WYOMISSING, PA, USA – June 30, 2005 – The world’s third largest manufacturer of aerospace fasteners has parlayed a pre-tested change in coating for its heading wire into improved part quality, increased productivity and reduced costs.
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| Numbers critical for identification are easy to read on bolts produced with Carpenter Technology Corporation KnightCote™ coating. |
The Blanc Aero Industries division of LISI AEROSPACE, which specializes in the manufacture of engine and other critical aircraft parts, has enjoyed these and related benefits while warm forming and heavily extruding 12-point bolts that are standard in GE-90, PW 2000 and comparable aircraft engines.
Blanc Aero Industries, in Villefranche de Rouergue, France, has been heading the bolts from coils of Pyromet® Alloy 718 (UNS N07718) and Carpenter Waspaloy (UNS N07001) supplied by Carpenter Technology Corporation.
The French company makes many thousands of size 1/4" bolts from Pyromet Alloy 718 wire, and similar large volumes in size 3/16" from Waspaloy wire.
Typically, the production process for a 12-point fastener consists of several operations including warm forming, extrusion, forging and thread rolling.
To facilitate this process, the fastener manufacturer originally used a heavy coating of copper, with an overcoating of MoS2 (molybdenum disulfide) on the heading wire because of the alloys’ relatively high work-hardening rates and the severe deformation required. This coating combination, however, produced a host of problems.
Variations in coating thickness and poor adherence caused inconsistent heading performance. The coating overload made it difficult, if not impossible to achieve the dimensional tolerances required. Carbide tools broke or wore out prematurely. Under some circumstances, heading machines would break down in the middle of a coil of feed stock, at serious cost in downtime for re-setup and lost productivity.
The heavy coating was such a challenge that Blanc Aero Industries had to install a drawer between the coil of feed wire and the heading machine to remove, in a skin pass, some of the excessive coating.
Coating Change
Asked for help to solve the problem, Carpenter regional metallurgist Anthony Guitterez suggested that the production team try a combination of copper coating with Carpenter’s environmentally-friendly KnightCote™ coating. This is a newer coating that can be used effectively as an addition to copper coated wire, or as a stand-alone coating over bare wire.
After successful trial runs, the new coating combination using KnightCote coating was adopted. It has provided consistently even adherence from one end of the wire coil to the other. Machine performance has improved, along with commensurate gains in productivity. Bolts have been better defined and headed predictably, in conformance with all critical dimensional tolerances.
Tool life has been increased an estimated 10% to 20%.
The Technical Manager at Blanc Aero Industries, estimates that in initial production runs the plant has been able to manufacture approximately 15,000 bolts before tooling had to be changed on the heading machine. Before the coating change, tooling had to be repaired or replaced more frequently.
With downtime for tool maintenance reduced and production processing enhanced, the plant has been able to shorten its lead time for product delivery. While saving the cost of excessive machine downtime, the company also has cut the cost, in time and parts, of re-starting shut down headers to stabilize them and restore them to full operation.
Quality Improvement
The surface finish of formed bolts also has been enhanced considerably, allowing inspectors to read small but essential identification numbers on the heads of finished fasteners. Before the coating switch, the original coating was so thick that it obscured these numbers. As a consequence, machines often had to be stopped so they and the dies could be cleaned for number verification.
Carpenter’s KnightCote coating is described as a relatively thin and adherent coating that can be applied uniformly on any heading-grade wire produced at its mill. It is considered suitable for cold and warm heading in many alloy systems, conditions and applications.
Developed to prevent metal-to-metal contact, KnightCote coating can minimize die wear while preventing seizure, scoring, galling and welding of parts. It can stand the high impact forces, heavy loads and elevated temperatures that are characteristic of severe upsetting and extrusion.
This specialty coating, when used alone, can be removed with more environmentally friendly alkaline detergent solutions and agitation. It can be used in a higher-temperature forming process than typical molybdenum disulfide-type coatings.
Blanc Aero Industries, which produces more than 40 million aerospace parts annually, has been heading aerospace fasteners since 1970 at its current location in southwestern France.
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For more information about Carpenter’s KnightCote coating or Carpenter alloys, you can access Carpenter’s technical data base at www.cartech.com or phone 1-800-654-6543. In Europe, contact the company’s Brussels Service Center at: phone 32-2-240-1840; fax 32-2-240-1830.
For more information about the Blanc Aero Industries Division of LISI AEROSPACE or its fastener production operations, please refer to:www.lisi-aerospace.com.
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