What is the Meaning of Using the Front and Back of the Washer?

Various washers that always come out when disassembling and maintenance are done. Even if it is out of the question that "some washers were left over" after reassembling, aren't you satisfied with putting washers in the place where they were and assembling them?

The washer has a role to play in the washer. Do you wonder why washers exist in the first place? Don't you think it's okay if I don't? Don't you think?

WebiQ is here to bring you a little happiness and motorcycle knowledge. It is a small story about the direction of the washer that the person who cares about it is concerned about.

Review: What is a washer?

A washer is a disc-shaped component used in various places on a motorcycle to Mainly donut-shaped parts punched out of iron sheets by press machines. Aluminum and copper washers have a role to seal the hydraulic pressure of the brake so that it doesn't leak, but in this case, it is a "washer shaped gasket" and it is different from the role of a general washer, so it is excluded this time.

In addition, there is a washer made of plastic and rubber, but because the story becomes complicated, I will ignore it this time.

This time, it is a story of the washer made of iron that is usually common.

Washer's role and function

There should be a bolt (or nut) where the washer is used. And bolts and nuts are used to fasten parts to parts.

By tightening the screws, the bolts exert a force similar to that of a wedge driven into the threads. A device for applying tremendous force to a bolt shaft. There is also a complicated formula, so if you do a quick calculation, you will see that even with a rather thin screw, the bolt shaft is subjected to a force that lightly exceeds 1 ton.

It is the underside of the head of the bolt that receives such a force, but by rotating the bolt, the axial force increases, so there isWhere there's a lot of pressure.

In addition, the part of "by rotating" is the key. At the end of the tightening process, the bolt must rotate to generate the axial force with a strong force, and the bolt must also rotate to receive the great pressure, so the screw head will be melted into the counterpart of the bolt or the counterpart will be shaved.

This is not good. For example, when you use a torque wrench, it is judged that the torque is reached before the specified torque is applied to the shaft due to the rotational resistance of the screw.

In addition, it is the part under the bolt that continues to receive the axial force after tightening, but if the contact area with the part to be tightened is small, the bolt will gradually melt.

When you say that the bolts are tight, it may seem like they are well tightened, but they are not. The opposite. The more you tighten the screw, the more axial force is lost, so despite appearances, these screws are not tightened as they should be.

What is the role of the washer? Reduce the rotational resistance when the bolt rotates.I'm sure you've heard of it.Increasing the contact area to prevent merricking even when subjected to axial forceIt's called the "Mere Old Man"

I think that it is sometimes explained as "in order to prevent the other side from being scratched by the bolt", but it is not wrong because it becomes so when the meaning of the above is explained very roughly. It's too zany to understand, though.

Method of manufacturing washers

There are two main types of manufacturing methods. Let's start with the most commonManufactured by pressing and punching how to do it.

The board material of the thickness of the washer that wants to be made is prepared, and it makes it by punching out the inner hole and the outer circumference.

Because this method is suitable for the mass production, the washer used in large quantities is usually a press method.

The other kind. Manufactured by cutting How to do it.

The plate material of the thickness of the washer that wants to be made is prepared, and the hole and the circumference of the inside are shaved out with a special machine tool, and it makes it.

The washer of the thickness which cannot be made by the press punching and the precision washer which requires accuracy are the cutting method.

Cross Section of Washer

In fact, basically all washers are not of uniform thickness on all sides. The washer of such a manufacturing method is very rare though only the high-precision cutting washer is the same thickness in any side.

Because the edge of the part pushed from the top inevitably becomes round because of the relation of the manufacturing method that it fits into the mold and punches out in the press manufacturing method that most washers adopt, and because the opposite side that was punched out will be torn off, the burr comes out and it becomes the section which rises.

Washers have a front and back.

Of the washers manufactured by this pressing process, the rounded side is called "front", and the side with burrs is called "back".

The reason why the rounded edge is the front is that the board already has a front and back before it is stamped out, and the front is smooth and the back has a certain finish. Because this slippery surface is made the upper side (that is, the front side), it sets to the press machine, and it punches out, naturally the washer which was punched out becomes the slippery surface up, and because it punches out from the top, the edge becomes round.

Surface

Back side

It's not enough to turn the front of the washer to the front.

The correct answer is to assemble it with the shiny and clean upper side (= front side) visible, that is, the bolt side!　It may seem to be ......, but it is an interesting point of the washer that it is not always so.

of the washer depending on the location and application.The correct orientation varies
It is not enough to assemble everything in a good-looking orientation.

Think carefully about the use

Let's look at the cross section of the washer again here.

Although it is written quite extremely, the washer cross section of the press manufacture is as shown above.

Now, if we recall the role and function of the washer again here, the purpose was to prevent the head of the screw from merging into the material, right?

In this case, the wider the contact area, the more the surface pressure can be dispersed, so you want to use the one with the widest contact area as the side to prevent roll-in.

When the cross section of the washer is seen, the contact area of the rounded side (= the side of the shiny surface) which was punched out from the top has decreased only for the rounded side. The large contact area is on the backside.

Therefore, the contact area of the washer which hits the material can be maximized by turning the front of the washer to the bolt side. In addition, since the bottom of the rotating bolt head will be in contact with a slippery surface, the rotational resistance when tightening the bolt can be reduced.

In other words, if you want to disperse the surface pressure so that the bolt does not melt, it is correct to assemble the washer with the front side (the one with the shiny and rounded edge) facing the bolt side.

However, because the burr of the washer bites into the partner material in this direction, the trace of the burr of the washer remains clearly when the partner is a soft material (such as aluminum).

There is a case that the direction of the washer is assembled in the opposite direction (= the back side of the washer is made the bolt side and assembled).

In other words, if the purpose is to prevent scratches on the screw contact area of the mating side, it is correct to assemble the washer with the back side (the one that is not shiny and has a sharp edge) facing the bolt side.

Depending on the purpose, the direction of the washer will be exactly the opposite

Read the designer's intent as to why the washer is inserted.

I assure you, I'm a manufacturer. There is no washer used in vain. It is always designed with an intention to pinch the washer.

However, no matter how much you look in the service manual or parts list, the direction of the washer is not specified. Because the manufacturer has designed it so that it can be used in either orientation. Because it is assumed that the direction of the washer is not checked every time in the site of the production line, and it assembles it by flow work.

"Then you don't have to worry about the direction of the washer! You might say, "But it's not.

It is true that even if you assemble it without paying attention to the direction, it will not break if the washer is in the specified position. However, as I've written so far, if you build it with the correct orientation, it will improve performance.

You can do what you can't do on a manufacturer's production line because of cost, but you can do if you do your own maintenance.

Tuning is a series of such things. Adjusting the direction of the washer is. Tuning you can do with $0.

So when you assemble the washers. "Why is it necessary to put the washer in this position? and assemble it. If you know the purpose of the washer, you will inevitably know in which direction it is correct to incorporate the washer.

Even if you make a mistake and put it together back to back, it won't break because there is no specification of the direction. Assemble them in the direction that you feel confident and correct.

It's just a washer.

But washers. If you are particular about the front and back of the washer, the performance will not improve immediately. However, if you become aware of the fact that washers have a front and back, you will realize that the same is true for circlips (E-rings and C-rings) that are used for retaining and positioning the shaft.

And the circlip, although the manufacturer doesn't specify the orientation. By using it in the right direction, it will surely work to prevent problems.

The probability that the trouble can be prevented by assembling the circlip and washer in the correct direction may be very small. But anyone who laughs at the slightest difference is not qualified to talk about customization or tuning. It's a take on a line from a certain manga about driving out of control on the bay shore line, but I agree.

Omake: Does the spring washer have any anti-loosening effect?

A spring washer is a washer like the image above.

When a part of the circumference is cut off and the twist is added, and the screw is tightened after this washer is inserted, the twist will be crushed, so it is said that there is a loosening prevention effect because it can put tension on the bolt like a spring.

I'll tell you the right answer right off the bat. >Spring washers have no anti-loosening effect. To be more precise, it would be "it has an anti-loosening effect, but its force is too weak for the tightening axial force of the screw to be meaningful". If you do a search for "spring washers don't work" you'll find a plethora of explanations.

But don't you wonder why spring washers, which are supposed to be ineffective, still exist?

Speculation. Aimed at preventing loosened screws from falling out.

If for some reason the lower part of the screw head floats, e.g. because the seat of the screw has caved in, the axial force is zero. If the screw head is floating, the axial force is zero and the screw could fall out. However, by applying even a small amount of tension to the screw head, the spring washer is able to create a frictional force on the screw thread and prevent it from falling off, even though the original axial force is not generated because it is loose.

In the case of the motorcycle, it is not "I do not want the loose bolt to fall out" but "I do not want the bolt to loosen", so the spring washer is almost never used.

It's not about that. It's about getting the right axial force. It's much more important to handle the screws correctly. And the direction of the washers, of course!