PWA International installs special Vacu-Blast "Vector" surface etching machine

Citation

(2005), "PWA International installs special Vacu-Blast "Vector" surface etching machine", Aircraft Engineering and Aerospace Technology, Vol. 77 No. 1. https://doi.org/10.1108/aeat.2005.12777aab.003

PWA International installs special Vacu-Blast "Vector" surface etching machine

PWA International installs special Vacu-Blast "Vector" surface etching machine

Keywords: Aircraft engines, Surface treatment

Aeroengine overhaul, repair and maintenance specialist, PWA International, has recently installed a new Vacu-Blast Vector 325P' automatic aluminium oxide surface etching machine at its state-of-the-art facility in Rathcoole, near Dublin.

The Vacu-Blast machine was introduced specifically to produce an effective, specified surface key on Pratt & Whitney engine cases, prior to plasma spray. The operation is carried out in line with “SPOP 21 A” and “SPOP 170” specifications, either over the entire surface or on selectively masked areas. The cases measure up to 3 m in diameter up to 1.2 m high and are made of nickel, steel and other aerospace alloys. PWA International says that the introduction of the machine – the first of its kind to be installed by the company at Rathcoole – has helped to enhance the capacity of the company's surface treatment department, which also includes specialised vibratory finishing, degreasing and washing equipment (Plate 1).

Plate 1 The new Vacu-Blast® Vector 325P' automatic aluminium oxide surface etching machine at PWA International's aeroengine repair and overhaul facility in Rathcoole, near Dublin. The machine was introduced specifically to produce an effective, specified surface key on Pratt & Whitney engine cases, prior to plasma spray

The new machine's acoustically lined blast etching enclosure measures 3.25 x 3.25 x 2.6 m high, and incorporates a three-axis, roof- mounted nozzle manipulator fitted with two individually adjustable blast nozzles. The workpieces are loaded and unloaded by overhead hoist and are retained on a 3 m diameter variable- speed 300 kg capacity powered turntable, which rolls in and out of the enclosure on rails.

Two heavy-duty, safety-interlocked doors seal the enclosure during operation.

The blast etching operation is governed by an NUM CMC unit, which allows different processing parameters – i.e. blast nozzle path, blast pressure and duration and turntable rotation speed – to be pre- selected according to the part being processed, and also ensures process repeatability.

The blast enclosure features a Vacu- Blast “Waffle Floor” a system that uses a series of “mini-hoppers” located under a floor grid to collect spent blast media, dust and debris during blasting. This material is then conveyed pneumatically via a common duct to a generator-reclaimer unit. The latter separates out degraded material and returns reusable media to the media hopper for reuse.

A special feature of the new machine is its ability to use three different grades of aerospace quality aluminium oxide media – 24, 60 and 240 mesh – and its generator- reclaimer and media separation systems have been specially designed to ensure efficient segregation of the different media types, in order to avoid cross-contamination.

Vacu-Blast International, Air Blast Division, ISPC Surface Preparation Ltd. Tel: +44 (0) 1753 526511; Fax: +44 (0)1753 538093; Web site: www.surfacepreparation.com

For more information, contact: PAW International. Tel: +353 1 4588100.