Materials Used for Making Springs Part II – Springs – Design of Machine


Hello friends here in this video we will see some of the common terms which are there in Springs and those terms they are called as Terminologies used in Springs so here I will mention some of the terms which are used in the Springs frequently the first one is Spring Index this Spring index is given by capital C it is equal to capital D upon small D your capital D is equal to mean coil diameter unit will be M m and small D is wire diameter so spring index the first term next is deflection deflection it is I can write it down it is the distance moved by spring under the action of load and deflection of spring it is denoted by Delta and that is equal to load upon K which is stiffness the next term which I am going to define this it’s unit will be mm so after spring index and deflection the next term is K which is stiffness stiffness it is defined as the ratio of load to deflection so that is stiffness it is the ratio of load and deflection denoted by letter K and it is W upon Delta and the unit of stiffness since it is load upon deflection load is Newton deflection is mm so it is either in terms of Newton mm or kilo Newton mm kilo Newton per mm Newton per mm etcetera next after stiffness the next term is shear stress factor sheer stress factor is denoted by K suffix s and it is equal to 1 plus 1 upon 2 see now you’re in shear stress factor we are getting the relation between shear stress vector and spring index see next after this we have walls correction factor walls correction factor is kW is equal to 4 C minus 1 upon 4 C minus 4 plus zero point 6 1 5 divided by C this walls correction factor is needed when we are designing the spring because this takes care of the curvature of spring next after these five terms next is solid length solid lengths of spring for that purpose here I’ll just draw a diagram to explain what is meant by solid lengths when the spring is subjected to load and because of the action of load when the spring is completely closed that is each of the wire diameters are in contact and there is no gap between two wires this entire length is called as solid length of Springs that is solid length it is the length of spring in fully closed condition so therefore solid length is equal to n into D here I have the formula where n is equal to number of turns of spring and small D that is equal to the diameter of this wire in mm after solid length next we have three lengths here for this also I draw a diagram and explain see this is the free length of the spring in short free length means the length of spring in the unloaded condition in free lengths we do not have any load on the spring this is denoted by LF L sub X F here and it is the length of spring in unloaded condition and for free length I’ll write the formula it is given by three length is equal to solid length plus maximum deflection plus 15% that is 0.5 times of maximum deflection this is the formula to calculate the free length of the spring now after seeing the free length the next terminology is pitch of spring now this pitch is given by the formula it is free length upon n minus 1 now when we are talking about pitch it means that I will draw the diagram and explain this now suppose this is a spring which means if we are selecting a point on a spring on one wire diameter if I select a point then on the next wire diameter if I select the point at the same location that is if it is at the center this distance would be called as which denoted by small P similarly we can select pitch on anywhere on the spring that is we can select the distance just we have to select a particular point and on the next wire we have to select the point at the same location so that will give us the pitch and pitch for a spring it remains same that is through the entire length the pitch has to be same for a given spring next after pitch then I can say that for squared and ground ends now what is the meaning of squared and ground ends Springs as we can see they are made up of wires means the cross-section is circular so when we will be placing this spring on a surface there are chances that under the action of load this spring it can shift it can slip so to avoid the slipping what we do we just make this and squared and we grind it so whenever we are having a spring we have to leave two of the turns four squared and ground NZ that is at the bottom and at the top for seating so I’ll say that therefore four squared and ground ends total number of coils will be equal to number of active coils plus two so when we are deciding that how much should be the total number of terms for a spring that total number of turns will be given by number of active coils active coils are those which take part in deflection because when we have a spring only the active coils will deflect the coils which are there at the bottom I can draw the diagram here itself like for this spring here if I provide squared and ground end then this spring will be fitted on this surface similarly at the top here I am providing squared and ground end for the seating arrangement of the spring and now there are the slipping chances are less so the coil at the top and the coil at the bottom they are fixed so they do not take part in actual deflection so here I have these three coils as the number of active coils so total number of coils would be the three active coils plus two so here I have total number of coils the formula becomes in – total number of coils is number of active coils plus two and this two we are riding for squared and ground ends next after this the last term which is left that is deflection is given by one more formula and that is deflection is equal to 8 WD cube into n upon GD raised to 4 this is another formula by which we can calculate the deflection for a spring and here we need to know all these terms so your W is the load on the spring unit it can be Newton or kilo Newton capital D it is mean coil diameter in mm n is equal to number of active coils G it is modulus of rigidity unit Newton per mm square and small D it is called as wire diameter so your in this video we have seen the terminologies which were commonly used in case of Springs that is when we are talking in terms of spring there are some technical terms which are to be used started with spring index second was deflection then it was stiffness shear stress factor walls correction factor then solid length free lengths along with the formula which of spring and then we have seen what is meant by squared and grounded and at last we have seen deflection

30 thoughts on “Materials Used for Making Springs Part II – Springs – Design of Machine

  1. hii sir
    My name is jay.i do like to learn from your video.ineed more video from you .
    Topics are conjugate beam method,strain energy,column struts,shear centre,unsymmetrical bending.

    i am waitng for your video

  2. I would like to give the suggestion to first draw diagram then define the definition it's better to understand or clear concepts with imagination

  3. Please explain wahl's correction factor with its derivation with proof not only explaining it by a single line definition.

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