To get started we have a mnemonic that spells actuator.

Accuracy defines the closeness to desired position as well as the repeatability possible with the given actuator.

Capacity is the loads moments and forces an actuator can bear.

Travel is the stroke needed to traverse the axis.

Usage encompasses duty cycle, dwell time, and expected design life.

Atmosphere includes details about how dirty or extreme the operating setting will be.

Timing is how soon the machine builder or end-user needs the actuator.

Finally, orientation and rates describe the actuators mounting and position in space and relative to the loads as well as the travel speed, accelerations, and other required motion profile features.

Now let's work through a specific example of sizing a belt-driven actuator with these The first step is to define all application parameters.

Let's assume we need accuracy to within plus or minus 0.5 millimeters.

The actuator in question must bear and transport a payload of 28 kilograms and that payload volume is 25 by 100 by 150 millimeters.

The actuator must move this load over a stroke of 3 meters for more than a million cycles per year. 1,051,200 cycles to be exact.

The atmosphere requires standard protection and the linear actuator is needed in six weeks.

It's oriented with its carriage to the side for a type 3 arrangement that's very common to linear motion applications.

Also, the actuator must accelerate to 1 meter a second squared to move at 1 meter per second for the majority of its stroke.

The second step in sizing an actuator is to define forces during regular constant speed operation.

For this we'll be using our capacity, travel, usage, and speed values to calculate forces in the X, Y, and Z directions as well as moments around the X and Z axes.

Fx is the payload plus the weight of the carriage multiplied by the coefficient of friction from the actuator supplier.

There's no additional lateral force on the carriage so Fz is zero.

Force in the Y direction is the acceleration due to the force in the Y direction.

The values for moments around the X and Z axis's depend on the amount by which the payload center of gravity is cantilevered off the actuator carriage.

Now let's work through the third step in sizing an actuator, that is defining forces on the actuator when it's accelerating.

Again, we'll employ capacity, travel, usage, and values to quantify forces and moments.

Calculation for Fx is the same as before, accounting for G on both the payload and carriage mass, except now we also account for the effects of these two masses on the actuator during acceleration.

Notice how Fx here is 35.9 Newtons, Fy is 294 Newtons, and Fz remains zero.

Moment Mx remains the same as well, but moment My is a different story.

Here the payload is multiplied by must also account for the effects of actuator acceleration on payload and its gravity center offset from the carriage face in the Y direction.

Added to that is the product of the payload, G, and the moment arm of the payload center of gravity offset in the X direction from the carriage center.

Step four when sizing an actuator is to obtain an equivalent load or PEQ value published in data sheets to account for all forces and moments during constant speed actuator operation.

We'll ultimately use this value to calculate the actuator's expected service life.

We enter our example application values into the PEQ equation for Roland eSmart 80 units.

Notice how actual application moments divided by maximum values published in the Roland catalog yield safety factors for the moments acting on our example actuator.

Step five in sizing an actuator is to repeat the process we just executed for constant speed conditions, but now to obtain a PEQ value safety factor for periods of acceleration.

With the loads and moments previously calculated along with our chosen actuators capacities, PEQ is 3935 newtons for periods of acceleration.

Step six in the actuator specification is to calculate the time-based PEQ value that accounts for P1, P2, and P3 representing equivalent payloads at all three portions of the motion profile.

P1 acceleration and P3 deceleration have the same value.

This equivalent payload PEQ with a calculated value of 3841.6 newtons is what we'll use for our life equations.

Step seven, the final step in specifying an actuator, is to calculate expected actuator life.

Here we use the dynamic load capacity value published in the Roland catalog for calculating the lifetime of the actuator.

This load corresponds to a nominal service life of 100 kilometers.

The service factor F sub I accounts for the effects of vibration and shock loading.

We chose 1.5 because our design isn't expected to be exposed to such conditions.

Actuator life is expressed in both kilometers of carriage travel and years of operation.

For our design, the Roland actuator we selected will deliver nearly 7.3 years of trouble-free operation.

As engineers and designers, we know how crucial it is to get the actuator specification right for any given project.

It can be a daunting and time-consuming task, but Roland has simplified this whole process.

Just visit my.roland.com and with just a few clicks you can easily size and specify the electric actuators for your design, including customization for specialty applications.

We also have a team of Roland representatives, distributors, and facilities in your area that are ready to help you every step of the way.

From selecting the right product to installation and support, our team is dedicated to providing you with