Hot-selling Metric Bolt Grades - DIN7991 Black Hex Socket Countersunk Head Cap Bolt – Qijing
Hot-selling Metric Bolt Grades - DIN7991 Black Hex Socket Countersunk Head Cap Bolt – Qijing Detail:
What is hex socket countersunk head cap bolt?
Countersunk bolts are flat headed bolt fasteners with hex socket drive into the head. Countersunk bolts have a cone type neck with flat head, flat head hex socket bolts, flat head socket cap bolts are other alias of hex head bolts. Countersunk bolts dimensions are defined in both metric and imperials sizes with unified national coarse pitch(UNC), fined pitch (UNF), fixed pitch(UN) and ISO metric thread profile. These are produced across all material categories and ASTM specifications but most commonly produced under F568 grade 8.8, 10.9,12.9, F593, BS, EN, ISO3506-1, SS304, SS316,2205, etc.
Applications
On the surface of the mounting hole on the connecting piece, a 90-degree conical round socket is processed, and the head of the flat machine screw is in this round socket, which is flush with the surface of the connecting piece. Flat machine screws are also used in some occasions with round head flat machine screws. This kind of screw is more beautiful and is used in places where the surface can allow a little protrusion.
Most hex socket countersunk head cap bolts are used in places where the surface of the part cannot be raised after installation. There are two types of parts to be fastened. The thickness of the head, after the screw is tightened, a part of the screw thread still does not enter the threaded hole. In this case, the countersunk head screw can certainly be tightened.
The cone of the head of the countersunk head screw has a 90 ° cone angle. Usually, the apex angle of a newly purchased drill bit is 118 ° -120 °. Some untrained workers do not know this angle difference, and often use a 120 ° drill Reaming, which results in that the countersunk head screws are not strained when tightening the countersunk head screws, but a line at the bottom of the screw head, which is one of the reasons why the so-called hex socket countersunk head cap bolts cannot hold tight.
Precautions during use
1.The taper of the reaming hole should be 90 °. To guarantee it, it is better to be less than 90 °, not more than 90 °. This is a key trick.
2.If the thickness of the sheet metal is less than the thickness of the head of the countersunk head screw, you can change the smaller screw, or rather expand the hole smaller than expand the hole so that the diameter of the bottom hole becomes larger and the part is not tight.
3. If there are multiple hex socket countersunk head cap bolt holes on the part, be more precise during machining. Once the drill is crooked, it is difficult to see the assembly, but it can be tightened as long as the error is small, because when the screw is not very tight Large (about no more than 8mm), when there is an error in the hole distance, the screw head will be deformed due to force when tightened, or it will be tightened.
Product Parameters
| Product name | hex socket countersunk head cap bolt |
| Standard | DIN7991 |
| Diameter | M3-M20 |
| Length | ≤800mm |
| Material | Carbon Steel, Alloy Steel, Stainless Steel, Brass |
| Grade | 4.8,6.8,8.8,10.9,12.9 A2-70 A2-80 A4-70 A4-80 |
| Thread | Metric |
| Finish | Plain,Black oxide, Zinc Plated(Clear/Blue/Yellow/Black), H.D.G, Nickel, Chrome,PTFE,Dacromet,Geomet,Magni,Zinc Nickel,Zinteck. |
| Packing | bulk in cartons (25kg Max.)+wood Pallet or according to customer special demand |
| Application | Structural Steel; Metal Buliding; Oil&Gas;Tower&Pole; Wind Energy; Mechanical Machine; Automobile Home Decorating |
Packaging and Shipment
Our Market
Our Customers
Product detail pictures:
Related Product Guide:
We have our own product sales staff, style crew, technical group, QC staff and package staff. We now have strict high quality management procedures for each approach. Also, all of our workers are experienced in printing subject for Hot-selling Metric Bolt Grades - DIN7991 Black Hex Socket Countersunk Head Cap Bolt – Qijing, The product will supply to all over the world, such as: Ecuador, Lahore, Italy, With a team of experienced and knowledgeable personnel, our market covers South America, the USA, the Mid East, and North Africa. Many customers have become our friends after good cooperation with us. If you have the requirement for any of our goods, make sure you contact us now. We're looking forward to hearing from you soon.
By May from Sri Lanka - 2017.10.27 12:12
The sales manager has a good English level and skilled professional knowledge, we have a good communication. He is a warm and cheerful man, we have a pleasant cooperation and we became very good friends in private.
By Kevin Ellyson from Sevilla - 2017.03.07 13:42
