Screw Sizing and Strength: How to Pick the Right Screw

Screws are multi-purpose components that hold things up and keep them together. While their tasks are similar in most cases, they are used for a number of different materials across a multitude of industries.

But how do you know which type of screw is right for your project? With a number of different materials to choose from, as well as length and thread sizes, it’s hard to figure out which one best fits your needs.

One of the hardest questions to answer is the size of the screw that’s needed. During assembly, you do not want to use a screw that is too large, nor do you want one that is too small. And while some screw specifications may seem second nature, the sizing and strength of a screw is much more complicated than it may appear.

While choosing a screw based on the weight that the screw needs to hold seems simple, it is not the case. Screw size doesn’t necessarily determine strength. Finely threaded screws are actually much stronger. In fact, a 1/4 UNF thread is roughly 14% stronger than a UNC thread, even if the screws are the same size.

If you need a screw to hold 100 lbs of force, then it’s easy to simply reach for screws that say “100 lbs” right on the package. But how much tension will it handle just during installation alone? Screws that are able to handle 100 lbs are recommended to be tightened to 80 lbs of tension, so how much weight will it be able to hold before it yields?

It comes down to physics. If the majority of the screw strength is used to hold the screw in place, then why would you trust that the screw is able to hold the entire specified load? Undersized screws could compromise the structure.

Conversely, when it comes to micro screws or smaller loads, it doesn’t make sense to overestimate the load and rely on a large, heavy duty screw. Everyday items like eyeglasses and laptops rely on custom screws and micro fasteners to hold the parts in place, but a larger, high weight-capacity screw can also compromise the construction of these items.

When it comes to purchasing screws, it’s best to contact a custom screw manufacturer to commission screws for your exact specifications.

U.S. Micro Screw provides both custom fasteners and micro screws for any and all industries where tiny screws are needed. Order some of our available products or have us build you a custom set of micro screws to meet your specific qualifications.

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