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Elliott Group powers up with VERICUT
Elliott Group powers up with VERICUT
Elliott Group powers up with VERICUT
Elliott Group powers up with VERICUT

Elliott Group powers up with VERICUT

Added to MTDCNC by CGTech Ltd on 29 June 2016

Every shop knows that scrap parts and CNC machine crashes should be avoided, but when the parts are more than 1,800 mm in diameter, a mistake can be disastrous. To ensure operator safety and eliminate scrapped parts, Elliott Group of Pennsylvania, USA implemented VERICUT CNC verification and simulation software from CGTech.

For over a century, companies around the world have used Elliott Group for the design, manufacture and service of their critical turbomachinery. Elliott’s primary products are centrifugal and axial compressors, steam turbines, power recovery expanders, and lubrication systems for rotating equipment. The company’s products and services are used across the globe in the oil and gas, refining, and petrochemical industries, as well as in other process and power applications. It is widely recognised for the quality, efficiency, and reliability of its products and services. Elliott Group is wholly owned by Ebara Corporation headquartered in Haneda, Japan.

Impeller manufacturing applies 5-axis milling to ensure the quality of the advanced impeller designs. Impellers are stress relieved, machine finished, balanced statically and dynamically, spin tested, and then mounted with an interference-fit onto the shaft. Shaft-to-impeller keys are used for extra stability in high pressure or high power applications.

Elliott Group Engineer George Slezak is an impeller programmer in Elliott’s Rotor Division. The impellers are very large, expensive, bespoke parts. They are primarily run on vertical turret lathe (VTL) CNC machines and have complex profiles, grooves, and tolerances as tight as +/- 12 micron.

“Our Ravensburg CNC machine is very complicated,” says George Slezak. “It is a unique machine, used mainly for cutting our turbine shafts. With more than 8 axes, machine tool clearance is always an issue. Some turbine shafts have small gaps between the disks on the shaft. We need to verify that the tools or machine quill is clear when going in between the disks.”

Prior to installing VERICUT, Elliott scrapped 27 parts due to programming errors. Most errors were related to gouging of tools, or to tool holders not clearing. In other cases the tool rapid-traversed across the part. To make matters worse, the parts produced in the rotor department are as large as 2 m in diameter.

“Parts this large can come off the machine tool due to a tool crash, seriously injuring anyone in the vicinity,” George Slezak explains. “CAM systems do not always show the post processor outputs. Our CAM systems can only verify CL data, not the actual G-code that the CNC machine tool reads.”

Elliott Group found the answer to its challenges with the installation of full multi-axis VERICUT machine simulation software. The ability to simulate from the same G-codes that drive the machine gives the programmers at Elliott Group the confidence to run parts without the risk of injury due to a machine crash.

George Slezak says: “The number one reason VERICUT was chosen was of course safety. Worrying about a crash used to be part of our day-to-day routine. Not anymore.”

VERICUT shows material removal at the workpiece level and simulates entire machine tools as they appear on a shopfloor. The program also simulates NC machine controls and supports advanced control functions to reduce the possibility of a machine crash. Machine Simulation detects collisions and near-misses between all machine tool components such as axis slides, heads, turrets, rotary tables, spindles, tool changers, fixtures, workpieces, cutting tools, and other user-defined objects. A user can set up near-miss zones around the components to check for close calls, and detect over-travel errors.

To get up and running quickly with VERICUT, Elliott Group also purchased an interface to its CAM system. All of the modelled elements from the CAM system are imported into VERICUT, including the raw material, fixtures, clamps, cutting tools and holders, and other machine structures. These elements must be positioned correctly to prevent collision with any other element during the machining process. George Slezak used the free downloadable training sessions that CGTech offers for many of the CAM interfaces available. He says: “The Quick Start training sessions were very helpful. When we implemented the interface to our CAM system it was very easy to use.”

Today, not a single part is lost due to programming errors, although output has significantly increased since the simulation and optimisation software was implemented. As a result, Elliott Group management sees VERICUT as a very good risk management tool and a big money saver. “Going from 27 parts scrapped to zero paid for the software and then some,” George Slezak concludes. “Programmers are extremely proud of the software. It saves time and money, and gives them piece of mind. We know exactly when we need to modify a tool or change tools to meet clearance issues. Machinists are now more comfortable when they hit cycle start, and rarely touch the big red emergency stop button.”

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