## 1 Introduction  
The use of adhesive bonding in the manufacturing of machining tools is well documented, having been a topic of study for over 40 years; though publication regarding this process has waned in the last decade. Most investigations have been devoted to assessing the thermal behaviour [1; 2; 3; 4] of the bonded joint integrated in the cutting tool or to the determination of the quality of cut and surface finish [5; 6; 7]. Other works have sought to obtain improvements in the joint capabilities via the addition of metallic and other conductive powders, increasing the thermal [8; 9] and electrical [10] conductivity. However, until now the use of adhesives in machining tools has been very limited, since many of the limitations inherent to this technique have never been fully addressed. In more recent years, studies performed by [PERSON] et al. [11; 12; 13] and [PERSON] et al. [14], have shown that adhesive bonding can serve as a substitute for brazing in woodworking tools, an application where the temperature, environmental conditions and the cutting loads are much more favourable for adhesive bonding. As a result, a much lighter tool can be obtained, because adhesive bonding facilitates the shift from steel to aluminium bodies, while maintaining a high strength safety factor, sufficient thermal resistance and the capability to be sharpened by non-thermal/contact methods, i.e., electrical discharge machining (EDM). However, these works do not address the long-term durability of this solution. For this, it is necessary to systematically characterise the effects of all the possible joint degradation phenomena present in the entire life cycle of a milling tool. The first step in this process consists of the definition of a typical life cycle for these types of tools. This can be observed in Figure 1.  
A common tool life cycle is composed of four stages: the design (Stage 1), production (Stage 2), work life (Stage 3), and maintenance (Stage 4). Stages 3 and 4 alternate for a few cycles until a tool reaches its end of life. The initial stage of joint design usually does not involve the assessment of degradation, but subsequent stages can affect joint durability. Therefore, designers must be aware of factors that can affect the joint's lifespan when using bonded joints and account for any negative effects. Figure 1: Typical life cycle of milling tools. Stage 2 involves the manufacturing cycle of milling tools, which includes several processes such as saw cutting, turning, milling, grinding, and EDM. Surface coatings may also be applied for uniformity and strength but only for aesthetic purposes. These coatings do not contribute to initial joint strength but can contribute to degradation. Finally, the tool is sharpened using electric-discharge machining (EDM) to prepare it for service. Stage 3 is the entire service life of the tool. Although the tools are mainly used in dry applications, such as woodworking, ambient moisture and temperature can still pose potential issues during this stage. To future-proof the concept, the possibility of wet milling, which involves contact with cutting emulsions, should also be considered for this stage. The fourth stage of the tool's lifecycle involves maintenance operations, including repair and cleaning/resharpening. When repairing the tool, it is important to determine whether individual cutting bits can be fixed or if all bonded cutting bits are affected and require reworking of all adhesive connections due to the possibility that multiple curing cycles have weakened the shear strength of the adhesive. The cleaning and resharpening operation involves several techniques, such as residue softening fluids and abrasive jets, which must be investigated for their impact on the shear strength of adhesive connections. The maintenance stage is crucial to ensuring the tool's longevity and performance.