Citation
(1998), "Delivery of better, high strength fasteners shrinks from two months to two days", Anti-Corrosion Methods and Materials, Vol. 45 No. 1. https://doi.org/10.1108/acmm.1998.12845aab.003
Publisher
:Emerald Group Publishing Limited
Copyright © 1998, MCB UP Limited
Delivery of better, high strength fasteners shrinks from two months to two days
Methods
Delivery of better, high strength fasteners shrinks from two months to two days
A New England manufacturer of speciality fasteners recently found a way to produce improved quality, high strength screws for a distressed parts distributor shrinking turnaround time from two/three months to two days. In the process, he saved his customer's business, with no increase in fastener costs!
Crescent Manufacturing, Inc., Burlington, CT, was asked by the troubled distributor if he could deliver, in a hurry, some M3 special screws ordered by a pneumatic valve manufacturer. They required an ultimate tensile strength of 120ksi.
The slotted cheesehead machine screws previously had been made from low-carbon steel by a European manufacturer. Deliveries were running very late because of the time required to heat treat, nickel plate and bake the fasteners prior to shipment.
Crescent, which deals in fasteners and engineered parts to meet special specifications, decided to switch to Carpenter Stainless Custom Flo 302HQ from Carpenter Technology Corp., Reading, PA. Jim Speck, Crescent vice president-engineering, wanted a stainless steel with superior headability and the inherent corrosion resistance to eliminate the need for subsequent processing.
The Carpenter speciality stainless has been designed for severe cold heading operations. Its carefully balanced analysis lowers the tendency to work harden; this minimizes tool wear and eliminates cracking.
Speck selected a heat of 0.116-diameter wire from his own in-house stock of Carpenter Stainless Custom Flo 302HQ that tested at 90 ksi. This was at the upper end of the hardness range for material he usually draws but, he explained, "by depending on Carpenter's certifications and following their specifications, we always have been able to work this stock without cracking."
Crescent drew the wire down to roll-thread diameter in two passes, then tested for hardness to be sure. The shop then cold headed and tested the blanks, slotted and tested, and threaded on a flat die roll threading machine, testing once more. After all steps had been completed, the fasteners 10m long with an M3 thread diameter tested at 120 ksi tensile strength, as specified.
When Crescent delivered its stainless fasteners in two days they had not only shrunk the delivery time frame incredibly, but they had provided improved quality, high strength, corrosion-resistant fasteners that Speck observed "looked like jewels".
"The part cost was a wash," said Speck. "This experience made a good case for using a headable stainless because it cost no more than taking the perceived "cheaper" approach of starting with a carbon steel, then adding the cost and time for heat treating, plating and baking."
Carpenter Stainless Custom Fio 302HQ has been used successfuly for cold heading nuts and all standard head configurations of recessed head fasteners. It is an austenitic stainless steel that becomes only faintly magnetic after severe cold working.
The alloy's nominal analysis: carbon 0.03 per cent max., manganese 2.00 per cent max., phosphorous 0. 045 per cent max., sulfur 0.03 per cent max., silicon 1 per cent max., chromium 17/19 per cent, nickel 8/10 per cent, copper 3/4 per cent.
Details from Carpenter Technology Corporation, PO Box 14662, Reading, Pennsylvania 19612-4663, USA. Tel: 610 208 2524; Fax: 610 208 2858.