Shop features prototype work

Jan. 23, 2009
Navico relies on feature-based programming/ machining to speed the design and manufacture of prototype electronic cases. Navico, a Norway-based producer of marine electronics for the ...
Navico relies on feature-based programming/ machining to speed the design and manufacture of prototype electronic cases.

Navico, a Norway-based producer of marine electronics for the recreational boating segment, relies on its development facility in Tulsa, Ok., for weatherproof cases that house and protect the company’s sophisticated electronics.

To make these cases, Navico development may write as many as 30 programs per day.

Building test equipment and assembly fixtures for the company’s production plants results in producing hundreds of different parts, and working through part details and ensuring produce-ability can be timeconsuming. The shop speeds this process using Delcam Inc.’s FeatureCAM software that is strong in featurebased programming.

Feature-based programming/ machining allows the shop to create a part program using features that describe that part, from simple holes to complex pockets to turned grooves, and the machining operations are automatically generated. Feature-based machining also frees programmers from the time-consuming chore of creating and managing each machining operation. And, since there are fewer objects to manage, they can complete part programming more easily and with fewer errors.

Used as building blocks to describe a complete part, features define the shape of the part, the faces of the part, the size and shape of pockets, slots, bosses and grooves, the locations and types of holes, and more – and whether those shapes have chamfered or rounded edges. With these capabilities, Navico programmers Bill Boyette and Craig Pitts can revise a program easily by simply changing one or more individual parameters, such as depth or radius, and in FeatureCAM, the entire part is updated.

Features also describe how to produce those shapes on CNC machines – for example, how and where material removal should occur, cutting depths, whether to use climb cutting, whether to spot drill or center drill, and preferred machining strategies for roughing and finishing.

When a part is constructed of features, the CNC programming process becomes automatic. Any changes made on the feature result in the end product being automatically and constantly updated, so a change to the part never requires starting over.

With FeatureCAM, programming automation occurs not only within a feature on a part, but also between features in the part process plan.

As Boyette and Pitts create features, FeatureCAM constructs a process plan based upon analysis that reduces tool changes, rapid distances required and the amount of tools used, allowing the programmers to increase efficiency by spending less time programming.

Users of FeatureCAM draw or import their part, identify part components as features and click on simulation to create a CNC program. For each feature, the software automatically selects the most suitable tools, calculates feeds and speeds, generates tool paths and produces NC code, in a single operation.

According to Rick VonDeVeld, who heads the Navico shop in Tulsa, the shop runs fairly smoothly, in part, due to FeatureCAM. As the shop finishes and checks programs, it uploads them directly to its CNCs.

“Before you could even setup the edge finder on a manual mill, we can have the program into the CNC machine. We design in Pro-E and create programs from that. Then we upload directly to the machine tools here and globally. In theory, we are a completely paperless machine shop. FeatureCAM is great for us in 2D work and mid-level 3D work,” VonDeVeld said.

On a recent project, Boyette and Pitts overcame a few challenges with FeatureCAM to design and machine a prototype case for marine GPS electronics. The aluminum part was to be prototyped for thermal testing in another Navico location.

The shop was asked to make the prototype case from a 50 series aluminum billet that measured 12 in. by 8 in. by 4 in. The part posed a programming challenge, in part, because of its deep section that had to be machined inside and outside. And it included fins to dissipate heat.

“Because it was such a complex part, we had to upgrade our computing power and purchase some very small onesixteenth long-reach carbide end mills to get into the 5-in.-deep pockets and other cavities of the part. We uploaded to the CNC mills and machined a plastic prototype where we found and eliminated possible problems,” VonDeVeld explained.

Once the program worked on the plastic prototype, the shop bolted the aluminum billet to a jig for machining the fin, or outside, after the inside was complete. Features included a draft angle on the inside and outside of about 3 degrees and bosses and pockets blended into multiple sweeping radii.

VonDeVeld said that programming and machining time was about 4 weeks, which seems like a long time. However, he pointed out that the whole process would have taken twice as long with conventional CAM software.

Boyette and Pitts also praise the feature-based FeatureCAM in pointing out some of the software’s other capabilities they find beneficial.

These include on-screen simulations and gouge protection to avoid problems prior to loading programs into machine tools, along with the features solid or “feature to a curve” and part comparison functions.

Feature to a curve helped them to blend the many curved surfaces of the design, check its surfaces and simulate the machining so they could keep the tool where they wanted it.

Part comparison helped the programmers determine if an area needed cut further or machined less. The feature’s “stop on gouge” tool identified if a tool was going to drag across the part.

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