Injection Molding Direct Joining (IMDJ) is a direct joining technology that employs surface pre-treatment of metals and plastic injection molding for joining, eliminating the need for additional components such as screws and adhesives. For surface treatment, we use microblasting, because it is a very simple and inexpensive method that reduces costs and enables high productivity and eco-friendly surface treatment. However, based on our understanding so far of blasting, many issues remain unresolved. The primary issue is the lower strength of single blasting. In this study, we perform surface pre-treatment by conducting a secondary blasting on the basis of the initial one. We utilize blasting particles of various sizes and types (such as white alumina and glass beads). We compared the joint strength and conducted a lateral comparison. Additionally, we employed a heating process to verify its effect on strength, since heating can produce microstructure. The results indicate that the secondary sandblasting method can enhance connection strength. The heating process also contributes to an increase in joint strength.
