What is a button head bolt​?

A button head bolt is a fastener with a low, rounded dome head and an internal hex socket, driven with a hex key instead of a wrench. I use the term for screws built to ISO 7380, where the wide, smooth head sits on top of the part and leaves no sharp corners. At Wisdom Titanium, we make this fastener from Titanium Grade 5 (Ti-6Al-4V) in sizes M3 to M24. The design suits tight spaces, visible surfaces, and weight-sensitive builds. In this guide, I explain the dimensions, material, strength, uses, and buying steps so you can choose with confidence.

Button Head Bolt Design, Dimensions, and Thread Options

What a Button Head Bolt Looks Like and How It Works

The bearing face of the head is flat, and the middle of the head is shaped like a hexagon. It seems like a flat dome. The round, low dome keeps clothes, skin, and cables from getting caught, and it makes the space that's out in the open look clean. The wide head of this button bolt spreads the clamp load over a larger area than a socket head cap screw with the same thread size. This helps with things that are soft or thin. Sometimes the term "button head bolt" is used in a broad way, so I always tell buyers to look at the drawing to see what the standard is. The standard head size for each thread size is given in ISO 7380-1. The following table shows the theoretical numbers for five common sizes in millimeters:

You can draw on these and compare them to your image. For M3 to M16, you can use ISO 7380-1. Send us a picture of your head for sizes M24 and up, and we'll take a look.

Size Chart for Common Sizes

ISO 7380-1 lists standard head dimensions for each thread size. The table below shows nominal values in millimeters for five popular sizes.

Treat these as reference values and confirm them against your drawing. ISO 7380-1 covers M3 to M16. For sizes above M16, up to M24, send us your head dimensions and we will review them.

Thread Types, Length, and Finish

You can get threads in metric, UNC, UNF, and special sizes from us. Make sure you check the diameter and pitch before you order because you can't mix metric and inch threads. An M6 x 1.0 button head bolt won't fit in a 1/4-20 UNC hole, even though the holes look like they should. The length goes from under the head to the tip because the dome doesn't sit in a countersink. Add up the thickness of the parts that will be fixed, any washers, and the amount of thread contact you need. Then choose the next standard length. You can ask for a different finish than the polished one we have.

Titanium Grade 5 Material, Strength, and Torque

Why Titanium Grade 5 (Ti-6Al-4V)

Titanium, about 6% aluminum, and 4% vanadium make up a grade 5 titanium metal. This kind of titanium metal is used the most. ASTM B348 says that Grade 5 bars must have a tensile strength of at least 895 MPa and a yield strength of at least 825 MPa. Because it has a density of 4.43 g/cm³ instead of 7.85 g/cm³, titanium is about 44% lighter than steel of the same size. Metal doesn't rust in many situations, even when it's in salt water, because a thin oxide film forms on the surface. The standards that our button head bolts are made to are ASTM B348 and ASTM F136.

Strength Compared with Steel Classes

Steel bolts are marked with 8.8 or 10.9 by ISO 898-1, but titanium bolts don't use those numbers, so I compare the real ones. Class 8.8 must have at least 800 MPa of stress, and Class 10.9 must have at least 1,040 MPa. In the middle is Grade 5, which has a pressure of 895 MPa and weighs about 56% steel. Because of this, titanium is a good material for bikes and motorcycles that need to be light. It's not a simple swap that can be used on any 10.9 joint. Also, it's not as stiff as steel, so make sure that parts that will be highly loaded have the right amount of preload. Most of the time, the small socket, not the thread, is the cap on button head bolts.

Torque, Galling, and Installation Steps

Why don't I give you a single number for torque? Because it's different for each bolt and relies on the thread size, pitch, lubrication, coating, and goal preload. Titanium threads can gall, which means that the two sides can stick together without using heat. Make sure the hex key is fully in the hole and that anti-seize powder is on the threads. Start the bolt by hand so that it doesn't cross-thread. Then, use a torque wrench that can measure torque and the number that comes with your joint to tighten slowly. If a bolt hits wet or salty aluminum, you should add a washer or sealant to keep the metal from touching. This is because aluminum rusts before titanium.

Button Head Bolt vs Other Fasteners and How to Choose

Button Head vs Socket Head Cap Screw

Both of them have a square inside, but their shapes are different. ISO 7380-1 says that an M5 button head bolt has a head that is 9.5 mm wide, 2.75 mm tall, and has a socket that is 3 mm wide. Another type of screw is the M5 socket head cap screw. Its head is about 8.5 mm wide and 5 mm tall, and its socket is 4 mm across. Because the button head bolt is lower and wider, it has a better shape and a bigger riding area. Because cap screws have a smaller hole, they need less power to tighten, so they can handle higher clamp loads. It's best to use button bolts because they look good, have enough room, and can handle light to moderate loads.

Button Head vs Flat Head

The head of an ISO 10642-style flat head screw sits flush with the surface while the hole is being ground down. Button head bolts don't need to be countersunk, so they sit on top of the surface. You can use them in thin panels and save time on the machine. If you need a flat spot for things that move, choose a flat head. With a button head bolt, you can get a clean dome that is easy to photograph and change with a hex key. Link the hole and the part to the head. A "hex socket bolt" can have a number of different head sizes, so use the usual number when you place an order.

Selecting the Right Button Head Bolt for the Job

I believe you should make a short list. First, figure out how much weight is on it and how much it’s shaking. Second, check that the length, thread, and hole diameter are all the same. Third, look around you for things like heat, moisture, salt, chemicals, and salt. Fourth, check to see if the metals close to the joint are galvanicallyconnected. Fifth, pick a place to end and start driving. Use the right preload, thread-locking compound, or a nut with a high prevailing torque to stop the shaking. If the part is very important for safety, you shouldn't use a catalog chart but instead use engineering figures and tests. You should choose Ti-6Al-4V if you want something that is both light and won't rust.

Button Head Bolt Applications Across Industries

Automotive and Motorcycle Parts

For trim panels, frames, covers, fairings, and other parts in the engine bay, button head bolts are often used. This is because the low dome makes room for parts close by and looks nice. It's used in motorcycles because it's lighter and doesn't rust in rain or salt. People who own cars also use titanium bolts for hardware that you can see in dress-up kits. When it comes to structural or brake joints, it's best to follow the manufacturer's instructions, since the drive size and head height of a button head bolt might not be enough to handle the load.

Bicycle Components and Accessories

Bikers keep track of grams, and brake pads, bottle cages, bumpers, racks, and accessory mounts all have titanium button head bolts on them. Parts for bikes often have the M5 size. A wide head spreads the weight, which is good for thin carbon or aluminum brackets. Riders see these button bolts every time they ride, and buyers rate them based on pictures and reviews, so the finish style is important. There is value in having smooth sides, clean threads, and a well-formed hole. On your drawing, write down what kind of drive a certain build needs.

Aerospace, Marine, Medical, and Electronics

People who work for us are in industries like medicine, electronics, chemicals, the marine industry, and oil and gas. Marine equipment made of titanium is safe from the effects of chloride in the water because it has an oxide film on it. It is important for electronics and instruments that they don't have a lot of weight and aren't magnetic. ASTM F136 materials are often sought after by people who make medical tools. I need to know more about your job before I can give you a price.

Buying Button Head Bolts in Bulk from a Titanium Factory

Low MOQ, Ready Stock, and Fast Testing

Our stock of at least 100 ready-to-ship items comes straight from the plant. That much can be used by online stores and small shops that want to try out different sizes before making a big order. Watch them for four to eight weeks to see how many people buy and return the three or four sizes that sell the most. Sort the winners back into groups. Send us your mix of sizes, and we'll talk about how to put it all together. We always have enough standard parts and raw materials in stock, and our prices stay fixed, which is why we keep getting orders.

Total Landed Cost and a Clear RFQ

The price per unit isn't the total cost. Transportation time, packing, inspection, and freight are some of the things that make up the total landed cost. The quote goes faster when there is a clear question. Give the size, the length, the thread type and pitch, the finish, the number, the location, and any packing instructions. The standard should be ISO 7380. A picture, a drawing, or a simple table will do. We send you an email with prices and lead times.

How to Judge a Titanium Fastener Supplier

You should look at the certifications, communication, and process control. With its ISO 9001 certification, Baoji Wisdom Titanium Industry and Trading Co., Ltd has been in business since 2016 and makes things. We are in Shaanxi Province's Baoji Titanium Valley. There is a lot of titanium made here, and this is one of the most important places in the world to do so. These are the places where you can find titanium material, ingots, bars, plates, tubes, and forgings. Our button head bolts are made from titanium pieces that are checked before they are sent out, and we do our own research and development on them as well. You can ask any supplier for samples, certificates of materials, and records of checks that have been done.

Conclusion

A button head bolt has a low profile, a dome-shaped head, and a hex hole. ISO 7380 lists the standard sizes for these bolts. Not as easy to tighten as a socket head cap screw because this bolt has a small socket and a low head. One thing that makes it look smooth is that it has a wide head. The least amount of stress that titanium Grade 5 can take is 895 MPa, and it is about 44% lighter than steel. It doesn't rust either, but it needs anti-seize compound to keep it from galling. Pick the right one based on the metals close, the thread type, the length, the load, and the job site. It's used for many things, from technology and military gear to bikes and motorbikes. When placing a large order, it's more important to check the quality of the supplier, see the total landed cost, and make sure the specs are clear than to look at the unit price.

FAQ

Is a button head bolt as strong as a socket head cap screw?

Not all the time. They can handle more clamp loads because the head is lower and the hex hole is smaller on cap screws. However, button head bolts don't work well for heavy loads.

What sizes and threads do you supply?

We have ISO 7380-compliant Titanium Grade 5 button head bolts in sizes M3 to M24. Metric, UNC, UNF, or unique thread are the options. You can choose to have the finish polished or left unfinished, and the order must be at least 100 pieces.

How do I prevent galling on titanium bolts?

Use anti-seize powder on the threads and turn the bolt by hand to get it going. Then, slowly tighten the bolt with a measured torque wrench. Fast power tools make a lot of heat and pressure, so stay away from them.

Request Button Head Bolt Quotes from Wisdom Titanium

Wisdom Titanium is an ISO 9001-approved business that makes button head bolts. Titanium Grade 5 is in stock and ready to ship. There is a 100-piece minimum order, and factory prices are fair. Please email sales@wisdomtitanium.com with the number of items you want, the type of thread, the finish, and the size. We will then send you a quote. At wisdomtitanium.com, you can also read about our goods.

References

1. ISO 7380-1: Fasteners — Hexagon socket button head screws, 2011
2. ASTM B348/B348M: Standard Specification for Titanium and Titanium Alloy Bars and Billets, 2019
3. ASTM F136: Standard Specification for Wrought Titanium-6Aluminum-4Vanadium ELI Alloy for Surgical Implant Applications, 2013
4. ISO 898-1: Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws and studs, 2013
5. Titanium: A Technical Guide, 2nd Edition, ASM International, 2000
6. Materials Properties Handbook: Titanium Alloys, ASM International, 1994