# Planing and slotting

Straight knife and corresponding holder

The planing and bumping are two cutting manufacturing method of the group machining with geometrically defined cutting edge , with the single-edge cutting tools are carried out: The planing tools and the impact chisel or knife . A plane, on the other hand, is a tool for a related process of woodworking . According to DIN 8580, they are assigned to a group as they are kinematically identical; the relative movement between tool and workpiece is therefore the same. When pushing, the cutting movement is generated by moving the tool while the workpiece is stationary; it is the other way around with planing. Slotting and planing are used to create flat surfaces such as grooves and recesses; however, they hardly play a role in industrial manufacturing because they have been largely replaced by milling , which is more productive and flexible. Important exceptions are gear planing and gear shaping for the manufacture of gears. The associated machine tools are the planer and the slotting machine . Advantages of slotting and planing over other methods are the low setup and tool costs as well as the lower heating of the workpiece. Disadvantages, however, are the long production times (uneconomical idle return stroke and limited cutting speed ) and, when planing, the machine size . Planing and slotting, along with turning and drilling, are among the oldest manufacturing processes. See history of production engineering .

## Definition according to DIN 8589

"Planing or slotting is chipping with step-by-step, repeated, mostly straight-line cutting movements and step-by-step feed movements perpendicular to the cutting direction ."

## Bump

When slotting, the tool performs the reciprocating cutting movement. It consists of a working stroke, in which material is removed, and a return movement, called the idle stroke, in which no material is removed. After the working stroke, the workpiece moves perpendicular to the cutting movement (feed movement) in order to ensure further material removal. When pushing horizontally, the tool moves horizontally, the workpiece can move either horizontally or vertically. With perpendicular pushing, the tool moves vertically and the workpiece within a plane that is horizontal to the ground.

## Planing

When planing, the tool is firmly clamped and the workpiece performs the cutting movement. After the return stroke, the tool continues to move perpendicular to the cutting direction and thus performs the feed movement. The cutting direction is practically always in the horizontal direction. The feed can also be up or down.

## Classification of procedures

In DIN 8589, all metal-cutting production processes are classified according to a uniform classification scheme. Planing and slotting bears the order number 3.2.4 (3rd main group: cutting , 2nd group: cutting with a geometrically defined cutting edge , 4th manufacturing process).

• 3.2.4.1: Planing and shaping: Used to create flat, i.e. flat surfaces.
• 3.2.4.2: Round planing and shaping: Used to produce round surfaces.
• 3.2.4.3: Screw planing and slotting: Used to produce screw-like surfaces.
• 3.2.4.4: Gear planing and gear shaping : Used to produce gears , e.g. B. gears or racks .
• 3.2.4.5 Profile planing and shaping: Used for the production of any surface with a profiled tool that contains the shape to be created as a negative.
• 3.2.4.6 Form planing and shaping: Serves for the production of any surfaces that are created by the controlled cutting and feed movement.

## Surfaces and accuracies

The surfaces produced have characteristic parallel lines that originate from the machining marks. The achievable roughness measured as mean roughness is R a = 2 to 4 µm. This can be achieved by using wide finishing tools in which the secondary cutting edge is about one and a half to twice as long as the feed rate and the tool setting angle of the secondary cutting edge is very small. The achievable dimensional deviations measured as achievable ISO tolerances are IT 8. In special cases IT 7 or IT 6 are also possible.

The roughness depends on the feed rate, the material, the cutting edge geometry and the cutting depth .

## Calculation of forces and services

The required power resulting from the cutting force , the frictional force on the guide table of the machine , the cutting speed and the efficiency of the drive to ${\ displaystyle P}$ ${\ displaystyle F_ {s}}$${\ displaystyle F_ {R}}$ ${\ displaystyle v_ {c}}$${\ displaystyle \ eta}$

${\ displaystyle P = {\ frac {(F_ {s} + F_ {R}) \ cdot v_ {c}} {\ eta}}}$.

The cutting force can be calculated using the Kienzle formula . These include the cutting depth , the feed rate and the specific cutting force : ${\ displaystyle a}$ ${\ displaystyle f}$ ${\ displaystyle k_ {s}}$

${\ displaystyle F_ {s} = a \ cdot f \ cdot k_ {s}}$

The frictional force results from the weight of the machine table and the weight of the largest workpiece and the coefficient of friction to: ${\ displaystyle G_ {T}}$${\ displaystyle G_ {W}}$ ${\ displaystyle \ mu}$

${\ displaystyle F_ {R} = (G_ {T} + G_ {W}) \ mu}$

## Guide values

The cutting speed depends on several factors. Among other things, the cutting material , the tool life criteria and the desired tool life .

### Guide values ​​for high speed steel

The following values ​​apply to tools made from high-speed steel and a service life of 60 minutes:

material Feed [mm] Cutting speed [m / min] Snow part geometry
designation Tensile strength [N / mm²]
or Brinell hardness
Clearance angle Rake angle Inclination angle
Gray cast iron up to 200 HB 0.4 to 1.0 18 to 13 8 ° 8 ° 8 °
1.0 to 2.5 13 to 10 8 ° 8 ° 8 °
200 to 250 HB 0.4 to 1.0 12 to 9 8 ° 6 ° 8 °
1.0 to 2.5 9 to 7 8 ° 6 ° 8 °
alloyed gray cast iron 250 to 450 HB 0.4 to 1.0 11 to 9 8 ° 6 ° 8 °
1.0 to 2.5 9 to 7 8 ° 6 ° 8 °
Structural steel /
hardened steel /
heat-treated steel
500 0.4 to 1.0 18 to 12 8 ° 14 ° 8 °
1.0 to 2.5 12 to 8 8 ° 14 ° 8 °
600 0.4 to 1.0 12 to 8 8 ° 12 ° 8 °
1.0 to 2.5 8 to 6 8 ° 12 ° 8 °
700 0.4 to 1.0 11 to 7 8 ° 10 ° 8 °
1.0 to 2.5 7 to 5 8 ° 10 ° 8 °
Cast steel 700 0.4 to 1.0 11 to 7 8 ° 10 ° 8 °
1.0 to 2.5 7 to 5 8 ° 10 ° 8 °

### Guide values ​​for carbide

The following values ​​apply to tools with soldered-in carbide cutting edges and a service life of 240 minutes:

material Feed [mm] Application group Cutting speed [m / min] Snow part geometry
designation Tensile strength [N / mm²]
or Brinell hardness
Clearance angle Rake angle Inclination angle
Gray cast iron up to 180 HB 0.4 to 1.0 K20 45 to 30 8 ° 15 ° to 20 ° −10 °
1.0 to 1.6 K20 30 to 25 8 ° 15 ° to 20 ° −10 °
K30 25 to 20 8 ° 20 ° −10 °
1.6 to 2.5 P40 30 to 25 8 ° 20 ° −10 °
K30 20 to 15 8 ° 20 ° −10 °
180 to 220 HB 0.4 to 1.0 P30 60 to 45 8 ° 20 ° −10 °
M20 50 to 35 8 ° 10 ° −10 °
K10 50 to 35 8 ° 10 ° −10 °
K20 40 to 30 8 ° 10 ° −10 °
1.0 to 1.6 P30 45 to 35 8 ° 20 ° −10 °
K20 30 to 25 8 ° 10 ° to 15 ° −10 °
1.6 to 2.5 P40 25 to 20 8 ° 20 ° −10 °