Established in 1919, just a few months after the creation of the independent Czech Republic, AERO Vodochody is one of the oldest aviation companies in the world. Until the end of 2006, Aero was a state-owned company but today it is a private operation that has been restructured for a profitable and secure future. CGTech’s advanced CNC simulation and verification software, VERICUT, is playing a part in the company’s ongoing successful development.
AERO Vodochody, located just a few miles North of Prague, is the largest aerospace company in Czech Republic, with a production floor area of 18,400 m2 and almost 1,500 employees. As well as its own range of combat trainer jet aircraft, the company provides both MRO services and aerospace components for civil and defence customers across the world. Complex aircraft structural parts, sheet metal fabrication and sophisticated subassembly operations are carried out for OEM customers, including Boeing, Airbus, Sikorsky, Bombardier, Embraer, Saab, Spirit Aerosystems and EADS.
Although some components are turned, the majority are milled to tight tolerances and Aero has invested significant in 5-axis machining technology to meet the increasing geometric demands of the components it supplies. Using Siemens NX CAD/CAM software all NC machine programming is done off line, with a team of 17 skilled people supporting 3D components, production jigs and fixtures as well as a further 5 providing 2D programming for the sheet metal production. All NC tool path verification support is provided by CGTech’s VERICUT.
Jiri Machacek, Technologist/NC Programmer, recalls: “Initially, we started using VERICUT to make our production tooling, because we had just one piece of material and we could not afford to scrap the raw material. Today, the tooling and production support departments are combined so we use VERICUT for both sides.”
Supplied and supported by its Czech agent, Axiom Tech, AERO Vodochody currently has two full seats of VERICUT software and one for 3-axis milling, but as the parts are moving towards 5-axis machining the company will upgrade the software. There is a business plan to increase to five seats, and one NX to VERICUT interface is currently being evaluated before further investment.
The goal for production is to follow a ‘batch of one’ philosophy, so machine set ups and changes are frequent. With small volumes, often between 3 to 10 parts, manually proving and testing a program is very difficult. Also, the raw material is expensive and the company no longer wastes material carrying out test cutting, all the testing is done in VERICUT. As Aero has 1,000s of live parts on its customer database and a new project will typically push around 350 new parts through the programming department and subsequently the machine shop, all time and cost savings becomes significant.
“Using VERICUT’s simulation capability we prove the NC code before it is issued to the machine,” says Jiri Machacek. “Previously we would verify a program using the NX-CLS data file, but the CLS does not contain information on the toolholder so there is a risk of collision. In the past CLS files have caused machine crashes and this is why we are moving towards full independent simulation provided by VERICUT during 2012.”
For Aero, most of the machined parts are aluminium, about 85 per cent, with some titanium and stainless steel components, and a few are produced from heat resistant materials such as Inconel. Components are typically on the machines for between 30 and 180 minutes for aluminium, while titanium parts can be running for up to 6 hours. Most of the machines are run unmanned overnight to meet customer delivery schedules. The machine operators are confident in the NC programs now with the knowledge that VERICUT has provided a full check of the toolpath, with post processed simulation files sent to the company’s network along with the technology list that they can read to set up the tooling and fixturing on the machine tool.
VERICUT further proved its manufacturing credentials recently for Aero. The complex CAD solid model for a new titanium helicopter component was issued by one of the company’s customers. For this type of work in hard materials Aero uses its DMG DMU 125 P duoBLOCK, that features a rigid 45o nutating head so the tool can be presented at any angle between the vertical and horizontal. Subsequently it has complex axes movements that are difficult to check for collisions without full simulation.
“We had to machine and check the new component without damaging the machine tool, as other customers parts were relying on it. We had the machine modelled and the kinematics applied to simulate its full motion. This was the first machine to prove the process, as we knew the component and the machine tool would be at risk without simulation. The result of the simulation was that the part was impossible to cut without extremely long tools, and we had to change the manufacturing technology. VERICUT saved a great deal of time proving the process was not capable on that particular machine,” Jiri Machacek states.
Using VERICUT software the company found a manufacturing strategy that would work saving many days of lost machining time capacity. Jiri Machacek says: “Now we use VERICUT to find the manufacturing technology to make the parts. We simulate during the programming process so we can check the machining of difficult part geometry against the CAD solid model.”
Although new parts such as this are supported by solid model CAD files supplied by the customer, older parts just had 2D paper drawings. These were programmed into the Siemens 3D NX CAD/CAM system to avoid any programming errors at the machine’s controller.
With an exceptional understanding of advanced software the company’s IT team is currently developing its own tooling database to manage the cutting tool and fixture inventory for the whole manufacturing facility. The Siemens NX tooling database has around 2,000 items, which can be selected by the CAD/CAM programmer, which is why the VERICUT interface is being evaluated.
“As the tool and holder database is already complete in NX the VERICUT interface will allow them to be transferred across. Full simulation needs the shape of the tools in the tool table, which is very time consuming to do manually. And, with the interface we can simulate one job while we are programming the next,” concludes Jiri Machacek.
Article published in Production Engineering Solutions, October 2012 [PDF]