B :1

Porosity

Bond Bridge

AbrasiveGrain

Vitrified-Bonded Wheel

B :2

Data taken from Peters, Snoeys & Decneut, The proper selection of grinding conditions in cylindrical plunge grinding, Proceedings of the 16 th International Machine Tool Design & Research Conference, MacMillan Press. Power normalized from Specific energy, grade approximation taken from The Shaw Hardness Method, Shaw, Principles of Abrasive Processing, 1996, eq. 5.13, Figure 121.

stubborn-grit region

Grits break out of bond material early. Keeps wheel sharp but gives poorer surface finish

Bond refuses to release dull grits causing higher grinding power but a better surface finish due to the dull grits.

quick-release grit region

middle-of-the-road region

Gri

nd

ing

Po

wer

7 kW

6 kW

5 kW

4 kW

3 kW

2 kW

1 kW

0 kW

Su

rfac

e F

inis

h, R

a

1.4 μm

1.2 μm

1.0 μm

0.8 μm

0.6 μm

0.4 μm

0.2 μm

0.0 μmH I J K

Power in kW, General Surface Finish

Wheel Grade

. .

B :3Making a grinding wheel is a bit like baking a cake.

Consistency? Yes

Logic behind the recipe? Well…. sort of. Sometimes.

FN: Normal Force

FT: Tangential Force

A dynamometer measures forces

in three directions

Source: J. Badger, Ph.D. Thesis, Trinity College, Dublin.

B :4How Are Grinding Forces Measured?

specimen

specimen holder

dynamometer

FTFN

Table velocity

Normal Force

Tangential Force

As the amount of wear flat area increases, the relative amount of rubbing and plowing will increase. Consequently, normal and tangential forces will increase.

Notice that normal forces increase at a higher rate than tangential forces.

K

K

I

I

G

G

Passes0 20 40 60 80 100

35

40

20

25

30

10

15

5

5

0

0

10

Tan

gen

tial

Fo

rce

(lb

s)N

orm

alF

orc

e (l

bs)

B :5

Kannappan, S. and S Malkin, “Effects of Grain Size and Operating Parameters on the Mechanics of Grinding,” page 834, figure 4

Forces vs. Time

C :6

feedrate in mm/s

width of cut in mm

Material Removal Rate (MRR) – Q

depth ofcut in mm

mm3

s

MaterialRemoval Rate

(MRR)= feedrate

in mm/sdepth of

cut in mmwidth of

cut in mm× ×

MaterialRemoval Rate

(MRR)= feedrate in

inches/min

depth of cut in inches

width of cut in inches

× ×in3

min

But that’s not what happened. The post-grinding run-out profile actually looked like this, in green.

Fro

m th

e pa

per

“Loa

ding

in G

rind

ing:

Che

mic

al R

eact

ions

in S

teel

s an

d S

tain

less

S

teel

s” b

y B

adge

r, M

urph

y an

d O

’Don

nell

, 201

0 IS

AA

T C

onfe

renc

e, T

aiw

an.

After Grinding

After Dressing

0.010 mm

0.010 mm

One grit diameter0.250 mm

64 grit diameters 16 mm

F :7

G :8What’s the Root Cause of Residual Stress?

6) Therefore, the hot material will be under compressive stress (as it wants to be larger than it is allowed to be)

strain

Co

mp

ress

ive

stre

ssTe

nsi

le

stre

ss

Single-Point

Cluster Blade &Blade Fliesen

Diamond Roll

Form RollDisk

Rotary PCDForm Roll

Overview of dressing tools H :9