Rollermills sieves & flaking

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					Digital Re-print - March | April 2009
Feature title: Rollermills sieves & flaking
Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2009 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872

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A role to play


Rollermills sieves & flaking
by Jonathan Bradshaw
erhaps, at first sight, an odd combination of milling topics to write on but nevertheless each has its areas of interest, and certainly all three are topical currently with recent developments in all three areas.
First, the rollermill, with seemingly new editions coming from all quarters. Buhler have introduced their Antares rollermill, immaculately engineered as we have come to expect from this company. Quite stunning in its looks and now with a portfolio of successful installations upon which to call for references. With increased load parameters that enable it to more easily match the enhanced modular range of sifters which Buhler are able to offer, the development of this new rollermill really does put them at the forefront of mill machinery development. It is by no means a cheap exercise to develop a new rollermill, whatever its original concept and to have the confidence in an industry that has been browbeaten for several years now, and to lay sizeable funds aside for such development is something to be respected. Similarly, Satake have developed their new rollermill, focused on ease of maintenance and again offering enhanced loadings
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We also see some offerings into the market from the Far East these days as well as from Eastern and Central Europe. Several of these machines are copies of better known manufacturers machines and are unreliable with very poor quality finishes to them. However, they do have a role to play and when a new entrant to the milling industry is seeking a low cost entry into the trade these machines allow him to establish a facility with little risk of capital. Should the venture prove successful and profitable then funds will soon be available to move up the ladder in terms of quality and reliability at a later date. Having said this, the offerings into the market place by certain Turkish companies are much better than those offered by their competitors in the Far East. Alapala and Ugur are able to offer some substantial pieces of equipment, particularly rollermills and sifters that will stand up to some exceptionally harsh treatment and are offered at some considerable discount to the more established engineers’ offerings.

to flexing of the plastic under heavy load conditions. Satake are thus able to offer a wider range of plastic sieves than many of the other engineers.

Modular design
Whilst this is a significant development in sieve technology the advantages of plastic is more of a maintenance issue rather than an enhancement to milling performance. There have been relatively few changes to the basic design of the square sieve plansifter in terms of internal workings, but we have now begun to see the effect of modular design in installations. This allows larger surface area for an individual machine and allows greater throughput per unit area of buildings space. It is much easier to install a modular sifter, simply because it can be taken into the building in smaller pieces and erected in situ, albeit a rather delicate and precise job to put one together in short order. The use of more sections per sifter and the increased loading of rollermills has enabled mill capacities to be increased with a given building area. Some of the mills being built now to replace mills of 30 or more years ago can be placed in the same buildings with some 10 to 15 percent more output. Not always an easy fit with wheat cleaning plant capacities, nor with finished product blowing systems but nevertheless a welcome option.

Flaking rolls
And so, to flaking rolls. We are all seeking ways to add value to cereals and flaking has come in for its fair share of attention in recent years. The use of flakes in the human food industry has greatly increased and the equine industry seems to be continually increasing its use of flaked and rolled cereals. The use of large diameter flaking rolls with narrow differentials has been traditional and continues into today’s machines.

Mix and match
At this point I would make comment that there are several milling engineers who are encouraging millers to “mix and match” when selecting equipment for new or replacement installations, choosing lower priced machinery for the lightly loaded passages and duties whilst retaining principal suppliers for prime passages, breaks and head reductions, etc. I leave the reader to draw their own conclusions as to what is appropriate in their own circumstances and act accordingly.


to fit in nicely with the increased surface available in their range of sifters, the new machine incorporates several new features such as ease of access, cleaning being easily effected by access underneath the machine. Practical as ever - something we have come to expect from Satake these days the machine is somewhat larger than we have seen from Satake in recent years but it certainly is a joy to work on and grind settings are very stable, something that cannot always be said for some of the lesser known manufacturers. The Buhler machine also has a very stable grind setting and with the fully automated version, using Wincos as the control program, the automatic roll gap setting changes are a real bonus. Having been in a mill when a grist change was being made from a hard wheat to a soft biscuit wheat, I initially thought the mill had been switched off when the roll gap adjustment kicked in - so effective and instant was the change.

Roll refurbishment
Roll refurbishment techniques have now meant that the whole roll cartridge is changed along with the roll chills. This has distinct advantages and the life of roll bearings has been significantly extended due to correct alignment of bearings and the

ability for the roll refurbisher to examine roll bearings much more thoroughly than was previously the case when a decision had to be made instantly, on the roller floor at the time of the roll change as to whether or not to renew the roll bearings. Invariably the engineer would err on the safe side and replace partly worn bearings. Now, with time available to examine and clean bearings between roll changes the useful life of the bearings has been extended, with significant economic effect. The increased need for enhanced access to rollermills has led to various manufacturers making the feed roll arrangement completely removable. This is not altogether necessary although, I must admit, it does allow for complete cleaning of the internal working of the rollermill feed assembly. The Satake rollermill allows for removal of the complete feed gate but the rolls stay in situ. Access is just as good however and there are likely to be fewer feed roll misalignment problems than with those rollermills where the feed rolls themselves are removed. The adjustment and setting of roll gaps is the major area that most practical millers are concerned with and in both cases, Buhler and Satake, the roll gap setting is easy, regular and reliable. Brush cleaners are easy to adjust, safe and effective.

Whatever the size,
our systems can handle it
Even after more than 140 years, PRECIA-MOLEN is still very vital and active in the international world of industrial weighing.

Let me move away from rollermills at this stage and address the issue of sifters, or perhaps more correctly “sieves.” The use of plastic sieves is now first choice for almost all the millers I speak with and there are few exceptions to this. With plastic sieves being offered at the same price as wooden ones there really is nothing to consider as the advantages of plastic sieves far outweigh the versatility of wood. Ease of maintenance, hygiene advantages and the elimination of condensation and associated “nasties” all stand as reasons for choosing plastic sieves. Buhler have taken the design concept a stage further and eliminated metal from the frames, although it is the removal of wood and melamine that has been the major stepping stone. The Satake offering was the first to the market and they are now getting to grips with the larger size of sieves, something which in early days presented a problem due

Being strong in heavy duty weighing both on static and dynamic applications, many PRECIA-MOLEN weighing equipment has found its way around the globe. The secret behind this longstanding experience and existence is based on simple parameters: Listen to your customers No compromises on quality Be innovative and follow market trends


Franse Akker 1, 4824 AL Breda P.O. Box 3246, 4800 DE Breda The Netherlands Phone +31 76 5242503 Fax +31 76 5228039 E-mail


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With greater loadings though the individual machine capacities have moved significantly upwards and much of this is down to bearing design where greater pressures can now be brought to bear and bearing life is much prolonged in comparison to the needle point bearing we saw being used in the late 1970s and 1980s and which failed regularly under heavy loads. Simple feed gates, where gates are used,

“Whilst water cooling of rollermills has lost favour, the flaking rolls of today have perfected the design & application and have benefited greatly from flaking roll engineers’ attention to means of cooling”
continue to be the norm as most flaking plants feed directly from the heater / cooker / micronizer to the nip of the flaking roll. Differentials are now brought about by way of individually driving each roll or bay adoption of HTD belt arrangements in the same way as flour mill engineers have adopted the same mechanism. The use of two drives has distinct

advantages, particularly in the machines where auto gap setting is required as product quality, thickness of flake etc is greatly enhanced. Most flaking rolls’ frames are of substantial construction and invariably cast iron which enhances the stability of the machines and handles the forces involved much better than fabricated construction. Many applications call for a very thin flake, increasing the pressure on both rolls and frames. Regardless of where the roll chills will be used, almost all chills are of a spun cast chilled iron, in flour mills and flaking plants alike. Roll technology has come on apace over recent years and whilst there are still relatively few manufacturers of chills, competition is fierce, quality is paramount and the milling industry has been the beneficiary of many technical enhancements in roll engineering that have largely gone unsung and unseen. Perhaps more of roll chills at a later date.

Turner, for example, who are one of the world’s leaders in flaking roll technology offer two cooling systems to suit different applications. Both are excellently engineered and extremely reliable. In combination with roll surface temperature monitoring and plc control of gap settings, differential, loading and cooling arrangements the flaking rolls of today are streets ahead of those we knew and operated only a decade ago. Whilst flour mill rolls are supported with air pressure most flaking rollermills of today use hydraulics to enable nip pressure to be maintained. Hydraulics can handle to high pressures involved better than air and engagement and disengagement is very positive. Turners however use gas accumulators as well to prevent significant damage being done to the chills by allowing the chills to part easily when ‘shocked’ by tramp entering the nip. In the case of the Turner rolls, scraper blades keep the roll chills clean, with blades being easily changed individually when required. Pressure is maintained between scraper and roll chill by either hydraulic or pneumatic engagement. I guess the days are gone when each and every farm had a flaking roll, driven by a steam engine, purely for the purpose of rolling oats and crimping barley to keep the other motive power on the farm operational – the horse. However, we are seeing more horses coming back on to the rural scene, albeit for recreational purposes and there is a definite niche market for equine feed supplies. The use of flaking rolls, however, is still on the increase as we consume an ever increasing amount of breakfast cereals and specialty breads with flavoured flaked toppings.

A good walk round
As I often advocate, a good walk round any facility first thing in the morning pays dividends and if it concludes with a tasty bowl of breakfast cereal whilst you are waiting for the rest of your colleagues to arrive at work, well, you’re off to a good start, aren’t you?

Looking for Rollermills?
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Water cooling
Whilst water cooling of rollermills in flour milling has lost favour, mainly because of leaks and poor water transportation problems, the flaking rolls of today have perfected the design and application and have benefited greatly from flaking roll engineers’ attention to means of cooling.

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• Rollermills sieves & flaking

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Description: Perhaps, at first sight, an odd combination of milling topics to write on but nevertheless each has its areas of interest, and certainly all three are topical currently with recent developments in all three areas.