For most manufacturers, tapping remains the go-to solution for generating threads in ID holes thanks to a readily available and wide range of affordable tooling options that allow for easy part programming and exceptional efficiency with processes that account for one tap per thread size throughout the design process. Maximizing tool life and minimizing tool breakage when tapping, however, requires special consideration in terms of toolholding.
When tapping, the overwhelming majority of errors will result in a scrapped part because it is often difficult and time consuming – if not entirely impossible – to remove a broken tap from inside a hole. And because tapping is usually performed as one of the final operations, it’s especially costly to scrap a part after factoring in the value added by operators, lost machining time and material costs. To avoid these issues, OEMs have developed a range of technologies to help engineers and operators tap high-quality threads. One of the most important developments is rigid or synchronous tapping, which involves synchronizing the spindle speed and feed rates in relation to the tap’s thread pitch for an extremely efficient way to produce threads.
An increasing number of machine tools now feature the advanced controls and powerful spindles required for rigid tapping, but for the most secure process, the toolholder must be up to the task as well. The synchronization eliminates any need for axial compensation, so toolholders can be far more compact for greater clearance, but they must be highly rigid to maximize tool life. ER collets with internal squares are good options, as they provide the necessary rigidity and clamping forces for effective rigid tapping.
Rigid tapping is usually the fastest method to make threads, but there are many situations in which it isn’t an option. Older machine tools, for instance, generally don’t have the computational power to do the fine speed and feed rate adjustments necessary for perfect synchronization. Even newer machines will slowly drift out of sync due to the dynamics of the spindle and linear drives, creating an unacceptable level of risk for many tapping operations, particularly as tool wear further increases the axial cutting forces that cause most tap breakage.
Historically, tapping with these machines has required relatively complex and specialized tapping heads that take up a lot of room and cost far more than simple taps. Today, most shops opt for tension-compression collets, a more compact axial compensation solution. These relatively simple solid collets have an internal spring that provide taps with the flexibility necessary to maintain optimal cutting conditions and compensate for axial forces generated when a tap runs into a hole and reverses to back out of it when threads are complete. While this usually isn’t as efficient as rigid tapping, it’s very cost-effective way to reduce risk and improve productivity in less stable machining conditions.
For critical machining operations like tapping, quality toolholding is one of the best ways to achieve optimal process security. REGO-FIX offers a complete range of ER tapping collets that have been designed specifically for full compatibility with our standard ER collet system and feature the same high build quality that enables exceptional performance and tapping precision. Learn more about REGO-FIX ER collets and tapping collets here.