INTRODUCTION:-
Shaving is the secondary cutting operation. It is done by removing (shaving) a small amount of material from the previously cut edge.
The purpose of shaving is
To improve the dimensional accuracy of the piece part.
To improve the cut edge characteristics of the piece part.
To improve the flatness of the piece part.
The purpose of shaving is
To improve the dimensional accuracy of the piece part.
To improve the cut edge characteristics of the piece part.
To improve the flatness of the piece part.
SHAVING CLEARANCE:
The cutting clearance in shaving operation may be practically non existent. It is common practice to use close fit between punch and die with minimum clearance possible. However in the case of larger shaving allowance a cutting clearance of 5% of shaving allowance will be acceptable .
SHAVING ALLOWANCE:-
The width of the scrap web removed by shaving operation is the shave allowance .
Shave allowance for steel
A = C+0.04 s.
Or minimum =0.08.
A1= c/2 or min 0.04.
Shaving allowance for brass, copper, German silver etc.
A = c or min 0.08mm.
A1 = c/2 or minimum 0.04.
C = Cutting clearance used for previous cutting operation
(prior to shaving).
A = Shave allowance for single shaving operation is employed.
A1= Shave allowance for second shaving operation is employed.
SHAVING DIRECTION:-
To improve the flatness of blank used to produce a better square cut edge, it is necessary to keep up side down in the shaving. The cutting action is opposite to that of the previous cutting and a more flat blank will be obtained.
The striking force required for shaving operation is two to three times that of the stripping force required for the blanking, piercing.
Example: A blank o outside diameter 40mm and inside diameter 10mm is to be shaved and outside in a single stage. Calculate the allowance and decide the component size for blanking. Material MS Thickness 2mm Tmax =360N/mm².
Given:
od= 40mm
id = 10mm
s = 2mm
Tmax = 360N/mm2
Shaving allowance of M.S.
In single stage A = C + 0.04s
In single stage A = C + 0.04s
C =0.005 x 2 x√360/10.
=0.06/side.
A =0.06 +(0.04 x2)
=0.14/side.
Size of blank for blanking = Ǿ40 + (2 x 0.14)
Size of hole for piercing = Ǿ10 - (2 x 0.14)
Out side Ǿ = Ǿ40.28.
Inside Ǿ = Ǿ9.72.
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