Some people define servo’s as closed loop versus drives which are open loop.  The term servo does require that there is a feedback device to provide the loop closure.  But there are many AC drive vendors making closed loop inverters to enhance the performance of the motor.  AC drives with feedback are generally used where positioning is required.  So the feedback element is not the determining factor for defining if an application is AC or DC.

The overall power level may define one versus the other, but not always.  Brushless servo motors are generally limited to 7″ or 8″ diameter and an equivalent horsepower rating of 20-30 horsepower.  There are frameless motors with even higher horsepower ratings.  But  the size and power rating are strictly a function of manufacturing and marketing constraints.  For a major manufacturer, the question is really, how many motors of a given size are we going to sell?  Based on the high cost of Neodymium permanent magnets, a larger servomotor is going to be very expensive.

But overall power ratings are not limited when you consider products from specialty companies like Powertec.  Powertec takes standard AC motor frame designs and increases the power density by adding embedded permanent magnets on the rotor.  Since the magnets are Ferrite, which aren’t as expensive, they are much more economical and allow designs as big as 400HP.  So power level by itself doesn’t determine what technology to use.

The real answer is in the load conditions.  What is the dynamic response required for the target application?  The rate of change of the load is the key.  Most AC drives are specified in terms of the frequency response or dynamic response of the power electronics.  This important parameter is expressed in Hertz.

Dynamic response is the ability of the drive to regulate speed when the load varies.  The load torque can change significantly, usually 90-100%, and the drive will recover the set speed within the time defined by the dynamic response.  Typically, an open loop AC drive has a 10 hertz dynamic response, which means that it will regulate to 1/10th of a second.

AC drive technology has improved to the point where dynamic response can reach 200 Hertz when a rotary encoder is added to the motor.  This means the drive can regulate load variations wiithin 5 milliseconds.  Which is pretty fast when the load mass is high enough to require a motor of 25 horsepower or larger.

The basic physics are simply that the bigger the load, the slower the dynamic response.  You just can’t make a ton of rotating mass change speed really quickly.  And that’s how the controls should respond.

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“We are very pleased to add Kaman Industrial’s selling capability and the value added approach they brings to their customers to our already strong distribution channel.” said John Hegel, President of Minarik Drives.  “Kaman’s penetration into the user and OEM markets will open doors for us that had been previously inaccessible and will help us serve a greater cross section of business across the U.S.”

Minarik Drives is an independent company that specializes in low to medium power electric drive and power applications.  It has been a standard, and a leader, in the DC drive business for almost 60 years.  With design engineering and manufacturing headquartered in S. Beloit, Illinois, it provides standard and customized solutions at a globally competitive price.  More information about Minarik Drives is available at www.minarikdrives.com or by calling 815-624-5959.

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Alternative energy in the US has failed to produce the return on investment or to create new jobs in any significant numbers.  Car sales have picked up significantly over 2011, but not nearly at the rate of 16 million cars/year as in the heyday of that industry.  The real estate bubble has burst after a decade of speculation and bad lending practices that continue to depress new construction.

The second industrial revolution, Henry Ford’s industrial revolution, was about mass production and cost reduction.  For almost 100 years we have been perfecting the centralized manufacture of almost everything around us.  Economies of scale that enable volume manufacturing of consumer electronics at lower cost year after year are the result of the Ford approach to manufacturing.

So where do we go from here?  We start re-inventing the industrial revolution.

The new wave of manufacturing has begun with the advent of the Maker Bot and a family of low-cost fabrication tools that can manufacture based on 3D printing techniques.  While solid model prototyping has been around for some time, the magic ingredient is a new family of machines that cost less than $2000. and some recent new entries around the $1000 mark.  At these price points, it doesn’t take a lot of volume to justify the purchase of one of these machines.

There are advanced processes that are becoming available to generate sintered metal parts, even titanium parts, using processes resembling the additive manufacturing process.

Amortization cost is the secret.  Lowering amortization costs and minimum order quantity at the same time results in a fantastic breakthrough in productivity.  It also lowers the barrier to entry into new markets.  So if you have an idea for something that’s never been done before, the cost for development may be a lot lower than you think.  And thousands of people have begun to jump into the mainstream economy because of the availability of these new tools.

While the “maker” tools are limited to plastics, there is progress in the metals arena as well.  The computer numerically controlled (CNC) machine tools have traditionally been the domain of 6 figure costs, HAAS has been making $50,000 machines and last year Tormach entered the market with the “Personal CNC”, a high quality machine that is priced at $10,000.

My prediction?  There is going to be a lot of activity at the $10,000 and below price point to come up with low cost machine tools as a complement to the “maker” bot 3D printer technology.  Additive manufacturing will require a complementary subtractive manufacturing infrastructure at a comparable price point.

And creative American engineers and tinkerers will be leading the way.

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Why?  First because losses in the sytem result in friction and heat.  Every time energy is converted from one form to another, there are losses.  In electromechanical systems these losses are most often heat.  If the application has high cycling rates, the heat created by the losses need to be considered.

Acme screws are a great solution that is inexpensive and widely available.    The design parameters for Acme screws are pitch, diameter, material, surface finish and nut.  The most significant issue is the pitch.  At low pitch ratios, the efficiency can be 60% or higher.   At high pitch ratios, like 10:1 lead, the efficiency of some Acme screws can be very low, 35-40%.  When thermoplastic materials are used for the drive element, the efficiency becomes a critical issue.  The efficiency translates as heat, with high cycling the heat will cause deflection in the material that can make for added difficulty in the actuator.

A recent project I worked on had a screw with 35% efficiency, which means that 2/3 of the power into the mechanism was being dissipated as heat.  Not a good situation when the load is moving constantly or at high speed.  As the parts heat up, the polymer nut finally heated up to the point where it melted.  By changing the drive train to a planetary gear reducer and a screw with low pitch, the screw becomes a low speed actuator with double the efficiency, cutting the load requirement and heating in half.

In ball screw actuators, the circulating ball bearings and lubricant reduce the friction dramatically regardless of pitch.  Some ball screw actuators are 99% efficient, so there are no significant issues to consider in the losses.  The increased efficiency comes at a substantial price, but it also comes with high precision.  So for high precision actuators, the ball screw is a natural choice.

Rolling bearing actuators are another solution to linear motion, which also have incredibly high efficiency.  There are many vendors using rolling bearings of various configurations.  With low coefficients of friction of 0.2%, rolling bearings are an incredibly efficient solution at a very low cost.  Most often the rolling bearing systems are driven by belt and pulley systems which are also very efficient.

Again, frictional considerations become very significant in subtle ways.  Early evaluation can insure higher performance and lower cost in many designs.

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Many of the constraints of the work are environmental.  If work is being done outdoors, then temperature and humidity are a factor.  Felling trees and in the forest requires extremely high forces due to the work needed to cut through a tree and drag it to a truck to be hauled off for processing.  Processing trees, even in a plant environment, requires some serious hardware, 125 horsepower band saws are not unusual.

Doing work on a ship or oil rig has additional constraints because of the presence of explosive fumes and fuels.  Often the need to avoid any possibility of igniting a combustible atmosphere causes engineers to apply pneumatic control systems.  Yes, there is still a compressor somewhere to generate the compressed air supply, but that is usually remote or contained to avoid exposure to the volatile atmosphere.

Environmental constraints come in many forms.  Extremely high temperatures push the limits of what is possible.  Making glass, semiconductors, and primary metal processing are all high temperature environments where engineers have developed whole technologies in order to bring us the materials we use in everyday life.

The simplest action of rolling or sliding becomes a real challenge when environmental constraints are added to the work statement.  Sawdust becomes a potential abrasive in woodworking environments that can introduce severe wear in moving parts.  Corrosive and explosion proof atmospheres as well as food industry applications introduce all sorts of chemical compatibility problems that require special materials and processes in order to meet strict guidelines for safety.

As always, resourceful engineers have worked out solutions for all of these difficult applications.  One family of solutions to rolling applications is the use of all ceramic bearings.  No steel, no lubrication.  None is needed because the ceramics are extremely high purity to start with and have extremely high precision surfaces eliminating the need for lubrication.  No outgassing or contamination to worry about.

Other solutions take the form of air bearings and non-contact material handling devices.  Air bearings have become more readily available for conventional applications, but are particularly compelling in large machinery applications where precision is required.  Large flat screen display glass  presents unique challenges that successfully addressed using a combination of air bearing regions and vacuum regions to move the glass without actual contact and with overall flatness measured in millionths of an inch.

A unique solution in pneumatic material handling takes compressed air driven into a funnel shaped recess and creates a vacuum in the center and an air cushion at the edges where the air is exiting.  This creates a vacuum pickup that never quite comes in contact with the part, leaving no marks.  Perfect for solar cell and some food and beverage applications.

Engineers continue to meet the unique challenges of industry and create commerce at the same time.  And that’s what it should be about.

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There is a complex interaction between the two that is often not expressed.  The hardware has “firmware” that defines the exact capabilities of the hardware.  The software is a tool for users to create programs that the hardware executes.  These programs are the embodiment of the useful behavior that the process or machine is intended to accomplish.

So is machine control hardware or software?  It’s both.  The hardware is only capable of executing instructions that we built into it by it’s microprocessor and firmware.  Those instructions are merely a library of possible functions.  The user program calls those firmware functions in an organized manner to accomplish some beneficial result.

There are a couple of really significant issues that are often overlooked.  One is experience.  A lot of experience is required to make good product selections.  The application of control systems involves understanding the application requirements and matching those requirements to specific hardware.  Motion systems that do “high speed registration” for example, require very specific hardware to capture the input signal to define where the registration target is, and then to turn off so that input noise is filtered out.  This is a very specific feature, and if you don’t have it, you generally can’t create it.

Complex control requirements like coordinated motion are both hardware and software dependent.  The simplest example is to draw a circle with two linear axes.  In order to know how to deal with this application the control system must have a dedicated motion controller either as a stand-alone element or embedded within the control architecture.  Most high end PLC’s offer a 4-Axis dedicated controller card that do this.

After all the wrangling is done to get the application and hardware properly scoped out, after all the software development work is done, there is still an aspect of control that is missing from this discussion.  It is the external wiring of power, power protection, and safety systems.  These circuits are separate from the control system hardware and software, and yet embody elements of control that are sometimes necessitated by the hardware itself.

Variable frequency drives and some servomotor drives require time to charge their capacitors.  Most drives has interlocks that will prevent operation until the caps are charged.  PLC processors require a time delay to insure that the I/O devices are powered before the processor “wakes up”.  If not, the processor will immediately fault.  The wiring of emergency stop circuits are physically separate and frequently use reverse power logic, they are energized when “off”, to all detection of broken wires.

All of these behaviors are part of the control system but generally not considered in the early phases of system design.  Yet all are required in order to make safe, working systems.

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This is rather ironic considering the billions of dollars that are spent on control systems across all fields. Is control fundamentally any different if it is inside a car, automating lighting and HVAC in a large building, on an automotive manufacturing plant floor, in a biological resesearch laboratory, or in a giant refinery where chemical products are made.  It’s all control.  And the more we try to define it, the more inclusive we make the definition, the more vague and ambiguous the term becomes.

Efforts continue to increase the power of the PLC (programmable logic controller) across many vendors. By increasing processor speed, memory and capability PLC’s are becoming the universal platform of control as a discrete controller, process controller and motion controller.

Simultaneously, motion control specialty companies continue to increase speed, processing power and I/O structures in an effort to expand the dedicated motion controller as a competitive platform to the PLC.  This is a necessary migration to address control applications where an external PLC could be eliminated.

Is there an ideal mix of motion axes and I/O that will help resolve which hardware solution is best?  Not really.  The fact is that the majority of the market is made up of motion control using stand-alone axes that are triggered by logical conditions in the system.  Coordinated axes require the sharing of pulse to pulse position feedback information.  Stand-alone axes do not share data at that low a level in time.  Most PLC controllers are well able to handle stand-alone axes, especially if an intelligent indexer is used.  This off-loads the motion to the servoamplifier and only I/O handshakes are used.

Part of the ambiguity here is that control is the result of hardware and software together.  ’Control’ seeks to generate complex behaviors using digital methods.  The digital methods, processors, depend on programming techniques in order to implement the desired behavior.  So when we talk about Control, we are talking about hardware and software simultaneously.

What matters most to users of automation technology is both logic control and motion control programming exist in a single environment.  It doesn’t matter if the programming environment is a PLC with motion blocks inside it, or a motion controller with logic blocks inside it.  What matters is that all aspects of a control system can be programmed using a single editor.  Controllers from the major electrical companies like Rockwell Automation and others have opted for the logic-centric programming environment with motion blocks in the ladder diagram.

This approach eliminates the complexity of multi-processor solutions, each with their own programming language, that were commonplace a few years ago.  Multiprocessors have their own unique programming environments and a significant amount of programming to create proper interaction between the various platforms.

Missing from this description is the hard wired control that is part of system start up, power management and safety.  More on this in the next installment.

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Considering the rules for servo tuning first, the ideas are basically simple.  Based on the use of 0-10V velocity command, the control system is designed to regulate motor speed.  A Proportional, Integral and Derivative gain value is used to “tune” the command signal sensitivity to allow the control system to regulate the motor and load performance.  This strategy has been created over the years and is used by almost all servomotor and drive suppliers in the motion control industry.

The Proportional term is the most important value in this approach.  The proportional value is generally the amount the 0-10V command signal will be increased in response to a following error.  The more gain, the more velocity will be commanded.  This will allow the control system to correct for changes in load conditions.  The proportional gain is how the system responds to current conditions.

The Derivative term controls how quickly the control system can add or subtract energy from the load.  The derivative can take the form of dI/dt or dV/dt depending on the specific controller.  This term has two important purposes.  As stated, it defines how quickly the system responds to changes in the load condition, and it exactly parallels the breakdown limit of the power transistors used in the motor amplifier.

The integral term provides correction on a cumulative basis.  All previous error information is integrated over time to provide the system with correction to the control command that “damps” reaction to disturbances.

Notice that all the gains are directly tied to time.  The faster the motion, the more P and D gain is needed to provide adequate response in the control.  Many motion applications have low enough dynamics that servo tuning needs to be very low performance compared to the capability of the equipment.

For most applications, and depending on the gear you are using, the best thing to do is start with I & D gains set to zero.  Use the amplifier autotuning for the motor without the load.  Sometimes these are default settings that are already loaded into the controller.  Tune the motor and amplifier until the P gain seems the best for a step input.  Then add the load and run the autotune again.  If possible, use a step response input that is similar to the type of move you will do in your actual application.

Then gradually add D gain until the leading edge of the step response has no overshoot.  If there was little overshoot without P gain, the motion dynamics are probably very slow and that’s OK.  With D gain set for the application, slowly add I gain and see if the trailing edge of the step response is improved.

If the axis is “hunting” after the motion stops, there is probably too much play in the mechanical system. Using a gearbox with a lot of backlash or a timing belt that is a little loose will produce just enough mechanical error that the servomotor will detect.

Tuning, like everything in motion control, is as unique as each individual application.  There are more complex analytical techniques that can be applied to the subject of tuning.  But I hold to the theory that the majority of applications can be dealt with using simple techniques.

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Sometimes the motion control aspect of a process is not the primary objective of the control system or machine being considered.  The process of clamping or crimping a can lid onto a can body is an example of this situation.  The motion control system must locate the can lid to the can body correctly, but the final process is the crimping or application of a thrust force to cause the parts to form a strong joint.  In this case the real process variable is the pressure that is exerted at the end of the motion.  The pressure is critical to joining the parts, especially when the can is an igniter for an automotive air bag.

Grinding and polisihing is another example.  The motion control application is required to bring the grinder or polisher into contact with the work piece.  The actual grinding or polishing is the amount of friction generated between the grinder motor and part being worked.  This is actually proportional to the current of the grinding motor, which can be measured and regulated.  If too much current is detected the part might be ruined and the control system can be commanded to move the grinder away from the workpiece.

Important physical attributes of motion include inertia, center of mass and momentum.  There are no convenient sensing technologies that help us with these seemingly basic attributes of the mechanical system.  This is probably why they are ignored in the control system.

However, if the machine was designed in a 3D solid modeling environment, then things like center of mass and inertia are directly available.  A momentum profile can be created as a product of the center of mass and the duration of the motion profile.  This gives us mathematical information that can be used to “inform” the control system in spite of the absence of a control signal that directly measures these properties.

With this in mind one can easily imagine a pick and place mechanism made from two linear stages mounted one on top of the other.  When the two axis are making high speed coordinated moves, the reflected forces of the upper axis put loads on the lower axis.  The data from the solid model becomes useful information in providing mathematical “filters” that can improve the motion in ways that are beyond the current technology of motion control.

There are ample opportunities for improvement in the control of mechanical systems.  We should be looking for new strategies that the modeling and simulation environments provide.

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The obvious thing to measure is motor speed.  That part is easy.  Servo motors have built in feedback devices. In the old days, the preferred feedback device was a small generator that produced a voltage proportional to the speed.  In the digital age feedback is by quadrature encoder that outputs a digital pulse that is primarily used for position control.  Most control systems are able to easily integrate the pulse train to derive the speed of the motor.

Unfortunately, most applications require relatively low speed.  Most motors are engineered for high speed.  This is in an effort to package more work related power in a smaller physical package.  Often, the motor is connected by pulleys or gear reducers to get the speed of the motor to more closely match the desired speed of the load.

Some of the important attributes of motion cannot be easily measured.  In addition to speed, torque is extremely important to controlling motion.  Torque can be measured directly from the drive electronics, but this is rarely used for control.

Torque and current are direct equivalents with a slight variation due to the temperature of the motor winding. As the temperature of the motor goes up, the resistance goes up and the current required goes up at the same time.  Since high performance motors have fairly high internal temperatures, this swing can be in excess of 100 degrees centigrade, and should be considered in the control scheme.

Most of the emphasis on current control is in terms of protecting the motor and drive electronics.  The first derivative of current over time  is the limiting parameter of the power electronic devices and is an important boundary condition in safe operation of the electronics.

More important information can be derived by considering the region of the motion profile and the current or torque requirements that are presented.  In order to accelerate a load, a lot of current is needed to overcome the mass of the load.  But once the load is moving the torque requirement drops off.  This creates an opportunity to profile the current requirement while using the conventional error detection scheme of the traditional control.

Other variable that are part of the mechanical system are things like momentum and center of mass.  In multi-axis mechanisms, there is usually a dependency of one axis upon another.  The idea that the mass of one axis is changing it’s center of mass and momentum with respect to the other axis is generally ignored.  This too is an opportunity to gain increased stability in the control and possibly improve throughput by having a better model of the application from which to create the ideal control.

Looks to me like there is a lot of room for improvement.  Let me know if you agree or disagree.

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As control technology has progressed over the last few decades, the performance requirements haven’t really changed much in a certain sense.  In the case of Computer Numerical Controls, the basic performance hasn’t really changed.  The big difference has been the cost.  The early CNC at $500,000 has been replaced by today’s production CNC at $50,000.

Certainly, there have been significant advances in capability, larger machine structures for aerospace applications, high precision applications and even the advent of the “maker bot” low end machines.  But the basic relationships required to shape parts in 3 dimensions are the same.

Yes, there are example of industries and applications that simply didn’t exist 50 years ago, like semiconductors, flat panel displays, etc.  Most of the improvements in electronic motor controls and motion control actually derive from the work done to improve the disk drive spindle motor.

But generally speaking, industrial control has migrated from specialized control hardware, to the PLC, a general purpose, high reliability form of controller, to personal computer based solutions.  Primarily due to the low cost and high performance computing power of the PC.

Some of the performance attributes have to do with how a given control is architected.  In the push for high reliability, the PLC goes to great lengths to insure that memory cannot be compromised, input-output hardware is extremely resistant to external electrical interference, and state changes are captured in a rigidly deterministic manner to insure that control code executes consistently.  In the PC there are PLC emulators that have been approved by various agencies that qualify their performance as equal to PLC’s.

Some attributes of performance are not obvious.  The operating system and its performance become part of the control system equation.  If the OS faults, the control system is down.  Hence the advent of Real Time Operating Systems, Linux and a host of other solutions aimed at reliability.

It can go deeper than that.  Exactly how the OS deals with interrupts can mean the difference between reliable operation and catastrophic failure.  Windows CE has different performance attributes over Windows for industrial control application.

In the PC architecture, how does data move from the disk drive to the operating program?  In the PLC how does the backplane impact the update rate of field I/O?

In the software realm, newer operating systems have made possible multi-threading programs that allow several task to execute simultaneously in the same hardware and software environment with complete coordination between tasks.  Robotic and CNC applications with multiple system operating in a single controller are able to execute separate programs with sophisticated anti-collision detection.

So exactly where the control system performance originates from is not exactly a function of a specific piece of hardware, but rather the result of hardware, OS and software combined to achieve a desired outcome.  Not a simple matter.

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There is a lot that can be done from the control system to improve overall performance.  Some of that improvement takes the form of sophisticated control algorithms.  Some improvement may take the form of increased power electronics to provide added acceleration and deceleration capability.  And sometimes projects get scoped to do things that are marginally impossible.  This is because there is gap between our understanding of the difference between mechanical and electrical properties of the application.

The gap in understanding is partly due to the educational system that teaches mechanics and electronics separately.  With the newer mechatronic programs that are available at many schools this gap is decreasing.

But there is a deeper issue.  The issue is context.  Mechatronics combines electronics and mechanics.  The missing context is that everything we do in the electrtronics, is an  analog for something mechanical.  If you don’t know how the mechanical relationships work, it’s unlikely that you will get the best results in controlling the system.

There are all sorts of examples.  A belt and pulley reducer is a mechanical system that turns a high speed input to a lower speed output.  The analogy in motion control is electronic gearing.  We can arbitrarily program any given motor to follow a speed reference from an encoder, tachometer or other motor, and follow the input signal at a programmed speed or ratio.

Electronic line shafting is a similar application that seeks to operate several independent motors and loads as if they were connected on the same mechanical shaft.  This application requires very high angular precision between the following loads which requires high speed regulation between the motor and associated electronics, but mathematically is very simple.

From the mechanical standpoint moving something from point a to point b seems pretty simple.  But as the time requirement for the motion decreases, the forces acting on the system become very significant.  As the load is accelerated from rest, it gains momentum.  Overshoot at end of the acceleration profile is a property of the momentum or kinetic energy of the system.  Tuning the system properly involves understanding the mechanical properties of the load and specifically how the control systems relates to the mechanics.

Does overshoot even matter?  Not so much if there isn’t a following axis involved.  At the end of travel it may be a concern if the load is positioning under a fixture or a next mechanical operation.  In many systems, there is settling time required for the load to come to a complete stop.  In these applications, the “S Curve” is an ideal solution because it compensates for the mechanical properties of optimizing the acceleration so that little or no overshoot takes place.

Maybe it’s less about the tuning and more about intelligent trajectory planning.

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In managing technical projects, there are similar issues.  In technology projects, there is stuff we like to do, and there is stuff we need to do.  And sometimes, the what gets done and in what order really impacts the results.

One aspect of project management that is often not considered is defining what is important.  And especially what the order of importance is.  Because there are always competing attributes in any automation project, and cost tradeoffs that need to be considered.  So a really valuable exercise at the beginning of the project would be to make a list of the project priorities and put the list in order of importance, so you and your team know what the important issues are.

The typical project priorities involve;                                                                                                                                                             speed as throughput in parts per minute or hour,                                                                                                                                   amortized cost which is the cost of the machine per part produced,                                                                                               and part precision or accuracy which can sometimes be measured as scrap rate

These are the most common issues in manufacturing.  There are certainly many unique constraints on project performance that can be identified in specific situations, but these are the most general and the ones with direct cost impact both in the development of the machinery project or process and in actual production practice.

The problem is that while the project is being developed, decisions will have to be made on the fly.  With a formal statement of what the project priorities are, it becomes easier to determine where money needs to be spent and how it relates to the final performance.  It also becomes easier to avoid pitfalls where spending money produces no benefits in terms of the project priorities.

Meeting part per hour production rates may be well within the  project forecast, but achieving quality goals and reducing scrap rates may have some cost tags that will need to be considered.  How much will it cost to reach the next improvement in production throughput?  How will it impact the amortized cost per production unit?  Will a new, expensive solution to part accuracy pay off in reduced scrap rates?

All of these questions get a little easier to deal with by knowing your priorities.

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Reducing the cost of manufacturing is always an issue.  Who doesn’t want lower prices?  But labor costs alone are not the whole story.  And its hard to compete directly when labor forces are wildly disparate.  With US labor costs of $12-45 an hour competing with costs of $.64 an hour in China, it is hard to deny the merit of the strategy of just moving everything over.

In fact, intermediate macroeconomics will tell you that all markets gravitate to the lowest price.  As trade between countries becomes more widespread, using foreign labor becomes more prevalent.  The US moved a lot of its automotive parts to Canada and Mexico for that very reason.  And high scrap rates out of Mexico were tolerated as we tried to take advantage of the proximity of the labor force and low cost labor.

This also makes the point that the main barriers to using foreign labor are distance, which means transportation costs, and quality which means scrap cost.  Transportation costs are constantly changing, as recent fuel cost show.  Transportation costs, which were steadily decreasing in the 1990′s, may have contributed to the “offshoring” strategy.  As fuel costs increase, the cost of using foreign labor increases as well.

Scrap cost or serious product deficiency that results in recalls or injury to customers creates huge expense and bad press for the product involved.  These situations can severely impact revenue and the risk may not be worth it.

Tariff and duty charged by national governments are cost barriers that are political means of creating barriers to foreign goods.  The US has had difficulty with balancing trade with its trade partners. Special situations where foreign governments have large loans to the US make negotiations even tougher.

The big issue is the value of currency.  As the dollar falls in value, other currencies become more expensive, so the relative cost of labor changes.  Again, a very dynamic situation over time.  And this is exactly the case with our largest trade partner, China.  Not only is the currency going up, but China’s millions of emerging consumers are experiencing inflation at the same time.

But beyond the standard economic factors, there are hidden costs to using foreign labor.  A growing number of US manufacturers have found that offshore labor costs aren’t the bargain they initially appear to be when the foreign manufacturer requires constant on site support in order to maintain promised product performance or delivery schedules.  Off-shoring involves significant risks.

All of which leads to returning manufacturing to the US.

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With regard to the technology discussion there was a great post regarding the fabled Thorium reactor.  By far, the YouTube post linked by a reader was the most informative piece I have ever seen on the subject.  At 16 minutes, it’s well worth the effort.  Please check out  http://youtube/WWUeBSoEnRk or Google search Thorium reactor and note the Google Tech Talk from 2008.

There is so much knowledge available and yet so little makes it into the mainstream of political decision making.  And this, I think, is the essence of a couple of comments from readers.  Will our politicians make good decisions?  Is it even possible?  There seems to be so much “influence” going around.  Does General Electric or Westinghouse really care about the technology they are putting out, or is it more cost effective to just re-hash the 40 year old water cooled reactor of the late ’60′s and just keep truckin”?

New technology does not guarantee performance.  It is simply that the improved solution is expected to have similarly improved performance.  But that performance has to be proven.  The thing to do would be to fund a demonstration program to construct a variety of technologies  and get some idea of how they really work.  Working hardware is easier to evaluate than concept drawings.

On the engineering side, a number of comments were focused on the nature of critical systems.  In the controls arena there is a combination between the control system software and control system hardware that has to properly designed in order to achieve the robust, stable operation required in many critical applications.  Electrical practice also includes a number of important conventions that impact operational safety such as removing power from part or all of the control equipment.

More complex issues exist in understanding the nature of the critical systems in nuclear power plants.  Clearly the water supply and pump for cooling the core of the reactor are critical systems.  The engineering challenge is to make the cooling system reliable in the event of  a power failure and in the event of earthquakes.  These are very complex circumstances to engineer around, but that’s the challenge.

The need for establishing higher reliability power and backup systems is critical to our future.  In order to achieve the power goals of the modern world, the fundamental technology options must be explored an the same time sophisticated methods of managing the equipment in order to keep things running.

All worthy goals which we need to pursue.   With all the available options.

Mechatronic Tips