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Turning – definition

Turning – what is this ? Turning is a type of machining – one of the basic and most popular. In order to obtain the desired shape and dimensions of the workpiece, the turning knife separates the top layer of the material. This method of machining applies to both external surfaces (turning) and internal workpieces (boring). When separating the excess material, we obtain chips of different length and elasticity – depending on the type of the turned material – they are a side effect of turning.

Turning a solid, but is it all?

Axially rotating shapes are processed in this way. In classical machining, the turning knife is stationary (or undergoes rectilinear motion), while the workpiece – driven by the machine spindle – rotates. The surfaces of the details are most often cone-shaped or cylindrical, but they can also be curved or spherical.

Materials

Very different materials are subject to turning. This is how you can process:

·     Unalloyed steel

·     Low alloy steel

·     High-alloy steel

·     Hardened steel

·     Stainless steel

·     Gray cast iron, compact graphite, nodular, ductile, isothermally hardened, malleable

·     Heat resistant super alloys

·     Non-ferrous materials (aluminum & copper and its alloys: brass, bronze)

·     Plastics

plastic turning

Basic assumptions of the turning process

The turning process depends on various parameters such as:

• Cutting speed

• Depth of cut

• Cutting power

• Metal removal rate

• The hardness of the processed material

• Machine time for turning

• Blade durability

High Precision

Classification of turning methods

Turning can be classified in a number of different ways. Depending on the direction of the feed movement of the knives in relation to the axis of rotation of the solid, we can distinguish:

  • Face turning
  • Longitudinal turning (the direction of the feed motion is parallel to the axis of the workpiece
  • Copy turning
  • Turning
  • Turning cones
  • Boring, drilling, threading, knurling
     

The movements accompanying turning can be divided into:

  • Basic movements: main and feed movement
  • Auxiliary Movements: Movements to correctly locate the tool while the machine is paused

Turning can also concern:

  • outer surface – rolling
  • internal surface – boring, boring
     

When we take into account the type of tool – we can distinguish:

  • point turning
  •   form turning
  • hobbing
     

Depending on the quality of the turning performed, we can divide it into:

  • very precise turning
  • fine turning
  • medium-fine turning
  • rough turning

When analyzing the position of the axis of rotation of the object, we notice:

  • Horizontal turning
  • Vertical turning
     

In the case of conical surfaces, there are several ways to process them:

  • Turning according to the ruler
  • Turning with a shaped knife
  • Turning by twisting the bottom bracket
  • Turning by shifting the tailstock axis
  • Turning on CNC lathes

Lathe

A lathe, also known as a machine tool, is a machine on which the turning process takes place. Until recently, in every metalworking plant it was possible to find a conventional or traditional lathe, which is now being replaced by CNC numerical machines. The CNC lathe ensures high repeatability, unquestionable precision and a fast pace of work, which is of great importance in serial production. Thanks to it, you can bring out a lot of identical details in a short time.

Lathes have machining tools – turning knives or drills. There are many types of lathes, such as: heavy, multi-tool, turret (also called revolver), carousel, disc, specialized, automatic, semi-automatic, production, special and industry-specific, and finally the most popular are CNC lathes.

Turning knives

The tool used for turning is the so-called turning tool. Depending on the type, they are used for the treatment of internal and external surfaces. 

We define by the shape: 

  • parting tool
  • turning tool
  • right hand turning tool
  • left hand turning tool
  • radius turning form tool
  • thread cutting tool
  • chamfering tool

Taking into account the method of making knives, we can distinguish:

  • uniform – completely made of one material
  • folded
  • combined – permanently connected working part and part used for gripping
     

Folding knives are most often used, because in this case it is possible to change the position of the insert when the cutting surface wears out, and also to replace it when the time comes. We can distinguish these tiles due to their shape. So we have triangular, square, pentagonal plates, they may differ in size, blade geometry and the material from which they are made (superhard materials, sintered carbides, ceramics).

Depending on the cutting direction, we can distinguish left, right and double-sided knives.

Source:

• own knowledge

• Wikipedia

http://bc.pollub.pl/Content/12886/PDF/ubytkowa.pdf