RAPID PROTOTYPING
January 25, 2011
RAPID PROTOTYPING
Being able to obtain prototype parts quickly to test for component form, fit and function can help get your product to market much faster than your competition. This can allow for adjustments in design, materials, size, shape, assembly, color and manufacturability of individual components and subassemblies. Rapid prototyping is one tool that allows this to happen. It also is a valuable tool for sales and marketing evaluation at the earliest stages of any program. Generally, an engineering scope study is initially performed in which all elements of the development program are evaluated. Having the ability to obtain parts “up front” is a valuable advantage available to companies and definitely can complement the decision making process. Several rapid prototyping processes are available for today’s product design teams while other prototyping processes utilize traditional manufacturing methods, such as 1.) CNC Machining, 2.) Laser Cutting,3.) Water Jet Cutting, 4.) EDN Machining, etc. Rapid prototyping technologies emerged in the ‘80s and have been improved upon over a relatively short period of time. When I started my career as a young engineer (we are talking about the dark ages) the only process available to us was as follows:
- Produce an orthogonal drawing of the component
- Take that drawing to the model shop so the first prototype can be made
- Wait one, two, three, four, etc weeks for your first part so the evaluation process can occur
- Apply the component and evaluate form, fit and function
- Alter the drawing(s) to reflect needed changes
- Resubmit the drawing to the model shop for the first iteration of the design. ( NOTE: This creates a REV. 1 drawing .)
- Again, apply the component for evaluation.
The entire process could take months to complete. Things have changed considerably. As prototyping processes continue to evolve, the product designer is constantly trying to determine what technology is best for unique application. There are several viable options for rapid prototyping as follows:
- (SLA) Stereolithography
- (SLS) Selective Laser Sintering
- (FDM) Fused Deposition Modeling
- (3DP) Three Dimensional Printing
- (Pjet) Poly-Jet
- (RIM) Rapid Injection Molding
In addition to these options, there is a variety of materials available to facilitate assembly and trial after completion of the model. The entire process starts as follows:
- Create a 3-D model of the component in a CAD program
- Appropriate software then “chops” your CAD model into thin layers—typically 5 to 10 layers per MM.
- The 3-D printer “paints” one of the layers exposing the material in the tank and hardening it.
- The platform drops down a fraction of a MM and the process is repeated. This is done layer by layer until the entire model is produced.
- Next, heat treating and firing may occur to further harden the part
The entire process may take as long as 72 hours, depending upon size and the complexity of the part but the results are remarkably usable and applications are abundant. Some of the applications are as follows:
- Dental Prototypes
- Orthopedic Prototypes
- Prototypes for sculptures
- Prototypes for manufactured components
- Items used to decorate sets for plays, operas, etc
- Forensic investigations
- Planning for surgical procedures
In addition to speed, very fine and intricate surface finishes can be had depending upon the material and process used to create the part. In short, rapid prototyping is definitely an extremely viable option when needing components quickly and with great quality. There are many vendors available when need arise and all will be more than happy to work with an engineer or manager to create produce the needed component or part. I can definitely recommend you take a look at this exciting technology.
HIGH QUALITY TEACHERS
January 21, 2011
HIGH QUALITY TEACHERS
The idea for this document results from an article by Mr. Leland Teschler. Leland is the editor of Machine Design Magazine, a Penton Publication. He asks the question—“do we really need high-quality teaching”? I don’t think there is too much doubt that, like other professions, there are good teachers and those that don’t quite “measure up” relative to existing standards. We have all gone through this at some time; a teacher who knows the subject “cold” but just can’t deliver the message. Can’t get is across. Can’t connect. Then there are others who simply don’t know the subject matter. A much more fundamental problem! One response received was from a teacher who said, “teacher quality did not matter much in what eventually happens to students”. Now, we have proof that good instruction from secondary school teachers does affect the earning power of a graduated student. Dr. Eric Hanushek from Stanford University provides us with the following information:
- One standard deviation in math scores for a graduating senior translates into a 10% increase in annual salary. The present value for lifetime income between the ages of 25 and 70 is $ 1.16 million. With that being the case, an improvement by one standard deviation would add $150,000 to that figure.
- There is a definite improvement in cognitive skills accompanying this improvement in math skills. This improvement would add $10,600 to lifetime earning.
- A significantly better teacher would add $300,000 to the lifetime earnings for a class of 30 students –just as a result of improved cognitive ability.
- If the lower 8% of teachers were replaced with average teachers, we would rank as highly as South Korea, Finland, Singapore, Hong Kong and Canada. Removing these teachers would drive our ultimate ability to produce graduates who could compete in a world environment.
MAYBE QUALIFIED TEACHERS DO MATTER.
TRIBOLOGY
January 19, 2011
TRIBOLOGY
I ask our five year old grandson if he could give me the meaning of the word “tribology”. He thought for a moment then said the following:
“OK Bob, (he calls me Bob) we’ve been studying Indians in school this year and triology (his word) is how a bunch of Indians live in teepees, around a campfire to cook and stay warm in the winter. That’s trilogy! What do you think?”
Not too shabby for pre-“K”. Actually, tribology is defined as, “a study that deals with the design, friction, wear and lubrication of interacting surfaces in relative motion (as in bearings or gears).”
As stated by the definition, tribology involves the study of three subject areas: 1.) Friction, 2.) Wear and 3.) Lubrication. The study is interdisciplinary and involves very complex mechanical mechanisms including the weight of the rolling or sliding members, surface roughness of the members, profile of the surfaces, any dirt, grit, etc. that may interfere with movement and several others. It has been estimated that six percent (6%) of our GNP is wasted and this waste results from friction and unnecessary wear of interacting parts. I know this is very difficult to believe but my sources are current and reputable. Even with this being the case, the average four year curriculum for mechanical engineering students involves only two (2) hours devoted to study and understanding friction and wear. To make bad matters worse, most references on the subject are greatly outdated and provide sketchy information at best. This is certainly true for more recent polymers and material composites. The work just has not been done.
Let us very quickly look at the three components relative to tribology. In this fashion, we will obtain a better understanding of the entire field of study.
Friction is a force that resists the sliding or rolling of one solid object over another. Sometimes friction is very desirable; i.e. walking, driving a car on city streets, etc. The negative effects become obvious when we consider we lose approximately twenty percent (20%) of an automobile engine’s power due to friction. A great number of machinery failures result solely from friction and wear.
Wear is the removal of material from a solid surface as a result of mechanical action exerted by one solid on another. There are four basic types of wear: 1.) Adhesive, 2.) Abrasive, 3.) Corrosive and 4.) Surface-fatigue. Wear physically removes material from the surfaces of the interacting member with the harder material wearing the softer material.
Lubrication is the introduction of a lubricant between interacting solid surfaces to mitigate wear and friction. The need for this dates back at least four thousand years. The ancient Egyptians understood friction and wear and used animal fats as a lubricant. There are three classifications for lubricants: 1.) Fluid film, 2.) Boundary and 3.) Solid. It is fascinating to me that our body produces lubrication in a continuous fashion. Our joints would not survive without this liquid lubrication and without this lubrication we would have a painful time in trying to bend, stretch, etc. You get the picture.
As you can see, this is a fascinating field of study but a very complex subject to be studied. If you are interested, I would recommend you taking a look at “The Journal of Tribology”. It is found in the ASME digital library and will provide the latest information and data relative to university research and corporate activity. I am in the process of completing a “white paper” for PDHonline that will provide much more information and basic grounding for the three areas of study we have just mentioned. If interested, please log on and take a look.
THE TWELFTH IMAM
January 11, 2011
THE TWELFTH IMAM
One of my new year’s resolutions is to read more. Generally, I read about two books per month but that’s dependent upon having enough time to really get into a good book. I’m not the type to begin a book, read five chapters then put it down for two or three months. The book must be interesting enough to “read through” or I don’t begin in the first place. I must admit that I am from the “old school” that says–you begin a book, you finish a book. Sometimes I do feel cheated but not with my latest “reading adventure”.
I just completed reading “The Twelfth Imam” by Joel C. Rosenberg, published by Tyndale Books. This is the first book I have read by Mr. Rosenberg and I must say I am very impressed by his style and ability to organize complex material into an exciting and coherent story. He is one of those authors who can produce a generous blend of fiction and fact; weaving those two elements together so that you really aren’t that sure as to which is which. He uses a writing style producing chapters that are two, three, four pages in length, which I consider to be definite plus. There are ninety (90) chapters in “The Twelfth Imam” and each chapter moves the story line in a fashion that generates continued interest and keeps the reader constantly engaged. I have, like all of us, read books in which the chapters are twenty-five to thirty pages in length with large doses of minutia spread in an ample fashion throughout. This book considers the reader and yet delivers with continuity. It is complex to the point that necessitates listing all of the characters at the very beginning and prior to chapter one. You get to know “who’s who in the zoo”. Very good practice in my opinion. The main character is Mr. David Shirazi (AKA Reza Tabrizi ). Mr. Shirazi is a CIA operative who uses a telecom in Munich as cover. His assignment is to infiltrate an Iranian organization working to produce a nuclear weapon of mass destruction. The twelfth Imam factors into the story as the “promised one” prophesized to bring about the destruction of the “great Satan” and Israel. The story line moves very very quickly but, quite frankly, ends in manner that leaves the possibility of several outcomes, depending upon your optimism –or the lack thereof. I think there is definitely room for a sequel and hopefully Mr. Rosenberg will do just that.
I can definitely recommend this book to you as a wonderful “read”. You will not be disappointed and it will be time well spent. I just hope the contents do not represent the future of the Middle East.
NATIONAL DEBT
January 30, 2011
NATIONAL DEBT
I have written before about our appalling national debt. From the web site poodwaddle.com/worldclock.swf, we see the following information:
These numbers were recorded on 01/20/2011 at 0843 hours. The first 19 days of our new year. If you visit that web site you will see the “debt clock” ticking and ticking rapidly. Our country, the greatest in recorded history, borrowed $80 billion in the month of December. This marked the 27th consecutive month of red ink for the Federal government. Federal outlays for December were $316.8 billion while receipts were $236.8 billion—up 8 percent over this time last year while taxes on corporations and payroll actually increased. For the first three months of fiscal year 2011, the deficit stands at $370.8 billion. We are on track to post a $1.00 trillion plus shortfall for 2011. The fiscal budget deficit for 2010 ($1.29 trillion) was the second highest on record, behind the $1.42 trillion reported from fiscal year 2009. I am an engineer and not finance major but, it seems to me that something needs to be done on the Federal level to make a much needed mid-course correction. (Just guessing here but it is a thought!!!!!!!!!!) With that being the case, let me suggest the following:
OK, time to stop. I’m really getting depressed because I know that nothing will be done. We just don’t have the political or national resolve. Our politicians have theirs. They are “fully funded”. Let’s face it—the individual “unwashed” common man is basically on his on although, I firmly believe that there is no problem we can’t solve if we are focused and put our collective minds to it.
Share this: