Preventive maintenance programs

by Jonathan Bradshaw
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  Long gone are the days when mills shut down over the weekend and started up again when the maintenance crew had finished its allotted tasks on Monday afternoon. Most, if not all, mills now run flat out 24 hours a day, seven days a week and only shut down every 10 weeks or so to carry out essential maintenance.

Obviously this makes sense as millers must strive to get the maximum output from their investment at all times. However, with downtime being limited, it falls on the shoulders of the maintenance supervisor and the mill manager to make best use of any downtime that is available. To assist these people in maximizing the efforts of the maintenance crews, a degree of planning is called for, and to that end you must call into use whatever tools are available.

Preventive maintenance programs have been around for some time. They range from simply producing a list of equipment needing attention based on the hours it has run, to the programs that fully list the spares used, lubricants applied, labor costs for time spent on the job and a projected life of the machine in question.

You must remember what the objective is when using these programs. They exist to be preventive, to prevent breakdowns and unscheduled downtime. If they don’t do this, then they serve very little purpose. Most millers will tailor a program to suit their own ends and the reporting protocols prevalent at their specific mill site.

Most programs will allow spare parts inventory to be reconciled and allow the user to establish whether everything is available prior to the planned maintenance shutdown, thus ensuring that no tasks are left unattended or incomplete because these parts are unavailable.

Mills do not employ more maintenance staff than is strictly necessary, and most will only have one or two  skilled workers working together with mill operatives to obtain best use of manpower resources. Drafting in other personnel during maintenance shutdowns is common, and nearly all milling engineers have staff available at short notice to assist during such times, though they would much prefer to have maintenance agreements with clients rather than have to provide skilled labor on short notice.

PLANNING IS CRITICAL

With the use of preventive maintenance programs, it is possible to create a schedule well in advance detailing what work will be carried out, when and by whom, and listing the spare parts and lubricants to be used. Such planning is now common, and millers who don’t use their program in this way not only miss an efficiency opportunity but also leave themselves open for breakdowns later on when the plant should be running at full capacity.

In flour mills, it is most common for the independent contractors to tackle such tasks as roll changes and sifter maintenance, leaving the resident crews to handle spout changes, airlock replacements, checking of drive belts and chains and inspecting elevators to make sure belts are not loose.

In feed mills, the independent contractors will deal with die and roll changes and probably replace filter sleeves. Resident crews are most likely to deal with the same items as are handled by their counterparts in the flour milling industry.

To be specific, the Buhler WinCos system, which handles plant automation, can be expended by the use of “plant care,” which deals with all the items mentioned earlier. This is now the backbone of many preventive maintenance systems and is being developed continuously to generate a much improved and easy-to manage program that assists not only with planning maintenance activities, but also with purchasing decisions. For example, spare parts, which are common to several machines, such as elevator belting and buckets of a common size, can be identified. When maintenance work is completed, the person responsible for purchasing such items knows precisely what quantities have been used, what remains in inventory and how much will be used at the next shutdown.

In this day and age of measuring performance by adopting Key Performance Indicators to highlight areas where mill performance can be improved, it is quite common and essential to build targets into your maintenance programs. Maintenance is such a key expense in the overall operating budget that good control of costs is vital.

All of these systems have the same basic principles instilled in them where work orders are generated that can be used as the main task list for any work to be carried out. The required spare parts are listed as well as the name or names of those who have been allotted the tasks of carrying out the work and an estimate of the time involved to complete the work. Provision is also made on the work order for the subsequent review and purchase of stock items and specialist items required for the next maintenance shutdown.

STAFF TRAINING

Obviously training is required for maintenance staff and any mill operatives who carry out maintenance work. Such training will cover safety aspects and will also cover the details of specialist machines. For example, the Satake Peritec system or debranning machines require some very precise procedures to be adopted, and trainees usually spend time with Satake personnel learning the right way to disassemble and re-assemble the machines prior to them being dispatched to the mill. Having carried out such training, it falls on the shoulders of those who have been trained correctly to maintain such items. The preventive maintenance program can acknowledge this and allocate such work to the nominated, properly trained staff.

As you seek to pin your costs down and cut out the “surprises” of when expensive items need attention, several engineers have begun offering all-inclusive maintenance packages which are tailored to the needs of a specific mill. If a client seeks to retain some  of his own personnel, this can be accommodated as can the wishes of millers who seek to have no permanent staff yet still require the availability of “on call” personnel, either at all times or perhaps just weekends.

With all-embracing maintenance schemes, the need to manage the maintenance function is also taken away. Ordering of relevant spare parts no longer presents an issue since this is done by the company carrying out the maintenance and they will use the same preventive maintenance program as the miller. The costs of such maintenance schemes can be spread over the year or phased in with seasonal profitability in order to manage cash flow as well as the practicalities of maintenance.

It used to be that maintenance schemes were offered to millers by all and were really just a way for engineering companies to occupy their staff between projects. Fortunately, reality has now dawned and those who offer planned maintenance programs and schemes take their responsibilities seriously. There are fewer people offering such services, but those who do really know what they are about and are constantly striving to find ways to improve their service. Today, with your mills needing to run at optimum efficiency, there is really little or no viable alternative to operating a preventive maintenance program with all the costs controlled as a direct result.

This does not mean that the mill manager can absolve himself of all responsibility for maintenance, and his daily inspection of the mill and fabric of the building will highlight areas in immediate need of attention. Any preventive maintenance program only addresses those assets which have been established as being within the scope of the program. Building fabric and yard facilities are generally not included since the maintenance of such items can be carried out when the mill is operational. However, a good preventive scheme allows for such items to be identified and fixed without throwing the whole system into chaos. It simply acts as a means of controlling the costs of such items.

 

Jonathan Bradshaw is a consultant to the agribusiness and food processing industries, specializing in project management and bespoke training programs through his company, J.B. Bradshaw Ltd. He has extensive experience in flour and feed milling in Africa, the Americas, Europe and the Caribbean. He may be contacted at jonathan.bradshaw2@btopenworld.com.

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