Thread Rolling Styles

Cold Forming (rolling) threads in metal has been used in the United States for about 65 years. Originally developed in Germany the technology migrated to the US in the 1950’s. Initially used on multi spindle screw machines the tooling styles have been altered to accommodate use on virtually all of today’s existing machine styles. Multi Spindle, Manual, Rotary Transfer and CNC Turning and Milling Centers.

Three styles of tooling have been developed for very specific applications. Axial rolling uses either a two-roll concept or 3 and 5 roll concepts. This style can create unlimited thread lengths by producing one thread pitch at a time. Process time is about 1 inch of thread length per second of cycle time. The process this style supports leaves 2 or more partially finished threads at the end of the thread journal. An undercut in the part design that can mask the unfinished thread will allow gauging to a shoulder with a full thread form.

Parts designed with less than a 2-pitch clearance to a shoulder can be rolled with a Tangential Style attachment. The Tangential tool is a 2-roll side entry tool. It can be used on multi spindle and CNC applications where the machine has mechanical control of tool movement. The Tangential process can roll within 1/2 pitch length to a shoulder with a full thread. Thread length is limited to the width of the roll and the complete thread form is rolled at once. Cycle time for this concept is typically 2-3 seconds for a complete thread.

A third and unusual method is available in the form of a Radial attachment. A Radial tool is a three-roll approach that has the same length limitations as Tangential tooling. The rolls are ground eccentrically and when at rest clear the part to be rolled. There is no regard for feed rates. When in position the head is tripped, and the rolls make 1 revolution to achieve a finished thread. Typical cycle time is 2 tenths of a second. The tool can mount on any machine that can rotate the tool or the work piece. It has become the tool of choice in high volume machining. It runs on any machine and frequently used in automotive production on CNC machines due to its short cycle time.

In any application where time and cost are relevant we have a thread rolling approach that will efficiently reduce both. Reviewing a drawing of your part will determine the style most suited to your specific needs.

Thread Rolling Works with Both High and Low Volume Jobs

Rolling threads on various materials became a necessity in high volume manufacturing in the US following its discovery in Germany after the second world war.

The most dramatic effect was in the production of spark plugs. In the US alone more than 10 million spark plugs were being produced daily by several manufacturers. Leaded fuels were necessary to lubricate engine valves but subsequently fowled spark plugs limiting their useful life to about 10,000 miles. When lead was outlawed in motor fuels in the 1970’s hardened valve seats became the standard and without lead deteriorating spark plug life increased more than 10-fold. This reduced product demand equally.

Thread rolling migrated from multi spindle screw machines to modern CNC machines for the very same reasons. Cold forming of threads became equally important in lower volume production from a time and cost consideration. Threads can be formed typically at 1 inch of thread per second of cycle time. A cold formed thread has greater yield strength and surface quality than a cut thread. Many materials that are difficult to cut are easy to roll. Time cycles and part volume create significant value in throughput cost. This value impacts on the final cost of the finished product. In a job shop atmosphere, it can be the strategic difference between winning the quote or losing the work to a lower bidder. Rolled threads can reduce the effects of corrosion improving life cycles in many applications. The relative ease of applying this technology to today’s metal working machines makes it even more important as a value-added component of the modern machine shop.

We can evaluate your part, your process and your machine when applying the application of thread rolling to your operation. Thread rolling was once conceived as a “black art” but is truly a straight forward application driven technology easily applied in any modern machine shop. Many military and aviation components demand rolled threads for strength and surface quality. Let us help with your application.  The cost implications can be the leverage your company needs to improve profitability.