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


 
 
 
------------------------------------------------------------------------------------------------------------------------


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.



 














3 comments:

  1. This comment has been removed by the author.

    ReplyDelete
  2. I like it your sheet metal and automobile post.really very interesting and useful information.thanks for share this post.we provide high quality automobile parts and sheet metal,in low cost.please have a look over here.
    sheet metal fabrication companies in india

    ReplyDelete
  3. it is really amazing...thanks for sharing.provide more useful information...I am expecting more interesting topics from you. And this was nice content and definitely it will be useful for many people.
    polycarbonate roofing sheets

    ReplyDelete