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This paper describes the principles of a new method to compensate for tool wear when drilling in complex materials such as Carbon Fibre Reinforced Plastics (CFRP), Carbon Fibre Reinforced Plastics / Titanium (CFRP/Ti) and Carbon Fibre Reinforced Plastics / Alloy (CFRP/AI) stacks. A reliable and repeatable hole quality is essential, especially in automatic drilling applications with robots or gantries. The method combines the unique feature to dynamically adjust the drilling diameter in very small steps in an Orbital drilling End-effector and a new type of software algorithm to predict and compensate for the tool wear in different materials. With this method a large number of holes can be drilled without changing the cutting tool, and a Cpk value of more than 2,5 can be achieved.

Fully autonomous systems are seen as the ultimate solution to all manufacturing problems due to their consistent quality and ability to improve rates, but they also have one key disadvantage: Limited equipment versatility. This shortcoming becomes most apparent when trying to apply automation to aircraft final assembly. The variety of jobs is great and would necessitate the development of many unique solutions. Therefore a robotic system designed for one job on one aircraft version might be useless on the next version. Also there are many tight spaces and complex jobs where automation is just not practical, meaning that workers with portable tools will always have some presence in production. The modern smart portable tool as exemplified by the Novator PM Series orbital drill motor is capable of matching the quality and speed of a robotic system while still maintaining the ability to be applicable over a wide variety of jobs.

This paper describes ongoing research into orbital drilling using standard industrial robots. The research is a part of an ongoing EU funded aircraft industry project - ADFAST*. Generally it is difficult to use standard industrial robots to automate drilling in the aerospace industry. The stiffness of the standard robotic device is not sufficient to resist the deflections caused by the cutting forces from the drilling process, therefore it is difficult to achieve the tight hole tolerance requirements. Orbital drilling creates lower axial cutting forces compared to conventional drilling and therefore allows the use of low-cost standard industrial robots for drilling holes within the required hole tolerances. This paper presents results from a study where forces, moments and dislocations produced during orbital- and conventional drilling have been measured.

This paper deals with orbital drilling of sandwich constructions for space applications. Sandwich constructions for space applications are typically made up of thin layers of carbon fiber composite skins separated by an aluminum or carbon honeycomb core. Drilling holes in such structures is required for assembly purposes. A common and significant problem occurs when drilling such structures with conventional methods, namely delamination on the exit side of the composite layers. In this study orbital drilling is investigated as a means of eliminating delaminations and other frequently encountered problems with conventional drilling of laminated composite structures. Holes of different sizes were drilled in sandwich panels using orbital drilling. Both automatic (CNC) and semi-automatic (portable) orbital drilling were investigated. Damage in the vicinity of the holes was assessed by means of microscopic evaluation.

The new materials and material combinations such as composites and titanium combinations used on today's new airplanes are proving to be very challenging when drilling holes during manufacturing and assembly operations. Orbital hole drilling technology has shown a great deal of promise for generating burr free, high quality holes in hard metals and in composite materials. This paper will show some of the orbital drilling development work Boeing is doing with Novator to overcome the obstacles of drilling holes in a combination of both hard metals and composites. The paper will include a new portable orbital drilling system designed for these challenging applications as well as some test results achieved with this system.