Archive for the ‘Mechanical engineering’ Category
Seven basic Quality Control Tools for manufacturing
July 11th, 2008
Quality Control Tools
Production environments that utilize modern quality control methods are dependant upon statistical literacy. The tools used therein are called the seven quality control tools. These include:
[Note: Examples have been included in this synopsis that correspond to a sample case study that can be accessed from the . Additional background information may be obtained by downloading the full (67k).]
Checksheet
The function of a checksheet is to present information in an efficient, graphical format. This may be accomplished with a simple listing of items. However, the utility of the checksheet may be significantly enhanced, in some instances, by incorporating a depiction of the system under analysis into the form.
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Pareto Chart
Pareto charts are extremely useful because they can be used to identify those factors that have the greatest cumulative effect on the system, and thus screen out the less significant factors in an analysis. Ideally, this allows the user to focus attention on a few important factors in a process.
They are created by plotting the cumulative frequencies of the relative frequency data (event count data), in decending order. When this is done, the most essential factors for the analysis are graphically apparent, and in an orderly format.
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Flowchart
Flowcharts are pictorial representations of a process. By breaking the process down into its constituent steps, flowcharts can be useful in identifying where errors are likely to be found in the system.
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Cause and Effect Diagram
This diagram, also called an Ishikawa diagram (or fish bone diagram), is used to associate multiple possible causes with a single effect. Thus, given a particular effect, the diagram is constructed to identify and organize possible causes for it.
The primary branch represents the effect (the quality characteristic that is intended to be improved and controlled) and is typically labelled on the right side of the diagram. Each major branch of the diagram corresponds to a major cause (or class of causes) that directly relates to the effect. Minor branches correspond to more detailed causal factors. This type of diagram is useful in any analysis, as it illustrates the relationship between cause and effect in a rational manner.
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Histogram
Histograms provide a simple, graphical view of accumulated data, including its dispersion and central tendancy. In addition to the ease with which they can be constructed, histograms provide the easiest way to evaluate the distribution of data.
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Scatter Diagram
Scatter diagrams are graphical tools that attempt to depict the influence that one variable has on another. A common diagram of this type usually displays points representing the observed value of one variable corresponding to the value of another variable.
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Control Chart
The control chart is the fundamental tool of statistical process control, as it indicates the range of variability that is built into a system (known as common cause variation). Thus, it helps determine whether or not a process is operating consistently or if a special cause has occurred to change the process mean or variance.
The bounds of the control chart are marked by upper and lower control limits that are calculated by applying statistical formulas to data from the process. Data points that fall outside these bounds represent variations due to special causes, which can typically be found and eliminated. On the other hand, improvements in common cause variation require fundamental changes in the process.
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Summary
The tools listed above are ideally utilized in a particular methodology, which typically involves either reducing the process variability or identifying specific problems in the process. However, other methodologies may need to be developed to allow for sufficient customization to a certain specific process. In any case, the tools should be utilized to ensure that all attempts at process improvement include:
- Discovery
- Analysis
- Improvement
- Monitoring
- Implementation
- Verification
Furthermore, it is important to note that the mere use of the quality control tools does not necessarily constitute a quality program. Thus, to achieve lasting improvements in quality, it is essential to establish a system that will continuously promote quality in all aspects of its operation.
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Two-legged dog roundup
June 25th, 2008
; am I right? Those brave little guys with only three legs and and make normal four-legged dogs seem a little lazy or something. But when people hear about dogs who can and on two legs, it seems like they're not so amazed by the tripods any more.
Listen: those two-legged dogs who can get around without any help are overachievers. Show-offs. It is not normal for a dog to be able to get around on two legs. Yo-yo the chihuahua can attest to this; her owners are trying to get her to walk on her own, but it's obviously . So I don't want anybody judging little puppy and saying she's a sissy for getting wheels put on:
I think Hope is fantastic. Someday she is going to travel to the Land of Oz and be a good guard dog for , . Hopefully before she goes, she can hook Yo-yo up with some of those nice wheels. She could definitely use some.
Photo from the Daily Mail
Senior Designer, Mechanical Engineering, Risley & Westlakes
June 24th, 2008
Senior Designer, Mechanical
Reference: 1214304270
ERS have a client seeking to appoint a Senior Designer in Mechanical Engineering. Thi is principally a design delivery role from a technical perspective working across a multi-disciplined design team. The Senior Engineer is usually responsible for delivering the design within their own discipline with frequent liaison / management of engineers within the design team from other disciplines. The Senior Engineer also provides technical guidance and imparts knowledge to Lead Engineers, Design engineers, Graduates and Designers.
Location
Risley & Westlakes
Salary
According to experience
Job Responsibilities
Development of designs to satisfy technical specifications.
Checking and approving design calculations of designers and other engineers within the team.
Probable lead of design reviews, safety reviews (risk assessments/ HAZOP’s) from technical standpoint within discipline.
Close liaison with client and project team to prepare technical specifications for the design.
Ensure quality and delivery of design documentation throughout the design process including scope of works, method statements, risk assessments, technical files and other technical documentation to comply with design standards, safety legislation/regulatory requirements and the needs of the client.
Management of installation, commissioning and operating documents.
Allocation of work to other members of team in order to ensure delivery of design to quality, time and budget.
Selection, strategy and management of work to sub-contractors
Tel: 01454 203 460
THERMAL ENGINEERING
June 24th, 2008
NEW PUBLICATION EDITION 2008
Price Rs.640
Author Name Prof D.K.Chavan, Prof. G.K. Pathak
Authors of Thermal Engineering are happy to present a long standing requirement of a book which will be useful to the students from first year to final year mechanical engineering course from various universities.
A TEXT BOOK OF INTERNAL COMBUSTION ENGINES
June 24th, 2008
NEW PUBLICATION FIRST EDITION 2007
Price Rs.280
Author Name R.K.Mohanty
The intent of this book is to present a complete course in Internal Combustion Engine for undergraduate students as well as practicing engineers. Its scope is limited to material that can reasonably be mastered by those who have studied fundamental thermodynamics, fluid mechanics and mechanics of machines.
AUTOMOBILE ENGINEERING
June 24th, 2008
JUST OUT NEW PUBLICATION EDITION 2006
[ENGINES, PERFORMANCE AND TESTING]
Volume-II
Price Rs.280
Author Name R.K. Mohanty
In this edition, the book consists of the topics like brakes, suspension, etc. with latest technology.
AUTOMOBILE ENGINEERING
June 24th, 2008
JUST OUT NEW PUBLICATION EDITION 2006
[BODY, FRAMING AND ACCESSORIES]
Volume: I
Price Rs.220
Author Name R.K. Mohanty
In this edition, the book consists of the topics like brakes, suspension, etc. with latest technology.
HYDRAULICS AND FLUID MECHANICS INCLUDING HYDRAULIC MAHINES
June 24th, 2008
(IN SI UNITS)
Price Rs.440
Author Name Dr. P.N.Modi , Dr. S.M. Seth
The popularity of all the earlier thirteen editions of the book among the students as well as the teachers has made it possible to bring out the fourteenth edition of the book so soon.
Pentagon’s New Program for Innovation, in Context
June 9th, 2008
FACT: According to , the Pentagon has announced "the selection of six university professors who will form the first class of the National Security Science and Engineering Faculty Fellows Program. The professors will receive grants of up to $600,000 per year for up to five years to engage in basic research -- essentially a bet by the Pentagon that they will make a discovery that proves vital to maintaining the superiority of the U.S. military."
ANALYSIS: This new program is an innovation from DoD's Director of Defense Research and Engineering (DDR&E), and since tomorrow I'll be at Ft. McNair for a two-day conference sponsored by DDR&E on Strategic Communications, I'll congratulate for the good idea.
But the Post article falls short in two ways: one immediate (it leaves out key information about next year's program and the upcoming deadline!) and one longer-term (it ignores the overall context of federal support for R&D). I'll fill in the blanks below.
Livio’s Mathematical Creations with Phun
June 9th, 2008
Are you having Phun Yet?
In my last Post I mentioned the incredible physics sand box or physics reality simulator . Here I will explain in some detail one scene created with Phun.
When you build physical simulations in Phun you are creating a visual representation that is attached virtually near physical behavior. In a way you are actually building graphically a very sophisticated computer program where each element have physical properties. Like being able to move, collide, bounce, gravity, velocity, acceleration etc. Naturally the simulation is no perfect but is very close to reality and that is what makes it very surprising and I believe useful. It's almost like using Lego blocks but this time you can build the building blocks by yourself!
I will name the process of building scenes "Phun programming" for the above reason and by extension a Phun programmer is he who creates a scene.
While many of the Phun programmers restrict them self to creating rockets and tanks some others have dedicated their time to create ingeniously intricate mechanism. I am still in complete awe by some of the mechanical things that people have created with Phun. Between those prolific creators I have found Livio Zucca from Turin Italy the home of world fame mathematician . I believe Livio's creations deserve more attention for his ingenuity.
In my prior post about the I extended a prior idea from Livio. The machine in question is a binary mechanical counter.
The main component to perform computations in this particular device is what is know as a and it should not be confused with a . The main difference between latch and flip-flop is that latches are transparent storage elements while flip-flops are not. Wikipedia point out this new distinction.
In the above picture you can see a magnified section of the machine. This we called the ball feeding mechanism and it's function is to collect balls and feed them up the two dimensional vertical tube on the left.
Let us explained in a bit of detail how this is achieve with Phun.
In Phun you can simulate gravity and can also simulate movement. You can define two types of hinges. The normal kind that is just a hinge that hinges and there is the one that can act as an engine or motor. This is just a programmatic simplification on Phun's designer part. It will be nice if there was some visual differentiation between them but at the moment there is none.
The crosses are used to attached things so they will not fall off the scene when gravity acts upon them.
Notice the green bar at the bottom of the picture. That bar acts as the collector of balls and it does have a very slight inclination this is useful in this design as it makes the balls roll slowly towards the left where the feeding mechanism is located.
You can also see a spring and I guess you must probably already know what a spring does!
and at last the actual latch
The latch acts like a and there is a hinge that can be visible if you magnify the picture a little bit more. The numbers have a double function in this particular case. They act as stoppers for the balancer and also as indicators of the state of the latch. As portrait above this latch is in 0 state.
As you probably know latches have two states. One can be use to represent 0 state as in this case and the other can be use to represent 1.
The latch alternates between this two states as you can see in the animation below.
You may also appreciate the mechanism for translating circular motion into linear upward motion on the left side. This mechanism brings back memories of the mechanism that provided steam locomotive with motive power in time past.
As you may have already guess by the picture of the machine and the name the function of this particular mechanism is to count balls dropping down from the device and this is done using the . The binary system is a numerical positional system that uses only two digits instead of the 10 digits we use in our decimal numerical system.
For educators Phun will be a source of inspiration. I believe it is very usefull for the instruction and motivation of Mathematics,Physics, Computer Science, Mechanical Engineering,Electronics. Phun is opening a new universe of interactive learning and should I dare also say FUN!
If you like to play,run or modify the Scene above in the Phun simulator you can download the Phun program and the scene from
If you like to see a short video of my modification then go
[blip.tv ?posts_id=923281&dest=-1]
I am planning to make more Posts with the Best of Livio's Phun Machines.
We will also post a video lecture about Phun at