Blog in Motion

Something's Missing Here...and other Linear Actuator Nightmares!

By: Michael Brown

Many considerations go into specifying a linear rod type actuator…   Will we use a servo or stepper motor?  What are the mounting and rod end selections?  Speeds and forces required for the application?  What duty cycle and life requirement do we need?  Often, a very critical consideration gets overlooked.

The image above shows a “ring” impression in the rubber bumper that shouldn’t be there – what was missing in this situation?

 A specification will often state the required stroke for the application.  What is frequently seen is that units are damaged by not following a simple requirement stated in the Installation Manual.  Best practices dictate the utilization of End of Travel (EOT) sensors used with actuators and drives.  This is done to prevent the actuators from striking the mechanical stops at each end, and typically a manual will clearly show where these sensors should be placed on the device.  Actuators do have built in “bumpers” to help absorb energy when the mechanical stops are struck, but they are not designed to provide unlimited protection against repeated strikes.   Does your car have a bumper at each end?  Does this mean your car is protected when a bumper strikes a fixed object?  No!  Like a car, protect your investment and incorporate EOT’s with the actuator, and keep you actuator from crashing!

Remember, additional length must be added to the stroke for the physical room that EOT sensors occupy, but also the length needed for the motor to bring the actuator and load to a stop.  This distance varies significantly by application, and should be considered as part of the decision on where to place the sensors.  

An example may be that if eighteen (18) inches of travel are required for an application, an actuator with a stroke of twenty (20) inches is probably necessary.

Tell us about your horror stories when end of travels were not included in the design…

 

Lets Back Up a Minute...

By Jim Coleman

Most of us have been there at one point or another…..wishing we had a backup copy of something.  Whether it’s contacts on a cell phone or a program file in a motion controller, data is important and valuable.

 

I have seen all too many times when some data gets lost and there is that moment of anguish.  Laptops can break beyond repair and old PC’s can crash for the last time.  Old devices can become obsolete and incompatible with newer technology.  It is one of those things that many of us think, “It won’t happen to me.”  Or we just don’t think about it at all.

It is simple and painless to keep a PC or laptop backed up to an external hard drive.  Hard drives are available these days with enough memory to back up several PC’s and at a very reasonable price.  I use an external hard drive with USB connection and a simple software package for managing the synchronization.  There are many software packages for this, each with their differences.  Wmatch 4.0 from PCMag was recommended to me and I like it.  It is fairly simple and has the features I need.  But before I switched to using that, I just used Windows Explorer.  It is a little more time consuming, but it is very simple and straightforward.  With Windows Explorer, there is no question whether or not the files were updated, because you do it manually.  Simple is good.  Lack of ambiguity and uncertainty is absolutely necessary when backing up valuable data.  When using a software package that handles synchronization, it is necessary to fully understand how the synchronization works.  Data can be synced to or from the backup memory location, and it can also be synced based on which memory location has the newest version of a file.  Some software packages have options for selecting the type of synchronization you want to use.  Make certain the data is being stored where you intend.  And to be sure, it is easy enough to double check the data by accessing it through a different route or from a different PC.

You might think it isn’t all that important to go to all the trouble to back up data and verify that it has been backed up correctly.  But data can be extremely valuable.  Some data is just irreplaceable.  Once it is lost, it is gone forever.  Other data can be obtained again, but with considerable effort and possibly embarrassment.  Not only can the person who had the data be embarrassed about losing it, but a company can lose face by losing important data.  Also, some data can be re-created, but usually with great effort, time, and expense.

I often talk to customers upgrading drives and motion controllers on their machine who do not have copies of the programs or the original application requirements.  When a controller fails catastrophically, it is too late to pull the program out of it.  The program must then be created from scratch, costing the customer a considerable amount of time and money.  Many times customers must select replacement devices based on the capabilities of the old devices, rather than sizing it based on the actual application requirements.  This often results in new motors, drives, and controllers that are over-sized and more highly featured than what is actually needed.  Having access to the original sizing information could save customers significant expense.  I always recommend finding the actual performance and functionality requirements before selecting replacement devices.  Not only can it save expense, but it’s best to size products based on the application, rather than on previous device selections. 

 

I encourage customers to save backup parameter files for drives and programs for controllers even during the installation and development.  Having backups from each stage of the integration process allows the customer to go back to a previous step at any time.

New Food Safety Regulations: Preventative Controls Review Extended

By: Andy Hansbrough

Food Safety Expectations

Consumers expect safe food.  The Feds expect a safe food supply chain—farm, processing, packaging, and distribution.  As we all work to consistently meet consumer food safety expectations, the need to prevent and control food adulteration and/or contamination is present in every step of the supply chain.  Our modern and globally expanding food and beverage processing and packaging industries have made and continue to make great strides in improving food safety by improving preventive, control, cleaning and sanitation methods.

Making the Food Supply Safer

According to the Centers for Disease Control and Prevention (CDC) estimates, about forty-eight million (or one in six) Americans get sick and three thousand die each year from foodborne diseases.  The CDC publishes food safety related information on their FoodNet site and found there, along with other useful data, is the Food Safety Progress Report (see Figure 1).

Figure 1:  FoodNet 2011 Progress Report on Six Key Pathogens

What the Future Holds for Food Safety

To broaden, build, and improve on this successful approach to food safety the US Congress passed a major amendment to the Food, Drugs, and Cosmetics (FD&C) Act called the Food Safety Modernization Act (FSMA).  The FSMA calls for an expansion of food safety practices to focus on preventive controls.  The first two rules on Preventive Controls and Produce were released on January 4, 2013 for 120 days of public review.  The public review has been extended until September 16, 2013.  See details at http://www.fda.gov/Food/GuidanceRegulation/FSMA/default.htm.

The rule on Preventive Controls will have the greatest impact on food and beverage processing and packaging businesses.  These preventive controls should be established and validated surrounding processes, environments and food allergens to ensure that the food will not be adulterated or misbranded under the FD&C Act.¹  Food companies will be required to implement preventive controls within their Food Safety Plan which should evaluate potential hazards, specify preventive controls, monitor results, maintain records and specify corrective actions. 

The Produce rule covers all fruits and vegetables which are typically consumed in the raw or unprocessed state.  It focuses on the growing, harvesting, packing, and holding of produce and the potential sources of microbiological contamination which include water, animals, hygienic practices, tools, machinery, and facilities.

If you would like to learn more, the following links are good places to start.

http://www.fda.gov/Food/GuidanceRegulation/FSMA/ucm334115.htm#  This link will take you to the Fact Sheet on the FSMA Proposed Rule for Preventive Controls for Human Food: Current Good Manufacturing Practice and Hazard Analysis and Risk-Based Preventive Controls for Human Food.

http://www.fda.gov/Food/GuidanceRegulation/FSMA/ucm334114.htm  This link will take you to the Fact Sheet on the FSMA Proposed Rule for Produce: Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption. 

1	Background on the FDA Food Safety Modernization Act (FSMA)”, Food and Drug Administration, November 14, 2011.

Work-Life Balance as a Remote Technical Support Engineer: 'Is that a Servo System I Hear?'

By: Teri Bosomworth

A year and a half ago I started a new adventure.  I left getting up in the morning and heading into the office and traded to getting up in the morning and heading downstairs. I now work from my 'home office' better known as my basement, as a Remote Technical Support Engineer.  Establishing work-life balance when working from home can be difficult, but it is very rewarding when you have mastered the balancing act.

I have a full office set up with two computers, an IP phone, and numerous demos including AKD, AKD BASIC, PDMM, as well as several legacy drives so I can test customer issues.  I am one of the primary technical interfaces for our customers and distributors, but few know I work from home.  As a technical support engineer, I help customers start-up new machines as well as troubleshoot existing machines. As a remote worker, I must continue to maintain a professional demeanor on the phone & via email in order to give our customers confidence in our organization and my technical abilities.  And just like in the office, I have to respond to their inquiries in a timely manner.  All this, while balancing the distractions and advantages of working from home.

That’s not to say that work and home don’t collide sometimes. I will never forget the time I received a call and a customer asked if I had a servo system running in the background.  Truthfully, it was my laundry.  But such are the quirks of working from home.

Some tips for those of you considering working from home:

• You’ll need to balance the distractions (dogs, bills, dishes, etc).
• You must have these skills: discipline and personal accountability.
• As a support engineer: solid knowledge base for large spectrum of products, motivated to investigate, and solve problems on your own.

Oh- and remember to close the door to the laundry room.

 

 

Switched at Birth: Servo Motor Winding Nomenclature Explained

By: Hurley Gill

If you have been following along on our Evolution of Kollmorgen posts, you realize Hugo Unruh was one of the first to successfully commercialize frameless motor technology.  What most people don't realize is that Kollmorgen's motor-drive phase identification standards (A, B, C) were based on these frameless motors.  Now the issue at hand is both sides of a frameless motor typically look the same, except for the side where the wire leads exit.

Thus the lead exit side of the motors was used to reference the label identification of the phases with a Clockwise (C.W.) rotation looking into the lead exit end of the motor. 

Looking at the lead exit end.                                                        

This C.W. rotation of the rotor, looking into the 'lead exit end', is of course Counter Clockwise (C.W.W.). looking into the shaft (torque end bell and/or mounting end) of most framed motors. 

Looking at the torque end bell.

This phasing convention: A,B,C with a C.W. rotation looking into the lead exit end, transferred over to Kollmorgen’s  standard housed motors looking into the motor’s rear or connector end.

However most of the world’s motor manufacturers started with housed motors, with the natural C.W. rotation looking into the torque endbell, often using the same labels: A,B,C.

In order to facilitate new drives and their introduction with phase labeling customized for phasing identification using the convention of a  C.W. rotation looking into the torque endbell, Kollmorgen identified these phases as U,V,W.  This minimized potential confusion between the two phase labeling conventions.

To convert one convention to the other for Kollmorgen’s rotary motors simply identify your desired convention with U = C, V = B, and W = A.   When motor/drive phases are looked at in a straight line, you are switching the two outside leads.

Looking at the torque end bell.

This method of always switching the two outside leads, regardless of who manufactures the motor will always minimize confusion of which motor phases where switched months and years later; otherwise, one is faced with trying to remember if they switched the top two or the bottom two, and it makes a difference.

Always refer back to the Kollmorgen outline drawings for phasing.  You can find out more details on the correct phasing for Kollmorgen motors, here. 

Tracing the Steps of the First Industrial Stepping Motor (and The Boston Whaler)

By: Paul Coughlin

There has been a lot of discussion over the years as to who created the stepping motor, or at least the industrial 1.8° motor we know today.

The two relevant companies involved with the design were Superior Electric, originally in Bristol Connecticut, and Sigma Instruments, originally in Braintree, Massachusetts.

Although Superior Electric seems to have the leading edge as being the first, it appears that Sigma Instruments may have been the true innovator.

In 1952 the General Electric Company designed a stepping motor to be used with the Superior Electric variable transformers and rheostats.  General Electric originally sold the motors to Superior, to attach to the rheostats, and Superior sold a complete system back to GE. 

General Electric sold the stepping motor design to Superior Electric and in the 1960s Superior improved the design and introduced the M Series hybrid stepping motors in 1970.  These were marketed under the name Slo-Syn.

However, in 1952 Sigma Instruments introduced the Cyclonome Stepping Motor, which is regarded as the first practical two-wire stepping motor.  Unfortunately it would be years later before integrated circuit electronics would allow for wide spread application use.

The Series 9 Cyclonome stepping motors were single phase, uni-directional stepping motors with step angles of 15° (24 steps/revolution) and 18° (20 steps/revolution).  Torque ranges were 1 – 12 oz-in.

Cyclonome 9 Series Stepping Motors

Shortly after, Sigma released the Series 18 AC Synchronous motor.  These were two phase, bi-directional permanent magnet motors with speeds of 360, 450, 600 and 900 rpm at 120 Vac, 60Hz.  Torque ranges were 0.6 – 11 oz-in.

18 Series AC Synchronous Motors

In 1969 Sigma introduced the 20 Series stepping motor, which had solid broached rotor segments  and is closer to the typical 1.8° (200 steps/revolution) stepping motor we know today.

The 21 Series motor, with laminated rotor segments, was introduced shortly afterward.  The laminated rotor segments allowed for cooler, high speed performance and the 21 Series motor became known as the High Performance Motor.

In 1984 Sigma took a giant leap in innovation and created the Enhanced Stepping Motor.  This was a revolutionary design in that we placed magnets within the stator teeth, thereby concentrating the flux field, and providing up to 50% more low speed torque.  This was released as the 802 Series motors.

Sigmax Technology Enhanced Motors

Along the way Sigma released Bipolar Chopper Drives with patented features such as Mid-Range Instability Compensation and 4-Phase Chopping circuitry which combined the best of recirculating and non-recirculating current regulation. 

In 1987 Sigma Instruments was sold to Pacific Scientific, to complement their AC Servo Motors and Permanent Magnet DC Motors with the Stepping Motors.

Since then other innovations have taken place for the Sigma Instruments motors, such as the Powermax, Powerpac and CT Series Stepping Motors, but that’s for another day.

Kollmorgen now owns and manufactures both the original Sigma Instruments and Superior Electric 1.8°.  Internally we (I) still argue as to who released first (eh-hem, Sigma!), but as a team of rivals, we offer the best in the industry.

One last note about Sigma Instruments, Inc. which I share with my Superior colleagues – Sigma invented the Boston Whaler.  Ok, not really, but here’s the connection: Included with the stepping motors being manufactured in Braintree, MA in 1977, Sigma Instruments manufactured power supplies, solid state and reed relays, sewing machines, outdoor lighting controls and capacitor switching devices.  The outdoor lighting controls and capacitor switching devices were part of a division called Fisher-Pierce.

Dick Fisher, of Fisher-Pierce, invented the Boston Whaler while at Sigma.  The Boston Whaler is a fiberglass flat-bottom boat, which was widely regarded as being unsinkable.  These were used by the Navy Seals in Viet Nam and more popularly seen with Bud and Sandy in the popular 1960s Flipper films and TV series.

 

Evolution of Kollmorgen: History of Innovation (Part III)

While all of this work by Fredrick Kollmorgen was going on another immigrant, named Hugo Unruh, was growing up in Germany. About the same age as Frederick’s son Otto, Hugo faced the harsh conditions in post WWI Germany with its rampent inflation and struggling economy. His family encoraged him to emigrate to the United States so he could realize his dreams.

Hugo was partially educated in Germany, but finished high school and two years of college while in the US. To help get through school, Hugo worked as a repairman at an X-Ray company. He began to find his niche working for Arnesen Electrical Company out of New York, manufacturing various motors. Hugo was quite successful and as WWII pushed Arnesen to expand, Hugo became president of a subsidiary plant in New Jersey (Ellacraft). After the war, business began to contract and Hugo was pulled back into the parent company as a general manager.

After the death of the original owner, disagreements with the new owners left Hugo unemployed at the young age of 42. But it was always Hugo’s dream to have his own business and he quickly saw the opportunity to purchase the used equipment and material from the remnents of Ellacraft and start his own company. Hugo paired up with Lewis Renaldi, purchased the equipment and in 1948 started Inland Motor in the basement and garage of his home. Why the name Inland you ask? It turns out, Hugo had lived near the ocean in New York for most of his life since he arrived in the US, so, when he established his new company, he had moved “inland” to Pearl River.

Hugo Unruh winding a frameless torquer

There is a myth that states the story was that since the German U-Boats were prowling the waters of the New Jersey/New York coast around WWII, the Navy requested that Hugo move inland to prevent his company from any possible attacks – since he had a relationship building motors for gyros for the Navy. Either way, it appears the name Inland came from not being “on the water”. At the Pearl River plant, Hugo formed a relationship with MIT doing research on motors used in generators and gyros for the MIT Instrumentation Lab. MIT called on Hugo to help solve a variety of engineering challenges on special rotating machinery, and this work led Hugo to design the first “Frameless Torquers” for use on early inertial guidence systems for missles and space vehicles.

It was this revolutionary product, the frameless torquer, which was able to be produced in hundreds of diameters and stack lengths, of different speed and torque ranges, that became the fastest growing, most important part of Inland’s business. This kind of innovation in rotating machine technology continues today at Kollmorgen with products unique to the market like the Cartridge DDR, taking the frameless torquer to a new level!

The move "Inland" from Brooklyn to Pearl River

Kollmorgen Marches Into The Local Christmas Spirit

By: Emily Blanchard

“With great power comes great responsibility” is a quote from the first of the recent Spiderman movies.  But even Peter Parker had some fun with his talent.  What’s fun in the winter? Snow!  This year, Kollmorgen decided to have some fun and bring snow and lights to three local parades in Radford, Blacksburg, and Christiansburg.  Big Blue brought eye popping lights and snow to the crowds while Kollmorgen representatives tossed out candy.  Big Blue even received the Grand Marshal’s award for the Radford parade.

The general public saw the fun of lights and snow, but the real show for Kollmorgen was that Big Blue could do it all with her Kollmorgen power generation system.  Big Blue is an “on-board” power demonstration vehicle.  She’s a Kenworth T300 truck with a Caterpillar C7 diesel engine that would make Tim Taylor proud.  The Kollmorgen power generation system is a belt driven system that is driven off of the crank shaft in place on the alternator.  (I think I just heard Tim ar, ar, ar, somewhere.)  Stockholm developed the drive electronics and Radford developed the generator.  This is a “dual use” system, meaning it has application in both commercial markets as well as potential military applications.  And it makes snow! 

This system can be used anywhere portable power is needed.  The unit produces 17kW at 28 volts at low idle (700 RPM) and 30 kW at high idle (1200 RPM).  To put it in perspective, a normal truck alternator may produce 60 amps whereas Big Blue’s generator produces 1,100 amps.  This truck as been to shows, conventions, customer sites in Detroit, Washington, Reno, New Orleans, Binghamton, Oshkosh, Chicago and many other locations throughout the U.S. and Canada.  And now its been to Radford, Blacksburg, and Christiansburg!

So, at parade speed we have about 700 amps- send us some ideas for our next parade!

Eliminate Unsightly “Bars” Across your Substrate with Direct Drive Technology

By: Tom England

Coating and lamination applications demand precise speed regulations in order to avoid velocity ripple that causes uneven coating and undesirable horizontal bars across the substrate.  The key to achieving the most uniform coating is minimizing the variations in velocity as well as in metering of the coating material.

Coating and laminating applications are characterized by compliance caused by the elasticity of the web, which in turn produces variations in torque requirements.  Web handling machines face the challenge of handling these loads while avoiding velocity ripple that can cause uneven coating and unsightly horizontal bars across the substrate.  As an example, consider film coating, where depositing a dark film onto the substrate material at varying velocity would result in a series of dark and light “bars” across the material.  As web speed and quality requirements have increased, the inevitable inaccuracies in the mechanical transmission and servo system have become a limiting factor on coating and laminating uniformity.

Effect of Mechanical Transmissions

Mechanical transmissions can have a negative impact on coating and laminating quality by causing tooth or belt chatter.  Backlash is inevitable in any mechanical transmission system.  Transmission components such as lead screws, gearboxes, and belts and pulleys all contribute error between the motor and the load.  Even when a geared system is tuned very tightly, within a short period of time the gears will wear and backlash will begin to occur.  Backlash causes the roller and cylinder to rapidly accelerate and decelerate as each gear teeth bounce back and forth against each other.  The result is uneven coating of the substrate manifested by the appearance of alternating light and dark horizontal lines on the product.

Advent of Direct Drive Systems

In some cases these concerns can be adequately addressed by selecting high-quality mechanical transmission components with ultra-precision tolerances.  However, the added expense can become prohibitive and the components will still wear eventually.  The ultimate solution is a direct drive rotary system, which eliminates the transmission altogether.  In direct drive systems, the motor directly drives the load.  The accuracy of a direct rive solution can be up to 60 times better than that of traditional systems and audible noise can fall by more than 20 dB.  Other measures such as servo response (bandwidth), machine parts reductions, and reliability also can improve dramatically.

When the load is directly coupled, there is no limitation on the inertia mismatch between load and motor (Provided there is no compliance introduced in the coupling method – see blog post “Reflecting” on Inertia Ratios).  The servo loop gains can now be increased significantly to provide the necessary servo stiffness to achieve excellent speed regulation to optimize product quality.

When the transmission components such as gearboxes, belts, rack and pinion, and pulleys are eliminated, the servo system becomes free of such negative factors as compliance, backlash, and component wear.  The accuracy increases, inertia-matching requirements relax, acceleration and deceleration improve, maintenance becomes unnecessary, and the product life increases by a significant degree.

Stop by our Knowledge Center at www.kollmorgen.com and find other White Papers related to direct drive solutions.

Feedback Choices – Hall Effect Device (Part III)

Among the simplest and least expensive feedback devices are Hall-effect sensors.  These are digital on-off devices that detect the presence of magnetic fields.  Made of semiconductor material, they are rugged, can be operated at very high frequencies (equating to tens of thousands of motor rpm), and are commonly used to provide six-step commutation of brushless motors.  They are well suited for torque control or coarse speed control, and simplify the drive electronics by directly switching the motor phase power devices.   For you history buffs, the Hall effect was discovered by (yes of course) Edwin Herbert Hall in 1879 at John Hopkins University – and by the way – this happened to be 18 years prior to the discovery of the electron.

 These digital on-off sensors detect the presence of magnetic fields, either by measuring the strength of an electromagnetic or permanent magnetic field.  At each pass of a magnetic field they generate a pulse.  Hall-effect devices come in stand-alone packages that are mounted within the servomotor housing.  In brushless servomotors, these sensors are sometimes embedded in the stator windings and switched by the rotor magnets.  These devices report the shaft’s position, which can also be converted to speed or acceleration data.

In servomotor applications, the most common function for Hall devices is six-step commutation, a type of electronic commutation requiring relatively simple drive electronics.  This may not suit some industrial servo applications because it can be less efficient at producing torque, and worse, can generate high torque ripple.  In this case, torque ripple results from abrupt current transitions resulting in torque fluctuations, which usually produce minute but detectable speed variations.  In some cases torque ripple can seriously deteriorate the overall performance of a drive system. 

With sinusoidal current drives, Hall sensors may be used in combination with incremental encoder feedback to provide precision sinusoidal commutation.  In servo drives, Hall sensors also function as current sensors to close the current loop.  In other industry applications, they sense the position of crankshafts, cams, or other mechanical devices.

Hall-effect devices are digital On/Off
 sensors used to sense the presence
of magnetic fields.

Kind of a neat device - simple, cost effective, and yet capable of contributing quite a lot to a feedback system!  To find out more, we point you to one of our Two Minutes of Motion videos, staring Gordon Ritchie, to help break down the Hall device event further – Check it out!