Haas To Showcase Advanced Machining At Grindtec

Haas has announced its plans to exhibit four of its advanced machining platforms at Grindtec 2010, which will be held near Munich from 17-20 March. The Haas Multigrind CB machine is designed for the flexible and universal machining of components such as aero-engine turbine blades, blisks and vanes, and enables all milling, grinding, and production belt linishing operations. Each operation is carried out automatically and the aero-engine blades are only clamped once, ensuring high precision.

The Haas-designed automatic tool changer and part-loader systems allow for unmanned operation. Represented in the UK and Ireland by Dorman Machine Tools, Haas is continuing to expand its operations into the aerospace and power-generation industries, while offering high-end production solutions for the manufacture of artificial knee joints and associated components for the orthopaedic medical sector. The Haas machines are equipped with full automatic probe systems to measure blade profiles - these determine the spatial position of blade castings and worn blade profiles, prior to grinding and linishing for refurbishment work.

The Haas CB production machine has a general capacity to handle blades of up to approximately 1,000mm in length and its automatic tool changer allows for milling heads, grinding-wheel sets and belt linishing heads to be automatically changed at will to combine all necessary machining processes in one fully automatic operation. The latest generation of high-speed dressable CBN wheels is used in conjunction with Haas' in-process constant wheel dresser, which can dress up to two grinding wheels simultaneously during the actual grinding process - with constant feedback of the wheel dimensions for automatic wheel-wear compensation.

Although Haas continues to offer the more conventional table-based diamond roll dresser devices, the use of the constant wheel dresser offers advantages for end users. This is because the grinding wheels are kept in the best possible condition at all times and there is no downtime associated with having to move the wheels to a table-based dresser device for regular wheel dressing. With its ability to interpolate all five of its major machining axes at the same time, this enables complex blade profiles to be milled and ground with ease, with the resulting, highly precise, form also being generated by the optional belt linishing heads.

Chris Boraston, managing director at Dorman, said: 'After the four or five-axis milling operations on the Haas CB machine, followed by the subsequent high-precision grinding operation, aero-engine blades can be automatically belt linished in a single operation without having to remove the blade and then remount it on a conventional linishing machine. 'This improves cycle time and precision, while avoiding the costs associated with requiring a separate standalone machining process. 'All linishing on the Haas CB machine is carried out wet using the oil used for the previous milling and grinding operations.

'The wet linishing process is said to be superior to a dry process as it generates a considerably better surface finish when using identical grades of belt, but also avoids the creation of any heat buildup that could damage or affect the finishes previously created by the Haas machine. 'Belt wear is also reduced, increasing belt lifetime. 'As all of the Haas machining processes follow the exact CAD component files, upon which the machines NC programmes are automatically generated, end users are assured that exactly the precise blade form required is machined.

He added: 'Belt heads are automatically exchanged, allowing an automated two- or three-step linishing process using different grades of belt without any operator intervention. Haas is able to take a complete solid rectangular block of material and mill and grind out the entire blade form from the solid, before linishing it, to arrive at what is essentially a finished, machined component. This includes the blade profile itself and the root fixture form that is ground out at high speed using the Haas balanced grinding spindle.

The spindle accepts wheels of up to 300mm in diameter from the CB's automated tool changer, which stores the necessary number of milling cutters, grinding-wheel sets and belt linishing heads. Dorman is arranging machining trials for a number of UK-based aerospace companies and end users are invited to send Haas a blank component, which will be machined and returned to them for inspection. The Haas CB machine is a further development of the Haas HT variant.


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