Spring is around the corner, although if you’re located near the Great Lakes, you might need convincing that winter ever came this year at all. Regardless, the page on my desktop calendar is March, which makes a perfect time to schedule a spring maintenance session for your industrial hydraulic equipment.

Even if you enjoy a southerly temperate climate to call home, your cool winter likely permitted efficient and reliable operation for your indoor machinery. Hydraulic oil and pumps, valves and actuators prefer a temperature operating window to provide the optimal viscosity for efficiency, performance, and reliability. Often, any potential concerns lay dormant until your ideal operating window expands.

Although spring-like temperatures are nothing to fear, this period provides a buffer of preparation time before the sh*t hits the fan in the summer. I’ve been around enough factories to see first-hand the chaos that erupts on a hot day. That smooth, quiet power unit purring with optimal temperature and viscosity now bleeds thin blood. The bleeding is primarily internal, although the suddenly-soft polymers installed anywhere are now subject to leaks, especially when time-tested.

The external leaks are what you prefer — they’re visible and easily actionable. The oily, dark mess on the tank top or floor signals to your maintenance team that it’s time to replace some seals. If you’re lucky, the small O-rings in a D03 valve stack have seen better days, but your project gets much more involved when the cleanout panel’s gasket is the offender. Either way, as long as the leak wasn’t catastrophic, you simply schedule some downtime to replace the offending rubber bits and then call it a day.

Internal leakage is often a nightmare, taking a more thoughtful and targeted approach to resolving. When the increased leakage stems from heat-induced viscosity degradation, the feedback loop creates more heat due to internal bypass. The effect is pronounced on old machines, where decades of internal erosion limit efficiency on a good day, but you can typically trace the offending location(s) with a laser thermometer. On the other hand, your goal is to prevent the downward spiral of poor maintenance-related failures, so it’s best to implement preventive maintenance to waylay potential problems.

I’ve got Four Tips you would benefit from introducing into your maintenance routine, pencilled in for spring to make life easy:

1. Clean — Ask any veteran car mechanic how much more reliable a clean engine bay is compared to a nasty, dirty one, and they’ll agree vehemently. For starters, the oil and grime everywhere make it impossible to easily identify leaks, and the systemic gunk absorbs and camouflages industrial fallout or ambient chemicals. It’s not just that the oil is there; it’s also what is in the oil.Needless to say, every hydraulic component made to welcome hydraulic oil inside is likely welcoming to oil on the outside. However, the electrical parts controlling hydraulics may not offer the same resilience. Circuit boards, connections, valve drivers, and cabinet cooling fans do better when not covered in black gunk.

   Oil and grime often act as insulators, preventing metal surfaces from radiating heat as effectively. Leaving a cake of insulation on your power unit encourages heat retention. If you’ve ever seen a thermal image of a power unit, you’ll agree that almost every surface provides heat transfer capacity. Also, any oil mist clogs the cooling fins of many liquid-to-air hydraulic coolers, reducing airflow and, therefore, cooling capacity.
   Additionally, when all that dirt envelopes your machine, the opportunity for contamination ingress is high during maintenance. Every time you remove the breather cap, change a valve or replace a hose, you’re inviting dirt into your system, which could lead to potential failures.

2. Oil Analysis — A regular oil sampling and testing program sets reliable factories apart from those performing maintenance by the seat of their pants. A lot can happen inside your oil over a year, so consider twelve months the minimum span between hydraulic fluid test dates. Ideally, you should test more frequently, but since so few are doing it, yearly is a great start.Oil analysis involves taking a small sample of hydraulic oil from an active flow location, which you then send to a laboratory for various tests most relevant to the fluid power industry. The lab will check for particle and water contamination, acidity, additives, wear metals and viscosity.The most critical factors are ISO particle count and water saturation. The ISO 4406 cleanliness guidelines define the number of 4, 6 and 14 micron particles in 1 milliliter of fluid, expressed as three numbers in a range. You must understand your system’s requirements to compare performance but know that fewer particles are better in every circumstance. If contamination is too high, upgrade your filtration package with finer media or consider adding offline filtration, which can be finer without creating excessive return-line back pressure.

   If you sent milky oil to the lab, you already know water contamination is a concern. You can dry your oil through machines such as vacuum dehydrators, so long as it isn’t past the point of no return with sludge and oxidation. The lab will provide either PPM or saturation percentage. The maximum allowable depends on a few factors, such as the base type of the oil, the additive package and operating temperature, but if you can keep it below the 300 ppm (0.03%) range, you should be okay. Remember that hot oil can hold more water in saturation than cold oil.

   Besides contamination markers, the lab will confirm that your viscosity is as advertised, and they can test for viscosity index if required. The acidity result communicates the oxidation state of the oil and, if caught soon enough, may allow you to treat the oil with additives to provide longer life. Knowing your ideal additive package (with the help of your oil provider) can also extend oil life — anti-wear, anti-foam, anti-oxidants and viscosity index improvers are all commonly replaced to extend the life of the expensive fluid.

3. Inventory — Most medium to large manufacturing plants carry a stock of critical replacement parts, especially for high-volume production facilities with little tolerance for downtime. Today’s supply chain climate isn’t favorable to short lead times for pumps, valves, actuators or service items, so it’s best to hedge yourself on the side of caution and maintain repair part inventory.For the same reason it’s important to clean in the spring, you may find a seasonable increase in part failures as the temperature rises. Reduced viscosity from high ambient heat reduces hydraulic oils’ capacity to protect critical wear components. Even if catastrophic failure isn’t the outcome, having spare valve plates, rotating groups, seal packages, and other standard service items prevents extended downtime.

   We all know computers aren’t much better at tracking inventory than human memory since computer data requires accurate inputs. How often have you initiated a repair order requiring a “stock” replacement only to find the computer wasn’t accurate? A regular inventory of repair and maintenance parts provides at least one accurate snapshot per year, and with the addition of cycle counts, you can reduce oversights.

   Plus, we all know that one maintenance technician who grabs parts off the shelf without telling anyone because they’re experimenting to diagnose an unknown failure. Even if the intent is altruistic, it still creates chaos in the purchasing department when they falsely believe inventory is accurate.

   Not to mention that within a 365-day timeframe, you may have liquidated or acquired new machinery. You may have obsolete parts stock that can be sold, but you may need to contact the machine manufacturer or local hydraulic distributor to secure replacement parts for new machinery.

4. Document Control — Just as with inventory, it’s easy for your schematics, parts lists, manuals and drawings to go missing or become obsolete. Having a document control system in place ensures all machine-related paperwork is filed correctly — physically or digitally. If your company is ISO 9001, there’s a chance you already have document control related to machine manuals, but if not, you’ll have the expertise to implement.To many, document control is a field of expertise unto itself. You must identify the documents as part of the control, create new documents if required, standardize your storage and access management, update versions as they arise, create a distribution list and offer training to the team members who access the documents.

   As with inventory control or homeowners insurance, you only realize the importance of document control once something goes wrong. That missing bill of materials from the machine manual could be the sole roadblock preventing understanding the oil- and coffee-covered schematic that was never scanned and filed correctly on the computer. A document control system could be as easy as an Excel spreadsheet but could save you the headaches related to poor documentation.

The springtime is such a period of hope and optimism, letting us sun-worshippers know the worst is over — convertible and beach towel season is right around the corner. A solid spring maintenance routine is not unlike your home spring cleaning, leaving you feeling personally renewed and ready to take on the next few months with positive energy. Don’t deprive your precious hydraulic equipment of that same attention and care — they’ll reward you for it when you’re soon complaining about the heat.

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Filed Under: Engineering Basics, Trending

 

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