Springs are mechanical components used in many products such as watches, automobiles, and cellphones. There are many types of springs, each with unique features making choosing difficult.
Therefore, there is a need to know about them. This article discusses the common spring types, their applications, materials and what causes a mechanical spring failure so that you can select the right one.
Hooke's Law: Understanding the Principle of Spring
Spring is a mechanical component that, when compressed by a load, stores the energy, and releases it when the load is removed. This is the normal way all springs function irrespective of their types, as expressed by Hooke’s law.
Hooke’s law relates the force exerted by a load on a spring and its elasticity. According to the law, the force exerted by a load needed to compress or extend a spring is directly proportional to the displacement, as expressed by the mathematical expression below: F= -kX
F = force exerted by the load on the spring
X = spring displacement (it is a negative value indicating the force to restore the spring is opposite the direction)
k = spring constant, which shows the spring stiffness and depends on the spring type
Types of springs and Their Uses
There are several types of springs used in different capacities. Generally, there are three main categories, and each category has its subcategories. Below are the properties of the different spring types and their applications.
Category One: Helical Springs
Helical springs have a general helix shape (hence the name) but different cross-sections. They are the most common types of springs in rapid prototyping and are widely applicable in product manufacturing. Below are the different types of helical springs.
Compression springs are open coiled springs with a constant diameter and space between each coil. The springs are compressible only one way as they resist axial compression. These spring types are widely applicable in product manufacturing, such as valves and suspension.
Extension springs are closed compression springs. They function by elongating during tension and storing energy. When on tension removal, the mechanical spring returns to its original shape dissipating the energy. Extension springs are an important part of garage doors, pull levers, jaw pliers, and weighing machines.
A torsion spring is attached to two components horizontally or vertically using their two ends. They function by storing and releasing rotational energy. The tighter the winding, the more energy the spring stores and releases on load removal. They are applicable in garage doors, watches, etc.
Spiral springs are rectangular metal strips made into a flat spiral that can store and release a reasonable amount of energy at a constant rate. Due to the constant release of energy, they are applicable in making mechanical watches, seat recliners, toys, etc.
Category Two: Leaf Springs
These spring types are from rectangular metal plates or leave bolted, clamped, and applicable in shock absorption in heavy vehicles. Below are the different leaf springs types.
Elliptical Leaf Spring
Elliptical leaf spring comprises two stacked, bolted, and clamped leaves with semi-elliptical shapes connected in opposite directions. Although they have opposite directions, there is no need for spring shackles due to the leaf’s subjection to the same amount of elongation on compression. These springs were important in old cars where car manufacturers attached them to the axle and frame. However, they are not much important nowadays.
Semi Elliptical Leaf Spring
Semi elliptical leaf spring comes from steel leaves having the same width and thickness but different lengths. The longest/uppermost leave is the master leaf. They are the most popular leaf spring in automobiles as they require less maintenance and have a long life.
Semi elliptical leaf springs have an end fixed rigidly to the automobile frame and the other to the shackles. Therefore, the length varies when driving in rough terrains, aiding in shock absorption.
Quarter Elliptical Leaf Spring
Like the elliptical leaf spring, the quarter elliptical leaf spring is olden. Also known as the cantilever type of leaf spring, it has one end fixed on the frame side member using a U-clamp or I-bolt and the other freely connected to the axle. Therefore, when the front axle beams experience shocks, the leaves can easily straighten and absorb the shock.
Three-Quarter Elliptical Leaf Spring
This leaf spring is a combination of the quarter elliptical spring and semi-elliptical spring. On the one hand, the semi-elliptical ends are attached to the vehicle frame and the quarter elliptical spring. On the other hand, the free end of the quarter elliptical spring is then attached to the vehicle frame using an I-bolt.
Transverse Leaf Spring
These are semi-elliptical leaf springs mounted transversely along a vehicle width. In this arrangement, the longest leaf is at the bottom while the mid-portion is fixed to the frame using a U-bolt. Transverse leaf springs lead to rolling. Therefore, they have limited use in the automobile industry.
Category Three: Disk Springs
Disk springs are springs with conical shapes and flexible effects. Consequently, they are applicable in limited space. Below are the types of disk springs.
Belleville Disk Spring
Belleville disk spring or coned-shaped disk spring has a cupped construction. Therefore, they don’t lie flat. They can compress and handle heavy loads. Therefore, they are applicable to products used in high-stress conditions.
Curved Disk Spring
Curved disk springs or crescent washers function by applying light pressure to the mating pair. Therefore, they can resist loosening due to vibration. They are applicable in products that use threaded bolts, fasteners, screws, and nuts in machines which high and constant vibration.
Slotted Disk Spring
Slotted disk springs have slots on the outer and inner diameter. Therefore, they reduce spring load and increase deflection. They are widely applicable in automatic transmissions, clutches, and overload couplings.
Wave Disk Springs
Wave disk springs look like architectural projects with their multiple waves per turn. Consequently, they are applicable in predictable loading as they can act as a cushion by absorbing stress when compressed axially.
Functions of Springs
Springs are an important part of many industrial products. Below are a few functions of springs and subsequent applications.
Shock Absorbing Properties
Springs can compress and extend due to applied load/force. Therefore, they have good shock absorbing capability. This use of springs is very important in the automobile industry as when a vehicle experiences a shock, the spring compresses to absorb the shock. It then releases the energy constantly.
Storage and Output Energy
Springs can store mechanical energy and release it constantly. Therefore, they can serve as an alternative to batteries in some devices. An important example is a mechanical watch and gun bolt.
Control the Movement of the Mechanism
Springs can control the movement of some components. Consequently, they are widely applicable in garages, doors, weighing machines, internal combustion engine valve springs, and control springs in clutches.
Springs also help in buffering or damping vibration. Therefore, they are important in making stable products in vibrating environments. Application of mechanical springs for vibration damping include cars and train cars.
Types of Materials Used in Making Springs
Springs comes from different material made using innovative processes. Below are a few examples of materials used and their importance.
Springs comes from different material made using innovative processes. Below are a few examples of materials used and their importance.
1. Low-Alloy Steel
Low-alloy steels contain nickel or molybdenum, making them superior to carbon steel. Springs made from these materials have the following properties:
- High heat resistance properties make them suitable for working in a machine that uses or generates high heat.
- High compressive strength, allowing them to last longer under axial stress.
- The addition of chromium, molybdenum, and nickel increases the spring’s creep strength and corrosion resistance.
2. Cold Drawn Wire
The cold drawn wire comes from work hardening, which improves the basic crystalline structure of the material. Therefore, springs made from cold-drawn wire have greater tensile strength, stress tolerance, and temperature tolerance.
3. Oil Tempered Spring Wire
Oil tempered wires have high resistance to fatigue, heat, and permanent set-in fatigue. Therefore, oil tempered springs wire is common in the automotive industry. They are also applicable in making products that use suspensions.
4. Bainite Hardened Strip
Bainite hardened strip comes from heat treating steel. Therefore, springs made from bainite hardened steel have great strength and fatigue resistance.
5. Stainless Spring Steel
Stainless steel contains chromium, nickel, magnesium, and even carbon. Springs made from stainless steel have great yield strength, corrosion resistance, and heat resistance. Therefore, they are applicable in washers, lock picks, and antennae.
6. Copper and Titanium
Copper or titanium alloy are anti-corrosive, heat resistant, strong, and durable. Therefore, copper and titanium springs are majorly torsion springs used in day-to-day door hinges, retractable seas, and some medical equipment.
Common Manufacturing Process of Types of Springs
Springs are made using a process of winding, heat treating, grinding, coating, and finishing option. The process is straightforward, although there are few variations depending on the types of springs.
The operator feeds the spring wire into a CNC machining or mechanical spring machine, straightening it. It then coils, forms, or bends the straightened wire to the desired shape. These processes can also be individual or in combination.
-Coiling involves using a spring coiler or CNC spring coiler machine to coil the straightened wire according to the desired coil. Coiling is applicable in making compression, extension, and torsion springs.
-Forming involves using a spring coiler or CNC spring former, which uses several bends, hoops, and radii to create several spring shapes. Forming is applicable in making extension springs, torsion springs, and wire forms
-Bending involves using a CNC wire bender to bend the straightened wire to several shapes. Hence, it is applicable in making wire forms.
2. Heat Treating
Heat treating the formed spring makes it undergo stress relieving process. Therefore, it can easily bounce back when you subject it to stress. It involves heating the spring to a specific temperature for a particular time, depending on the type and amount of material.
Heat treating is repeated depending on the type of material and the manufacturing process after which cooling occurs.
Grinding involves using a grinder to ground the spring’s end flat. Therefore, it will stand up straight when oriented vertically.
4. Coating and Finishing
Coating and finishing are important in improving the aesthetic and functional properties of the spring. For example, electroplating with copper makes the spring conductive, and powder coating will improve its aesthetic value. Finishing options include shot peening (cold-worked springs), plating, powder coating, and anodizing.
Fail Causes and Solutions of Types of Springs
Spring failure can lead to machine damage, an increase in maintenance cost, and subsequently, loss of trust in a product that depends on mechanical springs. Therefore, you should try and reduce spring failure. The best way to do that is to understand the causes. Below are the causes and solutions to spring failure.
1. Spring Stress
Spring stress occurs when you expose the spring to a force its design cannot handle. Therefore, leading to spring breaking. You can solve this issue by reducing the amount of force to what the design can handle or making a spring designed to meet such stress. You can make such a spring by using the right material or optimizing heat treatment.
2. Wrong Material Choice
The type of materials used for making the spring can determine the properties of the spring. For example, springs made from stainless steel and copper have high corrosion resistance. Therefore, using another set of materials would be wrong if you desire such property. You can avoid this by learning about the different materials used in making springs.
3. Poor or Incorrect Finish
Finishing options such as powder coating, anodizing, etc., help improve the spring’s aesthetic or functional properties. For example, you can use anodizing to improve the corrosion resistance of the spring. Therefore, applying such finishing poorly or not applying it on a spring that needs it can make it susceptible to corrosion leading to failure in harsh or caustic conditions.
4. Undefined Working Temperature
The spring must be suitable for the operating temperature. You can improve the spring’s heat resistance by choosing a material with the property, subjecting it to heat treatment, or using a finishing option.
5. Inferior Manufacturing Processes
Making springs must be with quality in mind. This will determine its functions and aesthetic appeal. Common examples of the machining operation used include CNC machining. Manufacturers should properly scrutinize the process and ensure that tooling is geared towards precision, reducing spring failure.
Springs are an important part of any product that undergoes motion. When compressed and expanded, they can store and release energy. Choosing the right spring comes with knowing the kinds of springs used nowadays.
Each spring has its own features and characteristics depending on the types of materials used, the design, and the manufacturing process. Therefore, when choosing to make a spring for your product, it’s best to consider the above factors Or you can get professional advice on springs from experts.
Custom Prototyping Service at WayKen
Do you have a product? And you’re worried about whether its spring function will work. At WayKen, our custom prototyping services are designed to help you quickly and easily find the right springs for any application. Our team of experts will work with you to ensure that you get exactly what you need, at a price that fits your budget. Contact us today for more information.
What are the three types of springs?
The main types of springs are helical, disk, and leaf springs. Each has several subcategories with unique features, functions, and applications. For example, the helical springs subcategories are torsion, extension, spiral, and compression springs.
What are the types of disk springs?
There are four types of disk springs, each with unique features and applications. The four are; Belleville, curved, slotted, and wave disk springs.
What is the most common type of spring?
Torsion springs are the most common type of spring. They are applicable in door hinges and work by storing rotational energy when you open the door. On releasing the door, the spring releases the energy to return the door to its original position.