: Determine if a washer is necessary based on the material being fastened and the desired clamping force. Softer materials generally benefit more from washers.
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Select the Correct Washer: Choose a washer with an appropriate inner diameter (ID) for the bolt size and an outer diameter (OD) suitable for distributing the load effectively. The washer should be made of a material compatible with the bolt and the materials being joined.
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Placement:
- Place the plain washer directly against the surface you are fastening.
- Ensure the washer sits flush against the surface; remove any debris.
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Install the Bolt/Nut:
- Insert the bolt through the washer and the materials being joined.
- If using a nut, place another plain washer between the nut and the material surface if desired (often recommended, especially on softer materials).
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Tighten: Tighten the bolt/nut to the specified torque, just as you would if you weren't using a washer. The washer will distribute the force as you tighten.
Example Scenario:
Imagine you're fastening a piece of sheet metal to a wooden frame using a bolt and nut. The sheet metal is relatively thin and could be easily deformed by the pressure of the bolt head alone.
- You would first place a plain washer against the sheet metal where the bolt will pass through.
- Then, insert the bolt through the washer and the sheet metal into the wooden frame.
- On the other side, place another plain washer against the wood and then thread on the nut.
- As you tighten the nut, the washers will distribute the clamping force, preventing the bolt head and nut from digging into and deforming the sheet metal and wood.
Key Considerations:
- Material Compatibility: Choose a washer material that is compatible with the bolt and the surfaces being joined to prevent corrosion.
- Washer Size: The outer diameter of the washer should be large enough to effectively distribute the load.
- Surface Condition: Ensure the surfaces where the washer will sit are clean and free of debris.
By following these steps, you can effectively utilize a plain washer to improve the strength and longevity of your bolted connections.
