Welcome to Misumi's new 19 minute Webinar Series.
For those of you here that are new to Misumi,
Misumi is a Global Supplier of configurable components.
You may ask, why configurable? What is it?
Configurable components solve the designers dilemma.
A designer has two choices for components: Standard or Custom.
Standard components have limited selection
and often force designers to compromise their designs.
These many pluses such as CADS, static part numbers,
fast delivery, often seen inexpensive
and convenient. The other choice is custom.
Custom components have many drawbacks.
Designers have to make the solid models themselves and all the manufacturing drawings.
Purchasers too can attest to the long wait for quotes, the expensive set up
charges for short runs
and the long lead times. We are forced to use custom components though
because of the flexibility.
Misumi offers configurable which is the best of both! Easy and Flexible!
Configurable components are easy to design with and purchase.
On line select the product geometry desired,
the material and surface finish, input the size for each configurable dimension
within the range and increments shown.
You'll get a smart part number, instant price and days to ship,
and the CAD model.
All of this configurability is available with our over 1 MILLION components.
Available at www.misumiusa.com.
Now I'll turn it over to our Misumi Engineer.
Hi, my name is Nick Waszak. I'm a Product Engineer with Misumi's Motion Systems Group.
And will be presenting this webinar covering sizing,
selection and a few application examples of our
LX linear actuators series as well as a brief comparison of common motor types
used for positioning. If you're interested in learning more about all
the options offered
in the full LX precision positioning actuators line,
please feel free to view part 1 of this webinar series
LX Series Actuators Competitive Design.
For every application, there are several considerations that need to be
determined
to properly select an LX actuator for an application.
These factors include actuator orientation,
stroke length, travel speeds, load to transport,
location of the load, environment,
accuracy required, and the repeatability
(also known as precision). In order to help demonstrate the typical applications
sizing and LX
actuators selection process, I'll be walking through the steps using
example applications. This system is a 6-axis actuator
8-axis demo unit from National Instruments built as a showcase for
their NI week 2013.
To begin isolate the first axis,
the actuator which is not supporting any other actuators,
and determine the application considerations
for that axis. In this example the actuators to be in a vertical
orientation
moving across six inches of stroke at speeds up to 12 inches per second.
The load includes a motor, clamp
and mounting bracket, requiring a positioning accuracy of
1/1000th of an inch
with repeatability of 1/1000th of an inch as well.
The actuator will need to be selected for safety considerations
as well as protecting the mechanism from any medium to large debris or objects.
The actuator orientation will dictate the size and type of motor used to drive
the LX actuator as well as the load ratings for
actuator motor combination. An actuator in a vertical orientation has a lower
load capability
and the use of an electromagnetic brake motor is highly recommended to prevent
the load from falling
during a power failure event.
In a horizontal orientation, the highest load capacity can be achieved
and a break is not required.
When comparing the two orientations using the same load,
a vertical actuator will require a larger more powerful motor
compared to the same actuator mounted horizontally.
When sizing application requirements to select an LX actuator,
careful consideration needs to be taken to select based on metric units.
In this example, the six inches of travel translates to approximately 150mm
of stroke.
Since this actuator will
have two additional supporting actuators below it starting by choosing a smaller
actuator, such as our LX20, will help reduce the load size for the base
actuators.
Choosing the correct actuator length will depend on whether one or two blocks
are used,
where an actuator with two blocks will have a longer overall length for the
same stroke.
You can refer to the effective stroke table to select the appropriate length.
In this example, only one block is needed so a 250mm length
LX20 can be used for 150mm of stroke.
Once again, making sure to convert
to metric units, the example speed of 12 inches per second is approximately
305mm per second. An LX2001 with 1mm lead ball
screw has a rated maximum speed of 147mm per second,
while the LX2005 with 5mm lead ball screw
has a rated maximum speed of 694mm per second.
Because the calculated speed of 305mm per second is greater than
the maximum speed of the LX2001
but still within the spec for the LX2005,
the 5mm lead LX2005 is selected
for this example. The next step is to verify
the load size and location. For this example the clamp is approximately
one pound while the motor and bracket are two pounds together.
This translates to about 13 Newton's,
which is well within the nearly 6200 Newton
allowable static load for a single long block
LX2005-B1. In addition to calculating and comparing the allowable
static load,
the position of the load plays an important factor in choosing the correct
actuator.
Overhanging or cantilevered loads can create moments or twisting forces on the
carriage of the actuator
calculated by multiplying the force by the distance offset from the actuator axis.
If the allowable moment is exceeded, the actuator could suffer damage.
Based on the combination of the actuator orientation and the low position,
there may be moment loads in as many as three directions.
Each direction needs to be evaluated and verified against the allowable moment
load of the actuator.
In the moment specs you'll note that the MA moment is the pitch,
the MB moment is the Yaw and MC is the role.
For our example, the center of mass of the load is located at 3 inches from
the actuator along the x-axis
or in this orientation the direction contributing to the Yaw moment.
The calculated moment from the weight of the load at 3 inches is one Newton meter.
Which is also well within the allowable static moment of the LX2005-B1-250.
Thus verifying our current actuator selection
so far. In order to understand the next requirements I'll briefly explain the
difference between precision or
repeat ability and accuracy.
Precision or repeatability is the ability to hit the same spot
each time. The actual position may not be the same as the commanded position;
however, each consecutive motion will be in approximately the same location
relative to the previous position.
Accuracy is the ability to hit within the same distance from the commanded
position
each time. This is like hitting the same ring from a bulls-eye
on a target. Combining both accuracy and repeatability is the best possible
scenario and is like hitting the bulls-eye
every time! Misumi's LX actuators have two precision options available:
high-grade and precision grade. Both of which provide
excellent accuracy and repeatability. Both grades have preloaded bearings on
the side carriage and the ball screw.
This preload limits the backlash, pitch
and roll, and improves the overall precision of the actuators.
The high-grade provides +/- 5 microns repeatability
and an accuracy of point 06-0.1 mm depending on the actuator size.
The precision grade provides +/- 3 microns repeatability
and an inaccuracy of 0.02-.025 mm depending on the actuator size.
The precision great actuators are select actuators
that are given an additional level of inspection and testing
to ensure that they meet these rigid specifications.
Not only does Misumi's LX actuator line provide great accuracy and
repeatability specs,
but the quality is tried and true. Consistently beating out our competitors
equivalent actuator in 800 hour
full load endurance tests. When comparing the High Grade and Precision Grade LX20 specs,
we see that for our application example which requires 1/1000th of an inch
or 25.4 microns accuracy and repeatability,
the precision grade is a better fit than the high-grade
due to the increased positioning accuracy of 20 microns
and the very fine repeatability of +/- 3 microns.
The final application consideration for this example is the environment.
The standard LX actuator has no cover but there is a cover type available
to protect against medium to large debris and for added safety,
as well as a class 10 clean room rated grease for environments requiring
minimal dust-raise.
Because this example application was designed to operate the full demo unit on
the show floor,
the cover type is selected for safety concerns.
As each option is selected in our online configurator the part number will be
narrowed down
helping to build your final part number for your application.
This process can then be repeated for each subsequent axis in your system.
For example, the base actuator in a multi-axis system is typically larger than the first actuator
so here we've configured an LX30 for the base.
By configuring the part online using our sizing and selection process
we end up with a final part number of LX3005-B1-F-300
which we can download the 3D CAD in order to insert into our design.
Another free online tool Misumii offers is the lifetime verification software
for the LX actuator. Available at www.misumiusa.com.
To use the software simply select your desired actuator based on your
application, sizing and requirements.
Fill in the operating parameters for that access.
Add the mounting conditions for that load including the wait
and position of the load with respect to the actuator and the software will provide
an expected
theoretical life of the actuator in the application.
The calculated life span will be given in kilometers, hours
and the years. But the recommended value for comparison is kilometers
or distance.
If the calulations show the actuator may fail before the typical lifetime,
usually 3000 kilometers or less, then the life span values will be given
in red.
In that case, you may want to reconsider the actuator you've selected
or adjust your application conditions.
In order to provide all the resources you need to size, select and incorporate an
LX precision actuator into your design,
you can find specifications and dimensions, LX online lifetime
verification software
and when logged into a free ww.misumiusa.com account
you have access to free 3D preview and downloads,
as well as being able to quote and order instantly.
Now that we've discussed sizing and selection of Misumi's LX Precision
Actuators,
let's take a look at a few additional application examples.
For each one we'll review the application requirements, the particular LX features
for selection
and finish with a brief overview of positioning motor types
and the applications for which their best suited.
The first example is a Precision Press-Fit Mechanism.
This requires a low profile design, consistent quality and parallelism,
the ability to move at a low speed and handle a high moment load.
The LX is a good fit for this due to sizes as small as 15mm
profile height, parallelism as low as 10 microns,
with a precision ball screw able to operate between 0 and a 150mm per second
and able to handle nearly 4,000 Newton meters moment load
with the LX45 into long block selected.
This next example, a 3-Axis MIG-welding fixture,
requires multi-axis assembly, high accuracy and repeatability,
and operating at medium speed where constant steady motion is key.
With standard 2-Axis transition brackets available
and configurable plates out of the Misumi catalog
the LX can easily be installed in a multi-axis set up.
The +/- 3-5 micron repeatability provides excellent
positioning precision
while the Standard rigid construction and preloaded ball screw
allows for constant steady motion throughout the entire speed range.
Including a medium speed between 100 to 400mm per second.
In this vision inspection gantry we once again are looking for a multi-axis
installation with high accuracy and repeatability,
and constant steady motion to ensure the product being inspected
is always in view. Due to high volume of products being inspected
ensuring minimal downtime is a priority as well.
Similar to the MIG-welding fixture, the transition brackets
excellent repeatability and standard rigid construction, are
all key features that help the LX succeed and the optional
MX Extended Lubrication Unit built into the actuator
can be selected to reduce the frequency of maintenance
and lubrication. This helps minimize the down time and keeps the system running smooth.
Finally with this Parts-Transfer or Pick and Place unit,
a multi-axis installation with high accuracy and repeatability,
simple and accurate alignment, and medium to high speeds are required.
The high precision and repeatability provided by the LX,
even up to the maximum speed range of around 1100mm per second,
provides outstanding positioning for precise time demotion
and with built-in Dowel Holes (part of every at LX actuator design)
alignment and installation is simple and accurate.
The last topic of this webinar will cover stepper motors;
both opened and closed loop and servo motors.
These are the most common electric motors used for precision positioning
and are often the driving motors chosen for our LX precision positioning actuators.
Stepper motors are widely used in a variety of positioning systems because
of their small compact size,
low-cost and high torque output for the small size.
Typical stepper motors can reach a maximum speed of up to 3,000 rpm
and produce a much higher torque at lower speeds.
With a holding torque when stationary to help maintain position
when power is supplied.
Stepper motors are usually open loop with the internal structure of the motor
allowing for the positioning functionality.
This is ideal for quick short moves providing fast response
and rapid acceleration. Closed-loop systems can be made by utilizing an
encoder or resolver
for position feedback allowing for greater control.
Servo motors are more expensive than stepper motors
but provide higher power output and higher speeds up to around 5,000 rpm.
The torch speed curve is mostly flat as well providing greater torque at higher speeds
then stepper motors and are all closed loop systems
using resolver or encoder feedback to position
based on deviation.
Both steppers and servos are excellent options to consider as drive units for
the LX precision positioning actuators
as the rotary position resolution capable ranges from about 1.8 degrees
down to fractions of a degree.
This fine tune resolution combined with the LX's fantastic accuracy and
repeatability specifications
allow for an extremely precise linear motion system.
Thank you and we hope you enjoyed today's webinar.
All of Misumi's configurable components and 1 MILLION products are available
at www.misumiusa.com.
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Full support is also available. Technical help at engineering@misumiusa.com
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