Hack and whack no more

Delphi Technologies has introduced what it is calling ‘Horizontally Structured Modelling’ at the sixth annual Pacific Design & Manufacturing show in Anaheim, CA.

At its core, Delphi’s concept is quite simple. It begins with the idea that a flexible and forgiving product design process enables the streamlining and flexibility of all processes that follow.

‘Our goal was to eliminate islands of automation within the company’s product design and manufacturing process,’ says Delphi Staff Manufacturing Engineer, Pravin Khurana.

To achieve this result Delphi inventors had to first look beyond the standard CAD/CAM training techniques and documentation supplied by vendors. They realised there was an inherent limitation in the way that traditional feature modelling processes (vertical feature modelling) used feature dependency, meaning that the creation and positioning of each structural feature in a design was dependant on the feature that was placed on or positioned before it. This method resulted in a design with multiple parent/child dependencies between features that could only be edited on the whole, and not according to the specific feature that needed to be changed – a problem commonly referred to as ‘hack and whack’ editing.

Delphi’s answer to the ‘hack and whack’ school of design is horizontally structured modelling. This technique allows engineers to capture design intent in a feature-based model without the need to create parent/child dependencies. Using Delphi’s method, if feature number 7 needs to be deleted, suppressed or reordered, the design engineer is free to isolate that feature and change it. Traditionally, in a vertically structured model, the program would disassociate or delete all of the features in the series that follow number 7 and the design engineer would be forced to recreate the lost relationships manually. Not only is this time consuming, but it also opens the door for errors and poor data integrity.

In the words of one inventor, Manufacturing CAD/CAM Coordinator, Diane Landers, ‘Feature dependencies inherently create big problems with downstream applications since product design is constantly evolving.’ Just how big is explained by the 50% reduction in model creation time and the 90% reduction in model editing time that Delphi realised using their new method for manufacturing process design.

Horizontal modelling also provides the foundation for the development and delivery of graphic process documentation used in manufacturing to graphically capture the step by step machining or assembly process. Delphi refers to this invention as Virtual Manufacturing. Prior to Delphi’s invention of virtual process models, there were two main methods of creating this manufacturing process documentation. Both were time consuming, and in turn costly, and both risked a loss of data integrity.

The previous method used by Delphi involved re-creation of geometry for process design in a 2D CAD system. This first method began with a production solid model which was then recreated manually in a 2D CAD system. The solid model was generally sent to an outside source where the model geometry was re- created in 2D and used to produce the in-process geometry displayed in the process sheets for manufacturing. Delphi lost valuable time waiting for the process sheets to be delivered, and since the design had been re-created off- site, even more time was spent verifying the process sheets’ accuracy before manufacturing could begin. It’s estimated that nearly 95 percent of the industry still relies on outside sources to produce process sheets.

There was some improvement in process sheet creation using Unigraphics’ traditional method of non-associative models, but it was complex to learn, and maintaining the separate solid models was a nightmare, according to Delphi inventor Khurana.

For example, a manufacturing component with 10 operations could require 40 solid models (multiple files). Based on Delphi’s new technique, Virtual Manufacturing, associative process models are created in a single file. And because the product model it is based on contains independent features, a change to any one of them results in an automatic update of the master process model and all of the operations associated with it.

Put simply, a single file instead of multiple files means improved data integrity and quicker, automated changes. According to Nady Boules, Director, Dynamics Innovation Center, the new approach has significantly reduced the costs for product and process design. For example in one case a 100-hour process sheet creation time was reduced to 24 hours. ‘We saw a 75% reduction in real time,’ he stated.

Delphi’s new methodology has enabled the development of other integrated operations like Automated Machining Process Design, NC/CMM Tool Path Generation, MBMR Metal Removal Process Simulation and Math Based Tool Drawings. It has also allowed them to perform more reliable analysis during process and product design, cutting out analysis time post-production.

In addition to improving these operations, inventors at Delphi have also been working on two new software technologies – a system that performs virtual machining with complex, non-standard tool shapes, creates virtual prototypes and performs automated virtual inspections; and 3D Packaging Optimisation Software which streamlines the process of packaging design and ultimately reduces wasted container space.

Delphi has patent applications filed to protect its Horizontal Structured Modelling Methodology and is marketing it to other users of high-end 3D CAD/CAM systems through training and licensing arrangements.

On the web