This section provides an overview for small truss head screws as well as their applications and principles. Also, please take a look at the list of 10 small truss head screw manufacturers and their company rankings.
A small truss head screw has a round screw head with a larger diameter than that of a pan head screw.
Since the installation surface is wider than that of a pan head screw, it is more difficult for the seating surface to cave in and loosen than a pan head screw, thus enabling stable fastening. The tip is flat, not drilled like a tapping screw, because it is used where a female screw is cut.
Because of their appearance, they are often selected and used from a design standpoint, similar to pan head screws. On the other hand, the screw stands out because of its large head.
When screwed in place, the seat does not easily sink into the material and can be securely fastened, so they are often used for fastening wooden members and for fastening large members. Like round countersunk screws, they are often selected for design reasons.
While the head is not as tall as that of the countersunk screw, it does not require counterboring, and the screw's large seating surface allows for more secure fastening, it also has the drawback of being conspicuous depending on the location where it is used.
Compared to the pan head screw, this male screw has a lower height and a screw head that looks like it has been cut out of a sphere. It is used where a female screw is cut out.
The diameter of the screw head is larger than that of a pan head screw or small truss head screws of the same screw nominal size.
The product package will indicate the nominal size, material of the screw, and whether it is plated or not. The materials are mainly stainless steel, but also iron and brass, etc. Nickel-plated or black oxide coated screw threads are also available. Screw threads are plus, plus-minus, TRX, etc.
Features of these screws are that they are more stable when tightened because of their larger seating surface.
Since they do not sink easily when fastened, they are useful for fastening wood members.
The main materials used for small truss head screws are steel, stainless steel, aluminum, titanium, and brass. As described in the section on proper usage, since they are related to strength, they should be thoroughly considered, especially when designing equipment where human lives are at stake.
Electrical corrosion is also an important factor. If the material of the small truss head screws differs from the material of the mating mechanical element or the object to be fixed, a difference in metal potential may result in corrosion. Particular attention should be paid to aluminum and stainless steel.
Surface treatments for small truss head screws include:
Select according to the corrosion countermeasure by electric corrosion mentioned above, appearance quality, and price.
If small truss head screws are not used properly, the nut on the mating side may be damaged, or the product or equipment assembled with the small truss head screws may be damaged.
To prevent this, the basic approach is as follows:
Even if small truss head screws are used properly, if they gradually loosen, the object to be fastened may become dislodged, which may lead to a serious accident involving human life depending on the object to be fastened. Therefore, when they have to be used in such locations, great care should be taken.
Loosening can be caused by the following two factors:
Tightening small truss head screws strongly is effective in preventing loosening, but it can also cause the small truss head screws to break or destroy the threaded hole. Especially when designing equipment that involves human life, it is necessary to calculate the allowable range of tightening force as described in the section on the proper use of small truss head screws.
When retightening screws in purchased products, if there is already a defined tightening force regulation, it is sufficient to tighten the screws accordingly.
Other methods to prevent loosening include using an anti-loosening adhesive, double nuts, spring washers built-in type, or other products designed specifically to prevent loosening.
Since the principle of a non-loosening mechanism is friction, it is actually difficult to guarantee that it will never loosen. Sufficient testing is also something to consider.
*Including some distributors, etc.
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