Sheet Metal Tolerance Standards

welding symbol: difference between ISO vs AWS welding symbol

2017-09-06T07:24:00.000-07:00

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

Unspecified Sheet metal tolerance followed in manufacturing industries

2016-06-19T20:30:00.000-07:00

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.

General tolerance for GD & T - geometric dimension and tolerance

2013-10-18T06:24:00.001-07:00

How to give General tolerance for (GD & T) Geometric Dimension and Tolerance as per standard

GD & T General Tolerance Values

Straightness and flatness

The general tolerances on straightness and flatness are given in below table. When a tolerance is selected from this table, it shall be based, in the case of straightness, on the length of the corresponding line and, in the case of flatness, on the longer lateral length of the surface, or the diameter of the circular surface.

Perpendicularity :

The general tolerances on perpendicularity are given in below Table. The longer of the two sides forming the right angle shall be taken as the datum; if the sides are of equal nominal length, either may be taken as the datum.

Symmetry :

The general tolerances on symmetry are given in below Table. The longer of the two features shall be taken as the datum; if the features are of equal nominal length, either may be taken as the datum.

Circular Run Out:

The general tolerances on circular run-out (radial, axial and any surface of revolution) are given in below Table. For general tolerances on circular run-out, the bearing surfaces shall be taken as the datum if they are designated as such. Otherwise, for circular radial run-out, the longer of the two features&all be taken as the datum; if the features are of equal nominal length, either may be taken as the datum.

for further Reference on Geocentric Dimension and Tolerance comment us we will guide you

V Groove Pulley Material Selection and V groove Pulley Standard Dimensions

2013-04-23T09:13:00.000-07:00

V Groove Pulley Material Selection

For generally purpose V groove pulleys are made by Grey Iron Casting IS: 210-1970

Grey Cast iron Material Grade and Properties
Code of Designation	Grades	Tensile strength	Transverse Test			Typical Applications	Note:
Code of Designation	Grades	Tensile strength	Breaking load Min, Kgf	Corresponding Transverse Rupture Stress Kgf/mm²	Deflection Min, mm	Typical Applications	Note:
FG 15	15	15	800	34.0	4.0	Parts Requiring no Special Grade for general Structural Purpose	Damping Capacity Decreases with increases in tensile strength
FG 20	20	20	900	38.2	4.5
FG 25	25	25	1000	42.4	5.0	Parts Subjected to severe strain such as cylinder parts, etc.
FG 30	30	30	1100	46.7	5.5
FG 35	35	35	1350	57.3	5.5	for extraordinary use
FG 40	40	40	1500	63.7	5.5	for extraordinary use

for general purpose pulley we can select FG 20 for which the equivalent grade is

SAE 111

DIN 1691/GG22

BS 1452/Gr 12

CSN 42 24 21

V Groove Pulley Design

V groove Standard dimensions as per IS 3142

How to select V groove pulley standard dimension like width, depth, Pitch line, etc is discussed below.

Based upon the belt used for transmission the pulley dimension are selected there are generally different Types of V belt A, B, C, D, E

the below drawing shows the Dimensions of the Sectioned double groove v Pulley.

And the values are taken from standard as shown in the table below

a sample pulley dimensions are given below

Bearing Standard tolerance for shaft and Housing, Selection of general tolerance for machined components

2013-04-10T08:01:00.000-07:00

The following procedure will tell,

How to select general tolerance for machined components.

1. For discussion a bearing housing is considered with inner diameter turned to ø60mm.

To provide a tolerance to the diameter we have to select what kind of fit to be used.
Let us considered the load acting on the bearing inner ring is varying as shown below.

Table 1.1

For our case considered the shaft is transmitting Power therefore inner ring is rotating.

From Table 1.1, third operating condition the fit is selected as interference fir for Housing
Now from Table 1.2, for normal & heavy Duty the tolerance Class is selected as N7

Table 2

From Table 1.3, the Tolerance is selected as -0.039/-0.009

Table 3

Sample dimensioning and Tolerances for a housing

How to select the general machining tolerance as per IS 2102 is discussed below.

2. For discussion a stepped shaft is taken as shown below.

From Table 2.1, given below Tolerances for linear dimensions can be arrived

Table 2.1 General Tolerance for Linear Dimensions

From Table 2.2-3, given below Tolerances for Fillets, Chamfers & Angles dimensions can be arrived

Table 2.2-3 General Tolerance for Fillet, Chamfer and Angular Dimensions

From the Given Table the tolerance for shaft for general Machining is selected and shown below (Note: this for a general machined shaft, cases where the shaft is going to be seat in bearing, a similar procedure as of housing has to be followed.)

Sheet Metal Tolerance Standards

How to select Sheet metal tolerance is discussed below

The main thing to be considered for selection of sheet metal tolerance is not just the Linear dimension as like IS 2102, the Reference from where to where the dimension take plays a vital role. Table 3.1 shown the unspecified Sheet metal Tolerance.

For edge to edge, hole to hole & edge to hole, tolerances shall be taken from column A

For edge to bend and hole to bend, tolerances shall be taken from column B

For bend to bend, tolerance shall be taken from column C

For Angular Tolerances ± 2 Degree shall be taken

Table 3.1 Sheet Metal Tolerance for unspecified tolerances

How to select general tolerance for Welding.

Welding Tolerance shall be taken as per ISO 13920

Welding Tolerance for Linear dimensions shall be taken from Table 4.1

Table 4.1 Welding Tolerance for Linear Dimensions

Welding Tolerance for Angular dimensions shall be taken from Table 4.2, in a similar way as discussed in general Tolerance for machined component Discussion (2)

Table 4.2 Welding Tolerance for Angular Dimension

General tolerance Selection

2013-04-10T06:33:00.000-07:00

sheet metal tolerance Standards

2013-04-10T06:28:00.004-07:00

Welding Tolerance Standards

2013-04-10T06:26:00.003-07:00