Wednesday, September 6, 2017

welding symbol: difference between ISO vs AWS welding symbol


Difference between ISO Vs AWS Welding Symbol
In ISO welding symbol, a identification line is additionally added when compared to AWS welding symbol
In ISO welding symbol, irrespective of weld symbol position either on top or bottom, the weld symbol placement on line is much concerned,
When the symbol is placed on the reference (continuous) line, it means the weld is on the same side, refer Fig 2.
And when the symbol is placed on the identification line (dashed line), it means the weld is on the other side, refer Fig 1.
The symbol is to be placed either above or beneath the reference line, in accordance with the following regulation:
OTHER SIDE FILLET WELD



FIG 1: The symbol is placed on the identification line (dashed line) side if the weld (weld face) is on the other side of the joint
irrespective of weld symbol placed either on top or bottom, when the weld symbol is placed on identification line (dashed line) it means that, the weld is on other side.

SAME SIDE FILLET WELD

FIG 2: The symbol is placed on the continuous line side of the reference line if the weld (weld face) is on the arrow side of the joint
irrespective of weld symbol placed either on top or bottom, when the weld symbol is placed on reference line (line continuous) line it means that, the weld is on same side.
SYMMETRICAL FILLET WELD
 



FIG 4: The identification line (dashed line) is not required for symmetrical welds
DIFFERENT BETWEEN z & a
 


FIG 3: when prefix "z" is used before weld size, it means weld leg long, when prefix "a" is used before weld size then it means throat thickness

Comparison between ISO Vs AWS Welding Symbol

the table comparison of ISO welding symbols Vs AWS welding symbol is show in FIG 5

WELDING SYMBOL STANDARD LOCATION OF ELEMENTS ARE GIVEN BELOW

 





Sunday, June 19, 2016

Unspecified Sheet metal tolerance followed in manufacturing industries

Unspecified Sheet metal tolerance followed in manufacturing industries





Unspecified tolerances for features

Feature
 
Tolerance (mm)
 
 
 
Edge
To
Hole
a
0.127
Hole
to
Hole
b
0.127
Hole
to
Self-Clinching Fastener (SFC)
c
0.254
Edge
To
Edge
d
0.254
Hole
to
Stud
e
0.254
Bend
to
Hole
f
0.254
SFC
to
Stud
g
0.381
Bend
to
Stud
h
0.508
Edge
to
Self-Clinching Fastener (SFC)
I
0.381
Bend
to
Self-Clinching Fastener (SFC)
j
0.508
Bend
to
Edge
k
0.254
Edge
to
Stud
l
0.381
Stud
to
Stud
m
0.381
SFC
to
Self-Clinching Fastener (SFC)
n
0.381
Bend
To
Bend
o
0.508


 
 
 
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Parallel and Compound Planes


The tolerance between features on two different planes is the sum of the tolerances between the first feature to the bend, the bend tolerances, and the tolerance between the bend and the second feature. An example is shown below.

+/- 0.015Hole (A) to Bend

+/- 0.020Bend To Bend

+/- 0.015Hole (B) to Bend
+/- 0.040 Tolerance between A and B


Surface Length
Surface Length (mm)
Flatness 
Straightness of Cut
0 to 25
0.127 mm
0.41 mm / meter
25 to 102
5 μm / mm of length
above 102
0.51 mm + 4 μm / mm of length
 
 
Squareness

Squareness
SHEARED EDGE
FORMED EDGE
SHEARED EDGE
1.25 mm
1.67 mm
FORMED EDGE
1.67 mm
1.25 mm

 

 
Unspecified Edges and Burrs
chamfer or radius
0.5 mm or 10% material thickness
projections by piercing / blanking 
0.15 mm  max
 

Bending


Right Angles

Angles that are not specified on the engineering drawing and appear to be 90 degrees are considered to be 90 degrees. The angular tolerance will be +/- 1degrees. The position of material (D) at the end of a bend will vary according to the length of the bend (L).


Acute Angles

The tolerance for acute angles is +/-1 degrees.



Obtuse Angles

The tolerance for obtuse angles is +/-1Ε


 
 
Bends and Material Grain
Whenever the bend configuration permits, a bend shall be made across the grain of the material, or at 45 degrees to the grain direction. minimum flange (bend length) the minimum recommended flange dimension should be at least 3.5 times the sum of the material thickness and the bend radius.
 
Distance of a Punched Hole from a Bend
 
The minimum inside dimension from a bend to the edge of a punched hole should be 1.5 times the sum of the material thickness and the bend radius. Punched holes located closer to a bend will have a tendency to distort and may lend to cracking of the material.
 
Material Thickness and Hole Size
 
Generally minimum hole size is limited to the thickness of the material.
 
Distance of a Punched Hole from Edge of Blank
 
To avoid distortion in sheet metal, holes must not be too close to an edge. For sheet metal 1/32 inch or less in thickness, all holes should be at least 1/16 inch from the nearest edge. The minimum distance from an edge for thicker material should be twice the thickness, but not less than 1/8 inch. The minimum distance between two punched holes should be at least twice the thickness of the material. If the holes are to have inserts, studs etc. pressed in the manufacturer’s recommendations for minimum distances should be observed.