Ryobi is a recognizable brand name for buyers of electrical appliances and power tools, but it’s also one of the better-known producers of diecastings in Japan. Since 1943, from its plant in Shizuoka, it has been supplying high-quality diecast components for electrical appliances, office automation, industrial machinery, and construction tools, as well as automotive castings, such as gearbox casings and cylinder blocks.
The diemaking operations at Ryobi’s Die Casting division plant have been using Sescoi’s WorkNC since 2001 to finish dies with three-axis machining and positional five-axis machining.
Sescoi is a software developer based in France, with sales and support staff located worldwide serving a range of industries. Its programs support CAM/CAD processes for two- to five-axis milling; uniform CAD applications for entire manufacturing processes; integrated “custom manufacturing” solutions; and job-management processes with quotation, time and resources, capacity, and delivery dates to optimize performance and profitability.
Because of the deep cavities of Ryobi’s die designs, and the surface qualities it requires, Ryobi used an extensive application of electrodes in the finish machining operations. Concerns over the difficulty of creating five-axis simultaneous toolpaths and the surface finish which they might produce, had prevented the operation from making a move into simultaneous five-axis machining.
However, producing a large volume of electrodes for the process was time-consuming, encouraging Ryobi to look for ways to machine more of the tool directly in order to cut the overall production time.
Ryobi’s die-finishing process involved four operations: heat treatment, followed by EDM die sinking, cavity machining, and jig boring. The number of process steps the division had to execute totaled 12, and so Ryobi evaluated different production options in its search for savings’ opportunities. This included ways to limit tool length, improve surface finish, reduce machining times, and reduce the number of electrodes used by cutting more of each cavity on the machining centers. Based on its research, Ryobi engineers concluded that the best solution was to adopt Sescoi’s WorkNC Auto 5.
WorkNC Auto 5 automatically converts three-axis toolpaths to five-axis simultaneous toolpaths, taking into consideration the effective tool length, the geometry of the holder and the rotational limits of the machine tool. To maximize efficiency Auto 5 leaves three-axis toolpaths unchanged where they can reach the part, and optimizes the machining speed, tool rigidity, and surface finish.
With Auto 5 the process of generating five-axis toolpaths suddenly becomes very simple. The Auto 5 software evaluates the three-axis paths to be converted, performs a collision check and post-processes the resulting toolpath – all with minimal operator intervention. Much of the complexity of five-axis programming is eliminated.
According to one Ryobi plant official, “Adopting Auto 5 enabled us to reduce five surface-finishing processes to three, while electrode manufacturing and EDM die sinking has been reduced significantly because we can machine the bulk of the cavity using three/five-axis toolpaths.” As a result, the number of finishing processes has been reduced from 12 to eight.
Starting at Ryobi’s “re-roughing’ stage,” a small tool picks out the excess material. “The parts that can be re-roughed from the top are machined with the Z-axis only,” the same official explains, “and areas that cannot be reached are cut simultaneously with five-axis machining.”
This procedure has improved the process, he continues. “We use the same method on the finishing operations to cut more of the mold by using five-axis toolpaths, where necessary.” He adds that because the number of operations has been reduced, machine downtime is lower, resulting in shorter lead times.
Machining times have been reduced by about 33%, according to Ryobi, and labor costs have declined accordingly.
Prior to the introduction of Auto 5, all of the dies Ryobi produced were machined using three-axis techniques. Programming time per die averaged 55.5 hours, or 35.5 hours for program preparation after heat treatment, followed by 20 hours for electrode manufacturing.
With the Sescoi WorkNC Auto 5 program, preparation for five-axis simultaneous toolpaths takes eight hours, starting from the existing three-axis toolpaths. Total programming timesavings is gauged at approximately 20% over the “three-axis only” method.
As a test, Ryobi programmed the same die using a combination of simultaneous toolpaths and positioning five-axis methods. Preparation time totaled 46 hours, proving that the WorkNC Auto 5 approach offers Ryobi the quickest approach for its die-machining processes.