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The purpose of this study was to investigate the thermal deformation effect of a machine tool frame on hole registration accuracy. Hole registration accuracy represents the drilling performance of a machine tool, and it greatly depends on the thermal deformation of the machine frame structures in practical engineering. Reducing thermally induced errors is crucial to improve the hole quality.

First, the thermal design of the machine frame was performed via an optimization procedure to reduce the thermal deformation at an early stage. Then, a thermal–mechanical coupling finite element method model was established to quantify the thermal deformation of the machine tool under environmental temperature fluctuations, and the validity of the presented model was confirmed experimentally using laser interferometry. Finally, a series of drilling tests, including micro-holes and medium holes, was carried out to practically investigate the hole drilling registration accuracy of the machine with a mineral casting frame under different thermal conditions.

Hole registration accuracy showed positional dependency and distinctly non-linear behaviour at different drilling axes which was closely related with the thermal conditions. The positional deviations of medium holes and micro-holes all showed an increasing trend in different degrees under the same temperature fluctuations, and the former were more sensitive to the latter. Therefore, keeping the drilling workshop under thermally stable conditions is crucial for improving the drilling performance of the machine.

The goal of this paper is to reveal the mechanism of hole registration accuracy variations with thermal fluctuations and to provide a strategy for the machine tool industry to further improve the drilling performance during the machining process.

The purpose of this paper is to investigate the concept of new drill bit geometry adjusted to a given composite type. This paper explores the possibility of drilling in composites without negative effects such as: delamination, rapid tool wear, matrix burns, pulling out of fibers, etc.

Appropriate modification of drill bit geometries applied to composite materials include, among other things: modifications of point angles, reduction of chisel edge width, modification of drill margins and proper preparation of drill bit corners.

Description of tool geometry for drilling of different types of composites, in particular drilling in parts included free grain surfaces but also drilling at a different angle than 90°.

Geometrical details of the tool for drilling are depended on the type of composite.

Making of montage holes in parts made of composites without negative effects during drilling.

Analysis of the current state of knowledge shows that there are insufficient solutions in terms of new drill geometry for drilling of composites. Existing solutions do not guarantee adequate stability and repeatability of the cutting process. It is necessary to create new geometry drills permit the elimination of negative phenomena during drilling.

IN this issue there is a Letter to the Editor (page 42). Its author is D. A. Barron, Chief Work Study Engineer of Marconi's Wireless Telegraph Co. Ltd., at Basildon. The letter is important from two aspects. Firstly, because it enables the writer of this column to clear up any misconceptions lingering in people's minds regarding references to Charles Bedaux in past editorials appearing in this journal.

The purpose of this paper is to analyze machinability of CFRP, GFRP, GLARE-type composites in drilling process taking into account their features and properties (the geometric characteristics, the volume fraction and the mechanical properties of the individual components of the composite). Drilling in non-plan surfaces and slope drilling.

The tests were carried out in two stages: perpendicular drilling of materials such as GLARE with special drill bits, and drilling of composite structures with non-planar surfaces made of unidirectional carbon fiber prepregs, using the modified special drill. Measurement of cutting forces and torque, stress distribution (photoelastic method) and a visual assessment of defects occurring during drilling allowed to determine the relationship between the type and geometry of the composite drill.

Identified great effect of kind of composite on the machinability of these materials has substantiated modification of the standard geometry of drills and matching this geometry to specific properties of the various type of composites.

Drilling of assembly holes for aerospace parts.

New type of drill geometry for different type of composite.

NC drilling and routing have come of age and have revolutionised the process of drilling holes in PCBs. Computer controlled (CNC) machines are being introduced and the microprocessor will speed this process. This paper demonstrates the improvements to be made in hole quality and machine usage employing machines originating in Europe rather than in the USA as was previously the case.

The purpose of this paper is to analyse and compare the downtime of four drilling machines used in two underground mines in Sweden. The downtime of these machines was compared to show what problems affect downtime and which strategies should be applied to reduce it.

The study collects failure data from a two-year period for four drilling machines and performs reliability analysis. It also performs downtime analysis utilising a log-log diagram with a confidence interval.

There are notable differences in the downtime of most of the studied components for all machines. The hoses and feeder have relatively high downtime. Depending on their downtime, the significant components can be ranked in three groups. The downtime of the studied components is due to reliability problems. The study suggests the need to improve the reliability of critical components to reduce the downtime of drilling machines.

The method of analysing the downtime, identifying dominant factors and the interval estimation for the downtime, has never been studied on drilling machines. The research proposed in this paper provides a general method to link downtime analysis with potential component improvement. To increase the statistical accuracy; four case studies was performed in two different mines with completely different working environment and ore properties. Using the above method showed which components need to be improved and suggestions for improvement was proposed and will be implemented accordingly.

Drilling is an important operation in aircraft wing assembly. In order to enhance this operation, automated machines are used. The purpose of this paper is to propose an off‐line programming system to generate NC code effectively and accurately for a five‐axis NC drilling machine applied in aircraft wing flexible assembly.

The NC program is divided into three hierarchical parts to correspond, respectively, to the whole wing, single rib and single hole. The programming procedure for such three‐layer wing structures is detailed, which includes product model modification, NC program generation and post‐processing.

By demonstration, the implemented system is proved to increase the efficiency and correctness of NC programming, and the generated program performed well on a flexible wing drilling system.

The system can only program for automated drilling machine at present, however with further development both automated drilling and riveting machine in aircraft wing assembly can be programmed by this system. Another development might make this system universal for different machineries and other aircraft components.

The paper indicates a new way to program for rapid wing flexible drilling, and the generated NC program is more adaptable and easier to update for various aircraft wing structures.

Drilling is the first process step in creating a plated‐through hole (PTH). The purpose of the PTH is for electrically interconnecting two or more circuit locations and/or providing a means for electrical and mechanical connection of components to the MLCB.

DRILLING, REAMING, COUNTERBORING, THREADBORING, ETC. THROUGHOUT the design of every machined part the designer should follow the practice of visualizing the machining involved, and make a genuine effort to design for “machinability” by avoiding all difficult operations. This factor cannot be over‐emphasized, as it is only too easy to complicate the machining of a part unnecessarily by lack of forethought during the design.

A large number of fastener holes have to be drilled with high quality in the circumferential splice region during the assembly of aircraft fuselage. The purpose of this paper is to design an automatic stepping mechanism for a circumferential splice drilling machine, to meet the requirements of large workspace and high accuracy in drilling at the same time.

A docking position detection method based on magnetic proximity sensors is proposed for the positioning of the arc-shaped rail with respect to the circumferential rails, which significantly improves the accuracy and reliability of automatic stepping. The slipping phenomenon of the end-effector is analyzed, and the optimized counter weights are used to eliminate the slipping and improve the working stability of the stepping mechanism.

An automatic stepping mechanism is developed for the circumferential splice drilling machine, which comprises the docking position detection method and the elimination/suppression method of the end-effector’s slipping.

The proposed automatic stepping mechanism has been integrated into the circumferential splice drilling machine for the fuselage assembly in an aircraft company in China.

An automatic stepping scheme for the circumferential splice drilling machine is proposed, which enhances the efficiency in circumferential splice drilling in aircraft fuselage assembly.