# Tension movement

As Spanungsbewegung all movements when are chipping refers to a change in position between the workpiece and cutting tool cause. The machining movements have the consequence that the tool and the workpiece are guided towards or into one another, the cutting edge penetrates the material and removes a chip . For the machining process, it is irrelevant whether the workpiece or tool executes the movement; only the relative movement between the two is important. According to DIN 6580, when considering the process, it is specified that the tool moves and the workpiece is stationary.

## Cutting movement

The cutting movement describes the cutting movement in the cutting direction. Together with the feed movement, it results in the active movement, which represents the separating movement of the tool cutting edge through the material . The cutting movement causes the one-off chip removal during one revolution ( milling , turning , drilling , sawing with circular saws) or one stroke ( planing and slotting , filing , sawing with hacksaws).

Since the cutting movement is the most important movement in machining, it is also called the main movement. The velocity in the direction of the cutting movement is cutting speed (of English. Cut = average) mentioned. The cutting force, a component of the cutting force (out of date ) , also points in this direction . ${\ displaystyle v_ {c}}$${\ displaystyle F_ {c}}$ ${\ displaystyle F}$${\ displaystyle F_ {z}}$

With a given cutting material (tool material) and workpiece material, the wear during machining is significantly influenced by the cutting speed: the higher it is, the faster the tool wears. On the other hand, high cutting speeds lead to shorter machining times and thus to higher productivity. As the cutting speed increases, so does the metal removal rate - the volume separated per time - which is used as a measure of productivity.

## Feed movement

The feed movement has the effect that the tool is continuously guided along the workpiece or into it and so a constant material removal takes place; if there was no feed movement, the tool would cut free at its position and then run empty. Together with the cutting movement, it results in the active movement that removes a chip from the workpiece. When drilling, the feed movement runs into the workpiece, when sawing it is the movement of the tool into the resulting joint, while turning and milling it is the movement along the outer contour to be created. When filing, planing and shaping, the feed movement takes place gradually after each stroke. There is no feed movement when broaching .

The speed of the tool in the feed direction is the feed rate . It is usually around 10 times less than the cutting speed.

The distance that the tool covers per revolution or per stroke is called the feed . It is specified in mm / revolution or mm / stroke and therefore has the dimension mm / 1 = mm. As the feed rate increases, the chip cross-section becomes larger and thus the width of the separated chip. The greater the feed, the greater the metal removal rate and the feed force on the tool. ${\ displaystyle F_ {f}}$

## Active movement

The active movement results from the superimposition of the simultaneously running feed and cutting movements. It represents the actual relative movement of the cutting edge during machining and indicates the direction of tool engagement.

Since the cutting speed is generally much higher than the feed speed , the direction of movement of the resulting effective movement deviates only slightly from the cutting movement. If, as with broaching , the cutting movement is not accompanied by a feed movement, the knitting and cutting movements are identical.

In the direction of the effective movement , the effective speed (from English effective , resultant of the cutting and feed speed) and the effective force , a further component of the cutting force. ${\ displaystyle v_ {e}}$${\ displaystyle F_ {e}}$

## angle

Speeds during longitudinal turning: cutting speed v c , feed speed v f , effective speed v e , feed direction angle, effective direction angle , speed n.${\ displaystyle \ varphi}$${\ displaystyle \ eta}$

The angle between the vectors of the cutting speed and the feed rate is the feed direction angle . It amounts to either ${\ displaystyle \ varphi}$

• constant 90 ° (turning, drilling, filing, planing, slotting, lifting grinding, honing) or
• it is variable during one revolution (milling, grinding with grinding wheels).

The angle between the vector of the cutting speed and that of the effective speed is the effective direction angle . ${\ displaystyle \ eta}$

## Positioning movement

The positioning movement describes all movements on machine tools that are necessary to position the tool before and after the intervention.

A distinction is made between three different positioning movements on machine tools, but they are not themselves involved in the removal of chips:

• The approach movement is the cutting movement that guides the tool to the point on the workpiece where the cutting process is to begin. The return movement, on the other hand, returns the tool to its original position. They are usually carried out in rapid traverse in order to increase the spindle running times and to minimize unproductive idle times.
• The infeed movement defines the thickness of the chip to be removed, but with some methods, such as drilling, there is no infeed in the classic sense because it is stored in the tool. When drilling, it corresponds to the radius of the drill bit or half the difference in diameter of a hole to be drilled. There is no infeed for broaching or plunge turning, for example . Since very small infeed depths cause the tool and workpiece to move away, in such cases one travels over the workpiece again without further infeed ( firing ). An edge finder can be used to determine the exact edge position of the workpiece .
• The adjusting movement usually leads CNC controlled corrective movements of the feathering and feed movement during the Spanens from, the result of tool wear are necessary or dynamic positional deviations between the workpiece and tool.

## literature

• Armin Steinmüller: Machining technology. 6th revised edition, Verlag Europa-Lehrmittel, Nourney, Vollmer GmbH & Co. KG, Haan Gruiten 2015, ISBN 978-3-8085-1496-2 .