How to Measure and Select Neck Finishes

In order to solve the problem of mutual matching between plastic bottles and caps, the Society of the Plastics Industry has developed a standard for plastic bottle necks. Bottles from the same series should match caps from the same series.

Standard Neck Measurement

T – Outside diameter of the continuous thread.

E – Outside diameter of the finish shaft excluding thread.

I – The inside diameter of the finish at the smallest possible point.

S – The distance between the top of the finish to the top of the thread.

H – Height from the top of the finish to the bottom where it intersects with the shoulder.

P – The distance between the corresponding points of two adjacent threads.

Standard thread profile for plastic containers

The standard thread profile of plastic containers has two forms, “L” and “M” (see the figure below).

Generally, the thread profile of plastic containers is required to be designed according to the above standards. This standard can be extended to a matching lid design.

Standard Neck Finish Sizes

In general, 18mm-28mm necks should use 410 series; those larger than 28mm should use 400 series; those smaller than 18mm should use 415 or 425 series according to product design requirements；The 444 series is usually not used.

Neck Finish is expressed as: Nominal Specifications-Series. For example, Neck Finish 20-410, means 410 series, with a nominal diameter of 20mm. Check the table below for other sizes of this specification.

If you still can’t choose neck finish, then consult Somewang’s packaging experts, and let Somewang give you the most suitable packaging solutions.