Лако-красочные материалы — производство

All adhesives display changes in their bulk properties when the temperature changes. This change is particularly marked (as with many engineering plastics) when the glass transition temperature (Tg) is passed. The Tg of a cyanoacrylate is of the order of 120 °C whereas a UV acrylic generally has a lower Tg (50-80 °C). These changes […]

The gap between the parts and therefore the thickness of the adhesive film has an important bearing on the characteristics of the joint [4]. A thick bond line (>0.25 mm) will generally be a weakening feature for cyanoacrylates as the mechanical strength of the cured cyanoacrylate film is likely to be less than the plastic […]

The butt joint can be in various configurations (Figure 5.19) and this is almost certainly the easiest and lowest-cost joint. The success of this joint will depend on the materials bonded, the loads on the joint and the thicknesses of the substrates involved. If the adherends are rigid and a moment or offset load is […]

Where a ‘blind’ hole exists if the adhesive is applied to the male part and the joint closed, it is likely that the air trapped in the base of the hole will push all the adhesive out of the hole and thus starve the joint of adhesive (Figure 5.17). The best practice is to apply […]

Another method of applying adhesive to cylindrical parts is to introduce the adhesive via a cross hole (Figure 5.16), although this does involve additional detailed mould design.

In many cylindrical bonding applications involving plastics, it is common practice to dispense the adhesive onto the inner (male) substrate and then close the joint with a rotating action. This in principle is fine but invariably excess adhesive is applied and the excess will be forced out of the joint as shown in Figure 5.13. […]

A common application for adhesives is where co-axial (cylindrical parts) require to be joined. Figure 5.11 shows a typical application where the black polypropylene spigot is to be bonded and sealed into the red elastomeric (thermoplastic elastomers) housing. In this case, both these plastics are low-surface-energy materials and so will require either a surface primer […]

A tongue and groove (or double lap shear) joint (Figure 5.9) can be an ideal joint design for many applications, especially for bonding a lid onto a box. The adhesive can be dispensed into the groove, thus ensuring positive location of the liquid adhesive and when the joint is closed and the adhesive cured, the […]

A fillet of adhesive is almost invariably formed outside the joint (Figure 5.7) and this can be beneficial in that it reduces the stress concentrations at the end of the joint. For this reason the excess adhesive should only be removed for aesthetic purposes. The lap shear joint has been the subject of much academic […]

In a standard lap shear joint, if the overlap length is increased, the strength of the joint does not necessarily increase linearly for the same standard conditions (i. e., same adhesive, same substrate, same surface preparation, and so on). In Figure 5.3 below the bond area has been increased from 1000 mm2 to 2000 mm2 […]