What's the neck finish?

Neck Finishes are the screw-threaded parts of the plastic containers that hold the cap or closure in place. A container must have a proper neck finish to match the corresponding cap.

Continuous threaded cap sizes are expressed as two reference numbers, such as 24-400,18-410, 20-415. The first number refers to the overall neck diameter including the threads outside in millimeter. The second number refers to the height and thread style of neck finish, which ranged from 300 to 2060, but most commonly used thread styles are 400,410, 415 in plastic containers industry.

Here is a quick look on the thread counts of those 3 type thread styles, which refers to the times the threads pass each other.

400 ---- 1thread turn

410 ---- 1.5thread turns

415 ---- 2thread turns

what is the plastic neck finish - 3plastics

How to Measure Neck Finishes?

Let's checkout these parameters below first:

T is the overall neck diameter in millimeter including the threads outside, such as 24in 24-400.

E is also the neck diameter, but measured with the threads depth excluded if compared to T diameter.

I is the inner diameter of the neck.

S is measured from the top edge of the mouth and stops when threading begins.

H is the height of the neck finish, which measured from the top of the mouth to the bottom of the closure rests.

Therefore, thread depth is also available now, which is the result from (E-T)/2.



400 neck finish chart - 3plastics

Parameters for Typical Neck Finishes

Neck Finish T(mm E(mm) I(mm) H(mm) S(mm)
20-400 19.69+/-0.20[.775+/-.008] 17.55+/-0.20[.691+/-.008] 10.26[.404] 9.42[.371] 0.94[.037]
24-400 23.67+/-0.20[.932+/-.008] 21.54+/-0.20[.848+/-.008] 13.11[.516] 10.16[.400] 1.17[.046]
28-400 27.38+/-0.25[1.078+/-.010] 24.99+/-0.25[.984+/-.010] 15.60[.614] 10.16[.400] 1.17[.046]
18-410 17.68+/-0.20[.696+/-.008] 15.54+/-0.20[.612+/-.008] 8.26[.325] 13.28[.523] 0.94[.037]
20-410 19.69+/-0.20[.775+/-.008] 17.55+/-0.20[.691+/-.008] 10.26[.404] 14.07[.554] 0.94[.037]
24-410 23.67+/-0.20[.932+/-.008] 21.54+/-0.20[.848+/-.008] 13.11[.516] 16.41[.646] 1.17[.046]
20-415 19.69+/-0.20[.775+/-.008] 17.55+/-0.20[.691+/-.008] 10.26[.404] 18.85[.742] 0.94[.037]
24-415 23.67+/-0.20[.9.32+/-.008] 21.54+/-0.20[.848+/-.008] 13.11[.516] 24.31[.957] 1.17[.046]
28-415 27.38+/-0.25[1.078+/-.010] 24.99+/-0.25[.984+/-.010] 15.60[.614] 27.48[1.082] 1.17[.046]


For further details about neck finishes, please contact us at sales@3plastics.com

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