Innovation in mechanical fastening technology for maintenance free joints Dr.-Ing. Hans-Albert Staedler Customer Engineering Director Europe Arconic Fastening Systems and Rings Industrial Products, Telford, UK Arconic Fastening Systems and Rings has many years experience in mechanical fastening technologies. Louis Huck (the founder of Huck fasteners) developed in last century in the middle of the forties the very first lock bolt system. The functionality of lock bolt systems is based on cold forming/ extrusion technology. A so called collar gets cold formed during installation by an anvil (part of a special installation tool) into unique locking grooves of a pin. After the installation the fastener is mechanical locked due to this volume controlled swaging process. The locking grooves are more times filled with collar material. The system of this builds a natural barrier against vibration and clamp loss. Lock bolt systems create vibration resistant and high fatigue life joints. Since the very first lock bolt these systems have been permanent optimized. A revolution was, when Arconic Fastening Systems and Rings came to the market with pintail less lock bolts. These systems do not more have a pintail end with blank and rust effected surface. The installation gets faster, smoother and with reduced noise compared with traditional lock bolts and much faster than ® conventional bolts. Germans highest construction authority DIBt tested the Bobtail in accordance with the EN 1993 regulation and approved it as opportunity to generate total maintenance free joints ® so far correct installed and the work pieces do correlate with. The Bobtail delivers also the performance of ISO 12944 C5 M corrosion protection. The tab 1 shows the evolution of lock bolt systems comparable with high strength conventional bolts. High Strength Traditional Advanced Huck 360® Bolt & Nut Lock Bolt Lock Bolt System Features Clamp Load Clamp Variation Removability 16mmTool Weight Vibration Resistance Tab 1: Lock bolt evolution; //Source Arconic Fastening Systems and Rings test lab. Waco// In the tab1 is included the newest innovation, the H360® In comparison to lock bolt systems the H360 does not more need a special installation tool. The Huck 360® is a removable & reusable nut and bolt system with lock bolt equivalent vibration resistance and high fatigue strength. It has the installation flexibility of high strength bolt and nut systems. Due to the tightening installation method the clamp variation is larger than Lock bolt systems, but smaller than conventional bolt systems. The ductile nut thread and its deformation during the tightening process generate a mechanical lock w

the hardened thread of the pin. This gives to the H360® the highest strength bolting system for connections requiring field service with standard tools. Interference between H360® bolt and ductile nut thread. Picture 1: Parts and functionality of H360® system; //Source: Arconic fastening Systems and Rings test lab Waco// The free running nut thread quickly spins down and tightens while minimizing damage to coatings. The H360® stays tight under severe vibration loading and superior fatigue strength holds up against high repetitive service loads. The preloaded H360® thread and conventional bolt/...

cross sectional area than a conventional bolt thread. The nut thread is designed in a style, which deform during tightening process enough material for the locking mechanism. The nut thread is in ductile hardness and allows the removability and reusability. This means, that the system is suitable to solve work piece surface imperfections and/ or screw installation strategies for instance in large flange wind turbine towers. 1. Preload thread detail Thread Flanks Thread Flanks move relative to bolt stress in thread root radius root radius 27% less stress in thread 3. Tension- tension Fatigue The...

The Arconic internal test results (pic 2) allow to draw the following conclusions. Tab 2: Huck 360® Summary of Features and Benefits; //Source Arconic Fastening Systems and Rings test lab. Waco// The below in picture 3 all hard metric and imperial size diameters shown, which are actual available. In accordance with construction industry need the additional diameters M24, M27, M30 and M42 on plan. Picture 3: Availability of H360® system; //Source: Arconic fastening Systems and Rings//

An example for usage of H360® system is the usage in mining industry. The Morbark Inc. was having poor insert (tooth) life on a Model 1300 Tub Grinder. Using %” stoverized nuts and Grade 8 Bolts. They were losing “upwards of 6 to 8 teeth a day” per the operator. Using the Huck 360® they were able to accumulate approximately 120 hours over a period of five weeks. During that period of time Picture 4 and 5: Morbark Inc. Grinder with H360®; //Source: Arconic fastening Systems and Rings // Other opportunities are in • Steel construction • Truck and trailer • Agriculture, harvest machinery • Rail...

For all applications in construction market an approval is necessary. We started in Germany the approach to a so called DIBt approval. This DIBt is the German authority for the fulfillment of technical tasks in the field of public law. This authority sets National Technical approvals. The DIBt is member of EOTA (European Organization for Technical Approvals). The actual status is of this approach is: 1. The approach has been generated and the DIBt decided the accredited test laboratory and the assessor. 2. The test program has been developed and approved. The test program includes the test in accordance...

Test results of characteristic preload and preload loss F The range of installed preload is due to the tightening installation method. The loss of preload is very close to a lock bolt system and shows the minimal setting effects in the installed system. The reason for this is the impact of bolt and nut thread style. The determination of preload loss F p,C has been identified for each one bolt after 24, 48 and 96 hours. Therefore a sensor has been placed into the preloaded connection. After 24, 48, or 96 hours the nut has been removed with an automatic screwdriver. The disconnecting of the joint...