Certain things like bikes, cars, and furniture use hexagonal bolts for fastening. Hex bolts can only be used with the right diameter key and they don’t slip like Phillips and Flatheads. Also, the hexagonal tip keeps bolts from falling so you don’t need a magnet to hold your fasteners. Furthermore, it’s easy to identify which Allen key you need for each fastener, and you can use ballpoint hex keys if you need to work at an angle.
Since the hex bolt design is so practical, why don’t we use this type of fastener for everything? Why don’t we see hex wood screws and hex drywall screws ?
Edit : I’m asking about fasteners in general (like screws, bolts, etc)
In: Engineering
Different screw heads are designed for different reasons, it’s not arbitrary. This article gives a decent rundown on the different styles and their uses.
https://www.maxavegroup.com/types-of-screws/
Although they are better than Phillips, hex cap screws 100% can strip out even with the right size. This is usually due to cheap metal and being over tightened though.
Different screw are used with different intentions generally speaking…. You want the right tool for the right application.
Mostly it a engineering thing to prevent over torque or enable a degree of precision balanced against cost of manufacturing.
drywall screws. always Phillips. cheap to produce and its design enables the screw to automatically detach from the screw head once it reaches a certain depth. a highly desirable feature with drywall installation. even if you dont have a depth gauge dealio when you are driving Phillips screws, the nature of the causes fhe bit to pop out of the screw at certain torque ranges.
torx heads are very good at precision adjustment and also very good at resisting stripping. These are frequently used in applications where a specific inch lbs torque spec is required. Electronics, Rifle Scopes are common applications for torx heads. the are expensive to produce and use in manufacturing though so unless you NEED those traits, you dont use those when designing a product
Its really dependent on the anatomy of the fastener, its deeper than the head of the screw itself.
Screws have a shaft diameter, strength grade, head diameter, and head type. a designer typically has a tensile strength that the fastener, the screw, needs to accomplish and the designer can get this by manipulating the above parameters.
Another important thing to bring up is who is servicing the equipment. Most times, if its to be serviced by an end user at home, they’d use a philip/flat head since those tools are more likely go be at ur house.
Almost everything in life comes down to cost.
If company orders ten million Phillips head screws to make their product and it costs 100,000 dollars. A hex key bolt may be a few Penny’s more each which can average to tens of thousands of hundreds of thousands .
I’ll add why use hex when torx is superior to hex and normal screws like Philips.
Hex took over because idiots use power tools. Build at home kits come with hex and an Allen wrench because when they came with Phillips or flat head idiots would use drills at full power and destroy threads or jam screws way to deep.
Wrong question (because hex heads aren’t really that great). The eternal question is why Robertson (square) heads are relatively uncommon (although becoming more common) in the U.S.
Once you get to bigger bolts which require more torque to get tight, then allen bolts become very easy to round off. traditional bolt heads are a much better design. But hex bolts are great for low torque applications, like you said they are usually seen on bicycles.
In Industrial settings we pretty much do, Phillips and Flat heads are solely for inside electrical panels where I work at
Hex bolts fill with dirt and rust. If it’s a bolt that takes a socket or wrench, a wire brush can be used to clean them well enough to fit a socket to it.
It’s much more difficult to clean rust or mud out of a hex bolt.
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