Author Archive
02/17/2010
2D drafting methods are not able to relay the quality and quantity of design information because 2D methods will always rely on human interpretation or visualization skills to interact with a 2D design. This is always difficult for non design staff and almost impossible for computer systems to extract this kind of information, because computers do not have the ability to interpret.
As a result, many human errors can occur with traditional 2D design methods. In the past problems such as component collisions, incorrect quantities or parts that don’t fit, would happen because a designer who works in only 2D is forced to hold much of the information mentally.
Reducing human error by using the 3D modeling design methods minimizes the need for re-work because the design quality is greatly improved. Using 3D design modeling greatly improves design quality because it is a more complete process than 2D design. One most important thing about 3d CAD design is that people can have view of the model from all possible dimensions. It is a highly detailed drawing of what your concept will look like as a finished product.
Whether you’re designing a new innovative product, creating technical manuals, or requesting quotes from suppliers, 3D CAD design is extremely powerful. But when a 3D CAD design is transformed into a physical 3D print or job shops’ product prototypes, there is no substitute for the tactile and visual feedback a physical model provides to all participants in the design process.
Mechanical Designers usually share their work space with drafters or other engineering technicians in quiet, well-lighted surroundings separated from production areas. Working from drawings, sketches, planning sheets, and other engineering and shop data, tool designers must visualize the Design, do the panning, document and verify every step of the way.
Because of reductions in defense spending, jobs for mechanical engineering type work will decrease; however, the employment of mechanical engineers is expected to grow about as fast as the average for all occupations through this year due to the demand for new and more complex industrial machinery and tools resulting from the development of more sophisticated automated production processes.
The use of 3D modeling technology is essential when you want to develop a superior product. Such a product will not be influenced by human interpretation. Furthermore, it will look like the final model.
Posted in 3d cad, 3d modeling, CAD Drafting, Product Design | Comments Off
12/14/2009
Detached drawings:
Detached drawings are designed so you can open and work in drawing files without the model files being loaded into memory or even being present.
You can save regular drawings as detached drawings, and vice versa.
With a drawing open, File>Save As. Change the Save as type to “Detached Drawing (*.slddrw)”.
To save the sheet format:
Sheet format files have extension .slddrt and are located in \solidworks\data.
Custom properties in the document are saved with the sheet format and added to any new documents that use the format. Click File, Save Sheet Format You can overwrite standard formats or create custom formats.
Posted in CAD Drafting, Solidworks 2D Drawing | Tagged 2D Drawings, drawings, file format, Solidworks | Comments Off
12/09/2009
G00 Rapid move G0 X# Y# Z# up to eight axes or G0 Z# X#
G01 Feed Rate move G1 X# Y# Z# up to eight axes or G1 Z# X#
G02 Clockwise move
G03 Counter Clockwise move
G04 Dwell time G04 L#
G08 Spline Smoothing On
G09 Exact stop check, Spline Smoothing Off
G10 A linear feedrate controlled move with a decelerated stop
G11 Controlled Decel stop
G17 XY PLANE
G18 XZ PLANE
G19 YZ PLANE
G28 Return to clearance plane
G33 Threading (Lathe)
G35 Bypass error checking on next line
G40 Tool compensation off
G41 Tool compensation to the left
G42 Tool compensation to the right
G43 Tool length compensation – negative direction
G44 Tool length compensation – positive direction
G49 Tool length compensation cancelled
G53 Cancel work coordinate offsets
G54-G59 Work coordinate offsets 1 through 6
G61 Spline contouring with buffering mode off
G64 Spline contouring with buffering mode on
G65 Mill out rectangular pocket
G66 Mill out circular pocket
G67 Flycut
G68 Mill out rectangular pocket with radius corners
G70 Inch mode
G71 Millimeter mode
G74 Peck drilling (Lathe) G83 Z# X# R#
G81 Drill cycle G81 X# Y# Z# R#
G82 Dwell cycle G82 X# Y# Z# R#
G83 Peck cycle G83 X# Y# Z# R#
G84 Tapping cycle G84 X# Y# Z# R# C#
G85 Boring cycle 1 G85 X# Y# Z# R#
G86 Boring cycle 2 G86 X# Y# Z# R#
G88 Boring cycle 3 G88 X# Y# Z# R#
G89 Boring cycle 4 G89 X# Y# Z# R#
G90 Absolute mode
G91 Incremental mode
G92 Home coordinate reset G92 X# Y# Z#
G94 IPM mode (Lathe) default
G95 IPR mode (Lathe)
G96 Constant Surface Feed On (Lathe)
G97 Constant Surface Feed Off (Lathe)
G110 Lathe Groove Face
G111 Lathe Groove OD
G112 Lathe Groove ID
G113 Lathe Thread OD
G114 Lathe Thread ID
G115 Lathe Face Rough
G116 Lathe Turn Rough
G120 Mill Outside Square
G121 Mill Outside Circle or Island
G122 Mill Out Counter Bore
G123 Mill Outside Ellipse pocket
G124 Mill Inside Ellipse pocket
G125 Mill Outside Slot
G126 Mill Inside Slot pocket
G130 3D tool compensation with gouge protection
G131 3D offset parallel to 3D profile
G132 3D tool compensation with gouge protection in the Z axis only
G135 5 axis tool compensation with gouge protection
G136 Included angle limit for gouge protection. G136 L#
G140 3D part rotation and plane tilting G140 U# V# W# R#
G141 Scale factor for the X axis only. G141 L#
G142 Scale factor for the Y axis only. G142 L#
G143 Scale factor for the Z axis only. G143 L#
G160 Mill 3D Cylinder
G162 Mill 3D Sphere
G163 Mill 3D Ramped Plane
G170 Set soft limits and crash fixture/chuck barriers to defaults
G171 Set backward crash fixture/chuck barriers G171 U# V# W#
G172 Set forward crash fixture/chuck barriers G172 U# V# W#
G181 Bolt Hole Drill
G182 Bolt Hole Dwell
G183 Bolt Hole Peck
G184 Bolt Hole Tap
G185 Bolt Hole Bore
Posted in CNC Machining, Machine shop, cad/cam | Tagged Fadal, Fanuc., G code, G codes, M code | Comments Off
12/09/2009
G0 moves from one point to another point at the maximum traverse rate of the machine. G0 is generally used when cutting will not take place when moving from one location to another.
Multiple axis moves begin by all axes moving together at the same rate until each axis move is completed. This gives the appearance of a forty-five degree move at the beginning of the move. For the remaining distances, each axis will continue to move to the end point.
G0 is modal and will remain in effect until it is canceled by the G1, G2 or G3 codes.
G0 will not cancel any feed rates used by the interpolation modes. An F word can appear on the same line with a G0 code; however, the F word will only be used when an interpolation code is used.
G0 can appear at any point on a line to make all moves on the line rapid.
EXAMPLE:
F30. (This F word is modal).
G0 G90 Z.1 (This line will be in rapid travel).
X1.5 Y2.5 (This line will be in rapid travel).
G1 Z-.25 (The G1 will cancel the G0 and use the F30. from above).
G91 X.5 (This will be at F30.0).
G90 Z.1 G0 (This line will be in rapid travel).
Posted in CNC Machining, Machine shop, cad/cam | Tagged CNC Machining, G codes, G0, Rapid Travel. | Comments Off
12/09/2009
This code is used for linear interpolation. Linear moves can be made by one, or any combination of, all the active axes.
Linear Interpolation is used to generate motion along a line, at a specified feed rate. The linear mode is established by the G1 code.
Some controllers can move up to 5 axes simultaneously, completing the movement at a point determined by the X, Y, Z, A, and B words.
EXAMPLE:
N1 O1
N2 M6 T1
N3 G0 G90 S2000 M3 E1 X0 Y0 A0 B0
N4 H1 Z.1 M8
N5 G1 Z-.25 F5.
N6 G1 G91 X1. F10.
N7 X1. Y1.
N8 X1. Y1. Z1. A360. B90.
According to the sample program above:
Block N6 moves the X axis linearly (G1 mode) 1.0 inch at a feed rate of 10 IPM. Block N7 moves the X and Y axes together forming an angular cut. Block N8 moves all possible axes together.
The G1 code will use the last feed rate established in the program with the F# word. The F# word is modal and is only canceled by another F# word. The F# will remain in effect throughout the program until another F# word is used. The F# word can appear on any line with other codes as long as the other codes have no restrictions. G1 is modal and is only canceled by a G0 code.
The G1 must be used again after using a G0 code in the program. A G2/G3 code will not cancel a G1 code.
This means that if a G2 or G3 is used it is not necessary to re-state the G1 on the following line. Also, if the arc center is not described, then a straight line will be generated.
Posted in CNC Machining, Machine shop, cad/cam | Tagged CNC Machining, G codes, G1, Linear Interpolation. | Comments Off
12/09/2009
A control mode in which the motion data input is in the form of absolute dimensions. The values programmed with the axis words are the locations to move to in relation to the current zero position.
Since blocks are processed in a left to right order, both G90 and G91 may appear in the same block. G90 and G91 are position sensitive; therefore the moves to the left of the G90 code will be in absolute until the G91 code is used.
The G90 code is modal and will remain in effect until the G91 code is used.
EXAMPLE:
N12 G90 X2.0 G91 Y1.0 The X move will be absolute; the Y move will be incremental
N13 Z-.02 G5 This Z move will be incremental
N14 G90 X4. This X move will be absolute
Posted in CNC Machining, Machine shop, cad/cam | Tagged Absolute input., CNC Machining, G codes, G90 | Comments Off
12/01/2009
The design control system has to be concerned with the creation and revision of documents, as well as the management of finished documents. Additional mechanisms are required to provide needed flexibility while preserving the integrity of design documentation. These additional mechanisms are embodied in the procedures for review and approval of various documents.
It is important that the design change procedures always include re-verifying and re-validating the design. Fortunately, most design changes occur early in the design process, prior to extensive design validation. Thus, for most design changes, a simple inspection is all that is required. The later in the development cycle that the change occurs, the more important the validation review becomes. There are numerous cases when seemingly innocuous design changes made late in the design phase or following release of the design to market have had disastrous consequences.
See the full story in this topic…
Posted in Industrial Design, Mechanical Design, Product Design | Tagged design changes, Document control, pdm | Comments Off
11/30/2009
Introduction
This International Standard is one of three International Standards dealing with quality system requirements that can be used for external quality assurance purposes. The quality assurance models, set out in the three International Standards listed below; represent three distinct forms of quality system requirements suitable for the purpose of a supplier demonstrating its capability, and for the assessment of the capability of a supplier by external parties.
a) IS0 9001, Quality systems- Model for quality assurance in design, development, production, installation and servicing for use when conformance to specified requirements is to be assured by the supplier during design, development, production, installation and servicing.
b) IS0 9002, Quality systems -Model for quality assurance in production, installation and servicing for use when conformance to specified requirements is to be assured by the supplier during production, installation and servicing.
c) IS0 9003, Quality systems -Model for quality assurance in final inspection and test for use when conformance to specified requirements is to be assured by the supplier solely at final inspection and test. It is emphasized that the quality system requirements specified in this International Standard, IS0 9002 and IS0 9003 are complementary (not alternative) to the technical (product) specified requirements. They specify requirements which determine what elements quality systems have to encompass, but it is not the purpose of these International Standards to enforce uniformity of quality systems. They are generic and independent of any specific industry or economic sector. The design and implementation of a quality system will be influenced by the varying needs of an organization, its particular objectives, the products and services supplied, and the processes and specific practices employed. It is intended that these International Standards will be adopted in their present form, but on occasions they may need to be tailored by adding or deleting certain quality system requirements for specific contractual situations. IS0 9000-l provides guidance on such tailoring as well as on selection of the appropriate quality assurance model, viz. IS0 9001, IS0 9002 or IS0 9003.
Read the full article here
Posted in Fabrication, Mechanical Design, Product Design | Tagged iso 9000, lean manufacturing, quality, Quality assurance, quality control | Comments Off
11/29/2009
Although the waterfall model is a useful tool for introducing design controls, its usefulness in practice is limited. The model does apply to the development of some simpler devices. However, for more complex structures or devices, a concurrent engineering model is more representative of the design processes in use in the industry and is key to success in any industry, where design and manufacturing come together “and stay together” from concept to finished parts, systems, and vehicles, reporting from both the manufacturing and engineering perspectives.
In a traditional waterfall development scenario, the engineering department completes the product design and formally transfers the design to production. Subsequently, other departments or organizations develop processes to manufacture and service the product. Historically, there has frequently been a divergence between the intent of the designer and the reality of the factory floor, resulting in such undesirable outcomes as low manufacturing yields, rework or redesign of the product, or unexpectedly high cost to service the product.
One benefit of concurrent engineering is the involvement of production and service personnel throughout the design process, assuring the mutual optimization of the characteristics of a device and its related processes. While the primary motivations of concurrent engineering are shorter development time and reduced production cost, the practical result is often improved product quality.
Read the full article here
Posted in Mechanical Design, Product Design | Tagged concurrent engineering, iso 9000, Product Development | Comments Off
10/24/2009
The Mohr-Coulomb stress criterion is based on the Mohr-Coulomb theory also known as the Internal Friction theory. This criterion is used for brittle materials with different tensile and compressive properties. Brittle materials do not have a specific yield point and hence it is not recommended to use the yield strength to define the limit stress for this criterion. This theory predicts failure to occur when:
s1 ≥ sTensileLimit if s1 > 0 and s3 > 0
s3 ≥ – sCompressiveLimit if s1 < 0 and s3 < 0
s1 / sTensileLimit + s3 / sCompressiveLimit < 1 if s1 ≥ 0 and s3 ≤ 0
The factor of safety is given by:
Factor of Safety (FOS) = {s1 / sTensileLimit + s3 / sCompressiveLimit} (-1)
Posted in FEA | Tagged FEA, FEA analysis, Mohr-Coulomb, Stress Criterion | Comments Off
10/24/2009
The maximum shear stress criterion is more conservative than the von Mises stress criterion since the hexagon representing the shear stress criterion is enclosed within the ellipse representing the von Mises stress criterion. For a condition of pure shear, von Mises stress criterion predicts failure at (0.577*yield strength) whereas the shear stress criterion predicts failure at 0.5 yield strength. Actual torsion tests used to develop pure shear have shown that the von Mises stress criterion gives more accurate results than the maximum shear stress theory.
Posted in FEA, Mechanical Design, Product Design | Tagged FEA, FEA analysis, Tresca Stress Criteria, von mises | Comments Off
10/24/2009
The maximum von Mises stress criterion is based on the von Mises-Hencky theory, also known as the Shear-energy theory or the Maximum distortion energy theory.
In terms of the principal stresses s1, s2, and s3, the von Mises stress is expressed as:
svonMises = {[(s1 - s2)2 + (s2 - s3)2 + (s1 - s3)2]/2}(1/2)
The theory states that a ductile material starts to yield at a location when the von Mises stress becomes equal to the stress limit. In most cases, the yield strength is used as the stress limit. However, the software allows you to use the ultimate tensile or set your own stress limit.
svonMises ≥ slimit
Yield strength is a temperature-dependent property. This specified value of the yield strength should consider the temperature of the component. The factor of safety at a location is calculated from:
Factor of Safety (FOS) = slimit / svonMises
Posted in FEA, Mechanical Design, Product Design | Tagged FEA, stress, von mises | Comments Off
10/23/2009
Inventors can obtain three different types of patents in the United States, namely, plant patents, utility patents, and design patents. Plant patents are rare and are used to protect a new plant that the inventor has produced asexually (without using seeds). A utility patent can be used to protect the way a new technology functions and is used. A design patent protects the visual characteristics of an item. There is often confusion among inexperienced entrepreneurs and inventors regarding the differences between utility and design patent protection. It is important to understand that a design patent protects only the appearance of an article and not its structural or functional features. It is different than a utility patent because it offers no protection for the way an article works and can only protect the unique visual “look” of a new item. As such, if you are looking to protect the way your invention works, a utility patent should be pursued. The proceedings relating to granting of design patents are similar to those relating to utility patents with a few differences. A design patent has a term of 14 years from grant, and no fees are necessary to maintain a design patent in force. If upon examination it is determined that an applicant is entitled to a design patent under the law, a notice of allowance will be sent to the applicant or applicant’s attorney, or agent, calling for the payment of an issue fee. The drawing of the design patent conforms to the same rules as other drawings, but no reference characters are allowed and the drawing should clearly depict the appearance, since the drawing defines the scope of patent protection. The claims of a design patent are different from a utility patent. A utility patent has multiple claims while a design patent is limited to a single claim. The drawings of a design patent provide a visual disclosure of the claim. In light of the differences between utility and design protection, it is important that an inventor understand the limitations of a design patent. A design patent should be filed only if the appearance of an invention is important. If it is possible to change the appearance of an invention without significantly altering its function, a utility patent is more appropriate.
John Rizvi is a Registered Patent Attorney at the Fort Lauderdale based law firm of Gold & Rizvi, P.A.-The Idea Attorneys® ( http://www.ideaattorneys.com ).
Posted in Patents | Comments Off
10/21/2009
Finite Element Analysis (FEA) provides a reliable numerical technique for analyzing engineering designs. The process starts with the creation of a geometric model. Then, the program subdivides the model into small pieces of simple shapes (elements) connected at common points (nodes). The representation of a given region by a set of elements (i.e., discretization or mesh generation) is an important step in finite element analysis. Meshing the model is the heart of any FEA analysis. The choice of element type, number of elements, and density of elements depends on the geometry of the domain, the problem to be analyzed, and the degree of accuracy desired. Local mesh refinement tools are very important to have good mesh with gradual transitions between the mesh densities. One should have a finer mesh in the areas of high stress gradient to ensure accuracy of the solution.
Posted in FEA, Mechanical Design, Product Design | Tagged FEA analysis, mesh, meshing, nodes | Comments Off
10/21/2009
What are the types of nonlinearities that can occur?In linear analysis, the response of a structure is directly proportional to the load. We assume that:
- the displacements and rotations are small
- stress is directly proportional to strain
- loads maintain their original directions as the structure deforms.
However any of the convenient assumptions that are made during a linear analysis may not hold good in real life situations. For example:
- A contact area may change as the load changes
- A material may no longer exhibit an elastic behavior especially after it starts to yield and flows into the plasticity region.
- The stiffness of the structure may decrease because of buckling or the material may even fracture!
- The displacements and rotations may become too large and thus there is a need to develop equations describing the equilibrium at various intervals instead of one single configuration.
The direction and magnitude of the applied force can change in large rotation problems.
Posted in FEA, Mechanical Design, Product Design | Tagged nonlinear, nonlinear analysis, timeline | Comments Off
10/21/2009
When loads are applied to a body, the body will deform and the effect of the loads will be transmitted throughout the body. To absorb the effect of loads, the body generates internal forces and reactions at the supports to balance the applied external loads. Linear static analysis refers to the calculation of displacements, strains, and stresses under the effect of external loads.
Posted in FEA, Mechanical Design, Product Design | Comments Off
10/21/2009
When loads are applied to a body, the body will deform and the effect of the loads will be transmitted throughout the body. To absorb the effect of loads, the body generates internal forces and reactions at the supports to balance the applied external loads. Linear static analysis refers to the calculation of displacements, strains, and stresses under the effect of external loads based on two basic assumptions:
Static Assumption All loads are applied slowly and gradually until they reach their full magnitudes. After reaching their full magnitudes, loads will remain constant (time-invariant). This assumption allows us to disregard insignificant inertial and damping forces due to negligibly small accelerations and velocities. Time-invariant loads that induce considerable inertial and/or damping forces may warrant dynamic analysis. Dynamic loads change with time and, in many cases, induce considerable inertial and damping forces that cannot be neglected.
Linearity Assumption The relationship between loads and induced responses is linear. If you double the magnitude of loads, for example, the response of the model (displacements, strains, and stresses), will also double. You can assume that the linearity assumption is valid if:
- All the materials in the model comply with Hook’s law, that is stress is directly proportional to strain.
- The induced displacements are small enough to ignore the change in stiffness caused by loading.
- Boundary conditions do not vary during the application of loads. Loads must be constant in magnitude, direction, and distribution. They should not change while the model is deforming.
Posted in FEA, Mechanical Design, Product Design | Tagged dynamic loads, linearity, Static Analysis, Time-invariant | Comments Off
10/21/2009
Thermal energy transfers from one point to another through the interaction between the atoms or molecules of the matter. Conduction occurs in solids, liquids, and gasses. For example, a hot cup of coffee on your desk will eventually cool down to the room-temperature mainly by conduction from the coffee directly to the air and through the body of the cup. There is no bulk motion of matter when heat transfers by conduction.
Posted in FEA, Mechanical Design, Product Design | Tagged conduction, thermal conduction | Comments Off
10/21/2009
Convection is the heat transfer mode in which heat transfers between a solid face and an adjacent moving fluid (or gas). Convection involves the combined effects of conduction and the moving fluid. The fluid particles act as carriers of thermal energy. The rate of heat exchange between the fluid of temperature Tf and the face of a solid of area A and temperature Ts can be expressed as:
Q convection= hA(Ts-Tf)
where h is the convection heat transfer coefficient, Tf is the temperature of the fluid away from the face of the solid. The units of h are: W/m2.°C or Btu/s.in2.°F Convection processes can be divided into two main classes:
Free (Natural) Convection The motion of the fluid adjacent to a solid face is caused by the buoyancy forces induced by changes in the density of the fluid due to the presence of the solid. When a hot plate is left to cool down in the air, the particles of air adjacent to the face of the plate get warmer, their density decreases and hence they move.
Forced Convection An external means such as a fan or a pump is used to accelerate the flow of the fluid over the face of the solid. The rapid motion of the fluid particles over the face of the solid maximizes the temperature gradient and results in increasing the rate of heat exchange.
Posted in FEA, Mechanical Design, Product Design | Comments Off
3dcadware
fredvierheller
bob92003
Deepak Gupta