Do you need precision threaded components (e.g. fasteners, aerospace bolts, nuts, screws) for critical applications in the aerospace industry? 

If you’re accustomed to choosing thread cutting for critical components, you should be aware that these parts fail during destructive lab testing at a much higher rate than a rolled thread. That’s because only thread rolling services can provide the exceptional tensile, shear, and fatigue strength your component requires. 

Thread Cutting vs. Thread Rolling 

Thread cutting involves removing material by physically cutting away at a workpiece, which weakens the component’s structural integrity. Thread rolling, on the other hand, is a cold forging process that actually changes (and strengthens) the material’s physical properties without removing any material.

The procedure supplants the component’s malleable material with a hardened steel die formed to spec. Unlike the weakening effect that results from removing material during thread cutting, thread rolling literally moves molecules into the thread form. This makes the thread denser, which in turn improves quality and strength. As an additional benefit, burnishing the steel dies used for thread rolling produces a superior micro-finish that reduces wear and further extends component life. 

Benefits of Thread Rolling 

The benefits of thread rolling include: 

Finish quality. Thread cutting often leaves cut marks and tool lines behind, producing a rough finish and yielding a brittle thread that’s prone to breakage. Thread rolling, however, leaves parts smooth and strong without the need for secondary polishing and finishing operations. 

Speed. Thread rolling machines operate at 3+ times the speed of thread cutting machines, which can significantly cut down on lead time.

Strength. Due to material compaction and work hardening, thread rolling increases the tensile strength of a component. The displaced material forms dense layers that are packed tightly together to produce a much stronger thread. Within thread rolling, there are two main thread forms that offer varying degrees of strength: 

  • Basic Unified National Thread (UNR classification). These standard threads are typically used in commercial applications where strength is important but safety isn’t necessarily a crucial factor.
  • J-formed Thread (UNJC or UNJF). These threads have a larger root radius that produces an incredibly strong thread when rolled. They’re ideal for critical applications where people’s lives depend on their functionality. J-formed threads are found in most aerospace applications. 

Tool life. Cutting tools are known to wear down easily, but a single set of precision thread rolling dies can roll thousands of precision threaded components without a problem.

In-House Quality and Testing at United Centerless Grinding & Thread Rolling

Thread RollingIn all cases, a higher percentage of threaded aerospace components will pass destructive lab testing if they’ve been rolled instead of cut. We offer this quality assurance service in-house atour East Hartford, CT facility for customers’ convenience. 

The process involves cutting the thread laterally to see a section-view of it, then mounting it in wax, polishing it and solution etching to examine it under a microscope at over 500x. We check for fatigue, material flow lines, density, cracks, laps caused by overrolling, and any imperfections in the thread that aren’t visible on the surface. 

A typical lab takes about 2 weeks to perform destructive lab testing, but our in-house capabilities allow us to complete this process in a day.. 

Don’t trust your threaded aerospace components with just any shop. Send them to United Centerless Grinding & Thread Rolling for expert thread rolling services. Contact us today for a free estimate!