While designing new machines and equipments, many designers don't provide enough space for functioning of the springs, which results into high cost, close tolerance springs and early failure.
In spite of having different design techniques, materials and manufacturing processes, all kinds of mechanical springs have some common considerations.
A good spring design should consider a lot of other things apart from dimensional and load considerations.
Other areas of considerations are
1. Frequency of Operations
2. Operating environment in terms of temperature, corrosive environment etc.
3. Desired spring life.
4. Speed of load
An intelligent designer should consider all the above factors and give better value for money to his customer. Here at IIS we can help you design a variety of springs for almost any type of application to suite you specific needs, Please feel free to contact us.
Material :
Deciding the material is a crucial for a spring designer. Since Deflection is directly proportional to load, the amount of material required to changes accordingly. A List of material used by us to manufacturer springs is available here
It is difficult to derive the amount of material required to be used in a spring based on the load vs. deflection requirement. Different materials have different tensile strengths, which are used in initial design calculations. The table below shows the approximate tensile strengths.
Springs selection, usage and life cycle
Generally, a product designer would like all the components to last the life of the product. Thus it is expected that the life of the spring must be equal or little less than the life of the product for which it is used. Spring life depends on many factors, which will eventually add to the cost of springs. Selection of right manufacturer, who have an idea & experience about the problems faced, is very important when a long spring life is required. No spring manufacture can guarantee zero failure in a batch of springs irrespective of time, money and efforts taken to guarantee long life. Intelligent design, right material and tight quality control in material and production process can increase the spring life. The detail test conditions, expected life and failure rate must be clearly defined instead of vague specifications. Predicting exact spring life has to be done with careful consideration and with manufacturer's consultation.
Burrs :
While manufacturing springs, several operations produce burrs. Since burrs are harmless in nature, they are often neglected. Burrs formed after spring end grinding or cutting can sometimes interfere with the normal working of the springs by creating friction in the guides or any parts holding the springs. It is necessary for the manufacturer and the customer agree on the limits of the burr based on the spring design and working.
Costs Vs Tolerances
Springs must be produced in a cost effective way because cost is a major factor in today's competitive environment. It is always better to use tolerances based on functional requirements. Therefore generous tolerances must be given to allow manufacturer springs by ordinary methods. This will provide an option to the manufacturer to make the necessary adjustments in the variations in size and properties of material. Tight tolerances reduce the production speed and rejection leading to increased cost both to the manufacturer and the customer.
Hydrogen Embrittlement :
The risk of Hydrogen embrittlement is more when material is subjected to high stress, is with high Rockwell Hardness and has high carbon content. At equal hardness level, tempered carbon steel has more chances of hydrogen embrittlement than cold drawn carbon steel.
Hydrogen gets absorbed into material when carbon steel is pickled for electroplating process preparation. This leads to early failure of springs at lower tensile stress even under short cycle tests. Many times the cracks develop in pickling or plating bath but appear only after plating or sometime when the plated springs are in use.
Hydrogen embrittlement cannot be checked quickly or detected by a testing method. Scragging the springs up to the maximum working load or up to the solid height for a long period can surface any cracks cause due to hydrogen embrittlement. To avoid failure due to hydrogen embrittlement it is important to bake the spring immediately after plating to drive the hydrogen out of the material.
Different Type of Springs for Different Applications :
1. Compression & Extension Springs
(Round wire & Square or Rectangular Section)
2. Torsion Springs
3. Power Springs
4. Hot Coiled Springs
5. Disc Springs
6. Spiral Springs
7. Belleville Washer
8. Constant Force Springs
9. Spring Dowel Pins
10. Flat Springs
11. Wire forms
12. Wave, Curved and Serrated Washers
13. Strip Springs
