Plastic springs were introduced in the early 19th’s as they are the best and lightweight option for motor cars. In lightweight cars, the plastic suspension can be a better option to absorb the major shocks from the road. In this article, I will discuss the 4 benefits of using plastic springs in suspension.
Plastic Springs in Suspension
The reinforced plastic suspension spring, that won the British Innovation Award for 1983 at the Design Engineering exhibition in Birmingham, in the English Midlands, has a very unusual appearance.
Comes from the Latin word sulcus meaning a furrow, and it is so named because it was realized that in designing a spring in fiber-reinforced plastics, the material could be more fully exploited by forming it with furrows.
The result is a structure made up of 4 corrugated strips of the fiber-reinforced material joint at the two ends so that in plane view it has the shape of a cross. That is not all elastomer is introduced into the corrugations.
It is not the first Spring in a composite material. Lead springs in carbon fiber-reinforced exposure resin have been known for a long time. It is seen that one had been taken out of a man after traveling 96,000 km and it was extremely surprising to find that its condition was Virtually as new.
So the benefits of Using plastic springs in suspension are-
1. Three Objectives
When the National Engineering Laboratory (NEL) at East Kilbride, Scotland, set out to design a new reinforced plastics spring, it had three objectives- first, maximum use should be made of the unique properties of composite materials, secondly, the cost should be comparable with that of steel springs, and finally, mast production manufacturing techniques currently used in the rainforest plastic industry should be used to ensure an adequate supply of springs if they turn out to be superior to their Steel counterparts.
Apart from the award. it looks as if the spring is going to be a commercial success, judging by the worldwide inquiries that have been pouring into NEL. In the first few weeks, they averaged 60 a day. Currently, the NEL is having detailed negotiations with four manufacturers.
2. Less Energy Consumption
A third benefit that stems from the use of plastic composites is corrosion resistance. These materials incidentally also need very much less energy to produce them than steel.
While these benefits result from the use of composites, the actual design of the spring has other advantages. Thus, the fact that four limbs make up the basic structure of the spring has an important bearing on safety. If one of these should fail due to a load peak, a catastrophic failure does not result because over 75% of the load can still, generally, be supported. Thus, vehicle control is extended during a failure condition unlike a coil or a leaf spring in which failure is invariably catastrophic.
With the sulcated spring, striking changes in spring rate characteristics are also available to the designer. There are some 14 input parameters that can control stiffness and damping behavior. This is nearly double that for a coil spring.
The stiffness changes are achieved by variations in geometry and material properties. In respect of the latter, for example, a variety of reinforcements is available -glass fiber, carbon fiber, aramid fiber, and a hybrid combination of these. For the matrix also, there is a choice of resins and here hard resins or elastomers can be used.
Again with the sulcate spring, it is possible to obtain a load deflection that is linear or one that is not proportional to the applied load. This nonlinearity is due to possible changes in section form when the spring is being deflected, leading to striking changes in the load-deflection characteristics. This is in fact, one of the main advantages of this type of spring, since it is possible to obtain almost any desired variation on spring rate, and also obtain a considerable range of deflection under almost constant load.
Read More- Basic Starter Motor Problems in a Car.
3. Noise Reducation Ability
This ability to tailor stiffness and sampling makes the spring particularly suitable for the motor car where a combined spring damper looks feasible on a small car. On larger cars, the spring dampers could also be used to augment the shock absorber properly, thus reducing its weight. All this adds up to great potential for the reduction of noise, vibration, harshness, and tire wear, and gives a greatly improved ride.
These benefits could, of course, come to naught if, as has already been pointed out, the cost is high compared with steel, or if the spring cannot be produced in the quantities necessary to satisfy the automobile market. On both these fronts the news seems good, however. With. cost, for example, though no final figures are available, the savings compared with the coil spring are said to be very encouraging.
This stems from the fact that the springs lend themselves to production by several high-volume fabricating techniques that are available-compression molding, resin injection, pultrusion, RIM (reaction injecting molding), and reinforced RIM-though with pultrusion some modifications to the process and the equipment may be necessary to ensure that the fibers are placed longitudinal y in the spring.
4. Expensive Tooling
Several of these processes will, of course, require expensive tooling but the quantities that are likely to be produced will take care of his expenses.
The only really serious problem is that of convincing largely metals-oriented engineers of the advantages of the sulcated springs over conventional steel ones. After all, the steel springs have been around for a long time and the problems associated with them and their drawbacks are well documented.
On the other hand, little as yet is known about how the selected spring will perform in use. It is the motor car steering wheel armature, currently in steel that can be replaced by a filament wound, reinforced plastic one. This is safer than the steel one because in an accident it will cause less injury to the driver. However, it is still undergoing evaluation in the United States of America though it was developed more than a few years ago.
Characteristics of Using Plastic Springs in Suspension
One of the most important characteristics of fibre-reinforced plastic composites i their fatigue resistance and of course that becomes a feature of the sulcated spring. Some recent project work has indicated fatigue endurance approaching 500,000 cycles at full load and 120. mm, sprig deflections without any failure. To this has been added improved fracture toughness by the mcorporat1on of the elastomer.
Another important characteristic of composites is their light weight; and because also of the skeletal structure in this application, the weight reduction is significant. It is difficult to give precise figures for this but it can be said that if a sulcated spring was to replace a coil spring weighing 2 kg, the weight • ‘1iuction would be a half-an important consideration for automobile manufacturers anxious to reduce all-up weight and improve fuel consumption.
The drawback of these types of springs in suspension systems is that they are a lot more expensive than their steel counterparts. That might not matter too much but for the fact that they cannot, as yet, be manufactured in three quantities necessary to satisfy the mass production demands of the motor industry.
Frequently Asked Questions(FAQ’S)
What types of plastic are commonly used in manufacturing plastic springs?
Commonly used plastics for manufacturing springs include polyethylene, polypropylene, nylon, PEEK (polyetheretherketone), and other engineering-grade plastics. The choice of material depends on the specific application and the required mechanical properties.
Can plastic springs be customized for specific applications?
Yes, plastic springs can be customized to meet the specific requirements of different applications. This includes variations in size, shape, stiffness, and other mechanical properties to ensure optimal performance in a given environment.
How do plastic springs contribute to sustainability?
Plastic springs can contribute to sustainability by being recyclable and, in some cases, made from recycled materials. Additionally, their lighter weight can lead to energy savings in transportation and reduce the overall environmental impact compared to traditional metal springs.