Tolerances and Machining Allowances Hot Forged products

dimension after  (% of every alloy elements < 5) (% of every alloy element < 5) (% of every alloy element = 5)
machining increese deviation increese deviation increese deviation increese deviation increese deviation increese deviation
mm b or h
(2 a)
B or H l
(2 a)
L b or h
(2 a)
B or H l
(2 a)
L b or h
(2 a)
B or H l
(2 a)
L
> 100 < 125 14 ± 3,8 17 + 17 / – 10 17 ± 4,8 22 + 21 / – 13 10 ± 2,0 16 + 14 / – 11
> 125 < 160 16 ± 4,2 19 + 18 / – 11 19 ± 5,4 24 + 22 / – 14 12 ± 2,3 18 + 14 / – 11
> 160 < 200 18 ± 4,9 22 + 20 / – 13 21 ± 6,3 26 + 22 / – 15 14 ± 2,8 20 + 14 / – 14
> 200 < 250 21 ± 5,6 24 + 22 / – 14 24 ± 7,2 29 + 26 / – 17 17 ± 3,4 23 + 16 / – 16
> 250 < 315 25 ± 6,5 28 + 26 / – 15 28 ± 8,4 32 + 29 / – 19 21 ± 4,2 26 + 18 / – 18
> 315 < 400 30 ± 7,7 32 + 28 / – 18 33 ± 10,0 36 + 33 / – 22 26 ± 5,1 30 + 21 / – 21
> 400 < 500 36 ± 9,2 38 + 33 / – 22 40 ± 11,9 42 + 38 / – 25 32 ± 6,3 36 + 25 / – 25
> 500 < 630 44 ± 11,0 45 + 39 / – 25 48 ± 14,3 49 + 46 / – 29 39 ± 7,8 42 + 29 / – 29
> 630 < 800 54 ± 13,5 55 + 45 / – 30 58 ± 17,4 58 + 51 / – 34 49 ± 9,8 52 + 35 / – 35
> 800 < 1000 66 ± 16,3 67 + 55 / – 36 71 ± 21,3 69 + 61 / – 41 61 ± 12,1 63 + 42 / – 42
Measures are expressed in mm
Example : unalloyed steels round b = 330 mm and l = 3500 mm. Diameter of turned raw material B = 330 + 30 = 360 ± 7,7
                         
                         
dimension after  (% of every alloy elements = 5)    
machining increese deviation increese deviation increese deviation increese deviation increese deviation increese deviation
mm b or h
(2 a)
B or H l
(2 a)
L b or h
(2 a)
B or H l
(2 a)
L b or h
(2 a)
B or H l
(2 a)
L
> 100 < 125 13 ± 4,0 21 + 18 / – 12 7 ± 1,5 14 + 14 / – 11 10 ± 2,1 17 + 14 / – 10
> 125 < 160 15 ± 4,6 22 + 20 / – 13 9 ± 1,8 15 + 14 / – 11 12 ± 2,5 19 + 15 / – 12
> 160 < 200 18 ± 5,2 25 + 22 / – 14 11 ± 2,2 17 + 14 / – 14 14 ± 2,9 21 + 16 / – 14
> 200 < 250 21 ± 6,0 27 + 24 / – 16 13 ± 2,6 20 + 16 / – 16 17 ± 3,5 23 + 17 / – 17
> 250 < 315 24 ± 7,0 30 + 27 / – 18 16 ± 3,2 23 + 18 / – 18 21 ± 4,2 26 + 19 / – 19
> 315 < 400 29 ± 8,4 35 + 31 / – 21 19 ± 4,0 27 + 21 / – 21 26 ± 5,0 30 + 22 / – 22
> 400 < 500 35 ± 10,0 40 + 35 / – 24 24 ± 4,9 32 + 25 / – 25 32 ± 6,2 35 + 26 / – 26
> 500 < 630 42 ± 12,0 47 + 42 / – 28 30 ± 6,0 38 + 29 / – 29 39 ± 7,5 41 + 31 / – 31
> 630 < 800 52 ± 14,9 55 + 49 / – 33 37 ± 7,4 47 + 35 / – 35 49 ± 9,4 49 + 36 / – 36
> 800 < 1000 64 ± 18,1 66 + 59 / – 40 46 ± 9,3 57 + 42 / – 42 61 ± 11,6 59 + 44 / – 44
Measures are expressed in mm
Example: tool steels round b = 260 mm and l
= 4000 mm. Diameter of turned raw material B = 260 + 21 = 281 ± 4,2
The ovalization , only for rounds, has not to be higher than the tolerance corresponding to diameter B
Tolerances and allowances for flats are valid when we have the following relation: b/h = 8 quality, special, alloyed and unalloyed steelsi; b/h = 5 base unalloyed steels.
Lucefin Group has fixed the tolerance of rough products on b or h in + 1 mm / + 3 mm