by Preben Hansen
This article originally appeared in Cutting Tool Engineering.
Live tooling, as a component on a lathe, is specifically manipulated by the CNC to perform various milling, drilling and other operations while the workpiece is being held in position by the main or sub-spindle.
These components, whether BMT or VDI, are also called driven tools, as opposed to static tools, that are used during turning operations.
Need a new tool?
When the need arises for a new machine tool, careful consideration should be made to determine which live tools are appropriate for your application. While a standard machine tool package will help you get started, it is important to anticipate job and volume changes, as well unforeseen machining challenges from the beginning, in order to avoid machine downtime.
Your examination can range from the simple such as external vs. internal coolant, for example, to the sublime including adjustable or multi-spindle configurations, to the custom tool, which may be required and built to suit your special application. Finding a supplier who has an in-house machine shop for the preparation of special tools is a great value-add.
Tool life is the product of cutting intensity, materials processed, machine stability and parts produced. Two seemingly identical job shops can have vastly different tooling needs because one is automotive and one is medical, or one specializes in the one-off and low-volume work, while the other has a greater occurrence of longer running jobs. The totality of your operation determines the best tooling for the machines being purchased.
Bearing construction and the resulting spindle concentricity drive the life of any tool. You might find that just a 10-15% greater investment in a better design can yield both longer-lasting cutters and consistently superior finish on your products.
Likewise, high pressure internal coolant might be desirable. Look for 2000 psi capabilities in 90 degree tools and 1000 psi in straight tools.
You need to ask another question, namely, is the turret RPM sufficient to handle the work to be done?
It’s possible that a live tool with a built-in speed increaser, often called a speed multiplier, would be helpful. Would it be beneficial to move secondary operations to your lathe? Gear hobbing can be accomplished in this manner, as can producing squares or flats, through the use of polygon machining.
Dedicated tools for large families of products may often be desirable for some applications, but do consider whether a flexible changing system would be more appropriate. Talk to your tooling supplier for the various options, before making that determination.
If standard ER tooling is suitable for the work, there are many good suppliers. It is important though, to pay close attention to the construction aspects noted above. For a quick-change or changeable adapter system, there are fewer suppliers in the market, so seek them out and be sure they can supply the product styles you need for all your lathe brands.
Testing live tool performance
Now, an application example showing clear evidence of the value of testing live tool performance...
One company was performing a cross-milling application using an ER 32 output tool on a Eurotech lathe, running 10 ipm at 4000 rpm. They were making three passes with a cycle time of 262 seconds and were having difficulties with chatter on the finish, while producing 20,000 pieces per year.
In the end, you may not need a universal adjustable tool or a multi-spindle live holder or even a quick-change adapter system, but do consider all these options. Talk to your machine builder and several tool suppliers, plus the most important people in this equation, your shop personnel, as their input is invaluable to keeping you up and running in a profitable, customer-satisfying scenario.
About the Author
Preben Hansen is president of Platinum Tooling Technologies Inc., Prospect Heights, Illinois, and a veteran of over 25 years in tooling and is considered a leading authority on the topic in the North American machine tool market.
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