Holding with Formed Head

The spinning operation consists of highspeed rotating and suitably shaped tool that creates frictional heat that will permit the stud to conform to the configuration in the tool. Pressure exerted on the tool and 

Ultrasonic head forming and welding is a fast assembly technique. It is a very rapid operation of about 2 seconds or less and lends itself to full automation. In this process high-frequency vibrations and pressure are applied to the products to be joined, heat is generated at the plastic causing it to flow, and, when the vibrations cease, the melt solidifies. The heart of the ultrasonic system is the horn, which is made of a metal that can be carefully tuned to the frequency of the system. The manufacture of the horn and its shape is normally developed by the manufacturer of the equipment. The results from this operation are not only economical, but also most satisfactory from a quality control standpoint. 

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In non-aqueous solvents, surfactants may form inverted micelles where the hydrophilic heads of the surfactant molecules are present in the center of the micelle with the hydrocarbon chains extending outward into the solvent. Dipole-dipole interactions hold the hydrophilic heads of the surfactant molecules together in the core, and in certain cases hydrogen bonding between head groups can also occur. 

Closures between heads and cylinders, often taking the form of clamps, split rings, or bolts, are also an important consideration in the proper design of the pressure vessel, for it is these components that must hold the vessel head to the cylinder. It is important to recognize the force that is exerted on the closure. For example, in a 1000 psi vessel, a circular head with a diameter of 12 in. will have over 110,0001b of force pushing on it. This force must be evenly divided between bolts or spread out over the clamp or split ring closure. 

The form and structure of the nut varies with each species. The doum palm produces fruits the size of small oranges, that each hold one kernel (nut), while the tagua produces fruits the size of human heads, that contain multiple kernels. Both types of kernel are about the size of a chicken s egg. The tagua is the nut most used today. 

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