The Application of Pro/ENGINEER in CADCAM SUHAIRI BIN AHMAD Mechanical Engineering Department Politeknik Tuanku Syed Sirajuddin 02600, Arau, Perlis MALAYSIA *e-mail:
[email protected] web: http://www.ptss.edu.my ABSTRACT The principle of CADCAM has been widely used in manufacturing sectors at present. This study reviews the method of application in using Pro/ENGINEER to fulfill the requirements of CADCAM system. Based on the observation and practice done in PTSS CADCAM Lab, there are 4 stages involve in integration of Pro/ENGINEER into CADCAM which are manufacturing model creation, manufacturing setup, tool path creation and machining. The study also identified the strategy to transfer the reference model into the manufacturing environment and create workpiece materials from Pro/ENGINEER feature toolbar. There is a hope that these findings will encourage people who have interest in this academic to further the study of Pro/ENGINEER applications and provide the basis for enhancing and developing a better understanding of CADCAM among PTSS staffs and students. These results are certainly beneficial to the PTSS management in terms of engineering education improvement and engineering profession. Key-Words: - application software, parametric software, CADCAM, Pro/ENGINEER
1 Introduction Application software is a computer program that functions and is operated by means of a computer, with the purpose of supporting or improving the software user's work. In other words, it is the subclass of computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform. This should be contrasted with system software or computer services processes integrators, which is involved in integrating a computer's various capabilities, but typically does not directly apply them in the performance of tasks that benefit the user. In this context the term application refers to both the application software and its implementation. An application therefore differs from an operating system, a utility, and a programming language. Depending on the work for which it was designed, an application can manipulate text, numbers, graphics, or a combination of these
elements. Some application packages offer considerable computing power by focusing on a single task, such as word processing; others, called integrated software, offer somewhat less power but include several applications. [1] There are many subtypes of application software such as educational software, simulation software and product engineering software. Product engineering software is used in developing hardware and software products. This includes computer aided design (CAD), computer aided engineering (CAE), computer language editing and compiling tools, Integrated Development Environments, and Application Programmer Interfaces. Solid modeling is a technique for representing solid objects suitable for computer processing. Other modeling methods include surface models and wire frame models.[2] Primary uses of solid [1]
modeling are for CAD, engineering analysis,[3] computer graphics and animation, rapid prototyping, medical testing, product visualization and visualization of scientific research. Solid modeling software originally used either constructive solid geometry (CSG) or boundary representation (B-REP) techniques to define solid shapes.[4] Beginning in the late 1980s, software developers began applying higher-levels of abstraction to solid modeling construction techniques. The first of these techniques, called parametric feature-based solid-modeling, was introduced in commercial software by Parametric Technology Corporation in September 1987.[5] These approaches made solidmodeling software easier to use and increased its acceptance among mechanical engineers.[6] A parametric feature based modeler is a Computer-aided design (CAD) software package that allows designers to define shapes using geometric features instead of the CSG or B-REP techniques. Features are higher-order CAD entities. For example, if an engineer designs a 3D brick with a hole in it, the hole is considered a feature in the brick. Parametric feature based modelers use change states to maintain information about building the model and use expressions to constrain associations among the geometric entities. This ability allows a user to make a modification at any state and to regenerate the model's boundary representation based on those changes. This ability is called a transmigration operation. Computer-aided design (CAD) is the use of computer technology for the design of objects, real or virtual. The design of geometric models for object shapes, in particular, is often called computer-aided geometric design (CAGD). However CAD often involves more than just shapes. As in the manual drafting of technical and engineering drawings, the output of CAD often must
convey also symbolic 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, or solids in threedimensional ("3D") objects.[7] While computer-aided manufacturing (CAM) is the use of computer-based software tools that assist engineers and machinists in manufacturing or prototyping product components. Its primary purpose is to create a faster production process and components with more precise dimensions and material consistency, which in some cases, uses only the required amount of raw material (thus minimizing waste), while simultaneously reducing energy consumption. CAM is a programming tool that makes it possible to manufacture physical models using computer-aided design (CAD) programs. CAM creates real life versions of components designed within a software package. CAM was first used in 1971 for car body design and tooling. Integration of CAD and CAM environment requires an effective CAD data exchange. Usually it had been necessary to force the CAD operator to export the data in one of the common data formats, such as IGES or STL, that are supported by a wide variety of software. The output from the CAM software is usually a simple text file of G-code, sometimes many thousands of commands long, that is then transferred to a machine tool using a direct numerical control (DNC) program. Pro/ENGINEER is a parametric, integrated 3D CAD/CAM/CAE solution created by Parametric Technology Corporation (PTC). It was the first successful, parametric, featurebased, associative solid modeling software on the market. The application runs on Microsoft Windows and Unix platforms, and provides [2]
solid modeling, assembly modeling and drafting, finite element analysis, and NC and tooling functionality for mechanical engineers. Pro/ENGINEER, integrated 3D CAD/CAM/CAE solution, is used by discrete manufacturers for mechanical engineering, design and manufacturing. It was created by Dr. Samuel P. Geisberg in the mid-1980s, Pro/ENGINEER was the industry's first successful parametric, 3D CAD modeling system. The parametric modeling approach uses parameters, dimensions, features, and relationships to capture intended product behavior and create a recipe which enables design automation and the optimization of design and product development processes. This powerful and rich design approach is used by companies whose product strategy is family-based or platform-driven, where a prescriptive design strategy is critical to the success of the design process by embedding engineering constraints and relationships to quickly optimize the design, or where the resulting geometry may be complex or based upon equations. Pro/ENGINEER provides a complete set of design, analysis and manufacturing capabilities on one, integral, scalable platform. These capabilities include Solid Modeling, Surfacing, Rendering, Data Interoperability, Routed Systems Design, Simulation, Tolerance Analysis, and NC and Tooling Design. Companies use Pro/ENGINEER 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 in Pro/ENGINEER enables users to make changes in the design at any time during the product development process and automatically update downstream deliverables. CADCAM application is widely used by the manufacturing industries today. There are various methods or approaches that can be utilized in order to produce the G-code (NC code) for machining purposes. However, what are procedures take place if parametric feature-based modeling software like Pro/ENGINEER is used. What are the basic procedures involved and how it can be exercised to create manufacturing simulation, G-code generation and numerical control machining.
2 Research Methodology 2.1 Manufacturing process is divided into 4 stages as shown in Figure 5. The preparation of manufacturing model involves a combination of design and workpiece model. Design can be done in .prt format in solid modeling application and bring into the manufacturing environment through 3 options in Figure 1 .While a workpiece material can be created by using 4 options that provided in feature toolbar in Figure 2 . Figure 1: Import Reference Model into Manufacturing Options (Assemble, Inherit and Merge)
Figure 2: Create Workpiece Options (Automatic ,Assemble, Inherit, Merge and New)
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In manufacturing environment setup, users have to define tools and workcells configuration. Based on tools and machine selected, machine operation can be justified. For this study, researcher will only discussed the preparation of G-codes codes of NC machining using pocket milling. The model is shown in Figure 4.
simulation and the real machining have the same arrangement. For tool path generation, it is only possible if the manufacturing model and manufacturing setup are completed. Later, the configuration is ready for tool path creation. Create the tool path required based on the machine operation and best practices for manufacturing situations.
These are the following tool configuration and machining parameters needed for the manufacturing of this model “POCKET POCKET.PRT” Cutting Tools Dia. 10 mm End Mill
Cutting Feed 100 mm/s
Position on Turret
Stock Size (mm)
Stock Material
1
300.0 (Length) x 300.0 (Width) x 50 (Height)
Nylon
Step Depth
Step Over
Spindle Speed
5 mm
500 rpm
3 mm
Figure 3: Tool and Machining Parameters
Figure 5:: Manufacturing Process Overview in Pro/ENGINEER (Courtesy of PTC)
Figure 4: Manufacturing Model (part to be machined)
Users also need to define the working coordinate system G54 by applying Machine Zero position in order to confirm that the
After completing the tool path creation, run the accomplished manufacturing sequences using Vericut or simulation in order to make sense of the movement. The NC sequences created are required to post processed into Machine Code de Data (MCD) using the predefined post processor that suitable for the machine. The real workpiece and necessary tools on the workcell or machine need to be set up. Calibration of G54 on the machine based on the coordinate system that [4]
is setup in the manufacturing model is essentials. Transfer the NC codes into the controller and test run the program. Satisfy with the dry-run and run the program with the necessary coolant if required.
3 Results and Analysis 3.1 Generic Steps for Preparing a Manufacturing Model in Pro/ENGINEER Wildfire 4.0 In this application, Pro/ENGINEER Wildfire 4.0 is being used to create the manufacturing model. In order to prepare the manufacturing model, user will have to prepare the reference model. This will include all the necessary features required for the finished model. User will have a choice of creating workpiece automatically or manually. Automatic workpiece creation is using the silhouette of the model to create either a block or a bar. Similarly, if the finished model is derived from a casting, then the workpiece for this type of models have to be created manually and assemble it to the reference model. User has to periodically save the model throughout the creation process. This is to avoid unnecessary data lost if the computer or program crashes due to memory timed out during complex NC tool path calculation.
3.1.2 Manufacturing Setup User needs to select Mfg Setup from the menu manager to set up the manufacturing environment required for this mfg model.
3.1.1 Manufacturing Model Creation User needs to start Pro/ENGINEER Wildfire 4.0 and creates a new manufacturing file. Place an appropriate name for the .mfg file and make sure that type is set to Manufacturing and sub type is set to NC Assembly. If you have previously set metric (millimeters) as the default template, then select OK otherwise, uncheck the Use default template in the dialog box. Then ensure that mmns_mfg_nc template is selected and select OK in the File Options Dialog box.
An Operation Setup Dialog box will appear indicating that the NC Machine, Machine Zero Coordinate System will be required to be identified. Retract references can be indicated as well, however it is optional as user can set separate retract references for different NC sequence.
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User needs to select the machine tool setup icon . A machine tool setup dialog box will appear. In this dialog box, user will be required to specify the machine configuration such as number of axis and machine type. Other optional setting will be pprint and cutting tools. After completing selection of machine and its required configuration in Machine Tool Setup Dialog Box, user complete and close the dialog box by selecting Apply and OK. 3.1.3 Tool Path Creation In this section, user will create the NC sequences. This section is only possible if the manufacturing model & setup are completed. In order to create a NC sequence, select Machining > NC Sequence > New Sequence > “Choose Required NC Sequence” > “Select Required Axis for the NC Sequence” > Done
The required information for the creation of this NC sequence has a green check-mark next to it. It is automatically checked by the system. Additional setup required can be checked by the user. Pro/ENGINEER will go through each of them following the sequence, for example Tool comes before Parameters, so user will see the tool creation dialog box then after completing the tool then the dialog box for parameter will appear.
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A number of NC Sequences needs to be created before the manufacturing model is complete. User needs to understand the relationship between the sequence, tool used, and parameter for the cut affects the outcome. Experience in this area will definitely be of help. In-Process Geometry or Material Removal is an optional process that can be done after the creation of NC Sequences to view the remaining material left after the NC Sequence. After setting up the required basic information to complete this NC Sequence such as cutting tool, parameters, geometry to machine by using Mill Window, Mill Volume, Mill Surface or Surface from the Reference Model, user can play the tool path, either through wireframe path or 3D material removal or better known as Vericut. Should the tool path cannot be played, it means that there are required information to successfully create the tool path is missing, insufficient or not valid.
Cutter Location (NCL) files is created when the tool path is generated. This is the coordinate location which Pro/ENGINEER locates the tool on. This is similar to G-Code but not readable on the CNC machine. In order for the G-code to be generated, the NCL file has to be post processed through a post processor which will convert the NCL file into a .txt file that is readable in the respective CNC controllers. To do this, first the user needs to setup the corresponding post processor files location in the config.pro file. The name of the configuration is “gpostpp_dir”. User has to ensure that the full directory address is used to identify the location of the post processor files. On the Menu Manager select the following: CL Data > Output > Select One > “Operation” / “NC Sequence” > Done
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Then select File > MCD File > Done User needs to select the required Post Processor to be used to transform the NCL file into G code. See the bottom of the Pro/ ENGINEER window to see the name for the post processor. Then enter the required program number and the post will be generated. The G code file should be created in the same folder where user saved the NCL file. User has to look out for the extension such as .tap, .nc, .h and other commonly used extensions for G code. There may be more to the list of the post processor compared to what is shown here below.
User will require saving a copy of the NCL file in the working directory or the folder which the manufacturing file resides. Then select Done on the menu manager for PP Options
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are 4 stages involved in these applications which are manufacturing model creation, manufacturing setup, tool path creation and machining using CNC controller. For this particular part, only a single tool and machining is being considered. In further studies, there are suggestions to use multiple tools and variation of milling processes since the real machining usually involve a complicated way to machine a part. There are questions of factors that affecting the machining time for particular cases. It is also a need to investigate the machinability of workpiece materials using end milling process. 3.2 The Machine Code Data (G-codes)
References:
The details of this machining part programming are shown in Appendix 1.
[1] Ceruzzi, Paul E. (1998). "A History of Modern Computing", MIT Press.
3.3 The Machining Characteristics of Pocket Milling for the Given Part
[2] Campbell, Kelly Martin (1996). "Computer: A History of the Information Machine", Basic Books.
i. ii. iii.
iv.
Machining Time – 401.494 minutes Axis Types – 3 Axis Tool Travel Envelope: Xmin – 30.0002 mm Xmax – 270.0000 mm Ymin – 30.0013 mm Ymax – 269.999 mm Zmin – 15(-ve) mm Zmax – 50 mm NC Sequence Parameters: Scan Type – Type_3 Cut Type – Climb
4 Conclusions In conclusion, the procedures of using Pro/ENGINEER in CAD/CAM environment have been successfully developed. The application of Pro/ENGINEER in CAD/CAM system can be done for the purpose of machining a part using pocket milling. There
[3] Machover, Carl (1996). "8". in Joanne Slike. The CAD/CAM Handbook (1st ed.). McGraw-Hill. pp. 69. ISBN 0-07-039375-3. [4] LaCourse, Donald (1995). "2". Handbook of Solid Modeling. McGraw Hill. pp. 2.5. ISBN 0-07-035788-9. [5] LaCourse, Donald (1995). "2". Handbook of Solid Modeling. McGraw Hill. pp. 2.3. ISBN 0-07-035788-9. [6] Weisberg, David (2008-09). "The Engineering Design Revolution". David E. Weisberg. pp. 16-5. http://www.cadhistory.net/chapters/16_Par ametric_Technology.pdf. Retrieved 2009-0626. [7] Farin, G.: A History of Curves and Surfaces in CAGD, Handbook of Computer Aided Geometric Design [9]
