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August 10, 2000

4 Min Read
Uptime strategies: cool and clean

ArticleImage11269.jpgCool and Clean
By Woody Woodrell, Pres., Woodrell Project Mgmt.

Editor's note: Woody Woodrell is president of Woodrell Project Management, an injection
molding consulting firm based in Anadarko, OK. You can reach him on the Internet at www.tanet.net/~woodrell/wpm. This column is his first in a series of troubleshooting articles.

The importance of keeping cool and clean cannot be stressed enough. We all can agree that keeping our bodies at a temperature that is comfortable (which sometimes can only be dreamed of when standing next to a press running glass-filled nylon) and washing our hands before we eat is important to maintain a healthy life. Just as in life, keeping our machinery cool and clean is important. Press uptime is directly proportional in most companies to what we are worth to that company. So let's talk now about the two leading killers of uptime on equipment: heat (more so than cold) and dirt (or contamination).

Heat

The most significant thing overlooked in the vast majority of molding plants is oil temperature in the press. While it seems simple enough to look at a thermometer on a machine, most of us don't until the press has problems, such as O-ring leaks and valve slippage. Even on newer machines that have level and heat indicators tied back to the controller, I've seen an alarming number of devices rigged to give a false feedback signal that the oil temperature and level are satisfactory. Almost everyone I speak to remembers the commercial on TV where the auto mechanic is about to pull the drain plug on an oil pan and says you can pay me now or pay me later, and then pulls the plug and nothing comes out. If you do not do periodic maintenance, it will cost you big time.

The other big problem that is often ignored is the temperature inside your control cabinet where your controller lives. Modern electronic equipment generates a great deal of heat, which can degrade processors and circuitry. It is important to keep the controller cool enough that if you pull a circuit board to inspect it (after shutting off power, of course) you do not have the impression of IC chips imbedded in your flesh.

Although difficult, it is ideal to keep temperatures at or below 120F in your cabinets. This includes the high-voltage cabinets and relay systems, not just solid state or microprocessor controls. In future articles I will get into specific things to check during periodic maintenance. For now try to keep cool electrically and hydraulically.

Dirt

There are three primary ways that your machine can ingest dirt:

  1. 1. During the initial filling and subsequent refilling of the oil tank.
    2. At removal and disassembly of components.
    3. By the unknown killer, the breathing of the oil tank.

The first item is easy to prevent by buying oil only from a reputable source and passing it through a good off-line filter. You should still have online bypass filtration running at all times.The second problem is equally easy to prevent. Practice good housekeeping measures, such as wiping your equipment clean before disassembly, keeping components clean, and making sure everything is free of lint, dirt, and other contaminants before reassembly. This includes your hands and tools.

I am surprised that more molders are not aware of, or at least don't try to prevent, the third item listed, breathing of the oil tank. Any time your cylinders move (particularly on a hydraulic clamp press) the oil level fluctuates in the cylinder. This causes "breathing" of the tank and pulls in contaminants from the outside air. Several companies supply bags that you can put on your oil tank to create a totally closed loop system for your oil. This bag is typically a plastic-coated heavy canvas; it has a throat opening that fits over the air breather on the tank. You simply attach this to the breather with all cylinders in the retracted position and you have a closed system that prevents contamination from outside air.

Assume for a minute the machine we are speaking of is your car. Running excessive temps or dirty oil in your engine is something you would not do because you know it will shorten the life of your car. Maybe you don't change the oil exactly at 3000 miles, but you do know better. Except for a few misguided teens, we don't drive around with our hoods off our cars and breathers removed so we can show off our new Holley Double Pumper carb and chrome valve covers (even though it seemed like the right thing to do at the time).

Keep your oil cool and clean so your machines will produce more parts, and not more downtime.

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