Large OD Flat Washer

Xiaoguo Inventory® Large OD Flat Washer has a smooth surface without burrs, fits tightly, and can be used in conjunction with sealing components to enhance dust-proof, oil-release, and water-proof performance.

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Product Description

The Large OD Flat Washer and the Standard Flat Washer have significant differences in appearance, functions, and applicable scenarios.

Project	Standard Flat Washer	Large OD Flat Washer
Inner diameter	6.4mm	6.4mm
Outer diameter	12mm	18mm
Thickness	1.6mm	1.6mm
Contact area	1 times	2.25 times
Distributing pressure	Generally, suitable for hard surfaces such as metals	Excellent, can effectively protect soft materials
Cost of raw materials	Low	Higher (larger in area)
Unit weight	Light	Heavier (same specification)

Size Comparison (Taking M6 as an Example)

Large OD Flat Washer

Usage steps

The usage method of the Large OD Flat Washer is not complicated, but following the correct operation sequence can ensure the best protective effect.

(1) Make sure the specs match

Check the bolt size – the Large OD Flat Washer's inner hole should be just a bit larger than the bolt's outer diameter.

Also check that the washer's outer diameter is big enough to fully cover the holes in the part you're fastening. If the hole is a long slot or has been worn out, the washer's outer edge needs to overlap the hole by at least 5 mm.

Think about the material and where it's going. For outdoor spots that are damp, near the ocean, or in chemical areas, go with 316 stainless steel. For general indoor use, 304 stainless or galvanized carbon steel will work fine.

(2) Clean the contact surface

Wipe off any oil, rust, paint chips, or sawdust from the area where you're working. Also make sure both sides of the washer are clean. If there's any rust-preventive oil on it, just wipe it off gently with a cloth.

Large OD Flat Washer

Mon	φ 16	φ 18	φ20	φ22	φ24	φ27	φ30	φ33	φ36	φ39	φ42
d max	17.27	19.33	21.33	23.33	25.33	28.33	31.39	34.62	37.62	42.62	45.62
d min	17	19	21	23	25	28	31	34	37	42	45
dc max	30	34	37	39	44	50	56	60	66	72	78
dec min	29.48	33.38	36.38	38.38	43.38	49.38	55.26	58.8	64.8	70.8	76.8
h max	3.3	3.3	3.3	3.3	4.3	4.3	4.3	5.6	5.6	6.6	9
h min	2.7	2.7	2.7	2.7	3.7	3.7	3.7	4.4	4.4	5.4	7

(3) Place the washer

Installation Location:Place a large-outer-diameter flat washer between the bolt head and the part to be secured.If soft materials such as wood, plastic, or thin aluminum are used,It is recommended to use large-outer-diameter washers on both the bolt head and the nut side.

Center Installation:Ensure that the bolt or nut passes through the center hole of the washer.Ensure the washer sits flush against the workpiece surface—it must not be tilted.

(4) Insert the bolt and hand‑tighten

Tighten the bolts or nuts by hand,Until the washer just touches the surface;Then adjust the position of the washer,Ensure it completely covers the hole.

(5) Tighten to the recommended torque

Correct Use of a Torque Wrench:Select the appropriate torque value and tighten gradually.During the operation, observe the washer carefully and make adjustments as necessary.

(6) Final check

Take a look at the Large OD Flat Washer to make sure it's sitting flat and properly in place.