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Coolant Pressure, Not Spindle Drive, Enables High-Speed Machining

Posted by: 11. November 2014

Most everyone’s had the experience of running a job that needs a little more travel, horse power, or spindle speed, than the machine available to do the job has got.  The part might be a little longer, or require heavy roughing, or have many small holes to drill.  When that happens, the job gets done anyway, but might require another setup, an extra roughing pass, or settling for slower cycle time and high tool wear due to less than optimal drilling speeds and feeds.   Features like travel, horse power and spindle speed are all limited by each machines maximums and can’t be turned up when a little extra is needed.  But now, tooling manufacturer, Iscar, has found a way to turn any machining center, no matter it’s top rpm, into a high speed spindle machine that’s capable of running small diameter round tools up to 50,000 rpm and higher.

How do you get 50,000 rpm out of a 3,000 rpm spindle?  Not by increasing the voltage, or adding a transformer, or changing the main spindle, itself. SpinJet is the solution. It’s not a solution designed to replace a machining center with a high speed spindle, but rather to more optimally power/drive small round tools that demand higher SFM, then the machine assigned to the job can provide. SpinJet upgrades the machining capability, improves machine performance (and potentially its spindle life), enables faster cycle times, better surface quality and extends tool life. SpinJet is a simple, relatively inexpensive, coolant-powered, turbine-driven tool holder that can rotate small tools set in the holder within ranges of 20,000 – 45,000 rpm, or from 30,000 – 55,000 rpm, or from 40,000 to 65,000 rpm.  The increased speed is dependent on certain simple machine prerequisites including, coolant flow through the main cnc machine spindle, with a minimum and maximum coolant pressure and a minimum flow rate, and coolant filtration, Most machines are already capable right out of the box, so the implementation is simple.

I can imagine using the SpinJet holder in jobs where many 3 mm or smaller holes were specified. But the application of SpinJet isn’t limited to just drilling. According to Tom Raun, Iscar Machine Tool OEM specialist, many different types of tools can benefit from increased speed using SpinJet, including high speed end milling, thread milling, engraving, chamfering, and even grinding.  SpinJet is even being used on high speed machining centers in applications where thousands of 1-3 mm holes are being drilled in aluminum. Why use SpinJet on a machine that already has a 30,000 rpm spindle?  According to the manufacturing engineer, the cost of replacing a machine spindle is many times the cost of a SpinJet holder. Running thousands of holes at 30,000 rpm, does take a toll on even the most well designed, high-performance machine spindles.  The company’s machines weren’t purchased solely to machine small holes, so saving the spindle by using SpinJet for the small hole operation is an efficient way to improve machining performance, tool life, surface quality, and cycle time, all while extending spindle life and reducing the total cost of operation over the life of the machine.

I didn’t fully appreciate the speed difference until I watched the YouTube video because I’d overlooked the gains to be realized by increasing feed rates as rpms increased.

Three SpinJet models are currently available for less than $6,000. An operations manual is available to download (20-50 seconds depending on your internet connection).

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