O&J Denmark had the idea to re-work dies and rolls over three decades ago with an intention to assist the market demand to grind and re-countersink worn dies into ‘as-new’ dies at a time when dies were very expensive.

1. Digital Re-print January | February 2014
Managing mill maintenance: Getting your dies and
rolls re-worked locally to global standards
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2. MILL MAINTAINANCE
Getting your dies and rolls
re-worked locally to global
standards
by Leif Wolf, Director, O&J Hojtryk AS, Denmark
O
&J Denmark had the idea to
re-work dies and rolls over three
decades ago with an intention
to assist the market demand to grind and
re-countersink worn dies into ‘as-new’
dies at a time when dies were very
expensive.
installed properly with particular attention
being paid to positioning of the roll assembly
correctly against the die production surface.
Failing to fit machines properly can result in
non-uniform wear in the ring die and nonuniform pellets.
The machines used for this work could
not be bought at the time so we undertook
the challenge to design, develope and manufacture such equipment ourselves.
Since then many others and some
from different perspectives have come up.
However, O&J has been at the very forefront of this industry and still is.
Clients of interest include:
• Feedmills - for livestock such as pigs,
poultry and cattle, shrimp feed
• Bio/wood mills including palm fibre mills
• Waste mills
• Others
The benefits from die- and rollrefurbishment include:
• Increases life time of pelleting
equipment
• Increase throughput
• Significant reduces power usage
• Securing higher pellet quality
A feedmill is only as strong as its weakest
link. Each machine has to work as its best.
Investing time and money in feed formulation can be quickly written off if the
pelleting machinery used isn’t up to scratch.
O&J Denmark has been able to establish
a strong brand in the marketplace, servicing
clients over very long distances.
Thanks to great trust from all our clients
we can offer a full re-working set up including logistic solutions.
The mills book all shipments directly to
our freight forwarding company operating
in their region, bringing dies and rolls to our
re-working center in Esbjerg, Denmark and
returning with the same afterwards.
Simple but highly effective – mills pay
no waste time!, 1 click and the goods are
booked and automatically returned again
when the re-work is complete.
In other regions throughout the g-lobe
this may be different due to existing infrastructure, labour cost etc.
At the re-working center dies and rolls
are checked on arrival, their actual worn
condition, any damage, etc, with assessment
of how re-working would be or not be
profitable to the client.
It is a partnership. If a die is wrongly worn
a contact shall follow from here giving a note
to the client helping him back on track again.
For example, a good client is a mill
running controlled production systems and
therefore will have a controlled degradation
Installation and usage
From the start, machines need to be
Die- and roll-refurbishment
of wear parts. It is worth remembering that
a full refurbishment and cost will depend on
the work required.
Deciding when to ship a die for re-working is always a balance. Ultimately it comes
down to a choice between controlled maintenance versus damaged based maintenance.
A full refurbishment includes cleaning
the die and checking for cracks by using the
O&J HPJC21 High-Press Blowout System by
means of water only – and without chemicals. The advantage of using this method is
that the water is strong enough, blowing out
with 1.250BAR/aprox 17,000PSI, to dislodge
stubborn material without harming the press
channels.
Next, comes grinding the die production
surface, skimming level and machining using
the O&J DG1700-1 grinding machine specifically designed for dies and rolls.
Finally, having it re-counter sunk again
by using the O&J CSV14-3 counter sinking
machine for ring dies.
Differences between regions
In the northern states of Europe and
Scandinavia, mills generally carry out reworking to both ring dies and rolls.
Ring dies get re-grounded, re-counter
sunk and cleaned up - schematically dies
get re-worked two or three times a
lifetime, depending to production and die
condition.
Rolls are normally ground the first time
and then given a new roll shell the next
time. Also, items such as axles, bearings,
cover plates and seal collars are cleaned up

3. 35 | January - February 2014
and controlled before re-assembling which
includes a new roll shell.
In other regions throughout the globe,
this may be different due to existing infrastructure, labour cost, etc.
However, we register from those other
regions an ever growing interest using our
techniques and machines to set up service
centers for re-working. We invest great interest in being at their service – working together
facing a common future and possibility.
A fine example is that a year ago we
fulfilled delivery of technical equipment
to the Philippines for a local service
Grain
centre in Cebu, which is now giving such
re-working possibilities to local mills in
that region. Even though there have been
a few obstacles to overcome, the region
shows great interest in the local set-up
having their dies and rolls re-worked
there and generally following the same
ideas as we operate here.
Apart from Europe, O&J machines are
in operation in India, Thailand, Singapore,
Korea, China, USA and Canada and there’s
more to come – O&J is creating a future
together with dedicated clients throughout
the globe.
More
&Feed millinG technoloGy
inforMation:
O&J Højtryk A/S
Tel: +45 75 14 22 55
Fax: +45 82 28 91 41
Email: info@oj-hojtryk.dk
Website: www.oj-hojtryk.dk
Empower your employees with tools and
problem-solving skills at IAOM’s Fundamentals
of Milling I and II courses, offered at Ocrim’s
International School of Milling Technology in
Cremona, Italy.
Fundamentals of Milling I: March 17-21
Fundamentals of Milling II: March 24-28
Die and roll re-working machines
Technical training courses that combine lectures and discussions
with hands-on laboratory and pilot-scale milling exercises.
Experience this unique learning environment where classroom,
lab, manufacturing plant, and pilot mill all come together.
International Association of Operative Millers
10100 W. 87th Street, Suite 306
Overland Park, KS 66212 USA
T: +1 913-338-3377 | F: +1 913-338-3553
E: info@iaom.info
For more information, visit: www.iaom.info/education
www.oj-hojtryk.dk
Phone: +45 75 14 22 55
Fax: +45 82 28 91 41
mail: info@oj-hojtryk.dk
O&J Højtryk A/S
Ørnevej 1, DK-6705
Esbjerg Ø
CVR.: 73 66 86 11
M

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