DESIGN OF I.C ENGINE CAM SHAFT Acamshaftis a shaft to which acamis fastened or of which a cam forms an integral part. Camshafts are responsible for the accurately-timed fuel injections required by internal combustion engines. Camshafts have multiple cams on them, which are used to open valves through either direct contact or pushrods. A camshaft is directly coupled to the crankshaft, so that the valve openings are timed accordingly. Then with the use of CREO three-dimensional model of the cam shaft is obtained. Once the CAD model is obtained, the part is analyzed using SOLID WORKS simulation tool by applying chilled iron material and the loads are applied. The materials used in the camshaft depend upon the quality and type of engine being manufactured. For most mass-produced automobiles, chilledcast ironis used. This material is a good choice for high volume production. A chilled iron camshaft has a resistance against wear because the camshaft lobes have been chilled, generally making them harder. When making chilled iron castings, other elements are added to the iron before casting to make the material more suitable for its application.

INTRODUCTIONCAM:A projection on a rotating part in machinery, designed to make sliding contact with another part while rotating and to impart reciprocal or variable motion to it.Cams are used to convert rotary motion into reciprocating motion

CAMSHAFT:A shaft with one or more cams attached to it, e.g. working of valves in an internal combustion engine is controlled by camshaft. Cam shaft is called the brain of the engine.

CAM TERMINOLOGY

Base Circle:The smallest circle centered on the cam rotation axis, and tangent to the cam surface.The size of the base circle is dictated by spatial restrictions of the application.

Trace point:A theoretical point on the follower, corresponding to the point of a fictitious knife-edge follower. It is used to generate the pitch curve. In the case of a roller follower, the trace point is at the center of the roller.

Home Position:The orientation of the cam that corresponds to 0on a displacement curve.

Reference Circle (or prime circle):A circle centered at the cam axis whose radius is equal to the distance to the trace point.It is the smallest circle from the cam center through the pitch curve

Pressure Angle:The angle between the direction of motion of the follower and the direction of thecamcontact forceis called pressure angle.Pressure angle should not exceed 30.Pitch curve: The path generated by the trace point at the follower is rotated about a stationary cam.Working curve: The working surface of a cam in contact with the follower. For the knife-edge follower of the plate cam, the pitch curve and the working curves coincide. In a close or grooved cam there is an inner profile and an outer working curve.

CAM SHAPE

1. PLATE CAMORDISC CAM:The follower moves in a plane perpendicular to the axis of rotation of the camshaft. A translating or a swing arm follower must be constrained to maintain contact with the cam profile. 2. GROOVED CAMorclosed cam:This is a plate cam with the follower riding in a groove in the face of the cam.

Grooved cam

1. CYLINDRICAL CAMOR BARREL CAMThe roller follower operates in a groove cut on the periphery of a cylinder. The follower may translate or oscillate. If the cylindrical surface is replaced by a conical one, a conical cam results 2. END CAM This cam has a rotating portion of a cylinder. The follower translates or oscillates, whereas the cam usually rotates. The end cam is rarely used because of the cost and the difficulty in cutting its contour.

Cylindrical cam and End cam

MOTIONOF THE CAM

When the cam turns through one motion cycle, the follower executes a series of events consisting of rises, dwells and returns.Riseis the motion of the follower away from the cam center,dwellis the motion during which the follower is at rest; andreturnis the motion of the follower toward the cam center.

Lift:Lobe lift is the distance the lifter moves in one directionLobe lift is the difference in measurement between the nose of the lobe and the base circle of the lobeValve lift is what most people are taking about when they refer to lift and is simply lobe lift multiplied by the rocker arm ratio

MATERIALS USED IN CAMSHAFT:

Camshaft material is the most important detail in stopping premature wear of performance camshafts.There are various materials that camshafts are manufactured from:-

CAST IRONS

1. HARDENABLE IRON:This is Grade 17 cast iron with an addition of 1% chrome to create 5 to 7% free carbide.After casting, the material is flame/or induction hardened, to give a Rockwell hardness of 52 to 56 on the C Scale. It is not the most suitable material for performance camshafts in overhead cam (OHC) engines.

2.SPHEROIDAL GRAPHITE CAST IRON KNOWN AS SG IRON:

A material giving similar characteristics to hardenable. Its failing as a camshaft material is hardness in its cast form, which tends to scuff bearings in adverse conditions. The material will heat treat to 52 to 58 RockwellC. This material was used by Fiat in the 1980s

3.CHILLED CHROME CAST IRON:Chilled iron is Grade 17 cast iron with 1% chrome. When the camshaft is cast in the foundry, machined steel moulds the shape of the cam lobe are incorporated in the mould. When the iron is poured, it hardens off very quickly (known as chilling), causing the cam lobe material to form a matrix of carbide (this material will cut glass) on the cam lobe. This material is exceedingly scuff-resistant and is the only material for producing quantity OHC performance camshafts.

CONCLUSION OF CAST CAMSHAFTS:When purchasing a camshaft, enquire which material the camshafts are produced from. A chilled iron camshaft may be more expensive, but its resistance to wear in all conditions, far exceeds any other type of cast iron.

STEEL CAMSHAFTS

1.CARBON STEEL EN8(BS970 080M40)/EN99(BS970 070M55):Used mainly in the 1930 to 1945 period and is currently used for induction hardened camshafts in conjunction with roller cam followers, due to the through-hardening characteristics of the material.2. ALLOYED STEELS EN351 AISI 8620 and EN34:Used by British Leyland in the A Series and B Series engine and best when run against a chilled cam follower.3.NITRIDING STEEL EN40B:The best steel for camshafts. When nitrided it gives a surface hardness and finish similar to chilled iron.We used this when replacing chilled iron camshafts in competition engines. This material is used on several of the current F1 engines.

CONCLUSIONIn general, steel is a good camshaft material. However, the type of steel has to be matched with the cam follower it runs against, as different grades of steel have different scuff characteristics.

DESIGN PROCEDURE:

Profile Design according to requirement:Design a cam for operating the exhaust valve of an oil engine. It is required to give equal uniform acceleration and retardation during opening and closing of the valve each of which corresponds to 69 of cam rotation. The valve must remain in the fully open position for 20 of cam rotation.

The lift of the valve is 37.5 mm and the least radius of the cam is 40 mm. The follower is provided with a roller of radius of 20 mm and its line of stroke passes through the axis of the cam.

Proposed Profile Design:ConstructionFirst of all, the displacement diagram, as shown in Fig 1, is drawn as discussed in the following steps:

1.Draw a horizontal line ASTP such that AS represents the angular displacement of the cam during opening ( i.e out stroke) of the valve (equal to 60), to some suitable scale. The line ST represents the dwell period of 20 i.e the period during which the valve remains fully open and TP represents the angular displacement during closing (i.e return stroke) of the valve which is equal to 60.

fig. 1

1.Divide AS and TP into any number of equal even parts (say six).2.Draw vertical lines through points 0, 1, 2,3 etc. and equal to lift of the valve i.e 37.5 mm.3.Divide the vertical lines 3f and 3f into six equal parts as shown by the points a, b, c. .. and a, b , c in figure 1.4.Since the valve moves with equal uniform acceleration and retardation, therefore the displacement diagram for opening and closing of a valve consists of double parabola.5.Complete the displacement diagram as shown in Fig. 1

Fig- 2

Now the profile of the cam, with a roller follower when its line of stroke passes through the axis of cam as shown in Fig 2

METHODS OF MANUFACTURING:

1.CASTING: Chilled cast iron is primarily used for production of cam shaft. The development of automobile industry and engine power brings up more advance requirement for properties of camshaft. In casting process, there are more chances of casting defects such as shrinkage defect, porosity, crack, insufficient pouring. However for higher loads in roller contact, cast camshafts with induction hardened cam lobes can be used.

2.FORGING: Forged or manufactured from a steel bar camshafts are also used for certain high loaded diesel engines. These are produced on computer-controlled forging systems with integrated heat treatment or machined from steel bar.

3.MACHINING:Machining is necessary for giving final dimension to the cam.

A.While using Casted or Forged CAM only Final Machining is require to achieve final size within the required tolerances. In this process casted or forged CAM are in the required shape but their size is maintained by machining and finishing operation.

B.While Using Metal Billet (metal rod), the profile of cam is obtained by removing excess material which from metal billet. In this process only machining is required to manufacture CAM.

A detailed description of the processes for mass manufacturing is as follows:

1.TURNING & DRILLING:The raw forging is put in this machine and center drilling and turning on one side is done here.

2.TURNING: Here the turning of the 6 journals takes place. There are 4 tools used for this turning Rough, Neutral, Left and Right tool. Also, Grooving and Parting operation is performed on the left side of the shaft.

3.DRILLING:This machine drills the diameter 4.5 dowel hole which is used as reference for further operations.

4.GRINDING JOURNALS:Here grinding and finish grinding of the 6 journals takes place. Carborundum wheels are used for grinding.

5.GRINDING ON FACE: An angular grinding wheel is used for the face grinding operation. At this stage, inspection is done after every 10 components using gauges.

6.DRILL DOVEL HOLE:Grinding of the Cam is done here. The dowel hole is taken as the reference.

7.LAPPING:To give superfinish in microns, lapping is done using lapping paper on the Cams.

8.SLITTING:This machine makes a slit in the right side of the shaft to fit in the engine. The cutter used is a Saw cutter and pneumatic deburring is done here.

9.AIR & WATER CLEANING:This is the Washing Machine where water and air jets are used to clean the component of dust, oil, chips etc.

10.INSPECTION:This is a Measuring Machine used to check for tolerances - Runouts and Diameters of journals ( all 6 and center 4). The machine then declares the component as OK, NG, or BAD.

INTRODUCTION TO CAD

Computer-aided design (CAD), also known as computer-aided design and drafting (CADD), is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer. CADD software, or environments, provides the user with input-tools for the purpose of streamlining design processes; drafting, documentation, and manufacturing processes. CADD output is often in the form of electronic files for print or machining operations. The development of CADD-based software is in direct correlation with the processes it seeks to economize; industry-based software (construction, manufacturing, etc.) typically uses vector-based (linear) environments whereas graphic-based software utilizes raster-based (pixilated) environments.CADD environments often involve more than just shapes. As in the manual drafting of technical and engineering drawings, the output of CAD must convey information, such as materials, processes, dimensions, and tolerances, according to application-specific conventions.CAD may be used to design curves and figures in two-dimensional (2D) space; or curves, surfaces, and solids in three-dimensional (3D) objects. CAD is an important industrial art extensively used in many applications, including automotive, shipbuilding, and aerospace industries, industrial and architectural design, prosthetics, and many more. CAD is also widely used to produce computer animation for special effects in movies, advertising and technical manuals. The modern ubiquity and power of computers means that even perfume bottles and shampoo dispensers are designed using techniques unheard of by engineers of the 1960s. Because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics (both hardware and software), and discrete differential geometry. The design of geometric models for object shapes, in particular, is often called computer-aided geometric design (CAGD).Current computer-aided design software packages range from 2D vector-based drafting systems to 3D solid and surface modellers. Modern CAD packages can also frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle, even from the inside looking out. Some CAD software is capable of dynamic mathematic modeling, in which case it may be marketed as CADD computer-aided design and drafting.CAD is used in the design of tools and machinery and in the drafting and design of all types of buildings, from small residential types (houses) to the largest commercial and industrial structures (hospitals and factories). CAD is mainly used for detailed engineering of 3D models and/or 2D drawings of physical components, but it is also used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components. It can also be used to design objects. CAD has become an especially important technology within the scope of computer-aided technologies, with benefits such as lower product development costs and a greatly shortened design cycle. CAD enables designers to lay out and develop work on screen, print it out and save it for future editing, saving time on their drawings.Types of CAD Software2D CADTwo-dimensional, or 2D, CAD is used to create flat drawings of products and structures. Objects created in 2D CAD are made up of lines, circles, ovals, slots and curves. 2D CAD programs usually include a library of geometric images; the ability to create Bezier curves, splines and polylines; the ability to define hatching patterns; and the ability to provide a bill of materials generation. 3D CADThree-dimensional (3D) CAD programs come in a wide variety of types, intended for different applications and levels of detail. Overall, 3D CAD programs create a realistic model of what the design object will look like, allowing designers to solve potential problems earlier and with lower production costs. Some 3D CAD programs include Autodesk Inventor, Co Create Solid Designer, Pro/Engineer Solid Edge, Solid Works, Unigraphics NX and VX CAD, CATIA V5.

3D Wireframe and Surface ModelingCAD programs that feature 3D wireframe and surface modeling create a skeleton-like inner structure of the object being modeled. A surface is added on later. These types of CAD models are difficult to translate into other software and are therefore rarely used anymore. Solid ModelingSolid modeling in general is useful because the program is often able to calculate the dimensions of the object it is creating. Many sub-types of this exist. Constructive Solid Geometry (CSG) CAD uses the same basic logic as 2D CAD, that is, it uses prepared solid geometric objects to create an object. However, these types of CAD software often cannot be adjusted once they are created.

INTRODUCTION:CREO1. CAD Computer aided design (cad) is defined as any activity that involves the effective use of the computer to create, modify, analyze, or document an engineering design. CAD is most commonly associated with the use of an interactive computer graphics system, referred to as cad system. The term CAD/CAM system is also used if it supports manufacturing as well as design applications. 2. Introduction to CREOCREO is a suite of programs that are used in the design, analysis, and manufacturing of a virtually unlimited range of product. In CREO we will be dealing only with the major front end module used for pan and assembly design and model creation, and production of engineering drawings Schamtickoo(4) . There are wide ranges of additional modules available to handle tasks ranging from sheet metal operations, piping layout mold design, wiring harness design, NC machining and other operations. In a nutshell, CREO is a parametric, feature-based solid modeling system, Feature based means that you can create part and assembly by defining feature like extrusions, sweep, cuts, holes, slots, rounds, and so on, instead of specifying low-level geometry like lines, arcs, and circle& features are specifying by setting values and attributes of element such as reference planes or surfaces direction of creation, pattern parameters, shape, dimensions and others. Parametric means that the physical shape of the part or assembly is driven by the values assigned to the attributes (primarily dimensions) of its features. Parametric may define or modify a features dimensions or other attributes at any time. For example, if your design intent is such that a hole is centered on a block, you can relate the dimensional location of the hole to the block dimensions using a numerical formula; if the block dimensions change, the centered hole position will be recomputed automatically. Solid Modeling means that the computer model to create it able to contain all the information that a real solid object would have. The most useful thing about the solid modeling is that it is impossible to create a computer model that is ambiguous or physically non-realizable.PTC was founded in 1985, by Samuel Peisakhovich Ginsberg, who previously worked at Prime Computer, Computer vision (CV) and Applicon. Pro/ENGINEER (a.k.a. Pro/E), the company's first product, shipped in 1988. John Deere became PTCs first customer. Once an initial version of Pro/ENGINEER was developed, the company received venture capital funding from Charles River Associates and Steve Walske became the CEO. Pro/ENGINEER was the first commercially successful parametric feature based solid modeler. Through a combination of innovative technology, and no-holds-barred sales tactics, PTC quickly became a major force in the CAD industry. Its strong ascent continued unabated until the mid-1990s, when the introduction of Microsoft Windows NT, and the availability of commercial geometric modeling libraries opened the door to a new generation of low-cost competitors and PTC's reputation for overly aggressive sales tactics alienated many of its customers. These competitors, symbolized by Solid works, squeezed PTC from the bottom, while more established companies like Uni graphics and IBM held the 'high ground' in automotive and aerospace industries. PTC's sales began a multi-year decline from which it took years to recover. It took a new CAD product and an expanded product line, but PTC has been able to transform itself over the past 10 years into the third largest provider of Product Lifecycle Management software.On December 29, 2006 Standard & Poor's bumped PTC off its S&P 500 Index, and replaced it instead with the newly spun-off natural gas company Spectra Energy Corp. (NYSE: SE). Parametric then bumped Pier 1 Imports Inc. (NYSE: PIR), a retailer of home furnishings, down one spot and off the bottom of the S&P Midcap 400 Index In 2008, PTC once again achieved revenues of over $1 billion something it had not been able to accomplish since 1999. Creo Elements/Pro, a product formerly known as Pro/ENGINEER is a parametric, integrated 3D CAD/CAM/CAE solution created by Parametric Technology Corporation (PTC). It was the first to market with associative solid software. The application runs on Microsoft Windows platform, and provides solid modeling, assembly modeling and drafting, finite element analysis, and NC and tooling functionality for mechanical engineers. The Pro/ENGINEER name was changed to Creo Elements/Pro on October 28, 2010, coinciding with PTCs announcement of Creo, a new design software application suite. CREO Elements/Pro (formerly Pro/ENGINEER), PTC's parametric, integrated 3D CAD/CAM/CAE solution, is used by discrete manufacturers for mechanical engineering, design and manufacturing.

Companies use Creo Elements/Pro to create a complete 3D digital model of their products. The models consist of 2D and 3D solid model data which can also be used downstream in finite element analysis, rapid prototyping, tooling design, and CNC manufacturing.

All data is associative and interchangeable between the CAD, CAE and CAM modules without conversion. A product and its entire bill of materials (BOM) can be modeled accurately with fully associative engineering drawings, and revision control information. The associativity functionality in Creo Elements/Pro enables users to make changes in the design at any time during the product development process and automatically update downstream deliverables. This capability enables concurrent engineering design, analysis and manufacturing engineers working in parallel and streamlines product development processes.Almost thirty five years, Pro Engineer has been the most powerful and popular three dimensional computer aided design software in the industry. It has the most variety in terms of advancement in product development capabilities that are currently available on the market. The current version of Pro Engineer is simple to use and learn. It is also very affordable, no matter whether you have small or medium size company.Basically, it has every functionality that a small business requires to be successful. There are many client testimonials that provide product feedback. This is very important because it is always good to hear it straight from your peers. Many people who represent the small business sector were recently asked about why they used this particular CAD software.The testimonials were located in various countries and represented various industries, too. They explained how the software provided a positive impact on their operations and the feedback was quite comprehensive. Almost everyone has business operations that involve daily tasks, including product design. Some types of projects and product design include the creation of an overall design for the primary components. This is an assembly type that could be assisted by the Pro Engineer program.Once you have created the digital model you may need to apply plastics on the form. The software allows you to create the styling and surfacing as it is able to simulate the characteristics of different materials. This step will then drive the design for all the product sub-components. The pro Engineer software allows you to drive the complete design from a single primary file. When this product is used, be sure to be aware of the specifications and references in the very beginning of the project.If changes need to be made, the software can do it automatically. Both the measurements and the design of the components can be altered according to your desire. This creates very big opportunities for time saving processes, which is why this software program is such a powerful tool. Without the ability to make changes so easily, you would have to make drafts for every component on an individual basis.If for example the complete dimensions of your design change, some types of software would force you to change each individual component where asPro Engineer allows you to change all the units and measurements easily in one go.It can also be used for production. When three dimensional files are sent to a manufacturer, they can construct the tooling straight from the files that were sent. Since the file is 3D and it has all the necessary measurements, it can save you from the task of needing to create the two dimensional sketches that the manufacturer used to have to have in order to review the part.You can easily make call outs to the important measurements that you want them to perform total analysis on. This is a real time saver. In fact, it can save about twenty per cent of the time that you would generally spend on the whole process.If you need a powerful solution for your product development process, Pro Engineer is a good choice, as it allows you to work more efficiently and with improved design verification.

There are six core CREO concepts. Those are:1. Solid Modeling 1. Feature Based 1. Parametric 1. Parent / Child Relationships 1. Associative 1. Model CentricThe display of CREO will be as below1. Hide the browser by clicking on the arrows at the right of the screen, as shown in the figure. You should now see the graphics area where parts will be displayed. 1. Select [File] -> [Set Working Directory] from the menu bar, and select the folder in which you downloaded the part. All work you do will be saved to the folder you set as the working directory. 1. Select [File] -> [Open] from the menu bar, and select the part you downloaded. 3 Capabilities and Benefits:1. Complete 3D modeling capabilities enable you to exceed quality arid time to arid time to market goals.1. Maximum production efficiency through automated generation of associative C tooling design, assembly instructions, and machine code.1. Ability to simulate and analysis virtual prototype to improve production performance and optimized product design.1. Ability to share digital product data seamlessly among all appropriate team members1. Compatibility with myriad CAD tools-including associative data exchange and industry standard data formats.

4 Features of CREOCREO is a one-stop for any manufacturing industry. It offers effective feature, incorporated for a wide variety of purpose. Some of the important features are as follows:1. Simple and powerful tool1. Parametric design1. Feature-based approach1. Parent child relationship1. Associative and model centric4.1. Simple and Powerful Tool CREO tools are used friendly. Although the execution of any operation using the tool can create a highly complex model4.2. Parametric Design CREO designs are parametric. The term parametric means that the design operations that are captured can be stored as they take place. They can be used effectively in the future for modifying and editing the design. These types of modeling help in faster and easier modifications of design.4.3. Feature-Based Approach Features are the basic building blocks required to create an object. CREO models are based on the series of feature. Each feature builds upon the previous feature, to create the model (only one single feature can be modified at a time). Each feature may appear simple, individually, but collectively forms a complex part and assemblies. The idea behind feature based modeling is that the designer construct on object, composed of individual feature that describe the manner in which the geometry supports the object, if its dimensions change. The first feature is called the base feature.4.4. Parent Child RelationshipThe parent child relationship is a powerful way to capture your design intent in a model. This relationship naturally occurs among features, during the modeling process. When you create a new feature, the existing feature that are referenced, become parent to the feature4.5. Associative and Model CentricCREO drawings are model centric. This means that CREO models that are represented in assembly or drawings are associative. If changes are made in one module, these will automatically get updated in the referenced module.5. CREO Basic Design ModesWhen a design from conception to completion in pro/engineer, the design information goes through three basic design steps.1. Creating the component parts of the design1. Joining the parts in an assembly that records the relative position of the parts.1. Creating mechanical drawing based on the information in the parts and the assembly.6 Assembly in CREO :Bottom-Up Design (Modeling): The components (parts) are created first and then added to the assembly file. This technique is particularly useful when parts already exist from previous designs and are being re-used.7.Top-Down Design (Modeling): The assembly file is created first and then the components are created in the assembly file. The parts are build relative to other components. Useful in new designsIn practice, the combination of Top-Down and Bottom-Up approaches is used. As you often use existing parts and create new parts in order to meet your design needs.Degrees of Freedom:An object in space has six degrees of freedom.1. Translation movement along X, Y, and Z axis (three degrees of freedom)1. Rotation rotate about X, Y, and Z axis (three degrees of freedom)Assembly Constraints:In order to completely define the position of one part relative to another, we must constrain all of the degrees of freedom.Mate, Align, and InsertMateTwo selected surfaces become co-planar and face in opposite directions. This constrains 3 degrees of freedom (two rotations and one translation) Mate OffsetTwo surfaces are made parallel with a specified offset distance.Align CoincidentTwo selected surfaces become co-planar and face in the same direction. Can also be applied to revolved surfaces. This constrains 3 degrees of freedom (two rotations and one translation). When Align is used on revolved surfaces, they become coaxial (axes through the centers align).

Align OffsetThis can be applied to planar surfaces only; surfaces are made parallel with a specified offset distance.Align OrientTwo planar surfaces are made parallel, not necessarily co-planar, and face the same direction (similar to Align Offset except without the specified distance).InsertThis constrain can only be applied to two revolved surfaces in order to make them coaxial (coincident). Fundamentals of assembly in CREO :In pull down menu File, select new and then choose Assembly option.

Adding Components:In the pull-down menu, select Insert >Component>AssembleOr pick the Add Component button in the right toolbar.Browse and open the file for the first component. CREO Modules Sketcher (2D) Part (3D) Assembly Drawing and Drafting Sheet Metal Rendering

Features of CREO engineering:Pro/engineering is a one-stop for any manufacturing industry. It offers effective feature, incorporated for a wide variety of purpose. Some of the important features are as follows: Simple and powerful tool Parametric design Feature-based approach Parent child relationship Associative and model centricSimple and Powerful Tool CREO tools are used friendly. Although the execution of any operation using the tool can create a highly complex model Parametric Design CREO designs are parametric. The term parametric means that the design operations that are captured can be stored as they take place. They can be used effectively in the future for modifying and editing the design. These types of modeling help in faster and easier modifications of design.Feature-Based Approach Features are the basic building blocks required to create an object. CREO engineering wildfire models are based on the series of feature. Each feature builds upon the previous feature, to create the model (only one single feature can be modified at a time). Each feature may appear simple, individually, but collectively forms a complex part and assemblies. The idea behind feature based modeling is that the designer construct on object, composed of individual feature that describe the manner in which the geometry supports the object, if its dimensions change. The first feature is called the base feature.

Parent Child RelationshipThe parent child relationship is a powerful way to capture your design intent in a model. This relationship naturally occurs among features, during the modeling process. When you create a new feature, the existing feature that are referenced, become parent to the feature.

Associative and Model CentricPro/Engineering wildfire drawings are model centric. This means that Pro/Engineering models that are represented in assembly or drawings are associative. If changes are made in one module, these will automatically get updated in the referenced module.CREO Basic Design Modes When a design from conception to completion in pro/engineer, the design information goes through three basic design steps.Creating the component parts of the designJoining the parts in an assembly that records the relative position of the parts.Creating mechanical drawing based on the information in the parts and the assembly.

CREO consider these steps as separate modes, each with its own characteristics, files extensions, and relation with the other model. As you build a design model it is important to remember that a information, dimensions, tolerances, and relational formulas are passed from model to the next bi directional. This means that if you change your design at any model level. CREO reflect it all model levels automatically.If it is planned ahead and the use associative features correctly, you can save significant time in the design and engineering change order process. Assembly in CREO:Bottom-Up Design (Modeling): The components (parts) are created first and then added to the assembly file. This technique is particularly useful when parts already exist from previous designs and are being re-used.Top-Down Design (Modeling):The assembly file is created first and then the components are created in the assembly file. The parts are build relative to other components. Useful in new designsIn practice, the combination of Top-Down and Bottom-Up approaches is used. As you often use existing parts and create new parts in order to meet your design needs.Degrees of Freedom:An object in space has six degrees of freedom. Translation movement along X, Y, and Z axis (three degrees of freedom) Rotation rotate about X, Y, and Z axis (three degrees of freedom)Assembly Constraints:In order to completely define the position of one part relative to another, we must constrain all of the degrees of freedom. Mate, Align, and Insert MateTwo selected surfaces become co-planar and face in opposite directions. This constrains 3 degrees of freedom (two rotations and one translation) Mate OffsetTwo surfaces are made parallel with a specified offset distance.Align CoincidentTwo selected surfaces become co-planar and face in the same direction. Can also be applied to revolved surfaces. This constrains 3 degrees of freedom (two rotations and one translation). When Align is used on revolved surfaces, they become coaxial (axes through the centers align).Align OffsetThis can be applied to planar surfaces only; surfaces are made parallel with a specified offset distance.Align OrientTwo planar surfaces are made parallel, not necessarily co-planar, and face the same direction (similar to Align Offset except without the specified distance).InsertThis constrain can only be applied to two revolved surfaces in order to make them coaxial (coincident).Steps for modeling of cam shaft in creo:A}Extrude material:

Solid Extrude1. Select the front plane and click at extrude icon. It will get you into the sketching window.2. Using a circle tool make a simple circle of your desired diameter (just for practicing) and click at ok button.

Now the creo parametric will show you the preview of your extrude. You can change the depth of extrude by moving the white square. To do this just click and hold at the white square and move your mouse to change the length.

Two types of extrude depth we can learn at this moment. Blind SymmetricBlind option is shown in above figure and it is by default active. To use symmetric option click at extrude depth tool menu and select the symmetric option you will see that extrude become equally distributed with reference to sketching plane.

IntroductionAn extrude feature is based on a two-dimensional sketch. It linearly extrudes a sketch perpendicular to the sketching plane to create or remove material. You can either select the sketch first or then start the Extrude tool, or you can start the Extrude tool and then select the sketch.In this exercise we will try to learn about Solid Extrude Extrude cut/Add Extrude Thicken Cut/Add Tapper

Also we will use extrude types such as Blind Symmetric Through all Through until To selected

Here is the dashboard option used in extrude tool. I label it to show you the function of the representative option.Solid:this option is selected by default to make solid extrude.Surface:This can be used to extrude the sketch as surface.Extrude depth tool: is used to control extrude by specifying some constraints.Depth value:used to specify the dimension of depth. Some extrude types do not need this.Invert tool:used to change the direction of extrude opposite to the reference direction.Remove material:this tool is used to remove the material while extruding.Thicken tool:is used to extrude as thick sheet. Thickness value can be adjust by entering the value in box (just right to the thicken tool). The invert tool next to the thicken tool is used to specify the direction of thickness by three ways.1. One side2. Both sides: thickness will be symmetric to the sketch boundary.3. Other side

When we click at the extrude depth tool a drop down menu will open in which you can see the following icons representing the specific conditions for extrude.one thing you should note that these option will be available when you will try to make extrude on existing surface or model.1) Blind:this is the default option. In simple words the depth is blind for program and we have to provide it.2)Symmetric:This option provides you the equal extrude on the both side of sketching plane.3)To next:using this option you can stop extrude to very next surface that extrude encountered. Depth dimension is not required for this option4)Through All:This option will generate extrude that through to the whole model. Depth dimension is not required.5)Through until:This option will cause extrude to stop at the specified/selected surface and section must pass through the selected surface.6)To selected:it is just like the through until option except that sectiondoes nothave to pass through the selected surface.

Insert plane parallel to extrude serfaceExtrude with the shape of cam profile as shown

Make liner pattern of above extruded feature