Plastic injection molding tolerance standards
Establishing tolerance with respect to product has significance importance on moldability and cost. It is recommended to indicate only critical dimensions with tolerances on a drawing. Depending on application, a division into three tolerance class can be made:
Normal, Medium & Fine
Cost of manufacture for Medium Tolerance part will be 1.7 times Normal toleranced part and it will be 3 times for Fine toleranced part.
General molding tolerances are shown below
|
Drawing code |
Dimension (inch) |
ABS |
AcetaI |
Acrylic |
|||
|
Commercial |
Fine |
Commercial |
Fine |
Commercial |
Fine |
||
|
A= Diameter* |
To 1.000 |
0.005 |
0.003 |
0.006 |
0.004 |
0.005 |
0.003 |
|
B=Depth** C=Height** |
1.000 – 2.000 |
0.006 |
0.004 |
0.008 |
0.005 |
0.006 |
0.004 |
|
2.000 – 3.000 |
0.008 |
0.005 |
0.009 |
0.006 |
0.007 |
0.005 |
|
|
3.000 – 4.000 |
0.009 |
0.006 |
0.011 |
0.007 |
0.008 |
0.006 |
|
|
4.000 – 5.000 |
0.011 |
0.007 |
0.013 |
0.008 |
0.009 |
0.007 |
|
|
5.000 -6.000 |
0.012 |
0.008 |
0.014 |
0.009 |
0.011 |
0.008 |
|
|
6.000 – 12.000 |
0.003 |
0.002 |
0.004 |
0.002 |
0.003 |
0.002 |
|
|
D=Bottom Wall |
0.004 |
0.002 |
0.004 |
0.002 |
0.003 |
0.003 |
|
|
E=Side Wall |
0.003 |
0.002 |
0.004 |
0.002 |
0.005 |
0.003 |
|
|
F=Hole Diameter* |
0.000 – 0.125 |
0.002 |
0.001 |
0.002 |
0.001 |
0.003 |
0.001 |
|
0.125 – 0.250 |
0.002 |
0.001 |
0.003 |
0.002 |
0.003 |
0.002 |
|
|
0.250 – 0.500 |
0.003 |
0.002 |
0.004 |
0.002 |
0.004 |
0.002 |
|
|
0.500 and over |
0.004 |
0.002 |
0.006 |
0.003 |
0.005 |
0.003 |
|
|
G=Hole Depth |
0.000 – 0.250 |
0.003 |
0.002 |
0.004 |
0.002 |
0.004 |
0.002 |
|
0.250 – 0500 |
0.004 |
0.002 |
0.005 |
0.003 |
0.004 |
0.002 |
|
|
0.500 -1.000 |
0.005 |
0.003 |
0.006 |
0.004 |
0.006 |
0.003 |
|
|
Flatness |
0.000 – 3.000 |
0.015 |
0.010 |
0.011 |
0.006 |
0.010 |
0.007 |
|
3.000 -6.000 |
0.030 |
0.020 |
0.020 |
0.010 |
0.015 |
0.010 |
|
|
Concentricity |
TIR |
0.009 |
0.005 |
0.010 |
0.006 |
0.010 |
0.006 |
|
Drawing code |
Dimension (inch) |
Nylon |
Polycarbonate |
Polyethylene,HD |
|||
|
Commercial |
Fine |
Commercial |
Fine |
Commercial |
Fine |
||
|
A= Diameter* |
To 1.000 |
0.004 |
0.002 |
0.004 |
0.003 |
0.008 |
0.006 |
|
B=Depth** C=Height** |
1.000 – 2.000 |
0.006 |
0.003 |
0.005 |
0.003 |
0.010 |
0.008 |
|
2.000 – 3.000 |
0.007 |
0.005 |
0.006 |
0.004 |
0.013 |
0.011 |
|
|
3.000 – 4.000 |
0.009 |
0.006 |
0.007 |
0.005 |
0.015 |
0.013 |
|
|
4.000 – 5.000 |
0.010 |
0.007 |
0.008 |
0.005 |
0.018 |
0.016 |
|
|
5.000 -6.000 |
0.012 |
0.008 |
0.009 |
0.006 |
0.020 |
0.018 |
|
|
6.000 – 12.000 |
0.003 |
0.002 |
0.003 |
0.015 |
0.006 |
0.003 |
|
|
D=Bottom Wall |
0.004 |
0.003 |
0.003 |
0.002 |
0.006 |
0.004 |
|
|
E=Side Wall |
0.005 |
0.003 |
0.003 |
0.002 |
0.008 |
0.004 |
|
|
F=Hole Diameter* |
0.000 – 0.125 |
0.002 |
0.001 |
0.002 |
0.001 |
0.003 |
0.002 |
|
0.125 – 0.250 |
0.003 |
0.002 |
0.002 |
0.015 |
0.005 |
0.003 |
|
|
0.250 – 0.500 |
0.003 |
0.002 |
0.003 |
0.002 |
0.006 |
0.004 |
|
|
0.500 and over |
0.005 |
0.003 |
0.003 |
0.002 |
0.008 |
0.005 |
|
|
G=Hole Depth |
0.000 – 0.250 |
0.004 |
0.002 |
0.002 |
0.002 |
0.005 |
0.003 |
|
0.250 – 0500 |
0.004 |
0.003 |
0.003 |
0.002 |
0.007 |
0.004 |
|
|
0.500 -1.000 |
0.005 |
0.004 |
0.004 |
0.003 |
0.009 |
0.006 |
|
|
Flatness |
0.000 – 3.000 |
0.010 |
0.004 |
0.005 |
0.003 |
0.023 |
0.015 |
|
3.000 -6.000 |
0.015 |
0.007 |
0.007 |
0.004 |
0.037 |
0.022 |
|
|
Concentricity |
TIR |
0.010 |
0.006 |
0.005 |
0.003 |
0.027 |
0.010 |
|
Drawing code |
Dimension (inch) |
Polyethylene,LD |
Polypropylene |
polystyrene |
|||
|
Commercial |
Fine |
Commercial |
Fine |
Commercial |
Fine |
||
|
A= Diameter* |
To 1.000 |
0.007 |
0.004 |
0.007 |
0.004 |
0.004 |
0.003 |
|
B=Depth** C=Height** |
1.000 – 2.000 |
0.010 |
0.008 |
0.009 |
0.005 |
0.005 |
0.003 |
|
2.000 – 3.000 |
0.012 |
0.008 |
0.011 |
0.007 |
0.007 |
0.004 |
|
|
3.000 – 4.000 |
0.015 |
0.010 |
0.013 |
0.008 |
0.008 |
0.005 |
|
|
4.000 – 5.000 |
0.017 |
0.011 |
0.015 |
0.009 |
0.010 |
0.006 |
|
|
5.000 -6.000 |
0.020 |
0.013 |
0.018 |
0.011 |
0.011 |
0.007 |
|
|
6.000 – 12.000 |
0.005 |
0.004 |
0.005 |
0.003 |
0.004 |
0.002 |
|
|
D=Bottom Wall |
0.050 |
0.004 |
0.006 |
0.003 |
0.006 |
0.003 |
|
|
E=Side Wall |
0.005 |
0.004 |
0.006 |
0.003 |
0.007 |
0.004 |
|
|
F=Hole Diameter* |
0.000 – 0.125 |
0.003 |
0.002 |
0.003 |
0.002 |
0.002 |
0.001 |
|
0.125 – 0.250 |
0.004 |
0.003 |
0.004 |
0.003 |
0.002 |
0.001 |
|
|
0.250 – 0.500 |
0.005 |
0.004 |
0.005 |
0.004 |
0.002 |
0.002 |
|
|
0.500 and over |
0.006 |
0.005 |
0.008 |
0.006 |
0.004 |
0.002 |
|
|
G=Hole Depth |
0.000 – 0.250 |
0.003 |
0.003 |
0.005 |
0.003 |
0.004 |
0.002 |
|
0.250 – 0500 |
0.004 |
0.004 |
0.006 |
0.004 |
0.004 |
0.002 |
|
|
0.500 -1.000 |
0.006 |
0.005 |
0.009 |
0.006 |
0.005 |
0.003 |
|
|
Flatness |
0.000 – 3.000 |
0.020 |
0.015 |
0.021 |
0.014 |
0.007 |
0.004 |
|
3.000 -6.000 |
0.030 |
0.020 |
0.035 |
0.021 |
0.013 |
0.005 |
|
|
Concentricity |
TIR |
0.010 |
0.008 |
0.016 |
0.013 |
0.010 |
0.008 |
