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 Designer's 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 CAD, 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 the both!
Easy and Flexible!
Configurable components are easy to design with and purchase.
Online, 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 on this configurablilty 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 Gordana Dahl and I'm the Product Engineer for Misumi's
Standard Mechanical Components Team. In today's webinar
I will talk about Couplings. We will cover what Couplings are,
what Couplings Misumi offers, including the special type of couplings
called Universal Joints. I will also go over a few real life examples using
Couplings
and at the end I will show you how to find,
select and Download 3D models for Shaft Couplings.
Shaft Couplings is a device designed to connect shafts
that are manufactured separately such as motor and connecting mechanism.
The main purpose is to transfer rotary motion or torque
from one shaft to another without changing rotational speed.
At the same time they need to compensate for any misalignment
in random movement between two shafts. They also need to reduce transmission
or shock load vibrations and to protect connected mechanism
from overloads. Couplings in general
do not disconnect from shaft during operation unless we are
using torque limiting Couplings. By careful selection,
installation, and maintenance Couplings protect expensive machine elements from
sudden excessive and unexpected loads by breaking or disconnecting.
When connected shafts
are misaligned, forces are generated and these forces can produce great stresses
on rotating and stationery components. Depending on application,
design and surrounding environment it is not always possible
to completely isolate misalignments. Using couplings help achieve
optimum alignment conditions in machinery. What kind of misalignment can
Couplings compensate?
One is anguler misalignment where Couplings compensate
for shaft eccentricity that is anguler error between
two shaft access. There is a lateral misalignment when Couplings compensate
for parallelism
error or offset between to shaft access.
An Axial misalignment
where Couplings compensate for end play of the shaft.
That is when shafts shift in axial direction. For each Coupling Misumi
offers you can find allowable misalignments value in technical section of Couplings.
All these values are empirical values.
One thing user has to watch for
is that misalignment values shown in a table are when each of the mentioned misalignment
is occurring individually. If more than one misalignment
are occurring simultaneously, then allowable values for lateral,
angular and axial misalignments will be reduced by 50% from original
value shown in a table.
This is a common oversight when selecting the Coupling.
Other measured characteristics important when selecting the Couplings
are Torsional spring Constant - higher the value the more rigid Coupling is,
Max. rotational speed and moment of inertia.
There are several ways to connect Couplings to the shaft.
One is using a set screw. For Misumi Couplings usually one or two set screws
placed at 90 degrees apart. This type of connection
is best used when shaft is softer than the set screw.
Unfortunately the set screw causes damage to the shaft
which makes the Coupling harder to adjust or remove.
It is common to machine small flats onto the shaft
at the set screw location to eliminate this problem.
We have a clamping style. Clamp style Couplings are designed to solve the problems
associated with the set screw type. Instead of protruding into the shaft
the screw compressed the coupling and lock
the coupling into the place. The ease of use is maintained with a design
and there is no shaft damage. Since the screw
compress the collar and a uniform distribution of the force
is imposed on the shaft, this leads to bigger holding power
then a set screw Couplings. Although the clamp type Couplings work well
on the relative constant load, shock loads can cause Couplings to shift.
Using either setscrew type with keyway or clamping style with keyway
can solve this problem.
Keyways are used as a positive stop that is more resistant to shock loads.
In general shaft couplings can be grouped into three groups:
High-precision, flexible
and pivoting couplings. High precision Couplings
tend to have higher stiffness and are suited to applications were shaft alignment
is relatively good. Flexible Couplings are better
able to compensate for radial
angler shaft misalignment. While great misalignment calls for use of
pivoting couplings. When it comes to coupling design
high precision Couplings come with a different design.
We have rigid couplings that have simple and robust cylindrical body
that is easily installed on the shaft but cannot tolerate
any misalignment. We have disc type that are available in different configurations.
Single, double or double with a spacer.
The choice of configuration enables different amounts of misalignment
to be accommodated.
but though increase of flexibility couplings loses its torsional rigidity.
In this group we also include bellow couplings. They have similar design to
disc type
but they have high rigidity due to its more solid construction.
Flexible Couplings are general, multi-purpose coupling.
They come with single or multi beam helical cut design
and can accommodate any combination of axial motion and misalignments.
Most popular are single beam Couplings where customer can choose between short and
long version.
Short for more compact and space restricted design
or longer models offering greater tolerance of misalignment by reduced torque accuracy.
Pivot type, if greater angular misalignment is needed, three piece construction
or universal joint complex are to be used.
Misumi offers variety of Couplings including the disc,
Oldham, Jaw, Flex,
Bellow & Chain and Rigid Coupling. What separates Misumi from other suppliers
is that Coupling bore size is configurable
and we also offer hybrid bores meaning one side can be metric
while the other can be inch bore size. In the next few slides we'll cover some
major characteristics of a Coupling groups.
Disc Couplings are designed to transmit torque between the bolts
through a series of thin, stainless steel disc assembled in a pack.
These bolts connect shaft hubs into one piece construction.
Misalignments are absorbed through flexing of a disc. Disc material
and the shape adopt to wide range of transmission capabilities.
Disc Couplings also have low (zero) backlash and therefor are suitable for high positioning
accuracy application. As a result,
they're also best suited for high torque servo motor application
that require high rigidity and zero backlash.
For servo motor application it is best to select Coupling
with a maximum torque capacity of 5-10 times more of a motor's
peak torque. Misumi catalog
and also online user can look at summary table
where all Couplings are compared and rated based on their main characteristics,
such as backlash, rigidity, torque, misalignment,
electrical insulation and bore size. This allows for
easy preliminary selection of Coupling based on user and design requirement.
Oldham Couplings are made of two shaft hubs that are connected with the spacer.
Misalignments are absorbed by sliding and flexing of spacer.
Large allowable misalignment allows for easy Coupling installation.
Depending on spacer material Couplings have different characteristics.
Like Oldham Couplings with aluminum bronze spacer have much higher rigidity
compared to Coupling with polyacetal or reinforced
resin spacer. Using comparison table for preliminary selection you can
easily see which Coupling excels in certain characteristics.
Important thing to mention is that Oldham Couplings
are offered for small size shaft diameters, starting from 1mm.
Overall these Couplings provide good balance in
torque transmission, torsional rigidity and misalignments
absorption. They also have good electrical insulating properties.
One thing to keep in mind is that for couplings using resin spacers
allowable torque values and other characteristics are based on
operational/usage temperature. If operational temperature is
outside of normal range of -20 to +30 degree Celsius
allowable values like torque and speed need to be corrected
using temperature correction factor.
Flex, helical or beam Couplings is single piece of material that becomes flexible
by removal of material along the spiral path resulting in a curved
flexible beam of a helical shape.
Since it is made from a single piece of material, this Coupling does not exhibit
the backlash found in some multi-piece Couplings.
Another advantage of being one piece construction is that allows
smooth torque transmission. They can absorb large
error misalignment and therefore are suitable for applications requiring high
positioning accuracy. But they do have smaller
torque rating then disc couplings. Flexible Couplings are made of aluminum
or Duralumin and stainless steel. They are waterproof,
oil resistantance and chemical resistantance. User can use
overview table to compare and select the Coupling based on application.
Bellow couplings construction is made of two piece couplings
that uses stainless steel and phosphor bronze
bellow to connect shaft hubs. Misalignment absorbed by flexing
of the bellow and the high moment of inertia and a low backlash.
as for Rigid Couplings they are one piece solid construction made of aluminum alloys
stainless steel. Design allows for high torsional rigidity
and no backlash. Beside covered major groups we also offer
jaw and N-coupling, chain and plastic Couplings.
I am mentioning these only by names but you can find more about these Couplings online or
or using Misumi catalog. Now that we are familiar with characteristic of major
Coupling Groups
selecting Coupling for certain applications should be easy. One thing to keep in mind is that
depending who is making Coupling selection different factors come to play.
Engineers are mostly concern about design requirements:
torque ratings allowable speed and misalignment, bore sizes.
Assembly and maintenance personnel are interested in easy installation,
reliability and maintenance costs. So using Coupling Overview or Summary Tables from
the catalog
online can really speed up the process because it allows users to see how
different Couplings
compared to each other. If for example application requirements
is to connect servo motor to precision ball screw we are looking for Coupling
that can transmit high torque
and speed and has a zero backlash. This translate
in coupling having high rigidity characteristics.
High rigidity is needed to cope with a high accuracy and high speeds
of a Servo system. Because if the Coupling rigidity is insufficient,
servo system delay occurs and positioning accuracy degrades.
and zero backlash is needed to cope with the high accuracy of a servo system.
Using overview table we can narrow down our choice to either disc
or flex coupling both rated to be used with servo motors.
Some other factors come into play when selecting a Coupling.
Some of the selection criteria are dictated by application
others are user preference - such us How to attached Coupling to the shaft.
Disc Couplings come as a clamp type, keyway type and keyless type.
At the end, just a few words regarding universal joint.
They're commonly used with a drive shaft and have allowable
operating
angle up to 30 degree which is much higher value compared to standard
shaft Couplings. Shafts are connected to joint using
pin set or keyway. User also has an option to select universal joint with
rubber cover.
This helps extend life of universal joint by protecting from dirt
and contaminants.
To select proper joint user needs to follow recommendation from the catalog
or online. Next few slides we'll cover real life examples of Coupling usage.
Coupling usage is straight forward, and most of the design time is
spent in selecting a correct type for application. In this particular case
we have a Coupling used to connect a motor shaft to a drive roller of a conveyor.
Oldham Coupling is a good choice for this application since high accuracy and
zero backlash
are not requirements, but at the same time Oldham Coupling have good misalignment characteristics
and can transmit a high torque. In this example
test fixture is using torque transducer as torque senor for measuring torque.
To connect motor and torque sensor with workpiece
we are using two Couplings. These Couplings need to minimize
any misalignment error since torque sensor needs to lay as flat as possible
and they also need to protect the sensor from overloading.
Major characteristic of the Flex Couplings are very low or zero backlash,
good torsion rigidity and good lateral and angular misalignment capabilities.
This makes them very suitable for this application. In this example
Coupling is used as part of a slide table in a welding station.
Coupling connects the servo motor to ball screw that moves
the workpiece table to required position or positions.
Disc Coupling used here is one recommended to be used with servo motors.
It has low backlash, high torsion rigidity, good allowable misalignment and torque capabilities.
During operation user should watch for external signs
such as abnormal noise and vibration that indicate premature Coupling failure.
This helps with understanding what caused the failure
and how and what to correct prior to installing a new Coupling.
During its life span Couplings should also be checked for sign of wear and fatigue.
For any questions and assistance in selecting a Coupling please contact
Misumi Engineering Department
or call me while I use online configurator for Coupling selection.
There are several ways you can search for a product on the Misumi website.
One is to type in the product name in a search bar
or click to Automation Components tab. You can search by product group on the
left hand side
or you can search by a picture index in the center of your screen.
We are looking for Shaft Couplings and that will be part of Rotary
and Power Transmission Motion. If you already know which Couplings you want to
use
you can click on a specific product type, in our case Disc Type.
If you click on the detail selection you will see
each Coupling described with a major characteristics.
This will help you narrow down the type that you need.
If you're not sure which Couplings to use you can filter,
use the filters on the left hand side to narrow down the selection.
These filters will allow you to select the Coupling based on application that
you have.
In case you're having a servo motor application and you need a high accuracy
you can make a selection on the left hand side. You can also make selection
based on material and the shaft bore that you need to connect.
on a specific product page you will make the final selection.
In this case we want to connect the shaft size of 6
and 10mm, OD of the Coupling of 28mm.
We're getting the full part number. Once we click on the price check we can get a
price
for the unit piece and the days to ship. By clicking
on the blue CAD download button we can download any native or neutral file.
This concludes our web presentation.
Thank you and we hope you enjoyed today's webinar.
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at www.misumiusa.com.
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