Switching to new computer numerical control (CNC) software has helped one marine components manufac-turer not only increase machining productivity, but also reduce its overall programming time.

In the past Springfield Marine used surface model based CNC software with limited flexibility in defining roughing operations that made it necessary to keep feed rates below optimum levels. The company then switched to a new generation of solid model based software that provides higher machining productivity by generating more efficient toolpaths. This new software au-tomatically generates roughing routines that walk around the outer boundary of the part, eliminating the need for plunging. The new routines make it possible to increase the feed rate from 75 inches per minute (ipm) to 200 ipm in machining mold cavi-ties.

By automating many routine tasks, this new software has also reduced pro-gramming time by at least two-thirds, on the average, over the company’s entire pro-gramming workload. For example, it automatically recognizes and catego-rizes features in a solid model and stores machining operations that can later be applied to create toolpaths simply by dragging and dropping them onto features.

“We have seen substantial improvements in machining productivity as well as reductions in programming time since implementing ESPRIT CNC software from DP Technology,” said Mike Mawhiney, Product Develop-ment and Information Technology Manager for Spring-field Marine Company in Nixa, Missouri.

Change in CNC Software Helps Reduce Cycle Time and Speeds Programming

Leading marine seating and hardwareSpringfield Marine is a leader in the innovation of seat-ing and hardware products for the marine industry, even though the company lost its complete facility to a devastating fire in November 1999. The fire destroyed the company’s entire manufacturing plant, yet within two weeks it was back in business by renting space and machines from other companies in the area.

Springfield Marine produces removable pedestals, seats, non-removable pedestals, table pedestals and

tables for the marine industry as well as many other products. The company makes many different styles of pedestals that are used in bass boats, pontoons, leisure boats and a large va-riety of fishing boats and also provides custom manufactur-ing services. Most of these products are built from die cast or sand cast aluminum and machined to final specifications. Some of the pedes-tals are fixed while others can be adjust-ed either manually or hydraulically.

The company uses a 60-30, three-axis

Fadal machining center and a Mori Seiki single-spindle lathe to produce molds, prototypes and machine cast-ings to specifications. In the past, the company used a surface model based CNC software to generate programs for these machines. This software could not read the solid models used to define the part geometry, so after adapting the design for manufacturing, the company’s programmers exported a wireframe IGES file and read it into the CAM software. The previous software read surface, but not solid, geometry so the programmer exported the CAD surfaces into the IGES

The sand cast swivel pattern being programmed in ESPRIT

neutral file format. The old CNC software read in the surface geometry without difficulty, but the program-mer then had to convert the individual surfaces into a continuous volume ready for defining machining paths. A considerable amount of manual rework was usually required because entities often overlapped, didn’t con-nect to one another or were lost in the IGES translation. On more complex 3D parts, it often took several days to simply modify the geometry to the point where the programmer could begin to create the toolpath. In many cases, the amount of time required for touchup made it faster to simply re-create the geometry from scratch.

Upgrading to new CNC softwareSpringfield worked with CIM Integrators, Inc., a com-pany that specializes in selling and supporting CNC software, to improve their programming processes. CIM Integrators recommended ESPRIT from DP Technology because it can read and automatically recognize fea-tures in native solid models and it allows programmers to store common machining operations as technol-ogy pages that can be recalled and quickly applied to features. The software also provides a wide range of roughing routines that circumnavigate the part at a con-stant depth of cut, avoiding plunging operations and making it possible to run at much higher feed rates.

Mawhiney provided an example of a how the use of ESPRIT has transformed the company’s programming operations. The part is a pattern for a seat swivel, used to produce a mold for sand-casting the part. The part was originally designed using AutoCAD. Mawhiney im-ported the DWG file into SolidWorks where he created a solid model that fully defined the part geometry. Spring-field Marine’s contract machining customers commonly provide STEP and Parasolid files which its engineers

import into SolidWorks. The ability of ESPRIT to accept solid geometry from SolidWorks and other popular computer aided design software eliminated the need to generate patches and stitch surfaces together, which is usually required when surface geometry is transferred.

Generating toolpathsMawhiney then created a boundary around the part rep-resenting the parting line of the pattern. The geometry was relatively simple so Mawhiney manually defined the features, including selecting the contoured surface as a single feature. For more complex parts, he typically utilizes ESPRIT’s automatic feature recognition capabil-ity to catalog the features in the solid model. Automatic feature recognition eliminates the need to manually select individual features such as pockets, islands, holes, bosses and grooves. The software automatically organizes each feature into a tree structure and the programmer can rearrange the features as desired to promote efficient machining.

Mawhiney then selected pre-defined technology pages to machine each feature. Each technology page in-cludes a tool and typical machining parameters, includ-ing cutting speed, feed rate and depth of cut. In this case, he selected a one-inch roughing end mill to rough out the cavity at 10,000 rpm, 0.200 inch depth of cut and 175 inches per minute feed rate. He also specified that the roughing operation leave 0.015 inch of stock for finishing. The software automatically generated a roughing pass that moved around the part at a constant z-axis level, maintaining a constant feed rate and depth of cut. This approach reduces time-wasting z-axis movements and keeps the tool continuously engaged in the material. The software automatically determined what areas of the part could be cut with the large-diam-

A sandcast aluminum swivel produced by Springfield Marine

The Springfield Marine facility in Nixa, Missouri

eter tool and backed off in areas that required a smaller radii tool in order to avoid gouging.

Simulating and validating machining operationsNext, Mawhiney defined a series of finishing operations using progressively smaller ball nose end mills of 1⁄2 inch, 1⁄4 inch, and 1/8 inch diameters. The 1/8-inch end mill was needed to cut out a series of teeth on the side of the swivel that locks the seat into position. When he had defined the final finishing operation, he viewed a simulation that showed every machining operation and made it easy to visualize exactly how the program will operate at the machine. He viewed each cutting tool being loaded and taking its assigned cuts along with the entire machining environment in dynamic 3D solids. He then zoomed in on the finished part to determine whether it matched the design intent. When he was satisfied with the results, Mawhiney used ESPRIT’s Universal Post Processing System to generate G-code. ESPRIT’s extensive post processor library contains posts for a large number of the more popular machine tools and the software includes a post processor generator to modify existing posts or create new posts from scratch.

Mawhiney concluded that the switch to ESPRIT has provided several major benefits. “First and foremost,

ESPRIT’s roughing routines have helped us improve machining productivity, which helps us more efficiently utilize our most valuable assets, people and production machinery. In the normally time-consuming operation of roughing out mold cavities, we have seen a better than two-to-one improvement. Another major advantage is that ESPRIT saves time in programming both simple and complex parts. It can read the native file format of our solid modeler and stores any and all machining operations so they can be re-applied whenever needed. As a result, ESPRIT has reduced the time required to program new parts to between one-half and two-thirds of what was required in the past. ESPRIT has also made it possible to easily program parts with complex contoured surfaces that were time consuming in the past. All in all, we are very satisfied with this software package and would recommend it to other companies with similar requirements.”

President/CEO of Springfield Marine Ron Mawhiney added that the major advantage from his point of view is that a prototype of a new design can be machined and tested to the American Boat & Yacht standard before investing the money in an expensive die cast or plastic injected mold.