3 Steps to Choosing the Right Hydraulic Cylinder

The process of choosing the right hydraulic cylinder for your specific application may seem routine or even repetitive at times, but it's important to maintain a fresh outlook in beginning this process and to always remember to consider several basic components.

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1. Consider the Size

Don't be such a bore.

The first key piece of information to consider when choosing a bore size is the operating pressure. The basic operating pressures that are commonly used range from: 500 psi to psi. These pressures match up with NFPA medium and high pressure cylinders. Knowing the operating pressure you would like to use will help drive the selection of the cylinder bore size.

The second key piece of information needed to select the bore size is the amount of force required for the application. A quick formula for finding the approximate bore size for the extend direction of the cylinder is as follows:

F = force required (lbs.)

P = operating pressure (psi.)

D = bore diameter (in.)

D = F / (. * P)

Typically the resulting bore diameter is rounded up to the next common standard bore size

2. Consider the Mount

Pivoted vs. Straight Line.

Cylinder mounts can be divided into two basic categories: pivoted and straight line. Selecting the right mount for an application mainly depends on the desired movement of the load. Pivoted mounts can be used where a load needs to move through an arc and include mounts such as Trunnion and clevis.

In comparison to pivoted mounts, straight line mounts are used when the load only needs to move in a linear direction and include mounts such as front head flange and side lug. It is necessary to consider the desired movement of the load specific to your application to ultimately determine the type of mount.

3. Environmental Conditions

Is it hot in here, or is it just me?

Knowing where the cylinder is going to operate is important for selecting the appropriate materials, seals, and finishes. The material of the cylinder can be modified to meet specific environmental conditions. A common example, is selecting stainless steel components for corrosion resistance on wash down food production equipment. The cylinder seals can be changed for a variety of reasons, including high or low temperatures or special operating fluids, such as water glycol or phosphate ester fluids. Cylinder finishes can include special metal plating or paint finishes to meet a variety of indoor and outdoor applications.

What other steps would you add to this list? Leave a comment with your thoughts below.

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1

Type of cylinders

First element to take into account is the type of cylinder. HPS International manufactures and sells 6 types of cylinders for various applications :

• Block cylinders (compact) for plastic injections, molding, cosmetics and packaging.
• Tie rods for plastic injection, molding and aluminum injection applications.
• Round cylinders (ISO, DIN, CNOMO) for plastic injection and molding.
• Special cylinders (made to measure, double bore) for plastic injection, molding and die casting.
• Auto-locking cylinders for plastic injections, molding, cosmetics and packaging.
• Cylinders for foundries for aluminum injection.

• Example : Block cylinder
• High Speed : Go for the RCVN
• Compact : VBL, VBLS, VCR, VXP
• With mechanical sensor : VCE
• With inductive sensor : VDI
• With magnetic sensor : VBM
• Cooling : VRE

2

Bore

The first essential information to take into account when choosing the size of the bore is the operating pressure.

Knowing the operating pressure you want to use will help you choose the size of the cylinder bore.

The second key information needed to choose the size of the bore is the amount of force required for the application. Here is a quick formula to find the approximate size of the bore in the direction of cylinder extension :

• F = required force (N)
• P = operating pressure (bar)
• A = Surface of the bore (mm²)
• D = bore diameter (mm)
• D = &#;4.F / &#;π.&#;p

As a general rule, the resulting bore diameter is rounded to the next standard bore size.

3

Rod

Now that you know the minimum size of the hydraulic cylinder bore, you must now choose the ideal rod size. Most HPS cylinders come with several rod options.

The correct rod is chosen based on the necessary stroke length, which has an effect on the buckling resistance of the rod.

When selecting the rods, the smallest rod in the bore should only be used for reduced stroke thrust loads or in reduced pressure applications. The largest rod should be used in cases that depend on its reliability and maximum strength.

If the desired rod diameter is greater than the largest diameter in the bore size of the selected cylinder, it is time to re-examine the cylinder design parameters. It is usually in these situations that the application requires a custom hydraulic cylinder.

4

Mounting

The hydraulic cylinders are divided into two types, depending on their mounting style, either a pivot mounting or a straight line mounting. Pivot mounted cylinders are used when a load is to be moved in an arc and includes supports such as a clevis and a trunnion.

Cylinders mounted in a straight line are used when the load is to be moved in a linear direction. It includes a flange support and a back or front foot.

5

Seals

A hydraulic cylinder must have the right seals, as they play a vital role in preventing any oil leaks. This, in turn, guarantees a continuous and flawless use of the cylinder. The seal should be selected based on the cylinder's applications, operating environment and the maximum operating pressure it can withstand.
HPS International offers 4 types of seals :

• Standard N Nitrile seals, for temperatures from -20 ° to + 80 ° C, an operating speed of 0.5 m / s. Fluids: mineral oil, filtration ISO 19/17/14.
• Viton V FPM seals, for temperatures from -20 ° to + 200 ° C, an operating speed of 0.5 m / s. Non-combustible fluids based on Ester Phosphate (HFD-R), ISO filtration 19/17/14.
• Glycol G nitrile seals, for temperatures from -20 ° to + 90 ° C, an operating speed of 0.5 m / s. Fluids: Water-Glycol (HFC), ISO filtration 19/17/14.
• PTFE P seals in viton / PTFE, for temperatures from -20 ° ... + 240 ° C, an operating speed of 0.5 m / s. Non-combustible fluid based on Ester Phosphate (HFD-R), ISO filtration 19/17/14.

Other elements to consider when choosing a cylinder such as power, operating mode and switches.

6

Sensors

HPS International offers 4 types of hydraulic cylinder sensors. The choice depends on the needs and demands of the clients.

• Mechanical : Adjustable, reliable, easy and fast assembly, compact (HPS).
• Inductive : Non-adjustable, reliable, easy and compact.
• Magnetic : Adjustable, popular, compact.
• Linear : Precise, compact (inside the stem).

7

Hydraulic concepts:
Pressure, force, flow

• Pressure (bar) : Power creation
  P = F/S
• Forces developed by pushing (daN) :
  F = P x S1
• Forces developed by pulling (daN) :
  F = P x S2
• Flow (l / min) : Speed Creation
  V = Q / S

• With unit :
• P : bar Q flow: cm3/min
• F: daN S: π x r² cm² Vspeed: cm/min
• N = 100 daN = 1KN = 0.1 Ton

For more info, please consult our Product Range catalog : Download PDF file

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