JTD SAS, based in Franche-Comté, France, specialises in turning micro-precision parts ranging from 1 mm to 60 mm in diameter. In the past, the company used manual computer numerical control (CNC) programming techniques to control the movement of citizens and other multi-tasking machine tools to produce parts for customers. After investigating the leading alternatives, the company made the decision to invest in ESPRIT CAM software from DP Technology, headquartered in California, USA. A key advantage of ESPRIT is its ability to store machining operations in a library from which they can be recalled to save programming time and also ensure optimised cutting paths.
Making regular use of these optimised machining cycles has helped JTD reduce programming time for parts, which are similar to those that have been programmed in the past from 90 minutes to 10 minutes. “ESPRIT has helped us substantially improve our ability to deliver the highest possible level of quality at an affordable price to our customers,” said Johann Thibaud, Managing Director, JTD.
JTD has long used CNC machines to ensure its ability to meet the demanding quality requirements of its customers. Recently, it has increased its investment in multi-tasking machines that can completely machine a cylindrical part without removing it from the machine. These machines work by automatically feeding barstock into the front spindle. Turrets and live tooling in the machine can then machine the front end of the part. The part is then cut off and transferred to the back spindle, while additional bar stock is simultaneously fed into the front spindle. Then, additional operations are performed on the back side of the first part, while the next part is machined in the front spindle. The machine also features the ability to probe parts and check whether they are in or out of tolerance.
CNC programming challenges
With the previous manual CNC programming methods, the company’s programmers separately programmed each spindle and turret and used the machine’s controller to combine the programmes. The problem with this approach is that it was very difficult to move operations from one spindle or turret to another & it did not give programmers control over when operations were started on the different spindles. The result was often dead time, while one spindle or turret sat idle, waiting for the other to finish.
Thibaud studied the most popular CNC programming systems and selected ESPRIT because it offers the strongest capabilities in programming multi-tasking machines. “At the time I looked at the various alternatives, ESPRIT’s multi-tasking programming capabilities were well ahead of the other players in the market,” Thibaud said. “Furthermore, I was very impressed with DP Technology’s record of continuously improving the software and its strong technical support infrastructure.” MHAC Technologies, a CAM solutions integrator located in Écully, France, installed two seats of ESPRIT and trained JTD’s programmers on turning, milling, and electrical discharge machining (EDM). JTD receives technical support and software upgrades through a support contract. Programmers have unlimited access to the MHAC Technologies Hot Line for advice on parts programming. Thibaud also noted that the company’s customers typically provide part geometry in the form of 2D paper drawings. For this reason, JTD purchased another CAD software package so the company could create solid models from 2D drawings that could later be opened in ESPRIT. JTD completely upgrades their design from 2D to 3D before producing the CAM program with ESPRIT.
Streamlining the programming process
The advanced capabilities of ESPRIT have enabled JTD programmers to streamline the programming process. The programmer first imports the geometry of the part to be machined from the solid model produced by the design team. Then ESPRIT recognises the features on the model that normally correspond to machining operations, such as pockets, islands, and grooves and organises them into a tree that includes the machining operations needed to produce them. The programmer reviews the machining tree and often manually creates, modifies or re-orders the features. The programmer then applies machining operations to each of the features, which consist of a tool, cutting speed, feed rate, depth of cut, etc. In most cases, these machining operations have been defined and optimised in advance to maximise machining productivity. The programmer can also quickly create new operations from scratch when needed.
The programmer then assigns the machining operations to the spindles and turrets of the machine that will be used to produce the part. Programmers can easily move operations back and forth between turrets and spindles and set up sync points to control the timing of operations. Programmers look for opportunities to make improvements, such as utilising time when a spindle or turret sits idle to perform an additional operation. Finally, the programmer simulates the complete machining operation, including the machine, turrets and spindles as a realistically rendered solid model. The simulation verifies the geometry of the part produced by the program. Programmers also view the simulation to look for inefficiencies that can be remedied to reduce cycle time. After the programmer has validated the program on the computer, he utilises the post-processor to generate NC code specific to the machine tool on which the part will be run.
Advantages of machining cycles
JTD programmers also use the ESPRIT CAM solution to create machining cycles that manage differences and repeatability in families of parts. “We often receive orders for stainless steel aircraft parts with tight dimensional tolerances that are similar to parts we have produced in the past,” said Florent Lambert, Technical Director, JTD. “To simplify programming of these parts, we have created a series of machining cycles that produce the complex features on these parts. Programmers can select the machining cycles needed for a new part, input parameters to adjust dimensions of the new part, and combine them to produce the new part. This approach reduces the typical time required to programme one of these parts from an hour and a half to only 10 minutes.”
In the past, the size of the blanks or workpieces that serve as the starting point for machining were measured at a few points and then programmed manually. The tool path was not optimised, which caused the tools to wear out relatively quickly. With ESPRIT, JTD programmers are able to much more accurately model the geometry of the blanks and use efficient canned machining cycles for roughing operations. The end result is that tool wear is substantially reduced. “In one case, the life of a tool was increased from 200 to 1,000 pieces,” Lambert said. “Overall, we have reduced our cutting tool expenses by 20% to 30%. In addition, we are able to hold more accurate tolerances and less time is lost in tool changes.” Besides providing machining cycle advantages, ESPRIT also helps JTD improve the accuracy of its sales quotes. JTD estimators use the 3D design files to measure dimensions that are missing on the part prints and visualise geometric details that were not clear on the 2D drawings. Estimators can also quantify cycle time and parts produced per hour with ESPRIT.
Recently, the JTD management team worked with a major German automobile manufacturer on a very challenging project. JTD proposed combining several parts together into a single part with a complex geometry that required a combination of turning and milling operations to produce. The result was a substantial cost reduction due to the reduced part count. In the past, JTD would not have been able to produce this new part because it could not have been programmed with manual methods. On the other hand, JTD was able to create the CAM program with ESPRIT easily. The end result was that the company won a substantial new order due to its programming capabilities. “Our plan for the future is to train more CNC programmers and leverage our technological advantage to address new markets and continue to grow the company,” Thibaud concluded.