Proper Tooling & Gauges to Thread Roll Pre-Plate Parts Efficiently for External Threads

A guide to the proper tooling and gauges required for efficiently thread rolled pre plate parts.


It is important when manufacturing component parts to take into account the correct plating requirements.  Having knowledge of the specific plating specifications as well as making allowances to the thread rolls and gages are critical in producing a functional thread. Below are some important things to consider that will ultimately allow you to run pre-plate parts efficiently.

Plating Thickness

It is important to determine how much plating thickness will be applied to the thread. Plating specifications and type of thread [included angle of thread form] will determine how much plating build up there will be. Pre plate thread gages should be utilized to ensure that parts will assemble and fit correctly. The pre plate ratios for the pitch diameter build up generated on various types threads are as follows:

    • 60° Unified thread = 4:1 most common
    • 29° Acme thread = 8:1
    • 7°/ 45° Buttress thread = 4.3:1
    • 10° Square thread = 23:1

 preplating image final.jpg

Determining pre plating dimensions for external threaded parts:

There are specific rules for determining pre-plate pitch diameters, pre-plate major diameters, and pre-plate minor diameters of parts. The calculated pre-plate specifications will be used to design the thread rolls to produce the proper pre-plate geometry, and are used for manufacturing thread rolls and gages.

Get specifications for plating thickness Min plating thickness and Max plating thickness:

(Key: PP = pre plate) 

Major diameter Max PP = Max major diameter – (2 x Min plating thickness)

Major diameter Min PP = Min major diameter – (2 x Max plating thickness)

 

For a 60° Unified thread:

Pitch Diameter Max PP = Max pitch diameter – (4 x Min plating thickness)

Pitch Diameter Min PP = Min pitch diameter – (4 x Max plating thickness)

 

If available:

Minor diameter Max PP = Max minor diameter - (2 x Min plating thickness)

Minor diameter Min PP = Min minor diameter - (2 x Max plating thickness)

Example Calculation Featuring 5/8-20 UN2A Thread

Major Diameter .6237 / .6156   

Pitch Diameter .5912 / .5869  

Minor Diameter Max (Reference) .5642

Plating thickness = .0002/.0004

Major diameter Max PP = Max major diameter – (2 x Min plating thickness)

.6237 – (2 x .0002) = .6233

Major diameter Min PP = Min major diameter – (2 x Max plating thickness)

.6156 – (2 x .0004) = .6148

Pitch Diameter Max PP = Max pitch diameter – (4 x Min plating thickness)

.5912 – (4 x .0002) = .5904

Pitch Diameter Min PP = Min pitch diameter – (4 x Max plating thickness)

.5869 – (4 x .0004) = .5853

If available

Minor diameter Max PP = Max minor diameter - (2 x Min plating thickness)

.5642 – (2 x .0002) = .5638

Minor diameter Min PP = Min minor diameter - (2 x Max plating thickness) - Not available

 

Using this process to design and produce thread rolls with pre-plating allowances will prevent gaging issues, and allow you to run pre-plate parts more efficiently. Threads will form, track and gage properly before and after plating is applied.

Send your thread and plating thickness specifications to CJWinter for review. Our team has the capabilities to design and manufacture a thread roll to produce the proper pre-plate geometry form on your part.  There is no additional charge for this service, and delivery is the same as a standard thread roll.  

img-ebook-thread-roll-solutions.jpg Access our Guide to Thread Rolling Solutions

Lib has been with the Brinkman International Group, Inc. for the last 29 years. Currently the Director of Global Sales, Lib has held numerous positions in Engineering, Operations, Sales and Product Management with CJWinter and its manufacturing divisions. Lib is a member and has served on governing boards for the Society of Automotive Engineers, The American Society of Mechanical Engineers, and Precision Machine Products Association.










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