The conventional lathe: what is this machine tool like and how does it work?

A conventional lathe is a machine tool capable of turning cylindrical, helical and conical parts; mainly with metal, plastic and wooden bodies, removing parts of them by means of a cutting tool or other tools until the desired shape is achieved.

Broadly speaking, these are heavy and complex machines, essential in the manufacture and shaping of parts that are considerably difficult to work, maximising both the scale of production and a uniform finish in series. There are currently different types, designed to meet multiple machining needs, although the general operation remains practically the same in each model.

What is it used for? Main operations

The main operations of this machine tool are:

• Cutting: To cut the workpiece to the required or desired size.
• Threading: For making screws and nuts.
• Roughing: To begin shaping the workpiece by removing large amounts of surplus material, which involves discarding large swarf.
• Finishing: Usually done after roughing, removing tiny layers from the surface of the workpiece to obtain a cleaner, shinier result. The swarf discarded is smaller and finer.

Essential components of this machine tool

There are many components that make up a lathe, but the most important are the following:

Bed

This is the main structure that serves as the base for the other parts of the lathe. The main carriage and the tailstock move along the guideways located on the upper part of the bed.

Chuck

A circular component with jaws that hold the workpiece, making it rotate around a central axis.

Tailstock

It is located at the other end of the bed with respect to the position of the chuck, perfectly aligned with it. It is a movable shaft that ends in a point and is the other component responsible for holding the workpiece, moving towards the chuck to clamp the workpiece.

Main carriage

It is one of the largest parts, responsible for producing the feed movement of the workpiece to be turned, and it does so by moving along the rails of the bed. It also serves as a support for the cross slide, the component needed to apply the depth of cut to the workpiece by means of a tool fitted in its turret.

Taper attachment

It is an attachment needed to work conically shaped materials.

Steady rest

Necessary to support the other side of the workpiece in case this cannot be done with the tailstock. It is located at the other end from the chuck, behind the tailstock.

STD/MM thread chart

The standard and metric thread chart is indispensable for making the adjustments to speed (revolutions) and gears that define the parameters for threading the workpieces.

What is it like? Technical aspects to bear in mind

Conventional lathes are regarded as machines and tools at the same time, given the complexity of their components and mechanisms. But there are some essential specifications that must be taken into account when buying one, so that production requirements are properly met.

Swing capacity

The machine's ability to accept workpieces of a certain thickness depends on this, that is, it is what determines the maximum diameter of the material to be worked.

Spindle bore

This aspect establishes the maximum diameter of the bar that can pass through the spindle. It is determined by the diameter of the spindle bore.

Between centres

This is the name given to the distance between the chuck and the tailstock, which determines the maximum permitted length of the workpiece to be worked.

How does a conventional lathe work?

The operation of a lathe is based on three basic movements: rotation, feed and penetration. These occur simultaneously and can be regulated in speed, pressure and angle in order to obtain the desired finishes on the workpiece.

1. Rotation: This movement makes the workpiece to be turned rotate on itself. It is mounted on a central axis; in this way, the cutting tool or machining tool can reach it from all sides.
2. Feed: With this movement the cutting tool advances in a straight line and parallel to the length of the workpiece, for which it uses the main carriage.
3. Penetration: Finally, the cutting tool moves towards the surface of the material, scoring, penetrating and cutting part of it until the desired shapes are obtained. As a result of this movement, the well-known swarf (waste/remains of material) is produced.

It is worth noting that, in the beginning, these machine tools were completely mechanical. However, nowadays electronic models can be found, including numerically controlled lathes working with programmable automation.

At Heller we have a large number of conventional lathes, with different distances between centres and swings over bed.

We also offer variable-speed lathes, which use an electronic element that makes it possible to control the rotation speed of the workpiece and the feed rate of the cutting tool.

If you are looking for an industrial lathe for your workshop, do not hesitate to consult the product range of lathes we offer at Heller Maquinaria.

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