M4 M16 Carbon steel Flat head Philip sclotted tapping metal screws Class4.8 grade 8.8 Black

Product Description:

1. Ordinary self-tapping screws - The thread is 'self-tapping thread', also known as 'wide thread'. The surface is mostly plated.

2. Self-cutting tapping screws - China's standard called 'self-tapping screws shaved end', the thread for the self-tapping thread or machine thread, cross groove is also 'H' type. Self-cutting tapping screws have the following types: cross recessed pan head self-cutting tapping screws, cross recessed countersunk head self-cutting tapping screws, cross recessed raised countersunk head self-cutting tapping screws, hexagonal head self-cutting tapping screws.

3. Self-extruding tapping screws (self-tapping lock screws) - Thread is generally machine thread, rarely use self-tapping thread. In the wrenching method, in order to ensure the use of high-speed automatic assembly wrenches, generally do not recommend the use of slotted. Self-extruding self-tapping screws have a three-pronged screw cross-section, so also known as triangular thread screws.

4. Self-drilling tapping screws (self-drilling screws) - Thread for self-tapping thread in China, Germany and international standards. U.S. ASME and SAE standards in the BSD type self-drilling tapping screws for self-tapping thread, CSD type self-drilling tapping screws for machine thread. Self-drilling tapping screws do not recommend the use of 'slotted' and 'ordinary hexagon head'.

5. Metal drive screws (metal tapping screws) - Thread for the multi-head, and with a certain helix angle of the special thread. Only the U.S. standard metal drive screws, our country and the German standard is not.

6. Wallboard tapping screws (drywall nails) - For the trumpet head, cross groove (H-type), 60° tooth angle of the special thread, the surface of more phosphate treatment (phosphating).

7. Fibreboard nails - Cross slot for Z-type, the surface treatment is mostly plating. Fibreboard nails have the following types: countersunk head, double countersunk head fibreboard nails, pan head, pan head flange (with pad) fibreboard nails, half countersunk head, half countersunk head flange (with pad) fibreboard nails.

8. Combination of self-tapping screws - Ordinary self-tapping screws, self-cutting self-tapping screws, self drilling self-tapping screws and flat washers, elastic washers (including spring washers, elastic lock washers shaped t into a combination of self-tapping screws.

9. Other self-tapping screws type - High and low teeth double lead self-tapping screws, coarse and fine teeth (different pitch) thread self-tapping screws, thread coated with sealing material (drop-resistant) self-tapping screws, a variety of composite groove self-tapping screws, other special equipment juice self-tapping screws.

Applications

Although there are many types of self-tapping screws, they all have the following common points:

• They are generally manufactured from carburised steel (99% of total production). They can also be manufactured from stainless steel or non-ferrous metals.
• The product must be heat-treated. Carbon steel self-tapping screws must be carburised, and stainless steel self-tapping screws must be solution-hardened to achieve the mechanical properties and the use of performance required by the standard.
• High surface hardness, good core toughness. That is, 'soft outside'. This is a major feature of the performance requirements of self-tapping screws.
• The surface of the product requires surface protection treatment, generally plating treatment. Some of the product surface shall be treated with phosphate (phosphating).
• Cold heading process is adopted. Recommended high-speed cold heading machine and high-speed thread rolling machine or high-speed planetary thread rolling machine production.

Blacking technology due to low cost, easy to use in the production of fasteners has a place. Blackening treatment is commonly referred to as ‘bluing’ or ‘oxidation’, through the oxidation of alkaline oxidising solutions, the formation of a layer of blue-black iron oxide film on the surface of steel is called bluing; the formation of a layer of black magnetic iron oxide on the surface of steel is called blackening. The method of forming a layer of black magnetic iron oxide on the surface of steel is called blackening.
Traditional blackening technology is in the 135 ~ 150 ℃ temperature treatment 30 ~ 90min, blackening treatment before the workpiece must be clean surface treatment. That is, the pre-treatment of degreasing and descaling (need to alkaline or acid washing and neutralisation, etc.), blacking process is completed to carry out post-treatment, saponification, oil immersion. The production cycle is long, energy consumption is large, labour conditions are poor, and environmental pollution is serious.