High speed machining (HSM)

A Presentation on,

By

NIKHIL R

CONTENTS:-

• History of High speed machining

• Comparison between conventional and high speed

machining

• Process parameters

• Machine details

• Advantages & Disadvantages

• Application areas of HSM

• Conclusion

• References

• First tries were made in early twenties of the past

century.

• The first definition of HSM was proposed by Carl

Salomon in 1931.

• He has assumed that at a certain cutting speed which is

5 –10 times higher then in conventional machining, the

chip tool interface temperature will start to decrease.

HISTORY OF HSM:-

Solomon’s curve

DEFINITIONS

• High cutting speed machining (Vc)

• High spindle speed machining (n)

• High feed machining (f)

• High speed and feed machining

• High productive machining

Finally,“HSM is a powerful machining method that

combines high feed rates with high spindle speeds, specific tools and specific tool motion.”

Effect of cutting speed on cutting

force

Effect of cutting speed on specific cutting force

for aluminium 7050

Transition Range of HSM for different

metals

HIGH SPEED MACHINING

ACCURACY

EFFICIENCY

REDUCED MACHINING TIME

QUALITY OF WORKPIECES

DECREASED COSTS

High Speed machining leads to -

Improvement of production when using HSM

FEATURES EFFECTS

Reduced heat

transfer in to the

work piece

Part accuracy

Reduction of

cutting forces

Part accuracy

Surface quality

Increased cutting

speed

Stability of rotating

cutting tool & feed rate

Increased material

removal rate (MRR)

Comparision between Conventional Machining and High

Speed Machining

Conventional HSM

The contact time between

tool and work is large

Contact time is short

Less accurate work piece More accurate work

piece

Cutting force is large Cutting force is low

Poor surface finish Good surface finish

Material removal rate is

low

Material removal rate is

high

Cutting fluid is required Cutting fluid is not

required

HSM EDM

Material removal rate

high

Material removal rate is

low

Dimensional tolerance

0.02 mm

Dim tolerance

0.1- 0.2 mm

There is no need of

making cutting tool

according to the

contour to be machined

Cutting tool has to be

made according to the

contour to be machined

Comparision between EDM and HSM

1) True cutting speed:-

• As cutting speed is dependent on

both

spindle speed and the diameter of the

tool, HSM should be defined as “true

cutting speed“ above a certain level.

Feed is given by,

2) Metal Removal Rate

The metal removal rate is given by,

Where,

ap = vertical distance from tool tip to the reference point

mm ae = step over distance mm

vf = feed speed mm/min

Surface finish is depends upon cutting tool geometry,

coating of the cutting tool, wear status of the cutting

tool etc.

3) Surface Finish:-

Machine tools available-

• 3-axis horizontal and vertical milling machines.

• CNC 4-axis milling machine offers the option

of tilting the milling cutters to improve the cutting

conditions.

• 5-axis machine with inter changeable spindle

units allow to rough, semi finish and finish with a

single set up.

Vertical High Speed Machining Mills

Specifications

Horizontal High Speed Machining Mills

Specifications

Machine tool requirements for HSM

1. TiN and TiCN coated Carbide for materials with

hardness less than 42 HRC

2. TiALN coated Carbide for materials with hardness

42 HRC and above

3. For special applications like hard turning (HRC

60-65) PCBN is used

4. Cubic boron nitrite (CBN) and ceramic for cast

iron

5. Poly crystalline diamonds (PCD) and Cermets are

used for aluminum

CUTTING TOOLS

ADVANTAGES

• High material removal rate

• High surface finish

• Increased productivity

• Possibility of machining of very thin walls

• Reduction in lead times

• Low cutting force

• Cutting tool and work piece temperature are kept low

• Connection time between the cutting edge and work piece is

short

• It eliminates the need of coolant

• Reduction of production process

• Need for expensive and special machine tools

with advanced spindle and controllers

• Excessive tool wear

• Good work and process planning necessary

• It can be difficult to find and recruit advanced

staff

DISADVANTAGES

Tool holder balancing problem:-

APPLICATIONS OF HSM

• HSM is not simply high cutting speed .It should be

regarded as a process where the operations are

performed with very specific methods and precision

equipment.

• HSM is not necessarily high spindle speed

machining. Many HSM applications are performed

with moderate spindle speeds and large sized

cutters.

• HSM is performed in finishing in hardened steel

with high speeds and high feeds often with 4-6

times conventional cutting speeds.

CONCLUSION

• HSM is high productive machining in small

sized components in roughing to finishing and

in finishing to super finishing in components of

all sizes.

• Even though HSM is known for a long time, the

research are still being developed for further

improvement of quality and optimization of cost.

The technical papers referred for this seminar are listed below.

[1] PASKO, R. - PRZYBYLSKI, L. & SLODKI, B, High Speed Machining

(HSM) – the effective way of modern cutting, Cracow University of

Technology.

[2] M.A. DAVIES, T. J. BURNS, T. L. SCHMITZ, High-Speed

Machining Processes: Dynamics on Multiple Scales, National Institute

of Standards and Technology, USA.

[3] J. KOPAC, Advanced tool materials for high-speed machining, 12th

international science conference paper, Faculty of Mechanical

Engineering, University of Ljubljana, Slovenia.

[4] HERBERT SCHULZ, The History of High-Speed Machining,

Darmstadt University of Technology, Germany.

REFERENCES