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ARE SMALL ROLLS TO BE CONSIDERED AS

COMMODITIES?

Dr. Karl H. Schröder

Primer Congreso y Exposición Nacional de la Industria del Acero

Monterrey, N.L. , Mexico

Technical DirectorBritish Rollmakers (China) Ltd

• Small Rolls and Commodities

• Some remarks on the Roll Foundry Industries

• How to make Small Rolls as non-commodities

• Analogies between Cutting Tools and Rolling Mill Rolls

• Conclusions on further expectations with Small Rolls.

Presentation Overview

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Rolls are “ Tools ” for Rolling Millsof limited service life .

COMMODITY

• Goods that can be bought or sold anywhere without anyspecial or unique specifications

• Example: Pig Iron, Oil, Gasoline, Screws

• The manufacturer of these goods is of lesser significance

• For sure, commodities can be very critical parts in manyapplications

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• Strictly specific concerning the geometry and the dimensions.

• The Rollmaker is of minor importance - despite all the wonderfulspecifications such as hardness, roll grade, composition, andmechanical properties.

• Most Rollmakers are capable of meeting all requirements.

• The Performance of Rolls from various suppliers is often withina narrow span

ROLLS

There are many standard Roll Grades in the market, variations of :

• Nodular Iron• Adamite• ICDP• HChr

It is the duty of the smart Sales People and Technical Services people tofind the best suitable grade.

But the Mill people are always helpful. Only if the Roll Grade is acommodity then they can really bargain!

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Are small rolls to be considered ascommodities?

YES !

This might be boring, but … !!! competition is hard and tough !!!

There have been and there will beNon-Commodities Roll Grades in the market

– but never for long

Non-Commodity Rolls become Commodities FAST !

Right now ….• Carbide Enhanced HChr is on the way to become a Commodity.• Carbide Enhanced ICDP are protected by Patents• Imitators fake and turn these Grades into Commodities – illegally!• HSS - ?

And in the Future, we expect more results from R&D…

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Who are manufacturing Small Rolls, and why ?

Fig. 1: Roll manufacturing costs and selling prices as function of roll weight

1 - Selling Price

2 - Material cost

3 - Total Manufacturing Costs

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Fig. 2: Different roll manufacturing costs in percentage oftotal roll manufacturing cost as a function of roll weight

Labor Costs Calculation

Total Labor Costs = ------------------

wherein:

Total Labor Costs is Money per unit Roll Weight (Kg) and includes allpayments to person in manufacturing, sales & service , overhead

Salary is Money per Hour

Productivity is (Kg / h) is a function of the weight of rolls, becausemachining and treatment times (main working time) decreases withdecreasing roll weight much faster than side times (handling, mounting,de-mounting from machines, centering, testing, etc.) Automation islimited ( CNC, robotics ) due to low numbers of identical rolls.

Salary

Productivity

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• costs-cutting on manufacturing, services, and support

• no more R & D, not affordable anymore

• high-tech Rollmakers may have to give up Small Rolls

• very little or no progress at all

• business goes to the cheap producers

Small Rolls to be considered as Commodities means:

Roll Efficiency = -------------------Performance

Roll Cost

Wherein:

Roll Cost means Money per Unit Roll Weight

Performance means Kg of Roll per unit weight of finished product (e.g. 1000t)

In case the Performance of All Rolls is Equal => Commodity !

In case the Performance of a particular Grade is High => Non Commodity !

- Sales Price might be High!

For Example:

Last stands of wire rod mills; Acicular Nodular Iron versus “Hard Metal” (WC) ; Priceand Performance of “Hard Metal” is High, Roll efficiency for “Hard Metal” is better thanthat of Nodular Iron (Commodity!).

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Better Wear Resistance and:

• longer rolling campaigns

• less downtime of the mill for roll change

• less redressing time for the rolls • better tolerances of the products

• better surface of the products

But there is big potential for practical development:

Fig. 3: Wear resistance of grey cast iron versus carbide content and hardness

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Fig. 4: Typical roll grades, their hardness range and content of carbides

(Range of alloys: 0.30-0.44% C, 0.02-0.38 % Si, 0.31-0.83 % Mn, 1.18-4.03 % Cr, 0.08-3.04 % Mo, 0.26-1.92 % V and 1.42-5.85 % W) [13]

Fig. 5: Wear versus alloy equivalent

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• gambling with Hardness

• small variations of alloying elements

• variations in Heat Treatment

Though these might be necessary and useful toincrease Roll Safety

Roll improvement does NOT mean:

Roll improvement means:

¸ more high hard special Carbides (Enhancements)

¸ new materials : HSS, WC, Ceramics

Fig. 6: Information about carbide forming elements, types of carbides and some hard particles.

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The development of

Rolls follows the development of

Cutting Tools .

Cu

ttin

g T

oo

l Mat

eria

lsR

oll

Mat

eria

ls

Fig. 7: Roll Grades & Materials for cutting tools

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Fig. 8: Wear diagram as guideline for development of new roll grades

Alloy Equivalent – (AE)

Range represents variations due tovariations in microstructure &hardness

• specific and total Roll performance

• safety against Rolling accidents

• support and services from Roll vendors

• total average cost per unit weight of Rolled Product.

To rate Rolls we have to look beyond Pricing alone:

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Not necessarily!

¸Small Rolls offer high potential for new materials/grades.

¸ The super high tech has already reached the last standof some mills with hard-metal and ceramic-rolls.

Are Small Rolls to be considered as Commodities?

Roll development…seems to be very slow most of the time (commodities ?).Occasionally, there are big improvements in short times(High-Chrome-Iron; High-Chrome-Steel; HSS, Carbide Enhancement)

Rolls will always remain as Tools…..but with the service life increasing.., maybe someday they may even match thelifespan of the mills and they will become capital assets!

But for certain, they will always require that special maintenance.

BRC sells commodities, of course, and is very competitive !

but the idea for the future is …

to add R&D to good roll commoditiesto achieve the

Best Roll Concept

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“Move Up With Us” “Move Up With Us”

Fig. 9a: History of cutting tool grades

1. Tool Steel

2. High Speed Tool Steel HSS

3. Coated HSS

4. Hard Metal HM

5. Coated HM

6. CBN - Cubic Boron Nitride

7. PKD - Polycrystalline Diamond

8. Ceramics

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Fig. 9b: History of roll grades

1 - Tool Steel “Adamite”

2 - High Speed Tool Steel HSS

4 - Hard Metal HM

8 - Ceramics

A - “Mild Hard”

B - Nodular Iron

C - Indefinite, IC

C’ - Carbide Enhanced IC

D - High Chrome HChr

D’ - Carbide Enhanced High

Chrome