PC-JUL23-PG42.1_Layout 1 18/07/2023 12:42 Page 42
PNEUMATIC CYLINDERS
prone to damage.
So, these are the problems, but what are the solutions?
Selecting a cylinder for harsh applications For harsh environments you will need to look to a more customised cylinder, but most of these are relatively straightforward and represent a good ROI.
ACHIEVING LONGEVITY IN HARSH ENVIRONMENTS
Japh Humphries, UK Sales & Commercial Manager, Matara UK, says selecting pneumatic cylinders customised to your specific site will prolong the service life of cylinders operating in difficult conditions
P
neumatic cylinders are an efficient, reliable and clean solution for moving loads in a linear direction (back and forth or up and down), with good levels of force and speed.
Cylinders are often the most important component of a linear motion system. If the cylinder fails, the linear motion system is unable to function. In a harsh environment where contaminants are heavily present, standard cylinders are going to fail all the more frequently, resulting in greater downtime. Cylinders can be contaminated internally from the air supply or externally from the operating environment.
What environmental factors impact cylinders’ longevity?
Airborne particles in the form of dust and grit are the most obvious threat to cylinders. If this penetrates a nose seal, it builds up and sits in seals and bearings with a similar effect to sandpaper. In a normal environment, with regular preventative maintenance, standard cylinders can cope well with basic levels of dust, but where these contaminants are prevalent, a more robust cylinder must be considered.
Water may not be deemed a contaminant in the usual sense, but when it comes to pneumatic cylinders it is very much a problem as where there is compressed air, there is water vapour. Furthermore, there are a number of industries, including food and
42 JULY/AUGUST 2023 | PROCESS & CONTROL
pharmaceutical, where washdowns are conducted regularly and very thoroughly. In these situations, the water collects within system components where it can block the flow of air through orifices, dilute or adulterate lubricants, corrode the barrel or rod finish and, of course, freeze in cold weather. Contamination from synthetic oils used to lubricate the air compressor can have a similar impact on cylinders to water. In harsh environments, greater quantities of lubricant are often used, which makes the contamination situation worst.
In applications where extreme heat is used, and/or where chemicals, paint or weld splatter are present, the piston rod and rod-seal are
Let’s start with the cylinder seals. Standard seals can be replaced with specialist versions to meet the needs of your specific application. Viton - a fluoropolymer elastomer and synthetic rubber compound - seals, for example, have been designed for use in some of the harshest environments, where temperature extremes and chemical interactions are common. These can readily be used in Matara’s standard rod type pneumatic cylinders and rodless pneumatic cylinders.
Moving further into the cylinder construction, with rod type pneumatic cylinders a rod seal/wiper can be incorporated to both stop contaminants from entering the inner body of the cylinder, with the wiper removing larger particulates from the rod. For added protection, the rod can be fitted with a rod bellow/gaiter which keeps contaminants away from piston rods.
For corrosive environments, including those where regular washdowns are conducted, the choice of rod material may need to be reconsidered. Standard rods are mostly manufactured from chrome, but swapping to stainless-exercised steel rods and fasteners, or even a stainless-steel rod, will provide extra protection. This will usually add an additional 10% on to the overall cost of the cylinder. For complete corrosive protection, Matara offers a range of 100% stainless steel pneumatic cylinders.
The other option is to stick with existing materials but use specialist coatings or epoxy paints. There are a good range of options here, including Armoloy TDC coating, which we use on our linear rail and ballscrews for maximum longevity in demanding applications and locations. Armoloy TDC is a hard (78Rc), thin, dense chromium coating with a micro-nodular surface texture which provides corrosion protection equal to 440 series stainless steel.
Having selected the right cylinder type for your environment, it’s important to conduct basic preventative maintenance to a regular schedule. This should include the regular cleaning of external parts of the system so that visual inspection of seals and other parts is straightforward; inspection for wear and tear; draining of air line filters and checking that the water traps are operating as they should; lubrication of the cylinder, rod seal, piston seals and surfaces; checking for air leaks and resealing where required; and last, but not least, replacement of air filters.
Matara
www.matara.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58
