Many reasons can cause spring failure, but in general, it can be from two aspects, one is the spring quality, and the other is improper use. The quality problems of the spring itself include unqualified spring material, unqualified heat treatment, damage in the manufacturing process, and so on. Improper use includes use beyond the limit of use, use in an environment where the temperature is too high, use in a corrosive environment, etc. The main failure modes are as follows:

The Main Forms of Spring Failure

Plastic deformation

The stress produced by the external load is greater than the yield strength of the material. After plastic deformation, the spring cannot return to its original size and shape.

Rapid brittle fracture

Some springs have material defects, processing defects (such as folding, and scratches), heat treatment defects (such as excessive quenching temperature leading to coarse grains, insufficient tempering temperature leading to insufficient material toughness), and so on. These springs may experience sudden brittle fractures when subjected to excessive shock loads.

Fatigue fracture

Under the action of alternating stress, the surface of the spring is defective, resulting in a crack fatigue source. Fracture failure occurs after crack propagation.

Springs used in corrosive media are prone to stress corrosion cracking failure.

Spring fittings used at high temperatures are prone to creep and stress relaxation, resulting in permanent deformation.

The main factors causing spring failure can be divided into 3 categories: spring material, spring design, and spring manufacturing process.

Spring Material

The chemical composition and mechanical properties of different steel grades in spring steel have their own characteristics. Generally speaking, the manufacturing material of spring should have a high elastic limit, fatigue limit, impact toughness, and good heat treatment performance. Commonly used are carbon spring steel, alloy spring steel, stainless spring steel and copper alloy, nickel alloy, and rubber. The spring material should be selected reasonably and correctly according to the stress requirements, service life requirements, and working environment requirements of the spring. Generally, we divide the tensile strength Rm into three levels, that is, the standards are given according to high, medium, and low.

If we use low-strength spring materials to produce springs bearing high stress in production, it is easy to produce permanent deformation and fail. If high-strength spring materials are used to produce spring products that require high fatigue life, the possibility of brittle failure of the spring under high-stress conditions increases.

The higher the strength of the spring material, the greater the tendency of the material to brittle fracture. Therefore, the correct and reasonable selection of spring materials with moderate mechanical properties can not only make the spring workload excellent, but more importantly, it can have excellent working performance under high fatigue life. Therefore, spring failure is closely related to the spring material.

Spring Design

A spring with good fatigue life needs to be designed by many people and through the knowledge of many disciplines.

When designing a spring, you need to understand what is necessary for a good spring fatigue life. Many spring products will fail due to unreasonable design parameters, resulting in permanent deformation in the early stage of use.

Spring Manufacturing Process

The forming, stamping, and bending of the spring during the manufacturing process may cause certain damage to the spring material. Some of these damages are obvious and some are invisible, especially for tension springs, torsion springs, and other special-shaped springs.

The maximum stress of the spring is on the surface of the spring material, and the fatigue fracture of the spring often starts from a small surface defect on the surface of the spring material. Then, under the action of alternating load, it gradually transitions and expands, and after a certain stress cycle, it will lead to spring fatigue failure.

KENENG has more than ten years of experience in manufacturing fasteners such as screws, nuts, bolts, etc., and can perform various surface treatments on them.

Common white screws mainly include electroplating white nickel, white zinc, and so on.

The process of electroplating white zinc is degreasing-cleaning-weak acid activation-electro-galvanizing-cleaning-white passivation-cleaning-drying. The difference from black zinc is that there is no over-sealing paint, and the passivation solution is also different. White passivation is a colorless and transparent zinc oxide film that contains almost no chromium, so the corrosion resistance is worse than that of black zinc, blue zinc, and color zinc.

The corrosion resistance of white zinc is better than that of white nickel, and its appearance is darker than that of white nickel.

The process of electroplating white nickel is degreasing – cleaning – weak acid activation – cleaning – copper plating bottom – activation – cleaning – nickel plating – cleaning – passivation – cleaning – drying – or sealing. The process of electroplating white nickel and electroplating black nickel is basically the same, the difference lies in the formula of the electroplating solution, without the addition of zinc sulfide.

Other Color Plated Screws

The plating of other colors mainly includes blue zinc, green zinc, colored zinc, and Dacromet.

The electroplating process of blue zinc and green zinc is roughly the same as that of white zinc. Blue zinc is a passivated zinc oxide film containing 0.5-0.6 mg/dm2 of trivalent chromium. Green passivation is due to the fact that the passivation solution contains phosphate ions, and the resulting green film is composed of chromate and phosphate.

The corrosion resistance of blue zinc is better than that of white zinc, and the corrosion resistance of green zinc is better than that of blue zinc.

Color zinc has relatively good corrosion resistance. The passivation process is: galvanizing – cleaning – 2%-3% nitric acid to emit light – cleaning – low chromium color passivation – cleaning – baking aging. Too low temperature during passivation will result in slow film formation and thin color film. The high temperature will cause the film to be thick and loose, and the adhesion will not be strong. It’s best to control around 25 degrees to ensure that you get the same color for a certain amount of time. After passivation, it needs to be baked to improve the adhesion and corrosion resistance of the film.

Dacromet

Dacromet is a new type of screw surface treatment, anti-corrosion coating with zinc powder, aluminum powder, chromic acid, and deionized water as the main components. The process flow is organic solvent degreasing – mechanical polishing – spraying – baking – secondary spraying – baking – drying.

The advantage of the Dacromet process is that the corrosion resistance is very good, but the disadvantage is that the coating is not uniform.

Surface treatment is a process method, which refers to the artificial formation of a surface layer on the surface of the substrate material with different mechanical, physical, and chemical properties from the substrate. The purpose of surface treatment is to meet the requirements of product wear resistance, corrosion resistance, decoration, and so on.

In the selection of screws, in addition to the main consideration, the color of the appearance and corrosion resistance should also be considered. Common surface treatment processes for screws include oxidation, electrophoresis, electroplating, dacromet, and so on.

Black Oxidation Treatment

Black oxidation treatment is a common method of chemical surface treatment, the purpose is to produce an oxide film on the metal surface to isolate the air and prevent rust.

The process is to use a strong oxidant to oxidize the surface of the steel into dense and smooth ferroferric oxide. This thin layer of ferroferric oxide can effectively protect the inside of the steel from oxidation. Divided into low temperature and high temperature.

Ferroferric oxide formed at low temperatures (about 350°C) is dark black, also known as blackening. Ferroferric oxide formed by oxidation at high temperatures (about 550°C) is sky blue, also known as bluing treatment. The blue treatment is commonly used in weapon manufacturing, and the black treatment is commonly used in industrial production.

Oxidizing the steel surface to dense, smooth ferroferric oxide requires a strong oxidant. The strong oxidant is composed of sodium hydroxide, sodium nitrite, and trisodium phosphate. When it turns blue, treat the steel with a strong oxidant melt, and when it turns black, treat it with an aqueous solution of a strong oxidant.

Electroplating

Electroplating is the process of using electrolysis to coat a layer of other metal films or alloy films on the metal surface. The purpose is to improve wear resistance, corrosion resistance, and aesthetics.

There are 2 types of black plating: black zinc plating and black nickel plating.

Black zinc plating is a kind of anti-oxidation processing of metal, which is suitable for hardware products. Zinc is chemically active and easily oxidized and darkened in the atmosphere. After galvanizing, it is treated with chromate to cover a chemical conversion film on the zinc, so that the active metal is in a passive state, which is the passivation treatment of the zinc layer. The passivation film can be divided into white passivation (white zinc), light blue (blue zinc), black passivation (black zinc), green passivation (green zinc), etc.

Usually, the process of electroplating black zinc is degreasing-cleaning-weak acid etching-electro-galvanizing-cleaning-passivation-cleaning-drying-sealing paint.

The black nickel coating obtained from the black nickel bath contains 40-60% nickel, 20-30% zinc, 10-15% sulfur, and about 10% organic matter. The black color is caused by the presence of black nickel sulfide in the coating due to the reduction of thiocyanate on the cathode to release sulfide ions. The copper bottom is added in the process, and the main function is to make nickel plating easier in the post process and to improve the corrosion resistance of the screw.

Electrophoresis

Electrophoresis refers to the phenomenon in which charged particles move toward electrodes of opposite electrical properties under the action of an electric field.

Black electrophoresis is the use of an external electric field to make particles such as pigments and resins suspended in the electrophoresis solution directionally migrate and deposit on the substrate surface of one of the electrodes. Electrophoretic black is widely used in the industry, taking the black process as an example: degreasing – cleaning – phosphating – electrophoretic paint – drying. It can be divided into anodic electrophoresis (resin becomes negative ions after ionization) and cathodic electrophoresis (resin becomes positive ions after electrophoresis). Compared with the painting process, it has better construction performance, less pollution and harm to the environment and its resistance to neutral salt spray is 300 hours or more, and the cost and corrosion resistance are similar to those of the dacromet process.

The washer is a kind of fastener with a flat circular shape. It is placed between the support surface of the bolt, screw, or nut and the surface of the connecting parts, playing a role in increasing the contact surface area of the connected parts, reducing the pressure per unit area and protecting the surface of the connected parts from being damaged. Generally speaking, the gasket has two functions. One of the functions is to protect the surface of the connected parts from friction damage by the nut. Another function is to disperse the pressure of the nut on the connected parts.

Flat Washers

When the bolts need to be disassembled frequently, in order to protect the surface of the connected parts from being scratched, it is generally necessary to place a flat washer at the position of the nut or bolt head, so as to prevent the surface of the connecting parts from being scratched.

In the bolted connection, the pressure transmission of the bolt head or the nut-bearing surface is gradually expanded in a trumpet shape. The larger the bearing surface, the smaller the compressive stress. Therefore, adding a flat washer can reduce the compressive stress on the contact surface of the connected parts and ensure the effectiveness of the bolted connection.

Spring Washers

The main purpose of the spring washer is to relax, and it is generally used on occasions where the bolt pre-tightening force is not high and the dynamic load is small. In fact, the spring washer has a little anti-loosening effect. Therefore, for the tightening occasion with a relatively high pre-tightening force and the connection is more important, the spring washer is not recommended.

KENENG is an excellent washer manufacturer, with an excellent design and development team, production equipment, perfect testing strict regulatory system, supply of complete specifications washer, attentively to select high-quality materials, strict testing product quality, price, and laminating the minds of the customer support a variety of materials and styles of customization, and warm after-sales service.

KENENG produce both standard and stock washers including copper washer, plastic washer, ss washer, steel washer, and other types. And all are used for supporting screws, there is a certain tolerance, and there is no problem with the use of screws. If you do not understand the size, please contact our customer service.

Non-standard washer customization needs customers to coordinate design and production with us, according to the actual use of the environment, installation space, size to choose the material of the washer, OD(Outside diameter) or ID( Inside diameter), size, and special processing technology.

Screws refer to a tool that gradually tightens a part using the mathematical and physical principles of the beveled circular rotation and friction of an object. Screws are a common fastener that is widely used in daily life and production. The general material is plastic or metal, and the grooves engraved on the surface are called threads, which are cylindrical.

Screws can be divided into:

Hexagon head, hexagon head with flange, square head, T head, mushroom head, cheese head, round head, pan head, countersunk head, raised countersunk head.
One-line slot, inner triangular slot, inner corner quad slot, cross slot, rice slot, flower slot, plum blossom slot, flower one-line slot, special slot, and hexagonal slot.

Why do screws have so many head types?

1. In many cases today, one-line head screws have been replaced by cross head screws. Because the one-line head screw is more likely to be screwed so that the pattern on it cannot be seen clearly, the screwdriver cannot be used. The contact area between the one-line head and cross head type and the tool is much smaller than the contact area between the inner and outer hexagon head and the tool. Therefore, there will be no problem with distortion and failure of the inner and outer hexagons.

2. Regarding countersunk head screws and non-countersunk head screws. The bases of laptops in our lives are countersunk screws. However, due to the complexity and cost of processing, it is not necessary to use countersunk head screws on some unnecessary occasions.

Bolts are mechanical parts that is a cylindrical and threaded fastener that requires a nut. It consists of a head and a cylinder with an external thread, which needs to be matched with a nut to fasten and connect two parts through holes. The bolts can be divided into ordinary ones and those with hinged holes according to the force of the connection. According to the shape of the head, it can be divided into hexagonal head, round head, square head, countersunk head, and so on. Among them, the hexagon head bolt is the most commonly used shape.

Nuts are a part that is screwed together with a bolt for fastening and has different classifications depending on the material, including stainless steel, copper, alloy, etc.

The main difference between screws and bolts is that screws work individually. The thread matched with the screw is machined on the workpiece. But the bolt and the nut work together, and the thread matched with the bolt is machined on the nut.

They play similar roles but in different contexts. Bolts and nuts are pre-purchased standard parts, and the objects to be connected only need to punch a suitable through-hole for each connection. Screws can be used in situations where one of the objects to be linked cannot make a through-hole, then screw links can be used.

KENENG is a custom screw manufacturer. Customized fasteners are available for special lengths, and tolerances regarding length or body diameters. Or due to certain strength requirements or corrosion situation requirements, these special cases may require special materials. In many of these situations, the customer’s engineering department will provide a CAD drawing showing all aspects of the fastener required for the company’s production. To guarantee high quality, KENENG has more than 500 sets of production and testing equipment, which are imported from Japan, Switzerland, America, and Taiwan, including cold forming, CNC, stamping, hot forging, turning, and cold drawing, heat treatment, and plating lines. We can undertake large quantities of orders, and ensure the quality of products and delivery time. Consistent purpose to price as the vanguard, service as the core, quality as the leading. Welcome to contact us and cooperate with drawings and samples.

For more useful information, see more on best guide to screws, bolts and nuts.

A magnet is defined as an object which is capable of producing a magnetic field and attracting unlike poles and repelling like poles.

There are many types of magnets, which are generally divided into two categories: hard (permanent) magnets (magnetic retention for a long or permanent time) and soft magnets (magnetic for a short period of time). The magnets we call generally refer to permanent magnets.

Magnet classification

Magnet Sort by material

(1) Alloy permanent magnet material

Including rare earth permanent magnet materials (NdFeB Nd2Fe14B), samarium cobalt (SmCo), aluminum nickel cobalt (AlNiCo)

(2) Ferrite permanent magnet material (Ferrite)

Magnet sort by shapes.

Tile-shaped magnets(Arc shape), special-shaped magnets, cylindrical magnets, ring magnets, disc magnets, block magnets, and various shapes can be punched holes.

Classification by production process

Rare earth permanent magnet material

Magnets applications

1. Electroacoustic field: speakers, receivers, microphones, alarms, stage audio, car audio, etc.

2. Electronic appliances: permanent magnet mechanism vacuum circuit breakers, magnetic latching relays, watt-hour meters, water meters, sound meters, reed switches, sensors, etc.

3. Motor field: VCM, CDDVD-ROM, generators, motors, servo motors, micro-motors, motors, vibration motors, etc.

4. Mechanical equipment: magnetic separation, magnetic separator, magnetic crane, magnetic machinery, etc.

5. Healthcare: nuclear magnetic resonance apparatus, medical equipment, magnetic therapy health care products, magnetized fuel saver, etc.

6. Other industries: magnetized wax inhibitor, pipe descaler, magnetic fixture, automatic mahjong machine, magnetic lock, door and window magnet, luggage magnet, leather magnet, toy magnet, tool magnet, craft gift packaging, etc.

KENENG is an excellent custom magnet manufacturer. We can manufacture neodymium magnets, permanent magnets, magnet rod and other magnets of different materials and shapes. We have 15 years’ experience in magnets design, manufacturing, coating, and export all over the world, we have won a good reputation in this industry for our excellent and stable quality, prompt delivery, and fast response.

KENENG support customizing making low-temperature and high-temperature resistant magnet assemblies, making general materials and special materials, and strong magnetic.

Various finishing methods

1. Zinc plating (bright and clear film with low corrosion resistance)

Used in high temperature and slightly corrosive conditions or limited anti-corrosion occasions where the surface is resistant to short-term pollution and discoloration

2. Zinc plating layer (rainbow or dark film with higher corrosion resistance)

Used in harsh atmospheric environments and high-demand anti-corrosion occasions

3. Nickel plating layer (including copper + nickel plating layer)

Exposure to the indoor atmospheric environment where condensation may occur, and it is required to ensure long-term stability and long service life of appearance and internal performance.

4.Nickel + tin electroplating layer

For the occasions where the surface can be soldered and electrically contacted

5. Phosphate layer

It has a certain short-term rust prevention ability, which is used for unfinished halfway transportation and rust prevention of short-term storage. The more ideas come from you, the more chances to change the world.

The battery holder can be used to assemble various batteries such as ordinary dry batteries, lithium batteries or other rechargeable batteries on the equipment that needs electricity, and is used to replace the special lithium batteries in the prior art, so that the types of batteries that can be used on multifunctional cameras Increased, even if the battery is dead, it can continue to function just by immediately replacing it with a new battery, which is very convenient.

The role of the battery holder in the camera

The battery holder in the camera is used in the battery bay. It is composed of a box body and a cover body. The box body and the cover body are combined together to form a hollow cavity for accommodating the battery. The hollow cavity is provided with conductors for realizing the electrical connection between the battery and the power supply terminal of the multifunctional camera.

By using the battery box, the number of batteries can be expanded and the operating time of the camera can be increased. The battery case can assemble various batteries such as ordinary dry batteries, lithium batteries, or other rechargeable batteries in a multi-function camera with video and photographic functions. It is used to replace the special lithium battery in the existing technology so that the types of batteries that can be used on the multi-function camera are increased.

KENENG is an experienced battery holder manufacturer, KENENG can also carry out custom battery holder services. We have a wealth of R&D and manufacturing personnel in the battery holder field, and have become partners of Medtronic, Sakura, BBC, Xiaomi, Gree, ZTE, Haier, BYD and so on. We have always provided wholesale battery holder services, and customers at home and abroad are welcome to contact us at any time.

Why choose KENENG battery holder?

Professional production base

KENENG has a professional production line of various types of battery holders. The scale of the factory has reached 10,000 square meters, with 150 employees.

Rich export experience

With more than 20 years of manufacturing experience.

KENENG’s battery holder export experience has reached 15 years.

High-quality products

KENENG has passed ISO9001, ROHS, Dun & Bradstreet certification. KENENG has a strict quality control system, and the pass rate of battery holders is as high as 99%.

Massive market share

Designated supplier to Medtronic and the BBC.

Occupy 50% of China’s electronics market

The marine mooring system refers to the use of equipment to fix the ship at the wharf or other places to limit its movement. So, how to select the best marine mooring equipment?

Choosing The Mooring Bollard

1. For the selection of mooring bollards, attention shall be paid to the requirements of the specification and size. Because of the different specifications and sizes of the ships, there are certain restrictions on the device.

2. Attention shall be paid to the restrictions on the installation position to avoid problems in the installation.

3. Attention shall be paid to the installation requirements, especially the power restrictions, to ensure that the installation of the device meets the stability requirements and ensures the effect.

4. It is necessary to pay attention to the functional requirements and functional limitations, especially the functional requirements of the cable and the limit of the bearing capacity, to ensure the stability of the device in use.

Choosing The Marine Mooring Chock

1. Corresponding types: Different types of products have different structural shapes. We need to choose the corresponding type chock to be able to use normally because of the appropriate structural shape.

2. Corresponding models: There are different models of the same type of mooring chocks, and there are certain differences in decoupling strands and materials between different models of it. Based on this situation, we need to select the corresponding model of products to be applicable.

3. High precision: Because the application has high requirements on the structure and quality of the mooring chock, it needs products with high precision, which will have better applicability because of the excellent comprehensive quality.

Choosing The Roller Fairlead

1. When selecting, it is necessary to see whether the surface of the device in contact with the cable is smooth. To avoid large abrasion of the cable during use, which may lead to the cable being easily broken and unable to be used for a long time.

2. Observe the steel parts except for the body and pin shaft. Generally speaking, there is no problem with the fairlead roller in the body and pin shaft structure. Therefore, it is suggested that when selecting the device, we should focus on other steel parts, especially paying attention to whether the steel parts other than the body and pin shaft have been galvanized or painted.

Selecting Marine Anchor

1.Bruce claw anchor is one of the most popular anchors among leisure rowers in North America. For most rowers, Bruce or delta is the best balance between price and performance.

2. Plow anchors are suitable for most bow rollers. Fluke anchors are the perfect choice for auxiliary anchors or stern anchors. They perform well in sediment and can be easily stored on most bow rollers.

3. The head anchor of commercial ships mainly adopts rod less anchor, and the tail anchor sometimes adopts rod anchor and dovetail anchor.

4. There are many types of anchor materials, the most popular are low-carbon steel, high-strength steel, stainless steel, and aluminum. Most of the traditional steel anchors we are used to seeing in the market may be low-carbon steel or high-strength steel. When selecting ship anchors, in addition to the factors such as the length and weight of the ship, it is also necessary to carefully select the anchor materials.

Mooring is an integral part of cargo transportation. During the mooring period, the ship faces various natural forces and human forces. The mooring system refers to the use of equipment to fix the ship at the wharf or other places to limit its movement. There are five types of common mooring equipment that is essential.

Mooring Bollard

The mooring bollard is mooring ship equipment installed in the superstructure of the wharf. It is designed and selected according to the berth capacity and wharf structure type to meet the requirements of the safe, reliable, and convenient operation of ships leaving the wharf, berthing, shifting, and turning. It is composed of a shell, anchor rod, nut, washer, anchor plate, and column core packing. The most common types in the shipping industry are column mooring bollard and Cruciform Bollard.

Marine Mooring Chock

Marine mooring chock is a closed-hole fairlead that is arranged on the bulwark and used to limit the leading out of the position of the cable. The basic shapes are round, oval, square, and closed mooring chock.

204 steel seamless steel pipe specified in GB 8162 is selected as the material of its body. It can also be bent from grade a steel plate specified in GB 712. 1Cr18Ni9Ti stainless steel plate specified in GB 4237 is selected as the stainless steel clad plate. At the intersection line of the body and the outer edge, the welding surface shall be clean and free of cracks, warpage, and skew. The cutting shall be straight and the sharp edge shall be removed. The stainless steel clad plate shall be flat with the body, and the weld shall be free of defects such as pores, cracks, and burrs.

Roller Fairlead

Roller fairlead is a fairlead composed of several independent rollers in parallel, which can be divided into the closed type and open type.

According to the number of rollers, the commonly used two roller, three roller, and four roller fairleads. It can export several cables at the same time, and its mass is smaller than that of the fairlead with rollers. It is mainly used on large and medium ships.

Rubber Fender

A rubber fender is installed on the wharf or ship to absorb the collision energy between the ship and the wharf or ship when berthing or mooring, and protect the ship and the wharf from damage.

It is divided into the following categories: cylindrical rubber fender, DA type rubber fender, D type super arch rubber fender, drum type rubber fender, DO type rubber fender, and V type rubber fender. They are different in reaction force, surface pressure, device maintenance, and convenience of use.

Marine Anchor

The main function of the marine anchor is to fix and stabilize the ship. After the anchor is pulled into the water bottom, it can provide berthing capacity for the ship.

It should be noted that this capability is not only accomplished by one anchor, but also by a long anchor chain.

There are many types of anchors, which can be divided into rod anchors (also known as naval anchors), Rodless anchors (commonly known as hall anchors and Speke anchors), high grip anchors (generally rod rotating claw anchors), and special anchors (commonly used for permanent mooring) according to different structural solutions and uses.

Spring is a mechanical parts using elasticity to work. The parts made of elastic materials are deformed under the action of external force and the original state is restored after removing the external force.

KENENG is one of the leading China spring suppliers, providing both standard stock products and customized service, with 20 years designing, researching and developing, manufacturing experience, a variety of standard and customized size available.

As a spring manufacturing company. KENENG have various specifications of a fully automatic computer spring coiling machine, computer spring grinding machine, continuous mesh belt quenching furnace, tempering furnace, spring tension and compression testing machine, spring fatigue testing machine, and a complete set of spring hot coil equipment. With complete production and testing equipment and advanced production technology, we can make many different kinds of springs to meet your requirement.

KENENG always adhere to the principle of “quality first”, select qualified materials, adopt advanced equipment, use professional production technology, adhere to a serious, responsible, united, and innovative working attitude, produce high-quality products, and provide humanized services, which has won the recognition of customers at home and abroad.

As a professional custom spring manufacturer, KENENG can meet various industrial requirements and the diameter can be customized ranging from 0.1 to 80mm. KENENG can provide spring customization as the drawings, turning direction including left hand and right hand, material, finishing, wire diameter, spring force, end type including closed, grounded, close and grounded, open, special processing technology for the spring all can be selected.

Non-standard spring customization needs customers to coordinate design and production with us, according to the actual use of the environment, installation space, pressure size to choose the material of the spring, line diameter, size and special processing technology.

The following basic data when ordering, so as to process and customize the drawings and samples. If there are no drawings, please send us the specifications.

(1)Specifications: wire diameter, OD (outside diameter) or ID ( Inside diameter), free length, coil numbers, active coil numbers.

(2)Technical requirements: turning direction ( left hand / right hand) , material, finishing, spring force, end type ( closed /grounded/ close and grounded/open).