The nozzles used by firefighters today are far more complicated than what they seem to be on the surface. For example, the nozzles produced by Task Force Tips in Valparaiso, Ind., deliver water at constant pressure regardless of water flow. This design increases the nozzle complexity, creating some interesting manufacturing challenges.
The molds used to make TFT nozzle parts have many geometric features that are held to very close tolerances. Previously, it took Task Force Tips’ computer numerical control (CNC) programmers four hours to generate the program for a nozzle component mold using conventional 3D programming software.
Reducing Required Time
The company has reduced the time required to only 30 minutes using knowledge-based machining methods, enabling them to predefine common machining operations and drag them onto the geometry that has been imported from computer aided drafting (CAD) software.
Chief Clyde McMillan of the Gary Fire Task Force, an auxiliary unit of the Gary (Ind.) Fire Department, invented the first automatic nozzles in the late 1960s. The task force often responded to large fires where initial water supply was not sufficient.
McMillan designed a nozzle that used a baffle and spring arrangement to maintain a stream of constant reach and pressure regardless of the flow coming into the nozzle. As the water enters the nozzle, it puts the spring under pressure. The spring then moves a baffle that changes the orifice size of the nozzle. As the water flow fluctuates, the orifice size changes to maintain the desired pressure level.
McMillan founded Task Force Tips to produce the nozzle and the company is still managed by the McMillan family. Approximately 10 percent of the employees are volunteer firefighters and the current president, Stewart McMillan, was a volunteer firefighter for over 30 years.
Task Force Tips has introduced many other innovative products while continuing to refine the constant pressure nozzle design, which is still one of the company’s leading products.
The design is naturally far more complicated than conventional nozzles, resulting in a difficult machining process. Many of the company’s other products provide similar challenges. Task Force Tips primarily uses Milltronics 3 axis CNC milling machines, Mazak Integrex mill-turn machines, and Charmilles wire electrical discharge machining to produce the product components.
Previously, they used conventional CNC programming software, beginning by importing the CAD geometry. Engineers defined toolpaths and then created machining operations for each toolpath by selecting a cutting tool and machining parameters such as feeds, speeds, and cut depth. This approach consistently produced high quality molds but involved a considerable amount of manual effort, particularly in defining the many machining operations required to produce most molds.
“What got us interested in ESPRIT [from DP Technology] is its knowledge-based machining capabilities that remove much of the manual drudgery from programming,” said Dave Tison, CNC Programmer for Task Force Tips. “… It enables programmers to focus much more time and attention on higher-level tasks such as optimizing the program to improve machining productivity and maintain high levels of product quality.”
Tison and Dwayne Tate, also a CNC Programmer for Task Force Tips, attended a programming class where they learned ESPRIT and came back anxious to use their new knowledge.
“Almost immediately a hot job came in,” Tate said. “I opened the SolidWorks solid model in ESPRIT. The program then automatically interrogated the solid model and organized the geometry into features. I had the option to review and reorganize the features any way I wanted but the program’s calls were pretty good, so I just made a few minor tweaks.”
The company has created a library of features that handle all of its normal operations. When a programmer creates a new CNC program he can simply drag and drop machining operations from the library rather than creating them from scratch.
Programmers have worked to maintain the library by modifying operations based on feedback from machine operators and other sources. As a result, the library has become optimized as the knowledge of programmers, engineers and operators has become embedded in it.
“By automating many of the routine tasks, knowledge based machining has substantially reduced the amount of time required to program typical molds,” Tison said. “Now that our library is populated with machining operations, we have reduced the time required to program a typical mold from two hours with conventional 3D CNC programming software to only 30 minutes.”
An important step is simulating the entire manufacturing process to verify that the mold produced by the program is correct. ESPRIT enables the programmer to view each individual cut in dynamic 3D solids. The programmer can also inspect the “finished” mold by comparing the as-machined work piece to the original mold design.
The final step is post-processing, where the code used to run the machine on which the mold will be manufactured is produced. ESPRIT’s extensive post processor library contains posts for many machine tools, and the software includes a post processor generator to modify existing posts or create new posts from scratch.
Strip molds are an example of how these improvements reduce manufacturing costs. Producing this model requires building an aluminum base, cavity and other components. The base is machined on a machining center and the cavity is produced using wire EDM. It used to take one to two months to build a single mold, including programming, metal cutting and wire EDM machining.
Recently, Task Force Tips built four of these molds in less than one week each. The time saved comes from dramatic reductions in programming time and improvements in machining productivity.
“ESPRIT’s knowledge based machining capabilities have been a catalyst for our recent improvements in the programming process,” Tate concluded. “We can now handle the most difficult programming tasks in considerably less time than was required in the past. The new software’s simulation capabilities have also substantially reduced errors, which provides further time savings.”
For information call 800-348-2686 or go to www.tft.com.