## 4 Conclusions  
This study had the goal of analysing a milling tool's life cycle and to thus assess how the degradation processes to which an adhesively bonded milling tool might be exposed influence the joint performance. This adhesive bonding process was previously studied and characterised by [PERSON] et al. and [PERSON] et al., making this work a new stepping stone in the study of this manufacturing process, one that is geared towards the long-term degradation experienced during a tool's life cycle. From this work, the following conclusions can be drawn:  
* In the production stage, the dielectric fluid showed no signs of uptake into the adhesive plates and, therefore, was subjected to an FTIR analysis, where no significant changes were observed between the control and the aged samples;
* The strength tests revealed that the ageing in this fluid has no effect on the strength of the adhesive joint when the adherent material is steel. However, there is some decrease in shear load capacity for aluminium specimens;
* Applying surface coatings to steel tools has a negative effect on the strength of the bond. Since the chemical treatments involve corrosive environments and high temperatures and are, oftentimes, undertaken for uncertain and unquantifiable periods of time--until the desired aesthetic finish is observed--it is very difficult to assess the true effects of the process. From a productive standpoint, these coatings should be avoided, and different surface finishes must be chosen;
* During a tool's usage, fluids such as water (ambient moisture, etc.) and cutting emulsion (metal-cutting tools) are in constant contact with the joint. Having said that, the gravimetric analysis led to the understanding that both water and cutting emulsion have a high rate of diffusion into the adhesive, through a relaxation-controlled process;
* Nevertheless, the cutting emulsion causes much higher uptake since its relaxation phenomenon is more severe. During strength testing it was determined that both fluids reduced the shear load withstood by the joint by more than 50%;
* Maintenance activities performed on the tool also raised concerns regarding joint degradation. However, the petroleum oil analysis allowed us to understand that the joint is still functional after six maintenance cycles;
* A maximum submergence time of sixteen hours was obtained for the petroleum oil, as more time than this would lead to a 20-30% decrease in the joint's shear strength;
* The ultrasound cleaning mixture produced very acceptable results, and was identified as the best alternative to clean bonded joint milling tools, as after six maintenance cycles the strength decrease was only around 10%;
* In general, these tools should not be cleaned with sandblasting, as, though the shear strength decrease was not critical, this procedure eliminates the beneficial adhesive fillet. Nevertheless, a maximum application of 10 s should be used and only if it is absolutely necessary for the removal of hard residue;
* The repairaability tests revealed that it is possible to repair just the bits that were broken during use, as the remaining cutting bits had no adverse effects on the multiple curing cycles;
* The concerns over the dimensional variation of the adhesive joints proved to be unwarranted, since the rate of dimensional fluctuation was too small to have an effect on the quality and accuracy of the cut. Finally, it is important to consider that these specimens were tested in isolation, and real-life conditions present a summation of different effects when all of these conditions are considered at the same time. Nonetheless, this study allowed us to precisely characterise the behaviour of bonded tools under diverse degradation conditions, and thus establish quality assurance guidelines for the manufacturing, storage, work and maintenance stages in the life of a bonded milling tool. Conceptualization, R.J.C.C., E.A.S.M. and L.F.M.d.S. ; Investigation, R.J.F.d.S. and P.N.G. ; Resources, P.J.C.d.N. and W.P.A. ; Writing--original draft, R.J.F.d.S. and P.N.G.