CAD
CAD (Computer Aided Draughting and Design) is much more than drawing lines by electronic means. There are many reasons for using CAD;
The most potent driving force is competition. In order to win business, companies used CAD to produce better designs more quickly and more cheaply than their competitors.
Productivity is much improved by a CAD program enabling you to easily draw polygons, ellipses, multiple parallel lines and multiple parallel curves.
The speed is increased by the use of automatic fillets and chamfers;
The computer ability to "snap" automatically to particular geometric points and features will spread the accurate positioning of linework.
Copy, rotate and mirror facilities are also very handy when drawing symmetrical parts.
Many hatch patterns are supplied with CAD programs. Filling areas in various colours is a requirement in artwork and presentations.
Different style fonts for text are always supplied with any CAD programs.
The possibility of importing different graphic file formats and scanning of material (photographs) into a CAD program is also an asset especially as the image can be manipulated, retouched and animated.
The ability to zoom in and out is an asset when drawing to scale. CAD information is stored in digital form and hence, irrespective of the size of the final printed drawings, it is possible to accurately dimension components automatically.
Another advantage of a CAD system is its ability to store entities, which are frequently used on drawings. Libraries of regularly used parts can be purchased separately or can be created by the draughtsman. For repetitive use on a drawing, a typical item may be retrieved and positioned in seconds, also oriented at any angle to suit particular circumstances.
Using CAD products, assembly drawings can be constructed by inserting existing component drawings onto the assembly drawing and positioning them as required.
Clearance between different components can be measured directly from the drawing and, if required, additional components designed using the assembly as reference.
CAD is very suitable for repetitive and fast documentation where a product is one in a range of sizes. Assume that you manufacture a range of motor driven pumps operating at different pressures. Many parts will be used in different combinations in the range and the computer database documentation is programmed accordingly.
A computerized tender can be sent with the appropriate specification and technical details. On receipt of an order, all of the documentation relating to manufacture, testing, dispatching and invoicing will be available.
Previously, engineers and drafters wasted almost 30% of their time looking for drawings and other documents. Editing drawings to effect revisions and produce updated parts lists is quick and easy using a CAD product.
When you're working on paper and a customer wants to change a drawing, you have to draw it all over again;
In CAD, you make the change immediately and print out a new drawing in minutes, or you can transmit it via E-mail or Internet all over the world instantly.
On paper creating complex geometry often involves a lot of measuring and location of reference points; In CAD it is a breeze and revisions are even simpler.
Many CAD programs include a macro or an add-on programming language that allow customizing it.
Customizing your CAD program to suit your specific needs and implementing your ideas can make your CAD system different from your rivals.
CAD can enable companies to produce better designs that are almost impossible to produce manually and to eliminate dubious options during the conceptual design phase;
For example in area of complex surfaces and Finite-element analysis.
Many CAD systems permit the rapid generation of models of proposed designs as wire-frames. The computer memory stores details of all the geometric data to define each part of the frame. From the dimensions of the components, the computer will calculate surface areas, volumes, weights for different materials, center of gravity, moments of inertia and radii of gyration; it can also use the applicable value for stress and other calculations, which are necessary part of design.
The solid modeling created in CAD can be transferred to a Finite Element Analysis (FEA) program, which will then verify whether the suggested design will be capable of supporting the expected loads.
The biggest contribution of computers to the design process is soft prototyping - the process of creating a 3D-computer model of a design that can be subjected to computer-based testing. Soft prototypes are almost faster and cheaper to built than real prototypes and are often better at their main activity than a real ones; That because model shop prototypes usually use processes and materials very different from those ultimately used for the production version of the product.
The soft prototypes can resemble the final product much more closely than any real material prototypes. Realistic images of the soft prototypes can be used by marketing people to produce sales collateral, manuals and the whole gamut of marketing materials. They can even be used for testing marketing to determine whether the product is worth producing at all. Sale departments use 3D illustrations in brochures and literature for promotional applications.
Presentation programs with rendering models and animation in 3D form a large part of selling and advertising in today competitive market.
CAD will be linked to CAM (Computer Aided Manufacture) whenever possible.
CAD/CAM systems could produce computerized instructions for computerized machine controllers: lathes, mills, machining centers, turret punches, welding equipment, automated assemblies, etc.
A typical design involves producing part drawings in a CAD program right up to completion of design and making layers of the geometry required for the CAM processing software.
The description of part created in a CAD program is translated into an appropriate format, such as DXF or IGES, and then loaded into the CAM program which are used then to create tool paths that trace this description.
This path can be edited and combined with other tool path files where necessary and the combined forms a complete program for the machine tool to manufacture the part.
The resulting NC program can be exported back into the CAD system to produce a simulated backplot of the toolpath or imported into a solid modeling NC program to produce a computer model for checking before manufacture.
CAM
What is CAM?
Complementary and alternative medicine (CAM) is a term used to describe a diverse group of healing systems that are not presently considered to be part of mainstream medicine. The goal of conventional medicine is to locate the physical source of a particular disease and then remove it. For example, if a patient has some sort of infection, a conventional doctor would probably prescribe a specific antibiotic to kill the invading bacteria. CAM practitioners, on the other hand, take a more "holistic" approach to healthcare. They believe that health and disease involve a complex interaction of physical, spiritual, mental, emotional, genetic, environmental, and social factors. In order to treat a disease or simply promote good health, CAM practitioners treat the whole body by taking all of these factors into account.
In the United States, this holistic approach to health has been labeled "alternative" for a variety of scientific, cultural, and political reasons. In many cases it is very difficult to scientifically test alternative practices, such as acupuncture, in the same way that certain conventional practices, such as medications, are tested. Although alternative therapies are often based on hundreds -- in some cases thousands -- of years of experience, the conventional medical community relies heavily on scientific evidence (rather than clinical experience) when evaluating the safety and effectiveness of a particular therapy. For this reason, many alternative practices that have not been thoroughly tested (or cannot be thoroughly tested) are considered "unscientific" by modern Western standards. In addition, many non-Western healing practices are not taught in United States medical schools, available to patients in U.S. hospitals, or even covered by health insurance in the country.
What does complementary medicine and alternative medicine mean?
The terms "complementary medicine" and "alternative medicine," although often used to mean the same thing, actually have quite different implications. Complementary medicine refers to medical practices used together with conventional medicine while alternative medicine is used in place of conventional medicine. An example of complementary medicine is the use of hypnotherapy together with pain medications to reduce anxiety and enhance relaxation in people recovering from severe burns. Following a special diet rather than taking medications to treat attention deficit/hyperactivity disorder (ADHD) is an example of alternative medicine.
What is integrative medicine?
The term "integrative medicine" is often used interchangeably with CAM, but it has a subtle and very important different meaning. Professionals who practice integrative medicine blend appropriate CAM therapies with mainstream medicine rather than simply adding one complementary therapy (such as herbs, for example) to a standard medical treatment. For example, an integrative treatment for Alzheimer's disease may include a combination of the following: (1) medications that increase certain brain chemicals, (2) antioxidants (such as vitamin E and ginkgo biloba ) that scavenge free radicals, (3) changes in lifestyle (such as walking programs and relaxation training) to reduce anxiety and improve behavior, and (4) music therapy to bolster the immune system. More and more Americans are becoming familiar with the term "integrative medicine," and studies have found that this blended approach to healthcare is safe and effective for a growing number of medical conditions.
What are the basic principles of CAM?
Although CAM therapies vary widely, several themes can be traced through them all:
* The focus is on the whole person -- physical, emotional, social, and spiritual.
* Prevention of illness is a primary concern.
* Treatments are highly individualized.
* Treatments are aimed at the causes of illness rather than at its symptoms.
* Treatments are designed to support the natural healing processes of the body.
Who is using CAM?
The barriers to integrative medicine are beginning to fall -- or, at least are becoming less difficult to overcome. Alternative healing practices are increasingly being tested for effectiveness and safety in well-designed research studies. The intermixing of diverse cultures in the West are bringing once distant healing practices to the forefront and more Americans are turning to integrative medical care than ever before.
The movement toward integrative medicine in the United States has been prompted by a growing consumer demand for CAM services. A landmark study published in 1993 found that more than one-third of Americans had sought CAM therapies, that in 1990 they had made more visits to CAM providers than to their primary care physicians, and that consumers had spent more than 13 billion dollars out-of-pocket for these CAM visits.
Studies suggest that demand for CAM services continues to grow at a startling rate. A 2001 survey found that nearly 70% of Americans have used at least one form of CAM therapy in their lifetime, making this "unconventional" medical approach one of the fastest growing sectors of American healthcare. Although herbs and supplements are not regulated by the U.S. Food and Drug Administration (FDA), pharmacies across the country are experiencing a tremendous surge in the demand for these alternative remedies. From 1991 to 1996 alone, the demand for over-the-counter natural remedies (including herbs and supplements) doubled. In a 1996 survey by Landmark Healthcare, more than 70% of HMOs reported an increase in requests for CAM by their members. Most patients (56%) requested acupuncture, followed by chiropractic (45%), massage (25%), acupressure and biofeedback (21% each), hypnotherapy (8%), and reflexology (4%).
Studies also suggest that U.S. medical schools may be warming up to CAM. As of 1998, 75 out of 117 (64%) U.S. medical schools offer at least one course in CAM. In a 1994 survey, 60 percent of doctors reported recommending CAM to their patients. Nearly half of the doctors who responded to the survey acknowledged that they used CAM themselves. More and more health insurance plans are also covering CAM, particularly treatments such as acupuncture and chiropractic, whose safety and effectiveness in the treatment of certain health problems has been fairly well researched. A number of health plans now cover the Ornish heart program, which has a basis in yoga and nutrition. All of these changes in American healthcare point to the careful movement—often with a healthy dose of skepticism—toward an integrative medicine system that incorporates the most useful therapies from the world's many healing traditions.
What are the major types of CAM?
The National Center for Complementary and Alternative Medicine (NCCAM) classifies CAM therapies into five major groups:
* Alternative Medical Systems: built upon complete systems of theory and practice. Examples include homeopathy, naturopathy, traditional Chinese medicine (TCM), and Ayurveda.
* Biological Medicine : use of substances found in nature, such as herbs, foods, and vitamins to promote health.
* Energy Medicine: involves the use of energy fields to promote health. Some forms of energy medicine (known as biofield therapies) are designed to influence energy fields that are believed to surround and penetrate the human body. Examples of biofield therapies include qi gong, Reiki, and Therapeutic Touch. Other forms of energy medicine (known as bioelectromagnetic-based medicine) involve the use of electromagnetic fields, such as electroacupuncture.
* Manual Medicine: based on manipulation and/or movement of one or more parts of the body. Examples include osteopathy, physical therapy, massage, chiropractic, Feldeinkrais, and reflexology.
* Mind-Body Medicine: uses a range of techniques that help boost the mind's ability to influence bodily functions and symptoms. Examples include biofeedback, deep relaxation, guided imagery, hypnotherapy, meditation, prayer, support groups, and yoga.
What types of changes in policy are happening in order to incorporate CAM into the U.S. medical system?
In 1991, under a Congressional mandate, the National Institutes of Health (NIH) established the Office of Alternative Medicine (OAM) with an annual budget of 2 million dollars to coordinate NIH research on nontraditional health practices. Specifically, OAM was to evaluate CAM practices, support CAM research and training, and establish a CAM information clearinghouse for the general public.
In 1998 Congress established the National Center for Complementary and Alternative Medicine (NCCAM) to supersede the OAM. With an annual budget of more than 68 million dollars, NCCAM's mission is to support basic and applied CAM research and provide information to healthcare providers as well as the public. Among other efforts, NCCAM focuses on research that evaluates the safety and effectiveness of herbs and nutritional supplements and their potential for interaction with medications. It also evaluates other CAM treatments such as acupuncture and chiropractic. NCCAM funds several research centers outside of the NIH (to learn more about the centers and their research agendas, visit NCCAM's web site at http://nccam.nih.gov/research/ ).
In July of 2000, the White House announced the establishment of a White House Commission on Alternative Medicine, designating the Chair and the first 10 members. The goal of the commission is to develop a set of legislative and administrative recommendations to maximize the benefits of CAM for the American public. Going beyond the research goals of NCCAM, the commission will set the agenda for the education and training of CAM practitioners as well as provide policy recommendations for the insurance industry coverage of alternative therapies.
What is the Future of CAM?
There are many encouraging signs that CAM is slowly becoming accepted into mainstream medicine. For example, breakthroughs in CAM research are frequently published in prestigious Western peer-reviewed journals such as the Journal of the American Medical Association and the Annals of Internal Medicine . Still, there are real obstacles to the achievement of truly integrated medicine. Some of these obstacles include cultural conflicts, lack of scientific studies, and administrative issues. However, because conventional doctors and CAM practitioners alike seek to create safe, effective, and affordable medical treatment for all patients, the integration of the best CAM into conventional medicine may not be worlds away.
CNC
In Industry it is not efficient or profitable to make everyday products by hand. On a CNC machine it is possible to make hundreds or even thousands of the same item in a day. First a design is drawn using design software, then it is processed by the computer and manufactured using the CNC machine. The machine featured below is the BOXFORD DUET. This is a small CNC machine and can be used to machine woods, plastics and aluminium. In industry, CNC machines can be extremely large. The Duet is one of the smaller CNCs and is ideal for use in schools.
Have a look at the photograph on the right. Can you imagine how long it would take a skilled worker to ‘carve’ this shape out of wood or a soft material - it would probably take a full day. We will be going through its manufacture, one step at a time using a CNC machine (next page). How long do you think manufacturing this product with a CNC machine will take ?
THE CNC MACHINE
The VICE: This holds the material to be cut or shaped. Material must be held securely otherwise it may 'fly' out of the vice when the CNC begins to machine. Normally the vice will be like a clamp that holds the material in the correct position.
The GUARD: The guard protects the person using the CNC. When the CNC is machining the material small pieces can be 'shoot' off the material at high speed. This could be dangerous if a piece hit the person operating the machine. The guard completely encloses the the dangerous areas of the CNC.
The CHUCK: This holds the material that is to be shaped. The material must be placed in it very carefully so that when the CNC is working the material is not thrown out at high speed.
The MOTOR: The motor is enclosed inside the machine. This is the part that rotates the chuck at high speed.
The LATHE BED: The base of the machine. Usually a CNC is bolted down so that it cannot move through the vibration of the machine when it is working.
The CUTTING TOOL: This is usually made from high quality steel and it is the part that actually cuts the material to be shaped.
• ANALYSIS
– Stress (deflection analysis,I.e. numerical
methods,FEM
– Simulation of actual use
– Optimizations
– Applications
– CAD/CAM integration
– Process planning
No comments:
Post a Comment