There are hundreds, if not thousands, of pneumatic models made according to the needs of different applications, environmental conditions, and load capacities. So, if you are looking to find out how to choose the best pneumatic cylinder for your project and the correct way to install it, you are in the right place!

1) Do numbers on Pneumatic cylinders tell us about mounting?

It is common practice to manufacture cylinder mounts according to NFPA (National Fluid Power Association) or ISO (International Organization for Standardization) norms to facilitate fitting and compatibility anywhere. These norms help you figure out and select the right mount for your apparatus.

• NFPA Mounting Codification

NFPA uses a system of letters and numbers to describe cylinder mounts:

• First Letter: Indicates whether it’s a Mount (M) or an Accessory (A).

• Second Letter: Describes the mounting style:

• B – Body
  • E – Head/Cap
  • F – Flange
  • P – Pivot
  • R – Threaded Nose
  • S – Foot/Lugs
  • T – Trunnion
  • X – Studs/Tie Rods

• Number tells us different versions or setups of the same mounting style.

Examples: MX1, MX2, MX3, MF1, MF2, MF5, MF6, ME3, ME4, MS3.

• Three-Letter Codifications

In some instances, you will see a 3-letter codification, especially when it comes to double-rod cylinder configurations. Where a rod is double, an extra letter D is included in the codification. For example:

• MDF1: Refers to a double rod cylinder with a front flange mount.

Knowing these ranges and codings per se, one can always select the appropriate mounting bracket, which guarantees fits and effectiveness in different machine functions.

2) Main 3 mounting styles of Pneumatic Cylinders?

When it comes to installation, there are three main orientation styles for pneumatic cylinders, no matter what the application is;

i) Fixed centerline mountings

ii) Fixed non-centerline mountings

iii) Pivoted centerline mountings

 

i) Fixed centerline mountings

“Fixed centerline mountings are best for applications where the forces act in a straight line in the cylinder body, and stability is also good in this type, especially in the power-extending stroke.”

Centerline mountings have three major types: lug, flange, and tie rods.

• Centerline Lug (A): A pair of rectangular tabs located at approximately the midpoint of the cylinder head and cap helps to hold the cylinder against the surface. This mode of mounting supports straight-line force-loading applications. For such centerline lug-mounted cylinders, the use of dowel pin fastening is necessary for anything with high shock or pressure.

• Flange (B & C): Flanges accommodate the cap-end (back) or the tube-rod-end (front) in accordance with either a pulling or pushing force load, respectively.

• Cylinder Tie Rod (D): Cylinder tie rod mounting consists of tie rods extending out past one end of the cylinder, where they can be secured to a lower assembly for attachment. Tie-rod mounted cylinders transmit both the push or pull forces along the cylinder’s longitudinal axis, thus enabling the mounting bolts to be tensioned without shear stress. Such cylinders usually conform to NFPA dimensions which make it easier to interchange parts of the cylinder.

Flange mounts are also strong and rigid but have a low tolerance for misalignment. Conversely, extended tie rod mounts have some leeway in rigidity at the expense of stiffness to exercise modular aspects in the mounting.

When using fixed centerline mounting, one needs to pay attention to a few important reasons. For example, to avoid misalignment or drooping when a load is applied, it is essential to fix the cylinder mount to a rigid structure like the machine frame. According to research, improper mounting can result in a cylinder loss of up to 20% efficiency, causing early wear and tear.

Below are some positions where fixed centerline mountings find usefulness:

• Manufacturing Equipment: Used for moving various materials rapidly in a conveyor belt.

• Automated Assembly Lines: These are useful for the desirable actuation of tools and assembly of parts.

• Robotic Arm Actuation: Enables accurate and steady outwards and inwards extension of robotic arms.

• Packaging Machinery: Modulates mechanised opening and closing in the packaging cycle.

• Material Handling Systems: Engages lifts and gates even while heavy loads are being moved.

ii) Fixed non-centerline mountings

In fixed non-centerline mountings, the cylinder thrust is parallel to the axis of the rod but is not axially located on the rod. This kind of mounting is almost always the easiest to implement and in most cases aids easy maintenance, repairs, and replacement.

The two most common types of offset mounting are side mount and foot mount;

• Side mount: (A) Side mount cylinders are normally secured on the surface in a fixed position and take a load transverse to the cylinder’s axis. When the system is operational, the surface being mounted has to withstand the torque applied by the mounting bolts and cylinder.

• Foot mount: (B & C) Foot mount attachment can be made on the cylinder itself in the front or back face. Shear stress for short-stroke large bore cylinders causes greater problems for foot-mounted cylinders as these may lead to shear stress-related misalignment of the cylinders.

The reason for the offset thrust line must be found since it results in bending loads and additional moments about the mounting bolts. With time, this would mean loose bolts or worn-out bolts. This kind of mounting should not be maintained in excessive tolerance and should be precise for maximum service and safety. The load should be moved in a straight line without any deviation, and adequate guidance and support shall be given to the system against both horizontal and vertical motions.

Rigidly mounted cylinders are especially vulnerable to differential axial misalignment, which is maintained with great consistency after complete retraction. Statistics show that even small changes in alignment in installation parts can be very harmful to the lifespan of the mounting bolts, up to 25%.

Facts notwithstanding, however, in heavy-duty applications, it is reasonable to tolerate a small but insignificant angular staggering at full retraction, which will lead to a proportional increase in stroke.

Here are some applications in which the fixed non-centerline mountings were effectively utilised:

• Textiles Manufacturing Machines: This kind of mounting supports the working of the sewing and cutting machines intimidating easy changes.

• Conveyors: Enables handling of materials on and across the conveyor belt with less extent of adjustment.

• Food Processing Machines: They provide the necessary drive for the machines that operate linearly for filling or sealing applications.

• Hydraulic Presses: Allows adequate force transferral without the constraint of locating heavy-duty operations precisely aimed within the target.

iii) Pivoted centerline mountings

Another set of mounts useful in situations where the trajectory of the load is apparently curved or where misalignment will occur is the pivoted centerline mountings. This style permits changing the position of the cylinder’s centerline or axis in one or several directions.

The trunnion and the clevis are the two most widely used methods of attaching a pivot mounting.

• Trunnion (A): Trunnion attachments can be fitted at either the cap-end, rod-end, or intermediate position and have the ability to perform rotations. A similar motion can be performed, but instead of a clevis, a trunnion is used as an attachment; in fact, trunnion attachments are intended for shear stresses, not bending stresses. Minimise the rotation of the trunnion ring for the trunnion pins so as to avoid the application of many bending stresses to the pins.

• Clevis (B & C): The clevis can be fixed to the pneumatic cylinder cap-end using bolts and clevis attachments. The shear loads applied during cylinder actuation by the nuts holding the clevis will be supported by the bolts in the clevis. There is a female and male coupling, used depending on the coupling the clevis mounts to.

The clevis mount is very economical and is particularly effective in short-stroke applications typical of medium and smaller bore cylinders. On the other hand, a trunnion mount is ideal in situations where the use of a clevis would result in excessive cylinder length.

An intermediate trunnion mount is best suited for long-stroke or heavy cylinders since it should be located just about the balance point for maximum thrust. Placing it wrong can reduce efficiency by even fifteen per cent.

Spherical mounts will provide motion of angular movement from 5 to 10 degrees and should be used with a grease fitting.

Lastly, confirm that the rod end attachment is free to swivel once again while using approved manufacturer’s brackets and tolerance pivot pins to ensure the rod end swivel attachment works correctly. This detail will improve the reliability of the pivoted centerline-mounted cylinders in manufacturing.

• Robotic Arm Applications: Flexibility of movement which is appropriate for different tasks.

• Heavy Equipment Steering: curved motion applied to the steering system of loaders or excavators.

• Material Handling Systems: In addition to the features mentioned, these systems help conveyors function properly even when they curve.

• Construction Machinery: Assists cranes and boom lifts in the articulated movement.

• Automated Guided Vehicles (AGVs): These are important for turning while manoeuvring in complicated situations, facilitating the needful rotation.

3) Other Factors affecting mounting in Pneumatic Cylinders?

There are many environmental and mechanical factors which can affect the installation method, efficiency, and lifespan of the pneumatic cylinders;

• Consider the Application: Firstly, you must look into the actuator’s purpose and application requirements. Proper application consideration will prevent 80% of mount failures.

• Cylinder Stroke: The next consideration is whether the stroke is long or short. Long strokes increase the stress on the mount by 25%, so they have to be of good strength.

• Plane of Motion: It is also necessary to clarify the direction—whether it is straight, vertical, or with a curvature. For example, a vertical motion can increase the stress on the mount by 15% compared to a horizontal motion.

• Size and Condition of Load: Besides, do you have to ascertain if the load is guided or unguided? In particular, guided loads decrease wear by 30%.

• Piston Rod Piston Strength: In the same line, you may also wish to check if the column strength fits the load to be carried by the column. If not, the risk of failure will increase by 20%.

• Installation Space: You may have to look for compact mounts where there is limited space because the design may call for such mounts. Indeed, 70 % of designs with space limitations revert to specialised compact mounts.

• Mount Material: In addition, you must consider anti-corrosive substances for mounting in extreme conditions. Using these materials can increase the lifespan of the mount by 50%.

• Operating Pressure: When working with high-pressure hydraulics, you also have to consider the pressure ratings. Twenty-five per cent of high-pressure failures occur because such limits are exceeded.

• Mounting Stress: In addition, wrong mounting increases the failure risk by 40%. Proper mounting reduces shearing and bending stresses.

• Best Cushioning: Finally, ensure that the cushioning is well set to the requirement. Misalignment of cushioning can waste 20% of cylinder life.

➔  Bonus Tips: Must take these Precautions

When handling your pneumatic cylinder, please utilise the following preventive measures:

! Minimise Side Loading: Ensure satisfactory mounting and alignment of components; use alignment couplers to avoid side loading.

! Lubricate bearings: Apply the bearing slide lubricant according to the manufacturer’s recommendations.

! To avoid Unsupported Loads, Use roller guides or slides to support the load rather than attaching it directly to the piston rod.

! Minimise Bending Moments: For long strokes and high shear weight, suspend the rod end from roller tracks and use an external bearing or guide to reduce side loading.

! Ensure Proper Alignment: Minimal alignment issues could be solved using alignment/ die set couplers.

! Condition air properly: Manufacturer-directed clean and dry air prevents pollution hence the use of dry and filtered compressed air is critical.

! Provide Additional Support: Use intermediate mounts or extra support for long-stroke cylinders to avoid sagging and, hence, damage.

! Torque Specifications: The required torque should be applied to the threaded pieces and tied against the thread shoulders to limit bending stress and prevent fatigue failure.

Even before using a cylinder, it is good to inspect the entire system. It is also essential to keep checking the operation of the cylinder to see if it appears to be movable and if the rod does not have too much motion. You can test such a capability using a flexible airline and a blow gun to check if the cylinder is orientated correctly and can be operated with minimal pressure. Respect the manufacturer and perform all necessary procedures to test the cylinder.

➔ Conclusion

Hopefully, after reading this reading, you will have got a basic idea of how to read the code on pneumatic cylinders and using that, you can know the installation procedure. That being said, if you are looking to find pneumatic cylinders for your industry or mini project, we at Foye can be your one-stop solution. We produce cylinders in all sizes and under different environmental conditions.