Interview with Dr. Hans-Joachim Graf

Interview With

Dr. HansDr. Hans--Joachim GrafJoachim Graf Consultant bei H-JG Consulting Awarded Erich-Konrad Medal in 2012 for

Commendable Achievements in Rubber-Technology

©2015 - Published by Rubber Machinery World. http://rubbermachineryworld.com

http://www.hans-joachim-graf.com/


Hello Dr. Graf. First of all thank you for accepting an interview with Rubber

Machinery World and sharing your thoughts. Your journey started from

pharmaceuticals and subsequently moved to rubber industry. Was this a

planned move?

11

After finishing my PhD in macromolecular

science I decided I did not want to stay in

university and become a researcher. I am

more of a hands on person. My first job was

with the owner of a small company as I felt

that fit me best. I put my nose in almost

everything from tooling to compound

development. I even established the first

manufacturing quality control system in this

company. There were new challenges every

day and I had fun. I cannot say it was planned.

It happened.

“There were new challenges

every day and I had fun. I

cannot say it was planned.

It happened. ”


Your journey from Design Process (at Kloeckner Desma) to Director of Materials (at

Cooper Standard Automotive) and now as an active educationist has been a long

and varied one. Which is the position that you enjoyed the most?

22

There were two positions I enjoyed most. The most innovative group

I worked with was at Desma. We developed many innovations, which

you can find even today in different publications. I utilized my group’s

expertise from mechanic to engineer, and electrician to chemist. The

group did not depend on anybody else in the company. My boss

protected me from the administration. We achieved the respect of a

lot of customers and that was our motivation.

The second position I enjoyed most was with Cooper Standard in

Canada. I was the elder in a very young dynamic group, but the most

multi-cultural I have ever seen in any company. We had Asians,

Europeans, North Americans and even Canadians in the group.

Whenever I go to Canada, I still get together with many friends. Here,

I utilized my engineering and chemist expertise in this group. This

group created one the most advanced mixing centres in industry. The

bad thing is, upper management never recognized it.

“I utilized my

group’s

expertise from

mechanic to

engineer, and

electrician to

chemist. ”


Would you say that rubber compounding has undergone change in the last 3.5

decades that you have been with rubber industry? What were the drivers for this

change?

33

The 50’s and 70’s saw the big polymer and ingredient

suppliers work out the basics of compounding.

Significant technological advancements were seen and a

large amount of literature was produced at this time. It

was needed because of the tremendous growth of the

rubber industry after Word War II. Following the first

economic crisis, along with early retirement programs

and more crises – for example, the breakdown of the

Comecon (specifically Europe) – technical knowledge to a

large extent was lost and polymers became

commodities. Leadership in the supplier industry

changed from technical to sales. From this time forward,

rubber parts manufacturers had to take the

responsibility of development in their own hands, but

with limited resources.

“……..technical

knowledge to a

large extent was

lost and polymers

became

commodities. ”


What role has machinery played in this change? 44

This is a difficult question for me. The machine

industry has followed the same trend as the

polymer industry. We had sophisticated machines in

the 80’s but slowly this position has worsened. This

is very different with the technology for the

machines used in the thermoplastic industry. At one

K-Show, machines were presented that had a cycle

time of less than 3 seconds! It is different with

rubber parts - because of its inherent slow heat

transfer qualities, the major influence on the cycle

time is the rubber. As a result, engineers believe

that machine time does not play a big factor. There

is no real optimization of compounds going on to

accommodate machine and mold necessities.

Engineers and Chemists do not work together. Both

parties see more differences than similarities

between rubber and thermoplastic processing.

“Engineers and

Chemists do not work

together. Both parties

see more differences

than similarities

between rubber and

thermoplastic

processing”


Design of Experiments [DoE], though being a standard tool in optimization of

materials and processes in many industries, has not many takers in rubber

manufacturing industry. Why?

55

In my opinion, it is the fear of failing. If an

experienced compounder is doing a DoE,

he has to design the experiment and leave

it up to a series of mathematical

equations. He cannot interact with the

experiments as he is used to do when

performing trial and error procedures. The

DoE results of the experiments may be a

confirmation of his existing knowledge,

but it may not. It may challenge and force

him to question that longstanding

knowledge.

“In my opinion, it is the fear

of failing.”


How does rubber compound development benefit with software? Do you see a

trend of increased use of software in this field?

66

Around the time the Design of Experiment was invented, some

companies (Cabot, Bayer beside others) performed some superficial

trials on filler / oil designs. After more than four decades this tool has

not penetrated the field of compounding as it should have. Its growth is

much too slow, and I would not call it a trend. Software exists today (like

FEA), for the engineering of rubber parts. This is standard. However,

interaction between part design and compounding is still trial and error.

While properties of a compound are an input for the FEA calculation, it

is rare to design a compound to fit the FEA requirements for the part.

On the other hand, compounding groups have created a lot of recipes,

but most of it is based on trial and error. From my perspective, it is lost

knowledge, because DoE Software cannot make any use of it. I felt that I

had to help to somehow utilize this data not only for my benefit but for

others. This is the basic idea behind the “GrafCompounder” software. I

have the experienced compounder in mind, who would like to use his

company’s historic compound date base instead of filing it away.

“.. it is rare to

design a

compound to

fit the FEA

requirements

for the part.”


What are the various tools and methods of recipe development and its advantages?

Which of these is the most optimized method that has clear economical advantages?

77

Preferably, the strategy for initial recipe development should be the

analysis of the compound in various machines and during its part

life. We call that: data analysis, time series analysis, correlation of

root cause and effect via observations. You have to work with the

compound - process system. This can only be done successfully if the

statistic experimental design approach is taken. The economic

advantage of this is clearly superior when you take into account the

reduced costs for statistical design experimentation versus trial and

error, minus the cost of the final result. A second development area

of similar importance is to ensure secure supply. This needs material

replacement and multiple approval strategies. It depends on raw

material, process and service life knowledge. This knowledge is

attained only again, through experimentation.

Upper management needs to understand that development

sometimes means failure and they have to allow for this. We all

learn from failed experiments. We never learn if everything is

running at a steady state

“You have

to work

with the

compound

- process

system.”


In 2004, you had stated that the extruder has been around for some time and

changed very little. And you viewed the extruder as a black box analyzing the

energy and mass (input and output). Is the extruder different today?

88

I have been out of the extruder industry

for some time and have not followed the

ongoing developments here close

enough to comment. What I can say is:

the combination of an extruder and gear

pump truly has its advantages, because it

is a volumetric pump and it pressure

dependence is zero. This provides

superior straining of a compound

without changing its properties.

Is a gear pump is useful for compounds

with very high viscosity? I do not know

its limits.

“the combination of an

extruder and gear pump truly

has its advantages, because it

is a volumetric pump and it

pressure dependence is zero.”


What are the key changes and trends happening in injection moulding? 99

We have been quite successful in decreasing

energy consumption during moulding. Next

we need to focus on developing a much

faster process to stay competitive with TPE.

The technique to induce heat into the

compound by shear is developed, but

control of the vulcanization process is

urgently needed. We have come a long way

with heating time regulation (Barber

Colman) to inline temperature history and

heating time close loop control (CAS-Jidoka)

and its linkage to crosslink density, but

injection molding machines should be

faster. Hopefully we see more development

as seen in the machine industry for

thermoplastic processing.

“We have been quite

successful in decreasing

energy consumption during

moulding. Next we need to

focus on developing a much

faster process to stay

competitive with TPE.”


Great! And one last question. What advice on “machinery selection” would you

give to buyers in rubber industry??

1010

I can comment on injection molding

machines only. One topic in my

“Injection Moulding” seminar is

about machine assessment. With a

couple of experiments one can

analyze the capability of an injection

molding machine. It is not rocket

science. It needs about two days of

intense experimentation. Another

topic I would like to comment on is

maintenance and spare part

management. This is all about

reliability. If you decide now to stick

with one (maybe two) machine

suppliers, then this time spent is a

very good investment.

“One topic in my Injection

Moulding seminar is about

machine assessment…….. This is all

about reliability. If you decide now

to stick with one (maybe two)

machine suppliers, then this time

spent is a very good investment. ”

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Interview with Dr. Hans-Joachim Graf

Engineering

Transcript of Interview with Dr. Hans-Joachim Graf