general delivery standards

Unless otherwise agreed at the time of enquiry and order, the specifications like size, length, straightness and related tolerances shall be as per following tables

General Delivery Conditions

Supply Condition Profile Size (MM) Length (MM) Cut-to-Length (MM)
Min Max Min Max Min Max
Cold Drawn Round 7 85 2000 6000 50 800
Hexagon 8 40 2000 6000 50 800
Square 8 40 2000 6000 50 800
Centerless Peeled Round 10 90 3000 6000 50 800
Centerless Ground Round 5 90 2000 6000 50 800

Length Tolerance for bars is 50 mm and for Cut-to-length is 1 mm

Centerless Peeled Tolerance Class
h6 h7 h8 h9 h10 h11 h12
Drawn - - - R R R, H, S R, H, S
Turned - - - R R R R
Ground R R R R R R R
Polished R R R R R R R

R = Round; S = Square; H = Hexagon

The ranges are all on negative side, that is, +0.00. For a 20mm bar of tolerance class h9 with a tolerance range of 0.052, the tolerance is -0.052/+0.00.

Tolerances on straightness

The general supply tolerances are shown in the following table.

Product Profile Deviation
Rounds 0.50 MM over 1 metre
Squares and hexagons 1.00 MM over 1 metre

Method

The preferred method involves supporting the bar on a suitable surface to eliminate or minimise sagging. If a 1 metre long straight edge is placed on the bar at any position, then the maximum gap between the bar and straight edge is measured by a suitable means such as inserting feeler gauges. The bar is deemed straight if the gap is less than that is accepted ass per General Delivery Conditions

The standard also describes a dial gauge method as an alternative to the gap measurement method. The bar is placed on a surface table, resting on V-Blocks, which are placed at a distance of 1000 mm. the dial gauge reading in between any two such blocks is the bar straightness reading.

Out of round (Ovality)

The standard states that the maximum deviation from "out of round" shall not be more than half the specified tolerance but never above the upper limit of the tolerance.

Reference for Tolerances on Cross Sections

Size (MM) Tolerance Class
h6 h7 h8 h9 h10 h11 h12
over 6 up to 10 0.009 0.015 0.022 0.036 0.058 0.090 0.090
over 10 up to 18 0.0011 0.018 0.027 0.043 0.07 0.110 0.180
over 18 up to 30 0.013 0.021 0.033 0.052 0.084 0.130 0.210
over 30 up to 50 0.016 0.025 0.039 0.062 0.100 0.160 0.250
over 50 up to 80 0.019 0.03 0.046 0.074 0.120 0.190 0.300
over 80 up to 120 0.022 0.035 0.054 0.087 0.14 0.22 0.35