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What Does “G” and “C” Mean in Regards to ACME Screw Threads?

What Does “G” and “C” Mean in Regards to ACME Screw Threads?

ACME screw threadsACME threads have been in use for more than 100 years. Despite the age of this thread form, it continues to be popular in a variety of industrial and equipment applications. ACME threads were developed as an alternative to the square threads that were common at the time because the square thread screws were difficult to make.

Despite the long history of ACME thread screws, many people may find some of the terminology confusing at first. This is because ACME thread screws and nuts have their own special nomenclature. One example of this special terminology is the designation for different ACME thread forms, which may be labeled as G (General Purpose), C (Centralizing), or Stub. So what do the terms G and C mean in regards to ACME screw threads?

General Purpose Vs Centralizing

General Purpose ACME threads, often labeled simply as G, are best used in designs where the screw and nut are both supported independently. This criteria is due to the fact that General Purpose threads have a tendency to wedge when they are subjected to an external radial load. This wedging may result in increased friction and premature wear of both the screw and nut.

Centralizing ACME threads are often preferred for situations that involve a load that is transverse to the axis of the screw. In these applications, the Centralizing threads effectively help to support the load by functioning as radial bearings.

There are some similarities in design between General Purpose and Centralizing ACME threads. Both classifications are designed with a thread angle of 29 degrees and a thread height that is one-half of the pitch.

When you need quality, ACME-threaded screws, nuts, or rods, Dependable ACME is your solution. We have been manufacturing ACME-threaded products for more than five decades. Contact us today at 800-893-3792 to learn more or to place your order.