What is the role of the steel helical inserts?

Stainless steel helical inserts are a new type of internal thread fastener, suitable for threaded connection, screwed and fastened in the threaded hole of one of the connected parts, forming a standard internal thread, the bolt (or screw) and then screwed into it, also known as the threaded wire sleeve, referred to as the wire sleeve. Its spring-like internal and external thread concentric body comprises cold-rolled diamond stainless steel helical inserts with high strength, precision, and a smooth surface. It is mainly used to strengthen and protect the internal thread of low-strength material. The principle is to form an elastic connection between the screw and the internal thread of the matrix, eliminate the thread manufacturing error, and improve the connection strength. The stainless steel helical Inserts are embedded in the thread holes of low-strength engineering materials such as aluminum, magnesium alloy, cast iron, glass fiber reinforced plastic, etc., which can form high-precision internal threads in line with international standards, have the functions of high connection strength, earthquake resistance, impact resistance, and wear resistance, and can disperse stress to protect the matrix threads, greatly extending the service life of the matrix, and is widely used in electronic applications.

The characteristics of stainless steel helical inserts

1. Extend the service life: Because the stainless steel helical inserts are made of stainless steel, their hardness is high, and they tens increase the thread life of the soft base parts hundreds of times. This increases strength and avoids tripping and random fastening.

2. Enhance the threaded connection strength: Applied to soft, low-strength alloy materials such as aluminum and magnesium, which can effectively improve the threaded connection strength. The tensile strength of the ordinary internal thread of the aluminum profile can reach 1394N, and the tensile strength of the pre-installed stainless steel helical inserts can reach 2100N.

3. Increase the force surface: It can be used for thin parts that need a strong connection and can not increase the diameter of the screw hole.

4. Improve the connection conditions: improve the bearing capacity and fatigue strength of the threaded connection: because the wire screw sleeve is an elastic fastener, the use of the stainless steel helical inserts can eliminate the pitch and tooth deviation between the screw and the screw hole, so that the load is evenly distributed, thereby improving the bearing capacity and fatigue strength of the threaded connection.

5. Anti-rust damage: the characteristics of the wire screw material itself and its surface are very smooth, used in harsh environments such as humidity and corrosion, and will not rust and damage the base of the match, and avoid the loss of replacing the expensive base due to the rest of the thread holes. It can be used in the chemical industry, aviation, military equipment, and other occasions requiring a high insurance coefficient.

6. Wear resistance, heat resistance, and corrosion resistance: due to the high surface finish of the wire screw sleeve, it can effectively reduce the friction between the internal and external threads, and the material itself has the characteristics of high-temperature resistance and corrosion resistance. It can be used for frequent disassembly. Install the parts and rotate the screw holes frequently to extend their service life.

7. Earthquake. Anti-loosening: The unique Structure of the locking screw sleeve can lock the screw hole in a strong vibration and impact environment without loosening, and its locking performance is better than other locking devices. It can be used for instrumentation. Precision and valuable power equipment. And aerospace. Airlines and other places where high insurance is required.

8. Easy maintenance: When thread processing errors or damaged internal threads are repaired, the use of stainless steel helical inserts can make the base recover, and the original screw can be used, both fast and economical. A simple example is a diesel engine body. Textile special parts. All kinds of aluminum mechanical parts. The lathe table will be abandoned due to screw hole damage. As soon as it is re-attacked, screw caps are installed, and the waste comes back to life.

9. Conversion: Using stainless steel helical inserts to convert metric → Imperial →→ International standard thread holes are convenient, fast, economical, and practical.

Performance and application of stainless steel helical inserts

1. Stainless Steel Helical Inserts performance: wire screw sleeve is a new type of connection fastening technology, in the screw connection can effectively improve the connection conditions and significantly improve the reliability of the screw connection; its advantages are as follows:

1) The application of Stainless Steel Helical Inserts in a variety of low-strength materials can significantly improve the wear resistance of screw connections and avoid damage to the connection thread.

2) Because the wire screw sleeve has a certain elasticity, the load distribution on each circle of the thread is more uniform, the pitch and tooth deviation between the screw and the screw hole are eliminated, and the vibration can be absorbed, thus improving the connection strength and fatigue resistance of the thread.

3) The locking type stainless steel helical inserts can lock the screw in the threaded hole so that the screw will not be loosened when subjected to impact vibration, and the process performance is better than that of the usual locking device.

4) Compared with the inlaid steel or copper bushing method, under the same strength conditions, screws with smaller size and higher strength can be selected, which can reduce the volume and weight.

5) The hardness of the stainless steel helical inserts is higher than that of the screw, so it has minor wear during the connection and disassembly with the screw and can be used repeatedly. According to relevant experimental studies, the tensile strength of the wire screw sleeve is more than seven times that of the screw, so the wire screw sleeve will not be damaged in the case of screw breakage.

2. The use of stainless steel helical inserts

1) Enhance connection strength and improve connection conditions. Low-strength materials such as aluminum and magnesium are used to avoid wire slip and misalignment, obtaining excellent connection performance.

2) Wear resistance. It is used for often disassembled parts, which can significantly improve the thread's service life.

3) Increase the force surface. It is used for parts requiring a solid connection without increasing the diameter of the screw hole.

4) Anti-loose. Especially for spacecraft and other products that require high safety factors.

5) Easy maintenance. The damaged screw hole is loaded into the stainless steel helical inserts, which can continue to be used after repair to avoid the possibility of reporting damage to the workpiece.

Stainless steel helical inserts classification

1. Classification by function

A . Common type of threaded Inserts (Helicoil Free-Running Inserts) marked "FR."

B. Locking Screw Lock Inserts (Helicoil Screw Lock Inserts) marked "SL"

2. Classified by steel helical insert material

A. Cr-Ni stainless steel material: Because of its combination of strength and material, it is usually used in light microstructures, aluminum alloy structures, seawater, chlorine-containing liquids, and increased corrosion resistance.

B. Copper alloy material: Use when needed in situations such as conducting electricity or self-lubricating, requiring copper, or often adjusting the rotation of the threaded connection.

C. Superalloy material: temperature at 500-750 ℃ heat resistant use; It is used for aerospace assembly technology, aircraft engines, and internal combustion engine turbine compressors operating at 750 ° C.

3. Classified by the type of internal thread formed

A. International standard ISO "M, MJ" series wire screw sleeve. Thread series marked "M," "MJ"; Spark plug Thread (Spark plug Thread) wire sleeve in this series

B.UNIFIED Thread "UN" Series of wire screw (UNIFIED Thread Series), coarse thread marked "UNC," fine thread marked "UNF," ultra-fine thread marked "UNEF."

C.non-thread sealed Pipe Thread (British Standard Pipe Thread) thread mark number is "G"

4. Classification according to the rotation direction of the stainless steel helical inserts

A. right-hand stainless steel helical inserts

B.left-handed stainless steel helical inserts

5. Classified according to whether the steel wire screw sleeve has a mounting handle

A. There is a mounting handle with stainless steel helical inserts

B. No mounting handle stainless steel helical inserts

6. According to the stainless steel helical inserts coating classification

A. No surface treatment layer stainless steel helical inserts

B. There is a surface treatment layer of stainless steel helical inserts such as silver plating, cadmium plating, coloring, oxidation, etc.

Structure and characteristics of stainless steel helical inserts:

1. The Structure of the stainless steel helical inserts

The stainless steel helical inserts are wound by high hardness corrosion-resistant steel wire with a diamond cross-section and a spring-shaped concentric body with internal and external threads. The outer thread is threaded into the thread groove, which is specially installed on the stainless steel helical inserts on the machine part. The inner thread is the standard internal thread used for fastening the connector, and the profile shape is the combination of internal and external two screws. The stainless steel helical inserts are divided into two types: ordinary type and locking type, each of which has no break slot and has a break slot.

The locking type is a multilateral locking ring with one or more rings added based on ordinary stainless steel helical inserts. The elasticity of the locking ring has a braking effect on the screw. The locking type stainless steel helical inserts has all the advantages of the ordinary type stainless steel helical inserts, does not affect the installation of the screw, and only increases the appropriate torque during installation.

2. The characteristics of stainless steel helical inserts

(1) The diameter of the stainless steel helical inserts in the free state is slightly larger than the diameter of the screw hole it is loaded into; the stainless steel helical inserts are subjected to an exceptional wrench torque to make its diameter smaller into the screw hole that has been tapped with a special tap, after installation, the stainless steel helical inserts produces a similar role of spring expansion, so that it is firmly fixed in the screw hole, and will never be brought out with the screw.

(2) Increase the bearing capacity and fatigue strength of threaded connections: The stainless steel helical inserts form an elastic connection between the screw and the internal thread hole of the installation stainless steel helical inserts, thus eliminating the screw moment and tooth half Angle error between the internal and external threads, and can evenly distribute the load on each circle of threads at the specified length, thus strengthening the internal thread and damping the vibration, so that the fatigue strength of the threaded connection of parts can be improved.

(3) Wear resistance: The stainless steel helical inserts are made of rigid cold-rolled stainless steel wire, the helix surface hardness can reach HRC43 ~ 50, and the mirrorlike surface (finish up to 2 ~ 4μm) reduces friction and wear, can reduce the torque generated by friction on the screw by 90%, to obtain the maximum tightening torque and screw tension with the most negligible tightening screw torque, to prevent screw loosening. Make the screws of various materials in the best-use state.

(4) Corrosion resistance: Due to the excellent corrosion resistance of the stainless steel wire screw sleeve, it can ensure its performance in a variety of materials and usual environmental conditions, and the assembly using the wire screw sleeve will not be stuck and rust.

(5) Heat resistance: the stainless steel helical inserts can prevent the thread connection from getting stuck or bruised at high temperatures.

(6) Material saving: compared with the ordinary standard internal thread, under the same strength conditions, after using the stainless steel helical inserts, to make the best use of the yield limit, the screw with smaller size and higher strength can be selected, so that a lot of materials can be saved, weight and volume can be reduced.

(7) The locking type stainless steel helical inserts can lock the screw in the threaded hole, and when it is subjected to vibration and impact, the screw can not be loosened and fall off, which is better than the usual locking device. The locking stainless steel helical inserts can be disassembled several times without reducing the torque of the thread and are also highly reusable.

Stainless steel helical inserts installation tool:Stainless steel helical inserts installation needs to use stainless steel helical inserts special tools, mainly including stainless steel helical inserts special tap, Stainless steel helical inserts installation wrench, punch, sleeve remover, and stainless steel helical inserts inner thread bottom hole plug gauge, among which, the tap is used for processing stainless steel helical inserts installation thread bottom hole, the installation wrench is used for stainless steel helical inserts installation, the punch breaker is used for the installation of the tail shank, and the sleeve remover is used for the removal of stainless steel helical inserts. The bottom hole plug gauge is used to check the installation of the bottom hole.

1. Bottom tap: It processes the internal thread installed by the stainless steel helical inserts. Because the external thread of the Stainless steel helical inserts is non-standard, this tap is different from the ordinary M tap in size.

2. Installation wrench: used for the installation of the stainless steel helical inserts in the bottom hole of the thread; the basic principle is to make the stainless steel helical inserts through a guide thread, forcing the outer diameter of the stainless steel helical inserts to shrink, to smoothly load into the bottom hole, divided into manual type and automatic type two.

3. Punch breaker: The punch breaker's purpose is mainly to break the mounting handle of the stainless steel helical inserts. The mounting handle must be punched for the through hole.

4. Sleeve remover: used to take out the wire screw sleeve installed in the matrix thread hole for the long-term use of the stainless steel helical inserts need to be replaced, and due to the installation is not in place, or the phenomenon of thread skipping during the installation process and need to be taken out.

5. Thread plug gauge: used to detect the inner thread bottom hole of the stainless steel helical insert installation. After the stainless steel helical insert installation, the accuracy of the internal thread formed depends on the profile manufacturing tolerance of the stainless steel helical inserts and the tolerance of the inner thread bottom hole of the stainless steel helical inserts.

Application range and advantages of stainless steel helical inserts:In addition to the aerospace military, stainless steel helical inserts are widely used in railway transport, construction machinery, textile machinery, medical equipment, paper, weapons, radar, rocket, ship, steam turbines, chemical, and other civilian products. In foreign countries, it is used not only in the aircraft and aerospace industry but also in ships, automobiles, machine tools, motors, textile machinery and instrumentation, and other industries. This silk sleeve is also widely used in light industrial products such as cameras, sewing machines, and composite furniture.

As a kind of screw sleeve fastener, the internal thread after preinstallation has obvious advantages compared with the ordinary thread:

1. Extend the service life: because the stainless steel helical inserts of stainless steel material have high hardness, the thread life of the softer base parts is increased by tens to hundreds of times, Increasing its strength but also avoiding the occurrence of tripping, random buckle phenomenon.

2. Strengthen the threaded connection strength: applied to soft, low-strength alloy materials such as aluminum and magnesium, which can effectively enhance the connection strength of the thread; the ordinary internal thread of aluminum profile, its maximum tensile strength is 1394N, and the internal thread of pre-installed stainless steel helical inserts, its minimum tensile strength can reach 2100 N. [2]

3. Increase the force surface: It can be used for thin body parts requiring strong connection without increasing the diameter of the screw hole.

4. Improve the connection conditions, and increase the bearing capacity and fatigue strength of threaded connection: Because the wire screw sleeve is an elastic fastener, the use of stainless steel helical inserts can eliminate the pitch and tooth deviation between the screw and the screw hole, so that the load is evenly distributed, thereby improving the bearing capacity and fatigue strength of the threaded connection.

5. Anti-rust: the characteristics of the stainless steel helical inserts material itself and its surface are incredibly smooth, used in harsh environments such as humidity and corrosion, and will not rust the matrix, avoiding the loss of replacing the expensive matrix because the thread hole rust can not be disassembled. It can be used in the chemical industry, aviation, military equipment, and other occasions requiring a high insurance coefficient.

6. Wear resistance, heat resistance, corrosion resistance: due to the high surface finish of the stainless steel helical inserts, it can effectively reduce the friction between the internal and external threads, and the material itself has high-temperature resistance and corrosion resistance characteristics. It can be used in frequently disassembled and installed parts and often rotated screw holes to extend its service life.

7. Anti-seismic, anti-loosening: the particular Structure of the locking screw sleeve can lock the screw in the screw hole in a strong vibration and impact environment. It will not be loosened, and its locking performance is better than other devices. It can be used for instruments, precision, valuable power equipment, aerospace, aviation, military equipment, and other occasions requiring high insurance coefficients.

8. Easy maintenance: In the occurrence of thread processing errors or repair of damaged internal threads, the use of stainless steel helical inserts can make the matrix back to life and can use the original screw, both fast and economical. Simple examples, such as diesel engine bodies, textile particular parts, various aluminum parts, lathe tool tables, etc., due to screw hole damage and scrap, as long as it is retapped, install the stainless steel helical inserts and the waste parts are resurrected.

9. Conversion: The use of stainless steel helical inserts for metric → Imperial → international standard thread hole conversion, which is very convenient, fast, economical, practical, and suitable for any import and export products.

Marking method of stainless steel helical inserts

Specification marking method:

1. According to the domestic production of stainless steel helical inserts marking method:

(1) ST (common type) STd (diameter) p (pitch) -ND

(2) ZST (locking type) ZSTd (diameter) p (pitch) -ND

(3) ZGST (high-temperature locking type) ZGSTd (diameter) p (pitch) -ND

2. According to foreign production of stainless steel helical inserts marking method:

(1) FR(common type)MD (diameter) ×P (pitch) -nD(diameter)

(2) SL(locking type)MD (diameter) ×P (pitch) -nD(diameter)

Standard marking method: D(diameter)×P(pitch)×N or W(number of stainless steel helical inserts rings in free state)

Note: Each domestic standard has specific provisions on the marking method of the stainless steel helical inserts; see each detailed specification table standard.

Stainless steel helical inserts installation steps:

1. Drilling: Select the corresponding standard drill bit according to different specifications, and the drilling depth is greater than or equal to the installation depth of the stainless steel helical inserts. Be careful not to drill the hole into a cone so chips do not fall. The hole after training should not exceed 0.4 pitch depth because the hole is too large and is not conducive to the screwing of the stainless steel helical inserts.

2. Tapping: The use of stainless steel helical inserts special tap marked with the specified thread specifications; the length of the tapping must exceed the size of the stainless steel helical inserts, for the through hole, to all tapping; The accuracy of tapping determines the tolerance zone of the final standard inner screw hole, the user should adequately select the tapping method and lubrication, and the blind hole tapping should be appropriately applied to prevent the tap from breaking. After tapping, the threaded holes should be cleaned, generally blown with a compressed air spray gun; blind holes should also use a long spray gun with radial holes for bottom-up cleaning; you can also clean the threaded holes by the cleaning method. When the precision of the threaded hole is high, the unique stainless steel helical inserts bottom hole plug gauge is used for inspection.

3. Installation: under normal circumstances, the manual installer is used for stainless steel helical insert installation. Put the stainless steel helical inserts into the installation tool, make the installation handle insert into the guide rod groove, turn the installation tool handle to screw the stainless steel helical inserts into the screw hole, and leave 0.25-0.75 circles of empty thread from the surface. When a small amount of stainless steel helical inserts is installed and when M14×2 or more coarse teeth stainless steel helical inserts are installed, a "T" type slotted or threaded head simple tool can be used to install, and be careful not to exert a large axial force on the stainless steel helical inserts mounting handle to prevent "random buckle." After installing the stainless steel helical inserts, the corresponding level plug gauge can be checked for the accuracy level of the standard internal thread hole formed.

4. Handle removal: For the stainless steel helical inserts with a broken slot, the mounting handle should be removed after screwing into the screw hole, and the handle removal tool is required. Through the hole, to break the stainless steel helical inserts installation handle, generally with the thruster to the installation handle, with about 200g hammer can be removed, for M18×2.5 coarse tooth stainless steel helical inserts and M14×1.25 delicate tooth wire screw sleeve, with needle nose pliers bending up and down the installation handle can be broken. Then remove the broken mounting handle from the screw hole.

Note: If the automatic punch is used, use the punch of the automatic punch to properly press the stainless steel helical inserts installed into the bottom hole to break the mounting handle.

5. Disassembly: Put the tip of the disassembly into the hole of the stainless steel helical inserts, press and hold the handle, and rotate in the counterclockwise direction to remove the stainless steel helical inserts.

Stainless steel helical inserts installation test:After the installation of the stainless steel helical inserts, the thread hole tolerance zone depends on the stainless steel helical inserts profile manufacturing tolerance and the stainless steel helical inserts mounting hole thread tolerance zone; the stainless steel spiral inserts manufacturer controls the former; the latter mainly depends on the tapping accuracy of the wire screw sleeve mounting hole, usually forming a 6H grade, when the accuracy is high, it can reach 5H, 4H grade tolerance zone, and the unified thread standard is 2B, 3B. The bottom hole thread can be tested using the corresponding level plug gauge.

Stainless steel helical inserts type standard:The production of stainless steel helical inserts is strictly implemented by specific standards. Commonly used are national military standards, navigation standards, German standards, American standards, and so on.

●HB6200-89 Aviation industry standard "with broken groove locking type wire screw sleeve"

●HB6201-89 Aviation industry standard "No break slot locking type stainless steel helical inserts"

●HB6202-89 Aviation industry standard "Locking type stainless steel helical inserts technical conditions"

●JB/T7604.1~4-94 Ministry of Machinery Industry standard "Locking type stainless steel helical inserts"

●Q/9D204.1~3-1999 Enterprise standard "Ordinary thread sleeve"

● German standard DIN8140 Part 1, Wire thread inserts for ISO metric screw threads

● US Standard MS 33537 Revision E, Assembly dimensions for screw thread inserts

MS 21209 Series, Insert, screw thread. Screw locking. Stainless Steel Helical Inserts for Particle-Free Environments, Made of Nitronic 60 stainless steel, these inserts prevent the screw from binding or sticking without any coating or lubricant that could contaminate particle-free environments. Also known as Heli-Coil inserts, they have coils that expand once installed to anchor the insert securely. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw. Installation requires a drill bit, a helical insert tap, an installation tool, and a prong break-off tool. Lubricated Stainless Steel Helical Inserts, A dry film keeps the screw from sticking or binding in these inserts during installation. Also known as Heli-Coil inserts, they have coils that expand once installed to anchor the insert securely. All have a prong for ease of installation. An installation tool grips the prong and reduces the coil diameter, enabling the insert to fit in tapped holes. Remove the prong to insert the screw.

Installation requires a drill bit, a helical insert tap, an installation tool, and a prong break-off tool. Inserts that meet DIN 8140 adhere to international standards for dimensions. Lubricated Stainless Steel Helical Inserts for Dissimilar Metals, Nickel Alloy Helical Inserts, Titanium Helical Inserts, Stainless Steel Screw-Locking Helical Inserts, Lubricated Stainless Steel Screw-Locking Helical Inserts, Stainless Steel Screw-Locking Helical Inserts for Particle-Free Environments, Screw-Locking Helical Inserts without Prong. Without a prong to break off and retrieve, these inserts are often used where debris could cause damage. Also known as Heli-Coil inserts, they have coils that expand once installed to anchor the insert securely. Installation requires a drill bit, a helical insert tap, and an installation tool. Add an extraction tool to remove these inserts.

If you are looking for high-quality steel helical inserts and fasteners or technical support for structural design, you are welcome to contact me. Thanks.Email:adelajonly@gmail.com

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