Introduce the right precision maintenance strategy and use best practice precision reliability skills to deliver lasting machinery health and world class machine reliability in your operation
With precision maintenance skills and practices machine vibration levels fall, and so do the operating and maintenance costs. Dramatically at first, then gradually and continually. Your machinery does not breakdown. It runs brilliantly for longer. Plant availability, throughput and productivity all lift. You get more time to make more product, at less cost, to sell for more profit, using fewer people.
When precision maintenance is properly applied there is amazing improvement in equipment reliability and a large, sustained reduction in overall operational costs that flows through to new and on-going operating profits. By implementing precision maintenance program you concentrate on ensuring failure prevention and defect elimination in the tasks performed on your machines and equipment by your maintenance and operations people.
Here a list of the key requirements for a precision maintenance program:
- Accurate fits and tolerance at operating temperature
- Impeccably clean, contaminant-free lubricant life-long
- Distortion-free equipment for its entire life
- Rotating parts running true to centre
- Forces and loads into rigid mounts and supports
- Laser accurate alignment of shafts at operating temperature
- High quality balancing of rotating parts
- Low total machine vibration
- Correct torques and tensions in all components
- Correct tools in the condition to do the task precisely
- Only in-specification parts installed
- Failure cause removal to increase reliability
- Proof-tests that precision is achieved
- A business-wide system to apply the standards and requirements in a successful way
You can see that there is nothing in that list that should not already be standard practice in every industrial operation. But it hardly ever seems to happen.
I believe the reason for that is no one sets the exact equipment condition standards to be met, and so every manager, engineer, operator and maintenance technician works to their own standards. This leads to wild variation, confusion and inaccuracy that, in time, causes you many operating problems and equipment failures. It is as predictable as night following day. But you can change that, and stop all your equipment failures, with a precision maintenance program.
Here is a list of standards that you must determine and set for every piece of equipment, every nut and bolt, every electrical connection, every motor base plate, every gearbox,… everything… in your plant and equipment.
What you will need to have in your standards are ‘the numbers’ that are to be measured and recorded as proof of compliance to the standard.
- Like the exact turn from snug to tighten a nut so the torque is correct (you could state newton-meters of torque and use a tension wrench, but the up-to 25% error in using a tension wrench may not be accurate enough for your needs);
- the maximum size and amounts of contamination you will accept in your lubricant;
- the exact gap between parts that you can test with feeler gauges;
- the size and dimensional tolerance you will accept for a shaft at a bearing location before you replace the shaft
- the amount of distortion you will accept on a part before you replace it with new
- the exact distance along a shaft from a datum to mount a disc;
- the exact alignment accuracy between drive shafts that you can measure with a laser or by twin reverse dial indicators,
and so on for everything on every machine and piece of equipment in your operation.
Once you have ‘engineering numbers’ to work to, you can prove if a thing is right or not. Once you measure and prove ‘the numbers’ (which are your minimum standards) then you know (almost without question) you are within requirements. You are virtually certain that the job is done right and the equipment is running precisely and operating under precision conditions! You could have had out-of-calibration test equipment that give you a false reading. But your quality management system should have stopped that happening. (You do have a quality management system controlling the quality of your maintenance tools… don’t you!?)
Starting a Precision Maintenance Program
When you start a precision maintenance program your intention is to introduce the thirteen precision requirements (listed at the start of this article) into your everyday practices.
Everything that everyone does that is related to your plant and equipment will need to meet the standards you set for those requirements. That includes the original equipment manufacturers, operations and maintenance managers, project and design engineers, procurement people, plant and equipment operators and the maintenance crews (yes… including all subcontract work you send out).
Item thirteen is the glue that keeps all the rest together. It says that you will need to install a business process that ensures all the other requirements are actually met for every machine in your operation. That includes recording the dates that the precision standards were met and, if necessary, later checked. You will have records for every piece of equipment, for its entire operating life, of the exact conditions it was built to and it was operated under.
Nothing is left to chance – nothing! And if you do leave things to chance to decide, you can be sure that most times it will eventually go badly for you.
Setting Precision Quality Standards for Your Equipment
The solution starts when management set standards, then promote them, train to them and enforce them. Where do these standards come from? The list below is an example. They already exist, and have existed for decades. Your challenge is to bring them alive in your operation.
- Accurate Fits and Tolerance – ISO/ANSI Shaft/Hole Tolerance Tables
- Clean, Contaminant-Free Lubricant – ISO 4406
- Distortion-Free Equipment – Shaft Alignment Handbook – Piotrowski
- Rotating Parts Running True to Centre – Shaft Alignment Handbook
- Forces and Loads into Supports – Shaft Alignment Handbook
- Accurate Alignment of Shafts – Shaft Alignment Handbook
- High Quality Balancing of Rotating Parts – ISO 1940
- Machine Vibration – ISO 10816
- Correct Torques and Tensions – ISO/ASME Bolt, Stud and Nut Standards
- Correct Tools in Condition – ‘As-New specification’
- Only In-specification Parts – OEM specifications, Machinery Handbook
- Failure Cause Removal – ‘5 Why’ ; RCFA
- Proof-test that precision is achieved – Direct measurement, Condition Monitoring at start-up
- A system to use the standards successfully – ACE 3T Standard Operating Procedures
You may have to look for additional standards to those listed above. Note that there are not always international standards for every standard you will have to set. In that case you use the written recommendations of experts in their field, such as for shaft precision alignment. When it comes to equipment distortion and shaft alignment you start by using the advice in John Piotrowski’s ‘Shaft Alignment Handbook’ until you need to set a higher standard. At that point you maybe the world-leader in a field of expertise and you will be setting your own standards to work to, which one day we will all follow.
You will only have done the job of introducing precision maintenance well when:
- you have written and published the specific details company-wide;
- you have held seminars to explain and discuss them with all the people that need to know and use them;
- you have purchased the measuring and testing equipment you need to prove compliance;
- you have written ACE 3T procedures for all activities, and
- you have trained people to the standards and they can achieve them competently;
- you have a document management system that records all important equipment information over its lif-cycle and allows everyone fast access to the information they need to make good decisions.
Too few companies are that good. But it does not need to be that way. With our help your operation can quickly join the world leaders.
My best regards to you,
Lifetime Reliability Solutions HQ
Read how our Precision Maintenance Consulting helps you to introduce precision maintenance into your operation within 100 days.
You can find out a whole lot more about precision maintenance from our Introduction of a Precision Maintenance Strategy training course PPT (PowerPoint) presentation available for purchase at the online store.