Metal Lathes: Universal and CNC

How to choose a metal lathe

A lathe machines rotational parts — shafts, axles, bushings, flanges, discs and rings: it turns outside and inside diameters, faces, grooves and tapers, cuts threads, and drills and bores on the axis. The catalog carries German Weiler and Seiger machines and machines under our own LUNA brand, made in China: from the compact Weiler Primus with a 280 mm swing over bed and 500 mm between centers to the Weiler E200 and Seiger SLZ 2000 with a 2000 mm swing and up to 16 and 20 m between centers.

Five types of lathes

The types differ in who drives the carriage — the operator, a cycle on the control or a program — and in how the spindle is positioned.

What to compare

• Swing over bed and turning diameter. The swing over bed shows what part clears the bedways, but the diameter you can machine over the carriage is smaller. The LUNA Altair 35 CNC has a 580 mm swing over bed and a 360 mm maximum turning diameter. For a part with a flange or collar, check both figures.
• Distance between centers. It sets the longest shaft: 650 to 1900 mm on the LUNA Altair 6140A, up to 10,000 mm on the heavy Altair 6180 and 6280, and up to 20,000 mm on the Seiger SLZ 1000 E and larger. A long, slender shaft deflects under the tool without support, so include steady rests in the configuration from the start.
• Spindle bore. Bar or tube is fed through it. The LUNA Altair 6140A has 52 mm, the 6140B/A with the same swing 80 mm, and the Altair 6180 and 6280 104/140 mm. For threads on pipe up to Ø340 mm there are pipe-threading lathes with a 300–365 mm spindle bore.
• Speed, power and torque. Small diameters and aluminium need speed — up to 5000 rpm on the Weiler Praktikant VCPlus. Large diameters need low speed and torque: 3.15–315 rpm and 22 kW on the LUNA Altair 61100–61160, and 8000 N·m at the spindle on the Altair 125 CNC series.
• Control. Manual, with a digital readout, cycle control or CNC. On flat-bed LUNA Altair machines you choose the CNC — FANUC, Siemens or GSK; on cycle-controlled Seiger machines, Heidenhain MANUALplus 620 or Siemens. Take the one your operators and setters know.

Replacing a 16K20, 1K62 or 1M63

The Soviet 16K20 and 1K62 have a 400 mm swing over bed, the 1M63 630 mm. The same class in the catalog is the LUNA Altair 6140A and 6140B/A at 400 mm and the LUNA Altair 6163 and 6263 at 630 mm. Compare not only the swing but also the distance between centers, spindle bore and power — against your parts, not the old machine’s data sheet. If the old machine makes repeat parts, look at cycle-controlled lathes as well. The AI analog finder helps find a replacement model by the old machine’s name. What to check before the swap is covered in Replacing a 16K20, 1K62 or 1M63 lathe.

Common mistakes

• Choosing by swing over bed without checking the swing over the carriage and the distance between centers.
• Buying CNC for repair and one-off parts: a universal or cycle-controlled lathe is easier to learn and needs no programmer.
• Budgeting for the machine only: chucks, steady rests, tool holders, live centers and tooling are a separate line in the budget.

Send a drawing or sketch of the part, the material, the largest diameter and length and the monthly quantity — we will select the type and model, chucks and tooling, delivery and commissioning. For faces, slots and prismatic parts, see milling machines; for holes and threads in housings, drilling machines; for finishing shafts after turning, grinding machines.