by Chris Corbell
How Does CAD/CAM Software address the Stock Setup Process?
CAD-CAM software makes programming cnc machines faster, smarter and easier. This being the case we are taking a look at how a CAD/CAM product addresses the stock setup process. The stock setup procedure will tend to vary from product to product. Even though this is true, every CAD/CAM software product should have a Material Database as well as a method for allowing a programmer to quickly establish the stock for the part within the process of creating a job.
– Material Database
– Stock Setup Procedure
Early CAD-CAM software products were wireframe based and relied on straight line and arc type geometry for creating toolpath in order to generate an NC program for a machine tool. Modern CAD/CAM products are much more robust, allowing much more flexibility in setting up the parts stock because of solid modeling technology development and behind the scenes intelligence that allows software to recognize all of the different geometry types and deal with them correctly based on feature design.
Because of this, most CNC software has the ability to set up stock based on:
– Drawn Geometry
– Basic shapes; Cylinders, Squares, Cone etc.
– Existing Wireframe or Solid Model Geometry
– An imported STL File
In addition, the software can automatically detect the boundaries of a solid model part file and use it for setting up stock. A programmer without the ability to set up stock ends up having to guess or speculate far too much. Every single action in the creation of toolpath and simulation along with the creation of the NC program takes stock information into account. Rather than have to position CAD geometry around a fixed zero position in a workspace, the software should provide as much flexibility as possible to enable the fast and accurate set up of the stock for the part. In addition there are big benefits to being able to import a stock STL type file. An example of this would be for a casting, where the use of an STL stock in the simulation process might show any errors between the actual machined part versus the exact STL stock model. These types of benefits are designed to save time, reduce waste and automate the process of NC programming as much as possible. Another example would be setting up the machine work coordinate. Without a stock setup procedure the programmer is lost.
The Stock Wizard Solution
Wizard technology is used in BobCAD-CAM software throughout the product as a way to keep things organized, provide a standard for performing an action and basically remove the guesswork from using CAD/CAM altogether. A wizard is a series of screens that step the programmer through performing a task. In addition to Machine Toolpath Wizards, the latest BobCAD-CAM software uses Wizard technology to a allow a programmer to create the stock setup process.
The BobCAD-CAM stock wizard is far more robust allowing the creation of:
– A stock shape or type
– Use existing geometry or not
– Define the stock size
– Stock orientation
– Create any necessary stock offsets or define an extrusion direction
– Set up the Machine Coordinate using an existing origin or a user defined X, Y & Z coordinate
– Create a Work Offset number as well as a defined X, Y & Z coordinate
– Definable machine clearance plane
Workflow efficiency is also considered in the stock setup wizard which means that several critical actions are taking place without the need for any guesswork by the programmer. As the initial phase of CAD/CAM programming involves the creation or importing of the part model itself, the second phase of programming is the stock setup. Within the stock setup process there are three important aspects.
Step 1
Define the stock type. Most common types of Stock used for machining are Rectangular bar stock and Cylindrical bar stock. These two types being most common, CAD/CAM software should allow the operator/user to create them with no additional geometry needing to be created in the CAD model.
A. Wireframe geometry. Wireframe is a simple extrusion to allow for more custom shapes. For example something that started as rectangular plate and then a waterjet cut it into a shape, or it had been pre-machined.
B. Solid Model. For example, this would be the solid part model being used in the software.
C. Import a stock STL file. Solid Model and STL are typical for manufacturers with casted, pre-fabricated, or parts that have already had a lot of machining done to them. These are very good for the complex stock geometry shapes.
The stock wizard is dynamic from this selection forward into the stock definition depending on what type was selected. Once the stock type is selected, the “Next” button is selected to advance the wizard.
Having an accurate stock model does many things for the programmer. The operator/user can more accurately set up his part, the toolpath calculations can utilize the stock information to eliminate air cutting, and the simulation is more accurate and can be depended on more if the stock in the system is exactly the stock at the machine.
Step 2
The second step requires the stock to be defined. The software will automatically detect solid geometry over any existing wireframe geometry or allow the programmer to pick any existing geometry or even enter in a specified size depending on whether “Cylinder” or “Rectangular” was chosen as the stock type. This stage includes defining the stock origin. Sometimes imported CAD geometry can be placed in various positions in the workspace. The extrusion option simply tells the software to create stock extruded along the X, Y or Z axis in an X or Y direction, all depending on the part existing orientation in the software workspace. These options offer everything the operator would need to correctly create stock based off of a parts orientation/position. Lastly the operator can extend or trim cylindrical stock geometry. If “Rectangular” stock was the selected type then the offset option would reflect a rectangular shape in terms of width, height etc. If wireframe geometry is being used and a stock offset is required, then an offset of equal value could be created prior to beginning the stock wizard and used.
Step 3
The final phase of the stock setup requires the operator to create the “Machine Setup.” This is important as it affects the programming, machining operations and posting of the NC program in the end. Therefore it’s made easy to use an existing User Coordinate System (UCS) or enter coordinates to create one.
Geometric entities are automatically created to assist the programmer in selecting the machining origin. The stock is outlined by lines and points, and a center line with points is also drawn. When selecting geometry for the origin or a direction, the programmer can select these entities.
The Machine Setup phase also offers the ability to create a Work Offset and enter a Clearance Plane for the program.
When finished, the operator simply clicks the OK button to load the stock data and actually create a Machine Coordinate that is loaded into the Job-CAM Tree. This is where all of the machining operations are located. Once again, keeping everything in the job organized and easily accessible.
Getting the Best Results
When implementing CAD/CAM into your shop or adding to an already existing line of software products, you will want to make sure that these solutions are available and easy to use.
Wizards specifically address the issue of having to learn something new, programming speed and they help remove the possibility of making a costly mistake due to omission.
For more information on CAD/CAM Wizard technology or implementing powerful and affordable CAD/CAM software into your business call BobCAD-CAM, Inc. at 877-262-2231 or 727-442-3554. Visit www.bobcad.com for a free demo and look at the advantages BobCAD-CAM software can give you right from the box.
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