Thread Whirling / Rolling
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What is Thread Whirling?
Thread Whirling is a form of the Thread Milling process with the exception that the cutters are mounted on the inside of a Cutting Ring or Cutter Holder rather than the outside of a milling tool.
Advantages of Thread Whirling-
Thread whirling offers several advantages over single point threading:
• Deep Threads – Bone Screws usually have a deep thread formation, Long thread lengths and increased or multiple pitch threads which can be machined very efficiently by whirling.
• Long Length to Diameter Threads – When used on a Swiss Type machine the Thread Whirling Spindle works close to the Guide Bushing for increased support and rigidity on long length to diameter screws. The process is usually performed in a single pass from stock diameter which maintains constant material support.
Thread Rolling: Long or Short threads
In this process the material is formed into a male thread through mechanical pressure as the screw blank is rolled between a roller die head. Thread rolling is better suited to high-volume production, and produces threads of diameters typically smaller than one inch.
Also, materials with good deformation characteristics are necessary for rolling although tough materials like 17-4 stainless can be rolled with excellent results.
Rolled male threads tend to be slightly stronger than cut male threads, because of the effect of the cold forming action on the metal’s grain structure.
* Produces external rolled threads.
* Material is plastically deformed and cold-worked
* Produces rolled threads with excellent strength and surface finish
* Forms major thread diameters greater than blank diameter
* Is a high production process
* It is usually three to five times faster than thread cutting.
* The threads produced are very accurate and strong because they are cold worked
-Thread rolling is the process used for making external threads. It is a important process in tooling and presswork manufacturing. A die, which is a hardened tool with the thread profile, is pressed on to a rotating workpiece. As the force is gradually increased, the thread profile is transferred to the workpiece. This process produces screws with greater strength than machined threads due to the cold working, as well as better material yield.