FASTENating Fastener Facts

Let’s talk about the vast field of fasteners. In a recent chat for USA Manufacturing Hour on Twitter, hosts Jason and Missy Moorefield, coworkers & spouses at Southern Fasteners and Supply a fastener distributor Headquartered in North Carolina, led a discussion on some of the most commonly used fasteners.


Inch Series

The chat began starting with the inch family. Participants discussed some of the designs you can find on the heads of some screws and bolts. The looked at three examples.Picture1 copy 

Ruby Rusine and the Social Success Marketing team said, “Maybe there's something wrong with the one that doesn't have a mark? - just my wild guess.

David Meyer from BizzyWeb said, “I'm going with levels of hardness (grades)”

Brett from FreightPOP said, “This is a good question! I'm not sure!”

Val W from Monofrax LLC said, “IDK. Sorry, but I'm the original clueless.”

Kati McDermith, the Manufacturing Hype Girl said, ‘Strength and grade marks ? I'm afraid I might not do well on this...”

Nigel Packer from Pelatis Online said, “Are they something to do with the grade of steel in the bolt?”

Pavel Stepanov from VirtuDesk said, “This has something to do with the type of screws to use. Not all screws and bolts have the same designs.

Gina Tabasso from Magnet said, “design standards

Hosts, the Moorefields replied, “Not exactly... but you're leaning in the right direction!”

Rebecca Prox said the Digital Marketing Pro said, “ooh, this is going to be one for me to learn something! Doesn't this tell me what kind of tool I need to use?

Hosts, the Moorefields replied, “No, but that would be a REALLY helpful bit of info. Hmm, may have to contact someone about adding that as a marking...”

Julia Gardner from Hourly – Insurance & Payroll said, “Something to do with the grade and material?

Felix P. Nater from Nater Associates said, “Could it be to simplify the industry's approach?

Stepanov added, “It's like a lock and key function. Without the right key, you won't be able to unlock it.

Hosts, the Moorefields said, “The markings can tell us the manufacturer, but we’re not going down that rabbit hole. Instead, we’re going to focus on some other details. These are only 3 of the 9 Grades in a single specification. There are dozens more specs for carbon steels. And don’t get us started on the plethora of specs for stainless, brass, or exotics.”

They continued, “The marks (or lack of) tell us various things about the screw or bolt such as:

  • Grade
  • Hardness
  • Material
  • Strength

The lack of markings means the screw or bolt has a lower strength range and it’s made of low or medium carbon steel.

Three lines spaced 120 degrees apart means the screw or bolt has a medium strength range and it’s made of medium carbon steel that has been quenched and tempered.

Six lines spaced 60 degrees apart means the screw or bolt has a high strength range and it’s made of medium carbon alloy steel that has been quenched and tempered.

While these markings give you this straightforward information, figuring out the Grade is a bit trickier.

Frequently, no mark means it’s a Grade 2 screw or bolt. However, different factors (such as the type of fastener, what it will be used for, and the environment in which it will be used) can impact the identification of the Grade or material. This is a peek into how complex the fastener world can be.

The three radial lines denote it’s a Grate 5 screw or bolt. But guess what… Different factors can impact the identification (told ya fasteners are complex). However, basically 99% of the time, this mark will stand for Grade 5.

Six radial lines indicate this is a Grade 8 screw or bolt. And that’s it! A screw or bolt with this marking will always be a Grade 8. Sometimes the fastener world is simple. But it’s rare.”


Metric Series

The chat then went on to discuss screws and bolts in the metric series. They looked at three examples.Picture2 copy 

Tabasso said, “metric classes, higher the number stronger the material”

Hosts, the Moorefields replied, “You hit the nail on the head... or should we say tightened the screw with the wrench?”

Prox Said, “Higher number = stronger steel, carbon, etc.?”

Hosts, the Moorefields replied, “Whoo-hoo, you got it!”

Rusine said, “Hmmm... Probably the tool you're going to use to tighten them? Or perhaps, the length of the fastener?”

Hosts, the Moorefields responded, “Nope. I'll give you "hint" ... it's just like the inch series”

Val said, “Size, maybe, possibly?”

Chris Giglio from Zero Surge said,“My simple brain would guess something to do with size, but I'm probably way off.”

Hosts, the Moorefields, said, “You'd think it would be something simple like that. But the fastener gods said "NOPE."”

Packer said, “Are these the grade markings on metric bolts?”

Hosts, the Moorefields said, “These are only 3 of 10 Classes in 1 specification. While inch Grades are sometimes “gray” in identification, metric Classes are clear & concise. The metric specifications for different Classes are also concise, with only 4 specs covering the vast majority.”

They Continued, “Just like in the inch category, the markings in the metric series tell you the exact same information. One small change – while the inch groupings are called Grades, the metric groupings are called Classes.

While some of the markings in the inch series can be classified into different Grades due to surrounding factors, the markings on metric screws and bolts are absolute. The markings can only be identified as one Class. Yay for simplicity!

Each of the Classes depicted here have a comparable Grade in the inch universe.

  • Class 4.6 is comparable to Grade 2
  • Class 8.8 is comparable to Grade 5
  • Class 10.9 is comparable to Grade 8

Not all of the metric Classes have an inch Grade twin”


Screws and Bolts

Next, participants shared the different types of screws and bolts that they knew.

Gardener said, “I'm going to wait for you to give me the nuts and bolts on this one”

Val replied, “Good one!”

Tabasso said, “hex bolts, sheet metal screws, drywall screws, wood screws, eye bolts are all I remember. Gotta ditch now to a client meeting. This one precision machines custom plastic components for the medical device, industrial, aerospace, electronics, power, etc. industries”

Rusine said, “Got some- woodscrews, Philips round. The most familiar ones for me.”

Val said, “0. People who work in hardware stores do not like me.”

Prox said, “Screws- Phillips, flathead, hex, double-hex, torx... Bolts - anchor, flange, eye, carriage... I better not show my answers to my husband. He has taught me more than I remember.”

Packer said, “Here is a starter for 10... Carriage bolts Decking screws Double ended screws Drywall screws Eye bolt screws Framing screws Fillister head screws Hex cap screws Hammer drive screws Lag screws Machine screws Masonry screws Oval head screws Pan-head screws Particle board screws Square head bolts Self-drilling screws Set screws Sheet metal screws Socket-head screws Thread cutting screws Washer-faced screws Wood screws Tamper-proof screw”

Rusine replied, “That's a very looooong list, Nigel!”

Giglio said, “Well I definitely know flat head and Phillips head screws by name, but that's pretty much it.”

Hosts, the Moorefields said, “If you think Grades & Classes can be overwhelming…combine those with the myriad of specifications for the different types of bolts and screws and the variations are literally endless. Didn’t we say this was a vast area?”

They continued, “If we were to list all the varieties of screws and bolts, you’d need to get a snack and clear your calendar for the rest of the day. We’ll settle with just listing a few. “

  • Hex Head Screw
  • Deck Screw
  • Tek Screw
  • Eye Bolt
  • U Bolt
  • Wood Screw
  • Carriage Bolt
  • J Bolt
  • Hex Head Bolt



The chat then shared if they knew what the nuts in the picture are called. They also shared any other types they could think of.Picture4 copy 

Prox said, “Sadly, I cannot name any of them. I just call them all "bolts."”

Tabasso said, “Hex nut”

Hosts, the Moorefields said, “Yes, ma'am! That is one type of nut (and that's what's in the picture).”

Austin said, “I do not know. I'll wait for the smart people to answer this questions”

Rusine said, “The only nuts I know are peanuts, walnuts, hazelnuts, and coconuts... just kidding... I know this is a nut that locks in the fastener... no idea about its name.”

Giglio said, ‘What is a hex nut!”

Packer said, “These are a few... Coupling nuts Flange nuts Hexagonal/ hex nuts Lock nuts Slotted nuts Castle nuts Square nuts Wheel nuts Cap Nut Capstan Nut Knurled Nut Wing Nut”

Nater said, “Coupling nuts Flange nuts Hexagonal/ hex nuts Lock nuts Slotted nuts Castle nuts Square nuts Wheel nuts Cap Nut Capstan Nut Knurled Nut Wing Nut Routinely Nuts

Hosts, the Moorefields said, “While all nuts have the same purpose - of mating with a bolt or screw to hold something together - each of the different types are used for specific reasons. Here are some of the more commonly used nuts

They continued, “While all nuts have the same purpose – of mating with a bolt or screw to hold something together – each of the different types are used for specific reasons."

Here are some of the more commonly used nuts:”

  • Hex (also called a finished hex or standard hex). This is the type pictured in Q3.
  • Heavy Hex (it’s hard to see here but it is thicker than a standard hex)
  • Jam (thinner than the above hex huts)
  • Square
  • Flange
  • Nylon Lock
  • Wing
  • Acorn (also called cap)



Participants then shared what they thought this type of washer is, and they shared any additional types they know of.Picture5 copy 

Prox said, “Oh dear. That's a big NOPE. They're all washers to me.”

Hosts, The Moorefields replied, “HAHA! Trust me, Missy's got the same frame of mind. Jason's the one shaking his head.”

Austin said, “I'm guessing not.”

Rusine said, “I'm tempted to say dishwasher- but no...”

Gardener said, “There's a washer/dryer in the basement of my apartment... (tell us!)”

Packer said, “Some of the types of washers. Spring washer Belleville or conical washer Dome spring washer Wave spring washer Finger spring washer Crescent spring washer Lock washer Split lock washer External tooth lock washer Internal tooth lock washer Plain washer Torque washer Flat washer Fender washer Finishing or Countersunk washer Shoulder washer C-washer”

Hosts, the Moorefield replied, “Someone study for the exam! Mr. Nigel, you are on fire today.”

Hosts, the Moorefields said, “Again, variations abound. Just like with nuts, washers are also chosen with the same criteria in mind.”

They continued, “Washers can be used for a few different functions. Originally flat washers were designed to distribute the load a bolt/screw and nut assembly can put onto a surface during the tightening process. As time went on, variations of washers were created for additional purposes.

Here are some of the more commonly used washers:”

  • Flat (washers under this heading can be broken down into subcategories)
  • Fender (this is the type pictured in Q4)
  • Lock
  • High Collar Lock
  • External Lock
  • Internal Lock
  • Square





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