Architectural Butt Hinge
Cooke Brothers Ltd discovered an application for plastic plain bearings on an architectural butt hinge for heavy duty doors in public and commercial buildings, schools, hospitals, department stores etc. The product had to offer high performance, maintenance free and trouble-free operation for any environment and for any application. In some instances, customers demanded a 25 year performance guarantee. Some hinges will wear and create problems, unless lubricated regularly. Such maintenance rarely happens on site; others will corrode in humid conditions, such as swimming-pools, or in the saline atmosphere near the sea. New building legislation, reducing the forces required to open a door, also needed to be addressed. The hinge had to conform to BS EN1935:2002: "Building Hardware. Single-axis hinges. Requirements and test methods". The Cooke Brothers Ltd hinges are tested to Grade 14 of the Standard, the highest Grade, where one hinge is subjected to an endurance test. The test door is loaded to 160kg and is operated for 200,000 cycles at a rate of approximately 10,000 per day (the test rig runs 24/7). Another hinge is subject to a static and overload test, with a door weight first of 320kg then of 480kg. The hinge is also subject to a shear test where it is loaded to 1500kg. Finally, it is tested for corrosion, to 240 hours. This is the highest grade required by BSEN 1935.
A special design polymer plain bush, manufactured for Cooke Brothers Ltd by igus®, replaces the metal type bearing previously used. Importantly, when the hinge is in operation, there is no metal to metal contact so that friction is reduced and less force is required to open the door. The bush runs up against a simple stainless steel washer which gives the necessary surface finish for the bush to operate efficiently. Lubrication, which rarely or irregularly occurs in practice, is not necessary. The hinge has already been tested by a regulated test house for ® architectural products. It has also been fire-tested on the Half Hour fire doors most commonly used in public buildings. The hinge passed all of the required tests, which means the new products can be CE marked: a requirement if hinges are to be fitted to fire escape doors. In addition to this, Cooke Brothers’ internal testing department have cycle tested a hinge in excess of 1,000,000 cycles. This hinge continues to run and is still within the requirements of BSEN 1935:2002. "The new hinge and bearing will more than satisfy the new Buildings Regulations legislation and help less able people, as well as reducing associated wear problems on the other door fittings."
Bill Platt
Development Engineer
Cooke Brothers Limited