In the process of rolling the most significant aspect is the generation of heat through friction and deformation in the roll bite.The most important aspects are: a) Maintaining uniform, stable roll temperatures, circumferentially around the roll and transversely across the roll width. b) Creating optimum thermal crowns and minimum differential in temperature in the upper and lower work rolls with optimum heat extraction.

1. Emulsion Temp-
Generally in any reversible type Reduction Roll Mill (can be 4- Hi or 6-Hi type)
for Multi pass, the emulsion temp should be in the range of 48 ~ 55 deg C. At
this temp the emulsifier package / other lubricate gets mix up and work well.
Sometimes case to case basis the emulsion temp in the Tank is to maintained
at a bit high, say app 55 ~ 58 deg C to get better lubrication property from a
special lubricate package inside the particular rolling oil.
But at no point of time the emulsion temp should be more than 60
degC, otherwise some of base oil and some emulsifier may lose its property.
At the same time at no point of time emulsion temp should go down below 40
deg C, because below 40 deg C, bacteria start growing in the emulsion and
emulsion Ph start changing its value. Once Ph change the total property gets
change.
Typical Strip & Coolant
Temperatures:-

2. W/R temp
 Generally in any Mill the temp of entry strip at 1st
pass would be at ambient temp. No problem for
this at the Roll byte. I could learn Quaker that for
a reduction app 25 ~ 30% , the roll biting temp
under rolling load could rise app 120 ~ 200 deg C
depending on the speed. But it is not necessary
that W/R temp would be that high. Now for a ideal
Mill where flow has been designed properly and
the emulsion temp is being maintained at around
48 ~ 52/53 deg C, one can expect the W/R temp
after final pass would be app 5 to 6 deg more
than the emulsion. If it is so then perfect heat
balance is taking place in side the mill during

3. Strip Temp-
 This is a bit controversial topics so far a Customer
for a Rolling Oil supplier is concern. Any rolling oil
supplier should maintain by designing the proper
rolling oil ( which should have the optimum
lubrication at the Roll bite) the exit strip temp after
final pass should be less than 100 deg. But it is
next to impossible to maintain the exit strip temp
below 100 deg C, while rolling thin gauge say
below 0.25 mm.
 Now here I will put my hands on experience in the
field as Mill Operation and subsequently as
Rolling oil expert, pl take a look at below table-

4. Input
Thickness(
mm)
Output
Thickness(
mm)
% of Total
Reduction
Final
Speed (
mpm)
Final Strip
Temp ( Deg
C)
4 1.2 70 900 85~90
3.5 0.8 77 1000 85~90
3.5 1.2 66 900 85~90
3 0.6 80 1200 90 ~100
2.5 0.5 80 1200 or more 90 ~100
2 0.3 85 1200 or more app 105 ~110
2 0.2 90
1200 or more
app 110 ~
115
1.8 0.2 89
1200 or more
app 110 ~
115
1.8 0.18 90
1200 or more
app 110 ~
115
1.6 0.15 91 app 110 ~

5.  If the actual strip temp comes above temp. mentioned in the table, then
I would say it is excellent design for Rolling mill as well as Rolling Oil .

 In any case the entry strip temp at 1st pass would be at ambient temp.
But in subsequent pass it would be better if there is strip cooling header
before entering into roll byte. Customer may use it or not, there should
be a provision for that. During thin gauge one should use it. While
thicker gauge Customer may not use that.
 In case of tandem Mill that is why both side flow is designed. But I would
opt for a strip coolant header for any reversible Mill.
 In my experience I have observed a strip temp after rolling down to
0.18 mm gone upto 140 deg C. Then after investigation it was found that
pump pr. Drop down drastically below 4.0 kg/cm2. Generally the pump
pr. should be in the range of 5 ~ 6 kg/cm2 at suction point and by the
time it reaches to Mill it should be app 4.8 ~5.5 kg/cm2. Flow should be
designed based on Mil Motor power. Excessive flow/ inadequate flow or
high pr / low pr from pump also lead to higher temp of the strip.
