Flatbed lathes

Flatbed lathes are widely used in heavy-duty turning and offer a reliable, stable and powerful machining process with high productivity.

Flatbed lathes machine configuration

Heavy-duty and flatbed lathes have extremely high stability but have a more limited tool changing and indexing possibility compared to slant-bed turning centers and vertical lathes. Large component/swing diameters combined with long lengths make steady rest and tailstock a standard fixture.

Flatbed lathes are generally considered to more easily accommodate the loading and unloading of large components. A "gap" between the headstock and bed can also be useful for permitting increased component swing diameters, which leads to the name "gap bed lathes".

Large machines often have large bore headstocks and some headstocks can have double chucks fitted to permit through-headstock loading.

The bed lengths are often well over four meters and easily permit the use of multiple steady-rests. However, it should be noted that these are often "fixed" steadies that normally cannot be used in the same way as the hydraulically operated "turn-through" types generally used on slant-bed machines or turning centers (the slant-bed design can also permit easier axial positioning).

Not all flatbed lathes are fitted with chip conveyors; therefore, always consider chip removal possibilities. Sometimes front and rear conveyors are a good option to reduce downtime.

Turret configuration

Turning operations can be classified as heavy-duty, requiring high stability, and the tool-post design is often preferred over the turret design. If the machine is to be fitted with an indexable tool post, then a VDI dovetail (DIN 69881) provides extremely good stability and is still the most robust solution for demanding cutting depths as well as for providing sufficient clamping stiffness for long boring bars. Sizes 115 and 140 are commonly used; 140 is preferred for heavy-duty cutting and long boring bars.

VDI dovetail

The VDI dovetail four-post-type turret gives plenty of adjacent tool clearance; however, with only four indexing positions for all operations, this produces some limitations when using shank tooling.

Long boring bars loaded to the turret may restrict the tool post from indexing. Quick change coupling boring bars are now standard up to Ø 100 (10 x D), which permits easy and accurate tool change to maximize the utilization of the machine.

External set-up

Internal set-up

Deep hole machining

Flatbed lathes are commonly used for deep internal machining. The following areas need to be considered:

• Boring bar saddle/cross slide Boring bars up to diameter 600 mm (23.622 inch) can be utilizedIt is important to have split-cap clamping on the saddle for at least 4 x DThe moment of the boring bar needs to be consideredA counterweight might be needed depending on the diameter/overhang
• Drilling spindle – rotating/stationary
• Pump capability for deep hole drilling – pressure/flow
• Coolant tank capacity

Quick change in flatbed lathes

Flatbed lathes offer high stability but slow tool indexing and changing. Shank tool holders are heavy, and with the limited number of tool positions, quick change has a dramatic effect on machine efficiency.Read more about quick change solutions