Developments in Hole-to-Hole Assembly

In this paper Stork Fokker presents its developments in hole-to-hole assembly. Conventionally, holes are drilled in stacks of parts during the assembly stage. This includes drilling in hybrid stacks, thick stacks or stacks that are badly accessible. Hole-to-hole assembly is an assembly philosophy in which holes are drilled full-size in both part and counterpart during the single part manufacturing. The main advantages are reduction in both non-recurring and recurring cost in the subsequent assembly process and improvement of the component's quality.

Within Stork Fokker research has been carried out to the impact of using hole-to-hole assembly on both the manufacturing process and the component's quality. Outcome of this research includes:

• A cost calculation model in which both non-recurring and recurring cost of hole-to-hole assembly and conventional assembly are compared for several applications;
• A statistical tolerance model to predict the probability on mismatches between the hole patterns of mating parts for several applications (material type, temperature, amount of holes, product size, etc.);
• Results of tests to the influence of hole misalignment, hole size and the drilling process on static strength and fatigue life.