GlossaryKind of term: Manufacturing termLive tooling and sub-spindle
What are live tooling and sub-spindles?
Live tooling lets a lathe drill and mill; a sub-spindle takes the workpiece over to machine the back end, so less manual reclamping is needed.
The live tools sit in the turret and take their rotation from a drive inside it; that way they can also tap, while the workpiece is held still or rotated under control. With a C axis the main spindle positions the workpiece at an angle or interpolates with the tool, for example for a spanner flat or a slot. A Y axis lets the tool work off centre as well. The sub-spindle, or counter-spindle, faces the main spindle, grips the workpiece before part-off and machines the back end.
What decides what a lathe with live tooling can do?
What a lathe with live tooling can do depends on the power, speed and stiffness of the driven holders, which are usually lower than those of a machining-centre spindle. Without a Y axis, many off-centre features can still be made with C-axis interpolation, but not all: a cross hole that does not pass through the centre needs a Y axis. Angled holes need an angled holder or a tilting axis. The transfer to the sub-spindle is an automated reclamp: the coaxiality between front and back depends on the accuracy of that transfer and on how the part is gripped.
How do live tooling and sub-spindles work in practice?
Live tooling and a sub-spindle can make a second operation on a machining centre unnecessary: the queue in between, the manual reclamp and setting a new work origin drop out, and turned and milled features are made in the same coordinate system. The trade-off is usually a higher hourly rate and more programming and setup time. A heavy milling operation can take longer on the lathe than on a machining centre. Which comes out cheaper per piece depends on quantity, rates, milling volume and the tolerances between turned and milled features.
What are live tooling and sub-spindles often confused with?
A lathe with live tools is not by definition a mill-turn centre. The line is not sharp; a mill-turn centre usually means a machine with a tilting milling spindle (B axis) and a Y axis that can take heavier milling. Nor is a tailstock a sub-spindle: the tailstock supports the end of a long workpiece on a centre, while the sub-spindle grips and turns the workpiece itself.
How do you see live tooling and sub-spindles in Blake?
In Blake turning and mill-turn are each a process of their own, with material, machining, setup and programming as separate lines, per piece and per batch. The lines use the hourly rate of the machine in the route and are labelled as estimates. More on mill-turn.
Frequently asked questions
What can a lathe with live tooling do, and what can it not?
A C axis gives cross holes through the centre, axial holes on a pitch circle and spanner flats; a Y axis adds off-centre radial holes and wider flats. Heavy milling and angled holes need a stiffer spindle, an angled holder or a B axis.
Is the transfer to the sub-spindle an extra setup?
Technically yes: the workpiece is released and clamped again in another spindle, only automatically. Whether your estimate counts it as a separate setup is a convention. For the tolerances between front and back it counts either way.
Why is the hourly rate higher with a sub-spindle?
The machine costs more to buy and maintain, and programming usually takes longer. In return the part often comes off complete. Whether that is cheaper per piece depends on quantity, milling volume and the alternative route.