Screw with a semicircular head, its types and scope

The screw with the semicircular head is used at manufacturing various kinds of furniture, in building branch, motor industry. It is a reliable way of fastening a wide variety of parts from wood, metal, plastic.

Types of screws, their classification

A screw is a hardware product that looks like a rod with a thread and a head of various shapes. Tapping is practiced along the entire length of the rod, or only partially. The main difference between screws from bolts is that they are screwed into a part, and a nut is screwed onto the bolt. It does not require the use of additional elements in the form of nuts. Used most often for blind connections. This type of metalware is classified:

• Like a hat.
• By thread.
• By lenght.

The screw cap can be made of a semicircular or flat shape. The fasteners are made and with the head missing. To transfer the torque in the screw cap, the slot (straight, cross-shaped, in the form of an asterisk), knurling or slot at the end of the rod.

The thread on the rod is small and large in size. It can be cut over the entire length of the screw or only partially.

The length is distinguished by short, medium and long screws.

Depending on the purpose, the screw with a semicircular head is divided into:

• Fastening hardware.
• Mounting hardware.

Fastening screws are used to connect parts with the possibility of further analysis of fasteners. The setscrews are used to fix the parts.

There are two classes of accuracy manufactured fasteners: A, B. Standardized production and size of hardware GOST 17473-80.

Such products are made of carbon steel with anti-corrosion coating or not galvanized. The most widely used electro-galvanized hardware with a strength class of 4.6. A screw with a semicircular cap is used in the inaccessible places of fastenings.

Self-tapping screws with a semicircular head

These hardware products are produced with a Ph-slot type Ph or a Torx slot. Used for cutting in the hole of one of the connected parts of the metric thread. Used for fixing plastic, metal or wooden connections.

By the diameter of the thread, self-tapping screws vary in size from M3 to M8. The thread pitch is large - from 0.5 mm to 1.25 mm. The minimum length of screws can be from 6 mm for size M3 to 16 mm for size M8.

Screws for furniture

The furniture screw with a semicircular head can be completed with a press washer at the request of the customer, has a cross-shaped slot on the cap. The press washer or shoe is a single element with a head. As a result, the bearing surface area increased at the fixing point is obtained, which considerably reduces the pressure on the material of the article and does not deform it. At the same time, the fastening is more durable. It is mainly used as fasteners for furniture fittings. The thread is cut on the stem partially.

The cross-shaped splines on the head are of the standard shape (Ph) and the improved shape (Pz).

By the diameter of the thread, the furniture screws vary from M3 to M8. The diameter of the cap can be from 7.5 mm for size M3 to 19 mm for size M8.

The length of the screw can vary between 6-120 mm.

Screw with a semicircular head and an internal hexagon

Hardware with a semicircular cap and hexahedron internal is used in assembly work to fasten different elements and assemblies of systems. Large sizes of hardware are used in construction and installation works. The internal hexagon in the body of the screw head is essentially a slot.

Also available are screws with a semicircular low and hexagonal cap for the key. They are used to tie the furniture elements together with the "Ericson" nuts or "Boconok" nuts.

One of the varieties is an antivandal secret screw with a semicircular head, a hexagon for the key and a pin in the head for a special bit. They are used as protection from unauthorized access to the place of connection, dismantling or deterioration of the fixed equipment. Are made of stainless steel A2. Alternatively, it is also possible to produce hardware with an asterisk on a turn-key basis.

There are also screws with a semicircular, increased low cap with a cross or straight slot, captive screws. Scope of screws with a semicircular head are very diverse. This is a type of hardware that is widely used for various hardware fasteners.