A screw is a tool that uses the physics and mathematics of the circular rotation of an object's beveled surface and friction to tighten artifact mechanisms in a progressive manner. Screw is a generic term for fasteners, an everyday verbal term. Screws for daily life in the indispensable industrial necessities: such as cameras, eyeglasses, clocks and watches, electronics, etc., the use of very small screws; television, electrical products, musical instruments, furniture, etc., general screws; as for engineering, construction, bridges, then the use of large screws, nuts; transportation appliances, airplanes, trolley buses, automobiles, etc., is the size of the screws and use. Screws in the industry has an important task, as long as there is industry on earth, the function of the screw is always important. Screws are thousands of years of people's production and life *** with the invention, according to the field of application, it is the first major invention of mankind.

Basic introduction Chinese name ：screw Foreign name ：screw Pinyin ：luó sī Category ：Metal fittings Basic meaning, brief history of invention, common specifications, common categories, length conversion, imperial screws, industrial application, common materials, material knowledge, screws, screws labeling, common threads, screws classification, general knowledge of the application, inspection methods, scope of application, use, performance, anticorrosive technology, moisture-proof measures, basic meaning, screws, also called screws, it is also called screws, according to the field of application, it is the first major invention of mankind. Meaning Screws, some people call it "Screw" [Screw] (screws), "screw" (screw rod). In fact, screws are commonly known as screws, screws, screws are different from each other. Screws are generally called wood screws; is the front end of the kind of pointed, larger pitch, generally used to fasten wooden parts, plastic parts. Screws are machine screws (machine screws), is the front end of the kind of flat head, pitch is smaller, uniform, generally used for fastening metal, machine parts. Screw A Brief History of Invention The first person to describe a screw was the Greek scientist Archimedes (c. 287 BC - 212 BC). The Archimedean screw was a huge helix in a wooden cylinder that was used to lift water from one level to another to irrigate fields. The real inventor may not have been Archimedes himself. Perhaps he was just describing something that already existed. Maybe it was the skilled craftsmen of ancient Egypt who designed it to use the banks of the Nile for irrigation. In the Middle Ages, carpenters used dowels or metal nails to wire furniture and timber-framed buildings together, and in the 16th century, nail makers began to produce nails with a helix, which were able to wire things together more securely. It was a small step from these nails to screws. The first metal nuts and bolts that appeared as fasteners in Europe around 1550 A.D. were made by hand on crude wooden lathes. Screwdrivers (rotary chisels) appeared in London around 1780. Carpenters found that screwing screws with a screwdriver held things in place better than hitting them with a hammer, especially when fine-grained screws were encountered. In 1797, Mozley invented the all-metal precision screw lathe in London. The following year, Wilkinson made a nut and bolt making machine in the United States. Both machines produced universal nuts and bolts. Screws became quite popular as fixings, as a cheap method of production had been found by then. In 1836, Henry M. Philips patented the cross-slotted nail head screw, marking a significant advance in the art of grounding screws. Unlike traditional one-slot nail head screws, cross-slot head screws have a cross-slot nail head screw head edge. This design makes the screwdriver automatically centered and less likely to slip out of place, so it is very popular. Commonly used nuts and bolts hold metal parts together, so that by the 19th century, the wood used to make machines to build houses could be replaced by metal bolts and nuts. Common Specifications A: Metric Screws B: American Screws C: British Screws A: Metric Machine Screws: Metric Ex: M3 x 6 - P P B : M3 Machine Screws, 6mm long, Phillips, rounded flat head, black plated. Finish Code: Finish specification Head Code: Head profile. Screw head profile. Cylindrical head. Semi-countersunk head. Countersunk head. Spherical cylindrical head. Disc head. Semi-circular head. Hexagonal head. Screw Head Profile Thread Code Screw Type Drive Code: Head profile, characteristic type Length Code: Screw Length (mm) A-1: Thread Code: Screw Type Metric screws are directly labeled with screw type by the screw O.D., e.g., M3 means that the screw O.D. is 3.00mm, M4 means that the screw O.D. is 4.00mm, M4 means that the screw O.D. is 4.00mm. Metric Thread Size x Pitch: Note: Metric screws are sometimes labeled with the pitch of the screw after the screw type. Such as M3x0.5, M4x0.70, M5x0.8, M6x1. But because of the standard specification, usually not mentioned. A-2: Length Code: Screw Length: For metric screws, the length of the screw is directly labeled in mm. The total length of the screw is only the length below the head, excluding the height of the head. The total length of the screw is only the length below the head, excluding the height of the head. A-3: Drive Code/ Head groove and characteristics. Common categories a. Slotted: One-type (Minus) b. Phillips: Phillips (Plus) c. Phil-Slot: One-type/Phillips d. Hex Socket: Hexagonal e. One Way: Unidirectional (locking in, not locking out) A-4: Head Code/ Head Shape. a. Flat: Flat (locking in, not locking out) a. Flat: Flat head (top of the head is flush with the workpiece after locking) b. Oval: Salad head, O-head, Semi-countersunk head c. Round: Round head Unit of Measurement for Screws d. Pan: Pan head e. Truss: Truss head f. Hex : Hexagon head. A-5: Finish Code. Metric Tapping Screws: Tapping Type is indicated directly after the product name. Ex: M3 x 6 -PPB,Tapping Type: M3 Tapping Screws, 6mm long, Phillips, Round Flat Head, Black Plated. Generally, the product type or labeling, and then determine the use of Sheet Metal or plastic parts. *** Threads are teeth per inch. *** Length Conversion The length of American Standard screws must be converted to metric mm dimensions. Conversion formula: (Length Code / 32) x 25.40 = Metric length in mm B-3,B-4,B-5 : Same labeling as metric. C-1: Thread Code: The denominator will be 8, and then the numerator will be called the number. Ex: 1/8 x 0.50 -PPB: 1 part screw x 0.50" long, PPB Ex: 5/16 x 0.50 -PPB = 2.5/8 x 0.50 -PPB: 2 part screw x 0.50" long, PPB Ex: 5/32 x 0.50 -PPB = 1.25/8 x 0.50-PPB: 1 part 2? centimeter screw x 0.50" long, PPB Ex: 1/4 x 0.50-PPB = 2/8 x 0.50-PPB: 2 part tooth screw x 0.50" long, PPB Ex: 1/4 x 0.50-PPB= 2/8 x 0.50-PPB: 2 part tooth screw x 0.50" long, PPB PPB Note: Sometimes labeled as coarse or fine thread. UNF: Fine Thread: Commonly used in the electronics industry. UNC: Coarse Thread: Commonly used in heavy machinery. Ex: 3/8 x 0.50,UNF -PPB: 3-point fine thread screw x 0.50" long, PPB. C-2: Length Code: Inches must be multiplied by 25.40 to convert to mm. Measured with a snap gauge, a thread that matches a metric pattern is a metric thread, and a thread that matches a fractional pattern is a fractional thread. You can also use calipers to measure the outside diameter of the threads and the pitch. Metric thread outside diameter is in millimeters, such as 6, 8, 10, 12, 18, 20 mm, etc. Pitch is also in millimeters, such as 0.5, 0.75, 1, 1.5, 2, 3, and so on Inch thread outside diameter is in inches, (each inch is equal to 25.4 millimeters), such as 3/16, 5/8, 1/4, 1/2, and so on, so the metric caliper measurement of the outside diameter readings with an often irregular decimal. Imperial pitch is expressed in terms of how many teeth per inch. The caliper is set at 25.4 mm, a ruler to align the tip of the thread tip, another ruler such as the tip of the thread tip is aligned with the British thread, such as the tip of the thread is not aligned with the thread tip should be metric thread. Measure the pitch of the best threads of the tip of the inverted print in white chalk, chalk on the print is clearer, easier to measure. Measurement of metric pitch should measure a length, such as 10, 15, 20, millimeters, etc., count the number of teeth, calculate the pitch of the thread specifications with inches as the unit for the British thread, such as: G1 ". With the metric unit of millimeters to specify the thread specifications for the metric thread. For example: M30. Imperial is an inch (2.54 cm) within the number of teeth to determine, generally 55 degrees angle. Metric system is the distance between the tip of the two teeth is how many MM to set the pitch, generally 60 degrees angle Ground screws: the machine and other screws fastened to the ground. Also called foot bolt. British screws and the difference between the United States with visual inspection is difficult to distinguish, Britain, the United States screws is the difference between the British screws rolling angle of 55 degrees, while the United States screws rolling angle of 60 degrees, the two standard screws in most of the time can be universal, but 1/2 specifications of the screws can not be, because of the British 1/2 of the standard threads of the 1/2 - 12 teeth, while the United States is 1/2 - 13 teeth. Industrial sets of the main purpose of industrial products to make the composition of a fixed one, often occur in the use of teeth and teeth can not be close to the tightening, too much force to lock the screw head break away, or poor thread locking can not meet the conditions of use, are the quality of the accuracy of the problem. Screws are "quantity products", not handmade works of art. In mass production, we aim to achieve high precision and stable quality and supply them to consumers at popularized prices. The accuracy of screws is usually 6g (Grade 2, U.S. specification "IFI" is 2A teeth), and 8g (Grade 3, "IFI" is 1A teeth) for rough screws used in construction projects. The value of screws is very important, there are examples in the world because of the poor quality of screws caused by the bankruptcy of automobile factories; there are also examples because of the poor quality of screws caused by the fall of the aircraft, vehicle upheaval. Commonly used types of screws A: Machine Screw: Machine Screw Screw B: Tapping Screw: Self-tapping screws (used in metal and plastic two kinds) B-1: Sheet Metal Tapping Screw. (Iron plate teeth self-tapping screws) B-2: Plastic Tapping Screw. (Plastic, self-tapping screws) C: Wooden Screw : woodworking screws D: Drywall Screw :Cement wall screws E: Self Drilling Screws Drilling screws (stainless steel drilling screws, composite drilling screws) F: Expansion Screws, four expansion screws, also known as: four geckos. The grade of expansion bolts is divided into: 45, 50, 60, 70, 80, Expansion Screws material: mainly divided into austenitic A1, A2, A4, 1 stainless steel plate, metal steel plate, galvanized steel plate, engineering installation. 2 metal curtain wall metal light compartment and other indoor and outdoor installation. 3 general angle steel, channel steel, iron plate and other metal materials combined with the installation. 4, automobile trunk, container box, shipbuilding industry, refrigeration, screw machine equipment and other assembly projects. Features: 1, drilling and tapping, locking a complete, strong combination. 2、Save construction time and improve working efficiency. E-1:STAINLESS STEEL SELF DRILLING SCREWS Stainless Steel Drilling Screws E-2:Bi-Metal Self Drilling Screws Composite Material Drilling Screws Screws are indispensable industrial necessities for daily life: such as miniature screws for cameras, eyeglasses, clocks and watches, and electronics; general screws for TVs, electrical products, General screws are used in engineering, construction and bridges; large screws and nuts are used in transportation equipment, airplanes, trams and automobiles, etc. Screws have important tasks in industry. Screws in the industry has an important task, as long as there is industry on earth, the function of screws will always be important. The type of screws, whether it is the miniature screws for eyeglasses or the large screws for large-scale heavy power projects, has many types. The accuracy of screws is usually 6g (grade 2, American standard "IFI" is 2A teeth), and the rough screws for construction projects are 1g (grade 3, "IFI" is 1A teeth). Common Materials a. Low Carbon Steel : Carbon steel is divided into low carbon steel, medium carbon steel, high carbon steel and alloy steel. b. SS-304 : Stainless Steel : Stainless Steel is divided into low carbon steel, medium carbon steel, high carbon steel and alloy steel. b. SS-304 : Stainless Steel 304, 316 belong to the stainless steel and so on c. SS-302: Stainless Steel 302: better structural toughness d. Aluminum 5052 :Aluminum Alloy 5052 d. Brass: Brass e. Bronze: Bronze f. UNS C11000 Copper: Antimony Copper Material Knowledge Before the market standard parts are mainly carbon steel, stainless steel, copper three materials.

A carbon steel. We distinguish low carbon steel, medium carbon steel and high carbon steel and alloy steel by the carbon content in the carbon steel material.

1 low carbon steel C% ≤ 0.25% domestic usually called A3 steel. Foreign basic known as 1008, 1015, 1018, 1022 and so on. Mainly used for 4.8 grade bolts and 4 grade nuts, small screws and other products without hardness requirements. (Note: Drill nails are mainly used 1022 material.)

2 Medium carbon steel 0.25%

3 High carbon steel C%>0.45%. The market is basically not used

4 Alloy steel: in the plain carbon steel to add alloying elements to increase some of the special properties of steel: such as 35, 40 chromium molybdenum, SCM435, 10B38. fangsheng screws are mainly used in the SCM435 chromium molybdenum alloy steel, the main components of the C, Si, Mn, P, S, Cr, Mo.

II Stainless steel. Performance grade: 45, 50, 60, 70, 80

1 main points austenitic (18% Cr, 8% Ni) good heat resistance, good corrosion resistance, good weldability. a1, a2, a4

2 martensitic, 13% Cr poor corrosion resistance, high strength, good wear resistance. c1, c2, c4 ferritic stainless steel. 18% Cr upsetting is better. Corrosion resistance is stronger than martensitic. Imported materials on the market is mainly Japan. According to the level of the main points SUS302, SUS304, SUS316.

Three copper. Commonly used materials for brass ... zinc-copper alloy. The market mainly uses H62, H65, H68 copper for standard parts. Screw marking The marking format of the thread marking is as follows: thread code - thread tolerance zone code (medium diameter, top diameter) - screwing length l) tolerance zone code is expressed by the number plus letters (internal threads with capital letters, external threads with lowercase letters), such as 7H, 6g etc., it should be noted that, 7H, 6g, etc. on behalf of the thread tolerance, and H7, g6 on behalf of the cylinder tolerance code. (2) The screwing length is specified as short (indicated by S), medium (indicated by N), long (indicated by L) three. In general, do not mark the thread screwing length, the thread tolerance band according to the medium screwing length (N) to determine. If necessary, the screwing length code S or L can be added, such as " M20-5g6g-L ". If necessary, the numerical value of the screwing length can be indicated, e.g. "M20-5g6g-30". Ordinary thread Ordinary coarse thread: Characteristic code M + nominal diameter + direction of rotation + thread tolerance zone designation (medium diameter, top diameter) - screwed length Ordinary fine thread: Characteristic code M + nominal diameter * pitch + direction of rotation + thread tolerance zone designation (medium diameter, top diameter) - screwed length Right-hand threads are omitted, left-hand threads are indicated by "LH". M 16-5g6g means coarse thread, nominal diameter 16, right-handed, thread tolerance zone 5g for medium diameter and 6g for large diameter, and the length of screwing is considered as medium length. M16×1 LH-6G means fine thread, nominal diameter 16, pitch 1, left-handed, thread tolerance zone 6G for both medium and large diameter, and the length of screwing is considered as medium length. Marking format is as follows: Characteristic code (G for cylindrical pipe threads, NPT for conical pipe threads) + Size code + Tolerance grade code + direction of rotation G1A--LH indicates inch non-threaded sealing pipe threads, size code 1in, left-handed, tolerance grade A. Rcl/2 indicates British thread sealing tapered pipe thread, size code 1/2in, right-handed. Screw classification The main classification includes common screws, machine screws, self-tapping screws and expansion screws. Cap screw Cap screw used to be limited to full-threaded fasteners. Hex cap screws Hex cap screws and large hex bolts Hex bolts As the name suggests, they are externally threaded fasteners with hexagonal heads, designed to be turned with a wrench. According to ASME B18.2.1 standard, Hex cap screws (Hex cap screws) have smaller tolerances on head height and shank length than general Hex bolts (Hex bolts), so ASME B18.2.1 Hex cap screws are suitable for installation in all places where Hex bolts can be used, and also include places where Hex bolts are too large to be used. Socket cap screw Socket cap screw also known as the nest head screw or), is the head of a hexagonal type of hole in the screw, with a hexagonal ruler (hex key, Allen wrench or Allen key) inserted into the hole in order to tighten or loosen. Hexagon socket head cap screws are most often cylindrical head cap screws, with a head diameter of approximately 1.5 times the main diameter of the thread (1960 series), while other head types include semi-circular head cap screws (Bottom head cap screw) for aesthetic surfaces, and flat head cap screws (Countersunk head cap screw) for tapered screw holes. The countersunk hole design allows the screw head to be turned without being exposed on the surface of the object to be fastened, so it is mostly used in places where the surface is small and traditional plate holders are inconvenient to use. Machine screw Machine screw generally less than ¼ inch diameter screws (4 # ~ 12 #), usually for the full tooth and by the screwdriver to turn, such as a slotted, Phillips or hexagonal. Wood screws, machine screws; but according to different uses can also be divided into many categories; machine screws within the category, can be divided into longitudinal fastening screws and transverse expansion screws; in accordance with the thread can also be divided into: A: triangular thread ( 60 degrees ) : combined / locking / expansion B: pipe triangular thread ( 55 degrees ) : combined / locking 3) C: trapezoidal threads (30 or 29 degrees ) : power transmission D: square thread ( 90 degrees ) : power transmission Stainless Steel Screws Screws And Shafts For Motorcycle Or Bicycle Stainless Steel Nylon Screws Screws And Shafts For Pin Turning Stainless Steel Screws Screws And Shafts For Sewing Maching Stainless Steel Screws Screws And Shafts For Needle Turning Sewing Maching Stop Screws Socket Set Screws Stainless Steel Coarse Thread Screws Stainless Steel High-Low Thread Screws Stainless Steel Machine Screws Stainless Steel Drill Tail Screws Stainless Steel Machine Screws Stainless Steel Drill Tail Screws Stainless Steel Machine Screws Stainless Steel Self Drilling Screws Stainless Steel Self Tapping Screws Stainless Steel Self Cutting Screws Stainless Steel Thread Cutting Screws Stainless Steel Tri-Lobular Thread Screws Model Description P refers to the head type is PAN head; A refers to the pointed end teeth, B refers to the flat end teeth, that is, PA round head pointed steel teeth, PB round head flat steel teeth. Self-tapping: ◆Round head self-tapping screws PA ◆Round head flat-tailed self-tapping screws PB ◆Round head cut-tailed self-tapping screws PT ◆Round head tapping screws PWA ◆Round head tapping screws PWB ◆Round head tapping screws PWT ◆Countersunk head tapping screws KA ◆Countersunk head tapping screws KB ◆Countersunk head cut-tailed screws KT ◆Semi-countersunk head tapping screws OA ◆Large head tapping screws BA ◆Large head flat-tailed screws BB ◆Large flat head tapping screws TA ◆Large flat head flat tail tapping screws TB ◆Large flat head cut tail tapping screws TT ◆Thin head tapping screws CA ◆Thin head flat tail tapping screws CB ◆Cup head hexagon socket head tapping HA ◆Drywall nails / wallboard nails / fiber nails Machine wire: ◆Round head machine screws PM ◆Round head machine screws PWM ◆Large flat head machine screws TM ◆Countersunk head machine screws KM ◆Semi-countersunk head machine screws OM ◆Big head machine screws BM ◆Thin head machine screws CM ◆Cup head machine screws HM set of common sense 1. First of all, remove the sludge on the surface of the broken screw section head with the center cannon will be the center of the cross-section of the cannon dead, and then use an electric drill mounted on the diameter of 6-8 mm drill in the cross-section of the center of the cannon hole in the hole, pay attention to the hole must be drilled through. After the hole is drilled through, the small drill bit is removed and replaced with a 16 mm diameter drill bit to continue to expand the hole of the broken bolt and drill through. 2. Take the diameter of 3.2 millimeters below the electrode with small and medium current in the broken bolt drilling holes from inside to outside for surfacing welding surfacing welding the beginning of the part of the broken bolt to take the entire length of half of the bolt can be. The beginning of the surfacing arc should not be too long in order to avoid the broken bolt wall burned through. Surfacing to the upper face of the broken bolt and then continue to surfacing out of a diameter of 14-16 mm high 8-10 mm cylinders. 3. Surfacing good with a hand hammer to hammer the end face of the broken bolt along its axial vibration. Due to the heat generated by the arc and the subsequent cooling plus the vibration at this time will make the broken bolt and the body of the threads between the loosening. 4. Observe carefully when found after knocking a trace of rust from the fracture leakage when you can take the M18 nut set in the pile of welding on the plunger and will be welded together. 5. Welded together slightly cool while hot with a plum wrench glove in the nut on the left and right back and forth twisting can also be twisted back and forth while using a small hammer to hit the end of the nut so that you can take out the broken bolt. 6. After removing the broken bolt with a suitable tap to the rack within the buckle processing once to remove rust and other debris in the hole. Inspection methods Screw surface inspection is divided into two kinds, one is the screw production is not plated before the inspection, the other is the screw plating after the inspection, that is to say, after the screw hardening, screw surface treatment after the inspection. Screws are produced without plating before, we screw size, tolerance and other aspects of the test. To see whether there is a national standard or customer requirements. Screw surface treatment, we plated screws for inspection, the main test plating color and there is no bad screws and so on. So that we send the screws to the customer, the customer receipt of goods to pass the test smoothly. Screws after treatment inspection: First, the appearance of the quality requirements Screws appearance inspection is from the appearance of the plating layer and other aspects of the inspection. Second, the screw plating thickness inspection 1, gauge method The amount of micrometers, vernier calipers, plug gauges, etc.. 2, magnetic method Magnetic method to measure the thickness of the coating layer, is a magnetic thickness gauge on the magnetic substrate on the non-magnetic coating layer of non-destructive measurements. 3、Microscope method Microscope method is called metallographic method, it is the fasteners after etching, placed on the metallographic microscope with microscopic eyepiece magnification, measurement of the thickness of the coating layer on the cross-section. 4, timing the liquid flow method Timing the liquid flow method is used to dissolve the plating solution flow injection in the plating of the local surface, according to the local plating dissolved in the time required to calculate the thickness of the plating. There are also plating drip method, anodic dissolution Coulomb method. Third, the screw plating adhesion strength test Assessment of plating and base metal adhesion of many methods, usually the following. 1, friction polishing test; 2, file method test; 3, scratch method; 4, bending test; 5, thermal shock test; 6, extrusion method. Fourth, the test of corrosion resistance of the screw plating The test method of corrosion resistance of the plating are: atmospheric burst test; neutral salt spray test (NSS test); acetate spray test (ASS test), copper-accelerated acetate spray test (CASS test); as well as corrosive paste corrosion test (CORR test) and the solution droplet corrosion test; impregnation test, inter-impregnation corrosion test, and so on. Scope of application Screws have a lot of call, each person's call may be different, some people call into the screw, some people call into the screw, some people call into the standard parts, some people call into the fasteners. Although there are so many ways to call it, but the meaning is the same, are screws. Screw is a generic term for fastener. The principle of screw is the use of the physics and mathematics of the object's beveled circular rotation and friction, step-by-step tightening of the instrumental mechanism of the tool. Screws in daily life and industrial production and manufacturing, is indispensable, screws are also known as the rice of industry. Screws can be seen in a wide range of applications. Screws are used in the following areas: electronic products, mechanical products, digital products, power equipment, electromechanical products. Ships, vehicles, water conservancy projects, and even chemical experiments are also used to screws. Anyway, it is a lot of places are used to screws. Special such as digital products used above the precision screws, DVD, cameras, glasses, clocks and watches, electronics, such as the use of miniature screws; television, electrical products, musical instruments, furniture and other general screws; as for engineering, construction, bridges, the use of large-scale screws, nuts; transportation equipment, airplanes, trolley buses, automobiles, etc. for the size of the screws and use. Screws in the industry has an important task, as long as there is industry on earth, the function of the screw is always important. The type of screws, whether it is a very small screws for eyeglasses or large screws for large-scale heavy electrical projects, there are many types of screws. The accuracy of screws is usually 6g (grade 2, American standard "IFI" is 2A teeth), and the rough screws used in construction projects are 1g. Screws are used in such a wide range, so the screw market must be relatively large, the demand must be relatively huge, and in the screw industry production screw manufacturers must be more. Procurement in the choice of professional screw procurement manufacturers, certainly need to first understand some of the professional basics of screws, such as screw classification standards and American screw specification table. Performance If we want to use a screw, then the first thing we need to do is to understand the performance of the screw that is, its characteristics, so that we can use the screw in the most appropriate place. Because there are many types of screws, each of these screws has a different performance, so the screw has a different use. In order to avoid the wrong use of screws, we must have a certain understanding of the performance of the screws, so that we can use the screws in the most correct place.

First of all, let's understand the self-tapping screws, for self-tapping screws with a diameter of 0.8mm to 12mm self-tapping screws. For these screws are generally with a high degree of hardness, self-tapping screws to be screwed into the test, that is, screw the screw into a piece of test plate, and then check the hardness of the screws in line with the standard, if it is not standard on the need to analyze where the problem lies? Thus find a solution.

There is also a drill screw , as the name implies is the tail of the screw is generally manifested in the shape of the drill tail, this screw hardness is also very strong, compared with ordinary screws, not only to maintain the ability to better, in the connection with the object of the effect is very strong, for the screw, the screws, the screws, the screws, the screws, the screws, the screws, the screws, the screws, the screws, the screws, the screws, the screws. This performance of the screws, generally do not need auxiliary processing, can be directly in the object directly drilled a hole in the top of the lock into the object, not only very convenient to use, but also can greatly improve the efficiency of the work. This drill screws in various fields can be said to be the first choice of staff.

From the above we can find that we use the screws for a variety of Screw performance is still very important to understand. Anti-corrosion technology Stainless steel screws are made of metal, and metal corrosion prevention methods are mainly four aspects, namely, the nature of the material itself, the use of the environment, the interface between the material and the environment and the improvement of the design of the metal structure, if the use of complete corrosion-resistant alloys to manufacture stainless steel screws, unless there is a special need, otherwise in the economic concept of the idea of the practicality of the screws or screws on the outside with the corrosion of the complete isolation of the environment will produce elements, in practice, also not seen to be the case. In practice, it is not necessarily feasible, may be very difficult. Improvement of metal structure design can be in a certain situation to improve the impact of special circumstances, but most of the design of stainless steel screws can not be fully corrected, and its maintenance role is not permanent, so this method can not basically deal with the problem, as long as the interface of the corrosion, that is, the appearance of corrosion treatment is the most widely used approach. Stainless steel screw appearance anti-corrosion disposal refers to the use of a variety of methods in the metal appearance of the maintenance layer, its role is to isolate the metal and corrosive environment, in order to inhibit the production of corrosion process, or reduce the corrosive medium and metal appearance contact, and to avoid or reduce the corrosion of the purpose. Maintenance layer should be able to meet the following requirements: 1, corrosion-resistant, wear-resistant, high hardness, 2, the structure of the tight, intact, small pores. 3, and the base metal separation of strong, good adhesion. 4, average distribution and a certain thickness. Maintenance layer is usually divided into metal coating and non-metallic coating two categories, metal coating refers to the use of corrosion-resistant metals or alloys in the corrosion-prone metal appearance constitute a maintenance layer, this coating is also called plating. Produce metal plating methods and varieties are quite a lot, of which the most common is the electroplating method, followed by molten metal dip plating method (hot dip plating) and chemical appearance disposal. Non-metallic coating refers to the use of organic polymer materials such as paint, and inorganic materials such as ceramics, in the metal equipment or parts on the exterior to form a maintenance layer, the maintenance layer can be a complete isolation of the base metal and the environmental media, to avoid the base metal due to contact with corrosion in the stainless steel standard parts medium and the formation of corrosion. Moisture-proof measures Iron screws if they are wet, or by the liquid drenched. In or by the moisture, etc., in this case, will be very likely to rust. Therefore, in order to prevent the screws from rusting, we have to prevent moisture and humidity on the screws. So how to prevent moisture and humidity treatment of screws! Screw moisture and humidity methods are as follows: (1), vibration machinery as much as possible with solvent-free paint. (2), the best choice of non-oxidizing components of the impregnating paint, such as epoxy urethane (Epoxy-urethane) based or undenatured epoxy (Epoxy-) based impregnating paint. (3), the use of cyanuric acid impregnating paint, should be adjusted to the curing temperature and curing time, curing temperature to slightly higher than 130 ℃ (such as 135 ℃) and curing time greater than 180min is appropriate, and must be strictly enforced process, especially in the high temperature and humidity season, rotary vibration sieve, because from the concept of rust, paint factory samples in the provisions of the lacquer drying (curing) time, is not necessarily sufficient, the motor has a specific The motor has a specific inner shape. (4), the use of non-volatile acid paint. (5), choose a good hydrolysis resistance paint.