Feature Recognition

Unfolding Shell Models

2010-11-29T09:39:00.000-08:00

For designing design sheet metal models, some designers use solid modeling commands rather than sheet metal commands. Such models are made initially using solid modeling commands and then shell command is used to get uniform wall thickness and finally the model is converted into a sheet metal model. Such models when received by manufacturing vendors are often not suitable for unfolding. There are two reasons for this (i) unripped edges and (ii) sharp bends. To handle such cases, Sheet Metal Feature Recognition library (SMFR) provides options like (i) ripping and (ii) insert bends.

Model with an Unripped Edge and Sharp bends

For example consider the model shown in the figure above. Faces A and B are connected together, whereas to unfold the model, both these faces need to be unconnected. The unripped edge shown in the figure needs to be ripped. Sheet Metal Feature Recognition library provides an option to rip such edges in imported solid models. The edges to be ripped and the rip gap are to be provided for ripping. The imported model after ripping is shown below.

Model after Ripping

The model has two sharp bends with inner radius and outer radius as zero. For accurate unfolding and sheet metal bending, inner radius has to be specified. Sheet Metal Feature Recognition library provides an option to automatically convert such sharp bends into cylindrical bends. The sharp bend and the inner radius are to be specified for automatic conversion. SMFR can also detect sharp bends automatically for such conversion. The imported model after conversion of sharp bends into cylindrical bends and flat pattern obtained using SMFR are shown below.

Model after Conversion of Sharp Bends into Cylindrical BendsFlat Pattern

Unfolding imported models with flanges

2010-06-09T06:14:00.000-07:00

Unfolding imported sheet metal models in CAD modelers always has limitations. Imported models having flanges as that shown in the figure below are not possible to unfold in most of the CAD modelers.

The latest version of Sheet Metal FR now has the capability to unfold imported models with such flanges. By enabling the patch stamps option, the above imported model can be unfolded with ease as shown below.

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Unfolding sheet metal models with stamp features

2010-02-22T02:14:00.001-08:00

Unfolding sheet metal models with stamp features is handled in different ways by different modelers. Louver, dimple, bridge, lance and features that require forming are referred as stamp features in this context. For example, the model shown below contains few stamp features.

FR unfold has two options for unfolding.
(1) Unfold bend features : This option automatically recognizes all the bend features and unfolds only bends. All other features including stamp features remain as such as shown below.

(2) Unfold with patch stamps : This option automatically recognizes bends and stamps. Unfolding is performed by unfolding bends and patching stamps as shown below.

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Cutout Recognition and Unfolding in Sheet Metal

2010-01-24T23:35:00.000-08:00

In sheet metal models, generally various types of cutouts are used. Even holes are special type of cutouts. There are different types of cutouts such as Internal cutouts, External cutouts, Multiface cutouts. Typical examples are shown in the figure below.

Internal cutouts are those which lie completely in a single plane. External cutouts are generally referred as notches and these cutouts lie along the boundary.

Multiface cutouts spread across multiple faces as shown in the figure below.

Sheet Metal FR identifies all these features and even gives flat patterns as shown below.

Application of Feature recognition in Manufacturing

2009-08-11T02:48:00.000-07:00

Why do we need Feature Recognition when we already have Feature Based Modeling Systems (FBMS)?!!

When we design a model in FBMS, we use Extruded Boss, Extruded Cut, Revolved Boss, Revolved Cuts, Loft, Sweep, etc. These are all design features. Even Holes, Countersunks, Counterbores can also be made using revolved cuts. But in order to manufacture the component, we need to infer manufacturing features from design features so that suitable CNC canned cycles can be chosen. This is a manual activity. Geometric’s Manufacturing View FR provides an automated tool for this activity. MfgView FR automatically extracts manufacturing features like Standard Hole types, Pockets and Slots. Even islands in pockets and slots are identified and further parent child relationships are also provided. So by using MfgView FR, a task that would take hours when done manually can be reduced to seconds.

Should Costing using Automatic Feature Recognition

2009-07-13T03:52:00.000-07:00

What is Should Costing?

Should costing is the process of determining what a product should cost based upon its component raw material costs, manufacturing costs, production overheads, and reasonable profit margins.

Benefits of Should Costing

Transfers pricing power form a supplier to a purchaser
Identifies and eliminates inefficiencies and diseconomies
Identifies cost reduction opportunities in the supply chain

Manual Costing Process

Reading 3D model assembly
Manual interpretation of features
Mapping features to specific processes
Determining processing time for each feature based on the dimensions and other parameters
Determining processing cost for each feature based on time and type of processes

Automated Costing Process

Automatic reading of 3D model assembly
Automatic Feature Recognition from individual parts
Rule based feature mapping to specific processes
Automatic processing time determination for each feature
Automatic processing cost determination for each feature

Benefits of Automated Costing

Faster Costing – Reduction of time and overheads involved in cost estimation by 90%
Accurate Costing – Manual errors and approximations are avoided
Competitive Edge – Fast and accurate costing gives the power to negotiate for better prices.
Optimized Product Costing – Multiple product and manufacturing scenarios can be analyzed to get an optimized product design.

For Geometric's Should costing services click here

What is History free editing? How to check whether a 3-D modeler is history free?

2009-06-13T06:21:00.000-07:00

Let me explain history free editing with a simple example. Make a model as shown in Fig A as per the sequence given below.
1. Make a cube (100x100x100).
2. Make a central hole (50 Dia. x 75height) from the bottom of the cube.
3. Make another cube (75x75x75) on top of the first cube.

Fig A. Test model

Now, try to modify the height of the cylinder from 75 to 150. In a history dependent modeler, the height of the cylinder after modification will only be 100 instead of 150 as shown in Fig B. Whereas, in a history free modeler, the height of the cylinder after modification will exactly be 150 as shown in Fig C.

Fig B. Modification in a
History Dependent Modeler

Fig C. Modification in a
History Free Modeler

The faulty modification caused in history dependent modelers is due to the fact that model re-evaluation is based on the chronological feature creation order i.e. a new boundary model is created by sequentially re-executing the operations in the modified history. Hence, even though the modified height of the cylindrical hole is 150, on subtracting the cylindrical hole with a cube of height 100, the hole becomes a through hole in the first cube. Then the second cube is placed on top of the first cube.

Whereas in history free modelers, the modification is handled in a different manner that only the immediate faces connected to the modified face/dimension are modified. Even though, such modelers are powerful in history free modification, model modification requirements such as converting a through hole/pocket into a blind hole/pocket or vice versa is better accomplished using feature information.

Geometric's Feature Recognition

2009-05-18T11:06:00.000-07:00

Feature Recognition is a state-of-the-art patented technology from Geometric with more than 100 man-years of research and development. Feature Recognition extracts a wide range of features from solid models and finds applications throughout the product lifecycle like modeling, finite element analysis, machining, inspection, process planning and cost estimation. FR from geometric is the most preferred feature recognition engine, selected by leading CAD/CAM vendors, as FR provides high quality, easy to use API interface and cost-effective to implement.

Feature based design received strong emphasis from the industry, with the aim to utilize feature data in downstream design and manufacturing applications. The time invested in developing parametric feature based designs is expected to have significant pay-offs in such automation. However, feature based design systems employ form/design features rather than manufacturing features, due to which further feature inference is often required for specific applications. Also, in contract manufacturing firms, majority of designs are imported geometry in neutral formats, where valuable feature information is lost. The model is generally received as a dumb solid and editing the model or inferring feature information for downstream applications becomes difficult. Further when a model designed in feature based CAD platforms has to be ported in other tools like analysis softwares or manufacturing softwares, etc., the model is often loaded in neutral formats, which is again a dumb model.

Geometric’s Feature Recognition technology helps to develop a smart, parametric feature based models from imported B-Rep solids. Feature Recognition breathes life into 3D CAD (solid) models and catalyses data re-use and interoperability.

Feature Recognition (FR) Technology

Geometric’s FR technology automatically identifies features from 3D models. It provides feature tree information and respective feature parameters, parent-child relationship in case of intersecting features and alternate interpretations of features. Features that are not recognized automatically are recognized using an optional interactive feature recognition mode. FR also supports local feature recognition where features from a particular region are identified. Further, it supports user-defined features. FR consists of three different libraries; namely, Design View FR, Manufacturing View FR and Sheet Metal FR.

Design view FR extracts design features from dumb models to facilitate model editing and to create variant designs. It can automatically identify various design features such as holes (simple, taper, counter-bore, counter-sunk, counter-drill, split holes, hole-chains), fillets, chamfers, extrudes (drafted, cut, boss), revolves (cut, boss) ribs, drafts, lofts and sweeps. FR facilitates recognition and suppression of features. During analysis, suppression of certain features like, fillets, chamfers and small holes can easily be done with feature data from FR. This helps to improve the mesh quality and to reduce analysis time. With feature data from FR, dimensioning can be automated and further it facilitates Geometric Dimensioning and Tolerancing.

Manufacturing view FR extracts manufacturing features and provides information suitable for downstream applications like CNC code generation, machining sequence generation, process planning, inspection planning, etc. It extracts a variety of features that can be processed by Milling, Turning, Mill-Turn and WireEDM. List of manufacturing features identified include holes (simple, taper, counter-bore, counter-sunk, counter-drill, split holes and hole-chains), hole patterns (linear, rectangular and circular), fillets, chamfers, pockets (blind, through, drafted, filleted and chamfered), slots (simple, drafted, filleted and chamfered), islands, machinable volumes, machinable slabs, intersecting features, external turned profiles, internal turned profiles, turned grooves (filleted, chamfered, vee, radius and dovetail), slots and pocket in turned profiles (mill-turn). Feature data from FR helps to use standard machining cycles in CNC code generation for drilling, counter-sinking, counter-boring, pocket machining, etc. It is also helpful to identify and cluster the features to be machined in a particular setup. The parent child relationship of features from FR further helps to determine the machining sequence to be adopted. It also helps to minimize the number of setups required. FR can be used to identify inspection features, which can be helpful in probe movement programming and inspection planning. With feature data from FR, design checks such as use of standard hole sizes, minimum distance between various features, etc., can be ensured. Such checks help to avoid costly design errors which are difficult to tackle during manufacturing. Features that are costly to manufacture can also be easily identified using FR, which can be helpful in cost optimization. FR data can be further used for manufacturing cost estimation.

Sheet Metal FR extracts features from a sheet metal perspective along with unfolding. It can also handle Tramoggia flattening. Various features identified include walls, bends, holes, counter-sunk, counter-bore, flanged holes, cutouts, flanged cutouts, notches, flanges (open hem, closed hem, teardrop hem, roll hem, jog flange, edge flange, contour flange), stamps (louver, lance, bridge, dimple, bead)and ribs. For sheet metal models, FR helps to edit models for creating variant designs and to create flat patterns. Feature data is useful in selecting tools required for specific features, tool availability checking, design for manufacturing, determining the punching sequence to be adopted, determining an optimal bending sequence and cost estimation.

Features

Recognizes features automatically and generates feature tree
Provides parent-child relationship for intersecting features
Provides alternate interpretation of features
Provides control to recognize features interactively or on a local region
Supports standard and user-defined features
Supports kernels including Parasolid (V18, V19, V20), ACIS (R16, R17, R18)
Supports CAD APIs like SolidWorks (2008, 2009), CATIA V5
Is available as 32 bit and 64 bit Static Library and DLL

Benefits

Facilitates integration of CAD and CAM
Enhances interoperability, recreates design intent, and improves process automation thereby reducing time-to-market
Improves productivity with minimal manual intervention
Enables automatic recognition of machinable features
Reduces errors in G-code generation through feature based machining
Provides scalability for varied component manufacturing
Allows 3D data reusability throughout product development

Applications

Design (Computer Aided Design) – Model editing, feature suppression, creating variant designs, auto dimensioning, geometric dimensioning and tolerancing, and flat pattern development from dumb solids for sheet metal (SM)

Manufacturability Analysis (Design for Manufacturing) – Design check, and manufacturing feasibility check

Analysis (Computer Aided Engineering) – Feature suppression (suppression of fillets, chamfers and holes) to improve mesh quality and to reduce analysis time

Process Planning (Computer Aided Process Planning) – Machining sequence generation, tool selection, setup planning, punch sequencing (SM), bend sequencing (SM)

Machining (Computer Aided Manufacturing) – CNC code generation (Milling, Turning, Mill Turn, WireEDM, PunchPress, PressBrake, etc.)

Inspection (Computer Aided Inspection) – Coordinate Measuring Machine (CMM) probe movement programming, and inspection planning

Costing – Design analysis for cost optimization, and cost estimation