feature story

5-axis work cells chop run time 20% for diesel impellers

Turbocam’s recently created high-production division, TAPS (Turbocam Automated Production Systems) of Barrington, NJ, installed work cells containing twin 5-axis machining centers and the results have the engineering manager stacking the productivity curves against any operation in the country.

The work cells, each containing twin 5-axis Chiron FZ08KSM machining centers, are fed by 250-capacity workpiece carousels and an ABB articulating robot.These work cells produce Type 2618 aluminum impellers for a diesel engine turbocharger.

A large part of the success at TAPS can be attributed to the speed, accuracy, control, and automation of these work cells, driven by the Chiron machining centers, according to engineering manager Andrew Hussey.

While the actual run time per cycle is proprietary between TAPS and its customer, a diesel engine builder, Hussey said the reduction in run time exceeded 20 percent, compared to the production method and machines previously utilized for this application.

Rob Bujeaud, vice-president of manufacturing for Turbocam and TAPS, said the company began with 5-axis machining right from the start.

“We perceived a market need for this type of service, where we could offer customers a complete turnkey package from engineering to application, software to machining programs, prototype to production runs, on a variety of complex parts,” he said.“Today, we make that scenario happen for our aerospace, automotive and commercial business partners every day.”

Turbocam focuses its 5-axis machining work on impellers, blades, blisks (bladed disks), and other mechanical components used in turbine engines, diesel engines, turbochargers, aerospace, and power generation equipment, as well as medical devices such as heart pumps.The TAPS group does high-production runs, primarily aimed at the automotive sector, with similar work products.

“Aluminum stock is turned on CNC lathes and then loaded onto the carousels,” Hussey said.“The CNC onboard the machining centers, a Siemens Sinumerik 840D, interfaces through our Profibus network to the robot controller and the carousel to maintain the workpiece load/unload cycles on the machines.

Each robot handles two Chiron machines for virtually non-stop production, where the cells are programmed to run in fully unattended mode.

The Siemens Sinumerik 840D is said to increase productivity on the manufacturing floor, especially in the challenging segments of high-speed and 5-axis machining.

The Chiron FZ08KSM machine used features a small 2.3sqm- footprint, fast chip-to-chip time of 1.9 seconds or less, rapid feed rate of 75m/min, acceleration up to 2g, typical spindle rate up to 27,000rpm, tool changes in 0.8 sec and, in this application, a 2-axis NCrotary/tilt table, a suitable combination for the aluminum workpieces processed at TAPS, according to Hussey.

The impellers run on these work cells measure approximately 4" diameter x 4" high and load/unload at the rotary table fixture via robot.Many passes are required to machine the impeller blades, so the speeds of the spindle, tool-changer, and rotary table are all critical for optimum cycle time.

Hussey also noted the advantages of the Siemens CNC and drive package, Simodrive 611U, in this process.

“The high speeds and 5-axis movement can create non-linear machine motion that affects the accuracy of the cutting and the CNC/drive package helps to smooth out those kinematics,” he said. “This is also an area where the CAMplete TruePath software compensates for non-linear machine motions.”

TruePath takes the APT or CL data as well as native CAM data such as MasterCAM .nci and OpenMind .pof and creates the CAM program, compensating tool path and communicating design intent in a manner comparable to a typical post-processor, with the ability to factor the machine motions into the sequence.

Despite the speeds involved, typical tolerances are better than +/- 0.002".The vibration monitors, spindle accelerometers, and laser position detectors onboard the Chiron machines further aid in maintaining the accuracy on these complex milled parts.A custom wash down kit is installed on each machine, as the intricacies of the part make an elimination of chip migration essential for process integrity.

Parts are checked on an in-house 5-axis CMM at TAPS before they are released to the customer.

Hussey and Bujeaud detailed how a typical job flows through the TAPS engineering department.

Technicians take the design data, PRO-E model or IGES file, then create the engineering model.They analyze the customer model to determine the proper surface integrity and curvature to reduce surface deviation, designing the 3-axis tool path, as well as the 2-axis rotary table movements.

Tool path placement is the result of the TruePath software and internal Turbocam coding.With this “clean data,” technicians determine the tool position and tool axis vectors in an APT format with XYZ positions in 3D space.The approaches and retracts are automatically determined in the TruePath software, which saves time.

“We are able to do the first run-out on the actual production machine much sooner than in the past and with much more predictable results,” Hussey said.“We’re even able to simulate the execution of the program on different materials, using our existing performance databases.The TRAORI (transformation orientation) feature of the Sinumerik 840D also gives us great control over the entire process, because it’s based on workpiece orientation rather than tool position in a predetermined program.

“This results in a more consistent finish and less chatter on the surface of the material, an absolutely critical factor in these turbocharger components,” he said.

Turbocam processes a variety of aerospace, automotive and medical grade materials, including aluminum, magnesium, nickel-based alloys, titanium, 304, 416, 17-4 and 15-5 stainless, HP1318 surgical, and various tool steels as well as impellers for the medical industry.Turbocam operates facilities in Dover and Barrington, NH.

Rob Bujeaud and Andrew Hussey of Turbocam/TAPS, Karamarie Gerbracht and Marty Demers of Chiron America, and Jim Rodgers of Siemens Machine Tool Business contributed to this article.

Chiron America

Siemens Energy & Automation Machine Tool Business