Application method joint-assembly methods

Press Fit. In press or interference fits, a shaft of one material is joined with the hub of another material by a dimensional interference between the shaft s outside diameter and the hub s inside diameter. Press-fit joints can be made by simple application of force or by heating or coohng one part relative to the other. This simple, fast assembly method provides joints with high strength and low cost. 

Automated methods for preparation, adhesive application, and bond assembly give the best reproducibility and best control of durability however, such automation is frequently not possible. Manufacturers recommendations in data sheets and on containers should always be followed and particular attention paid to storage conditions, mixing procedures, adhesive or sealant application, and joint assembly. 

In some applications the butt joint may be the only possible method of assembling the component parts and, if aesthetics are important, the small fillet of excess adhesive outside the joint (which adds to the strength of the joint) may also be undesirable. One example of this in the plastics industry is the assembly of shelving where acrylic or polycarbonate sheets are bonded together to form points of sale display equipment. 

The applications described are but a few of the many thousands of joints that are assembled using adhesives. They illustrate the varied applications and some detail of the benefits of using adhesives compared to other joining methods. 

To make an economical and practical joint, the surface preparation methods must also meet several other requirements. They must be safe to handle and should not be flammable or toxic. They should be inexpensive and provide fast processing times. The prebond processes should be easy to monitor and control in a production situation. In addition, the process should not in itself leave a weak boundary layer. If chemical solutions are used, they should rinse off easily and not continue to react with the surface past the time when the bond is made. The surface preparation process should allow for practical working time between preparation and application of the adhesive or sealant. Finally, the surface provided by the treatment should not change once the assembled joint is made and placed into service. 

An adhesive is a material that is used to join two objects through nonmechanical means. It is placed between the objects, which usually are called adherends when part of a test piece or substrates when part of an assembly, to create an adhesive joint. Although some adhesives form joints that nearly immediately are as strong as they will be in actual use, other adhesives require further operations for the adhesive joint to reach its full strength. Adhesives can be made in several different physical forms, and the form of a given adhesive will define the possible methods of its application to the substrate. 

A different method of creating UHMWPE fibre-reinforced UHMWPE composites was presented by Mosleh et al. [179]. In this method, dry UHMWPE powder was mechanically oscillated through a funnel onto subsequent layers of short (25 mm) chopped UHMWPE fibres, or pieces of continuous UHMWPE fabric. By repeating this process with many layers of short chopped UHMWPE fibres or UHMWPE fabric, a layered stmcture was reported to have been created. These fibre assemblies were then heated under pressure to consolidate the structures. The short UHMWPE fibre-reinforced composites had a fibre volume fraction between 25 and 75%, while the continuous UHMWPE fabric-reinforced composites had a fibre volume fraction of 60%. Investigations into the potential application of these homocomposites in an articulation surface for a knee joint prosthesis were also described, as were the challenges associated with measuring the tribological performance of such fibre-reinforced materials [180]. 

As already stated, the durability or permanence of a bonded assembly is dependent on the intended use and service conditions to which the bond will be exposed. However, the joint design, choice of substrates, adhesive selection, substrate preparation, and primer selection, where appropriate, plus the method of application and assembly all have significant impact on the service life of adhesively bonded materials. Most or all of these considerations are interdependent, for example, the joint design and substrates chosen will limit the range of suitable adhesives that can be employed. In a similar way, the durability of a sealed joint is only as good as the adhesion of the sealant (and primer) to the surfaces forming the joint. Primers and/or sealants will adhere to surfaces only if those surfaces are properly prepared. A very large proportion of all sealant joint failures result from poor or inadequate surface preparation. 

There is now enough evidence of their successful application to model engineering problems to convince even the most sceptical of us that the modern techniques of adhesive assembly and sealing have an important place in the amateur workshop. I hope that this handbook will prove useful in designing suitable joints for items of workshop equipment, as well as for models of all types where the methods are applicable. It is also intended as a guide in selecting the most suitable products to use for different materials and under differing conditions. 

A method has been presented for computing the dynamic response of a serial link manipulator with flexibility in both the links and the joints. Robotic applications of this work are vibration control, reduction of cycle time, compliance control for assembly operations. Numerical results were presented for a one-link structure with... 

---