5. Pitanje Obrada Okretnim Pločicama

8/17/2019 5. Pitanje Obrada Okretnim Pločicama

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PRODUCTIVITY INCREASING BY APPLICATION OF ROTARY MILLING CUTTER


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PRODUCTIVITY INCREASING - OBJECTIVE

The main outcome of raised productivity is achieved by much higher cutting speeds

and feed rates. While the speed increases, the cutting time decreases.


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Why rotary cutting tool is applied?

to overcome cutting temperature rise when cutting speed

is high –

how ?

as the cutting tool rotates and it is cooled during the non-

cutting time in one rotation of the tool, it is expected that

the temperature of the tool will decrease

it is also expected that the rotary cutting tool can be used

for high speed cutting of difficult-to-cut materials

Rotary cutter (RC) : actively driven tools (ADT) or self-propelled tools (SPT)


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temperature

time

FIXED TOOL

temperature

time

ROTARY TOOL

contact time


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Why rotary inserts ?


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The cutting inserts applied on rotary heads result with

30% improved cutting time with the incomparable better

results of tool wear.

Tool wear is dispersed over the entire length of the round

cutter, thus, efficiency of tool usage is better.


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The insert material selection

–

hot hardness


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The insert material selection – tool wear

0

20

40

60

80

100

120

140

Conventional

Carbid inserts

Rotary Carbid

inserts

Rotary Silicon

Nitride insertsProductivity 60 90 130

Productivity


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The insert type (fixed or rotary) selection – tool wear

ROTARY INSERT

ROTARY

INSERT

ROTARY

INSERT

FIXED INSERT


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The insert type selection – chip forms (by turning)

ROTARY INSERT FIXED INSERT


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Work-piece material - WNr 1.2311 (40CrMnMo7) tensile strength of 950-1100 MPa

hardness level of approximately 50 HRC

C Si Mn P S Cr Mo

Min % 0,35 0,2 1,3 1,8 0,15

Max % 0,45 0,4 1,6 0,035 0,035 2,1 0,25


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The row material - thickness 300mm (medium and large sized)


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The tools used for machining


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CUTTING CONDITIONS

Insert diameter 6mm. Cutting head diameter is 66mm

Rotation speed of cutting head 1100 rpm

velocity of cutting 275 m/min,

depth of cutting 3 mm.

consistent surface finishes of 2.0 - 3.2 micrometer Ra can

be obtained.

The Rotary Milling Cutter is most efficient at depths of cut

less than 4 mm

When using silicon nitride inserts, coolant is generally notrequired


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CONCLUSIONS

Milling cutters play an important role in performing millingoperations. The knowledge aimed in this direction assists in

determining the type of cutter(s) to be employed,

Application of rotary milling cutter results with raised produ-

ctivity in comparison with conventional. While the cutting

speed increases, the cutting time decreases, With application of the same insert type, cutting time is 30 %

better for rotary milling than for conventional milling method,

Tool wear results are several times better for rotary milling

cutter,

Tool wear is dispersed over the entire length of the roundcutter, thus, efficiency of tool usage is better.

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5. Pitanje Obrada Okretnim Pločicama