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What causes machine downtime?
Finding the answer to this question and more importantly the cure would make life easier for all within an engineering company from Ronald Bakker, our Product Application Specialist.
Keeping hydraulic machines fully operational, 24 hours a day, seven days a week and keeping downtime to a minimum is the challenge facing all engineering and manufacturing companies.
Common cause of hydraulic machine downtime
The quality and performance of hydraulic oils is key to equipment downtime and finding the right solution for your machine can have a great impact on increasing productivity. Drilling down deeper into this issue about what affects the hydraulic oil, there are several reasons.
In order to look at the issues affecting hydraulic oils in-use, we have studied results from Shell e-Quip, our condition-monitoring system, which analyses oil taken directly from plant machinery. e-Quip findings show that contamination and poor filtration accounts for 60% of problems, abnormal wear 22%, oil degradation 12% and oil properties 6%.
Get maximum performance and reduce downtime
Regular hydraulic oil and oil filter analysis
In order to tackle any hydraulic oil issues before they force operational downtime, you should carry out regular analysis of the hydraulic oils in your machinery. By using an oil condition-monitoring system, such as Shell e-Quip, you can get a constant indication of the health of a given piece of equipment. It also flags up any potential faults before they rise to real problems.
Another area which should be looked at is the differential pressure over the oil filter. In a good working filter around 0.6/0.8 bar is lost during the oil going through the filter. As a filter starts to build up deposits and fill up, the pressure lost will increase as additional pressure is required to send the oil through the filter. This will continue to rise until the filter needs changing.
Typically, when the pressure gets between 2.5-3.5 bar you need to look at changing the filter to ensure it is working effectively but you also need to monitor how often you are changing the filter and check OEM guidelines. Rather than looking at the effect (the filter needing changing) you should look at the cause of the problem.
Looking at both the oil and air filtration is another way of maintaining the quality of your hydraulic oils. A key fact to remember is that air filtration is just as important oil filtration. An issue that often occurs in an installation with long cylinders or piston rods, is that they take in a large amount of air per movement. In order to ensure impurities carried by the air do not get into the oil, which can cause a range of problems to a machine including increased wear and oil life, you should fix a air filter or ideallyan air breather silica gel filter on the air vent.
Oil viscosity check
The final point is, when was the last time you checked you were using the right viscosity (thickness) of hydraulic oils? If the viscosity is too high then you are wasting money due to the extra energy required to pump the fluid.
In addition, machines take longer to warm-up in the morning, the pump fails to deliver fluid, finished work pieces are damaged and additional noise is caused due to the additional force on the system to move the oil. If the oil viscosity is too low, you are looking at a number of other issues including increased pump noise, more system wear and higher oil leakage, all adding significant maintenance costs.
Our customer's case study
By sorting out your hydraulic oils you can make substantial savings. Shell recently worked with a company that was suffering frequent pump failures, with a typical pump lifetime being six months on a heavy duty operation. It was a 250 ton plastic injection moulding machine, which manufactured 25 litre polypropylene buckets and had a vane pump. The machine had one of the highest levels of downtime on the site.
Following the introduction of a new hydraulic oil (Shell Tellus) and regular oil monitoring the reliability improved significantly with downtime due to hydraulic failure 75% less than the pervious year. From a cost perspective, the machine increased production time by 73 minutes a week and the pump was still in good working condition 12 months later. With a weekly saving of £270 due to reduced downtime and the annual saving of a pump (£1,500) the engineering company is now saving over £15,000 per year.
Oils might not be the most expensive part of a hydraulic system but they can certainly save you the most money.