5-axis Milling Machine Research Articles

Conversion CL Data to NC Data Using an Instinctive Method for Non-Orthogonal Table-Type 5 Axis Machines

Since different types of 5-axis milling machines have their own unique rotation mechanisms, the solutions developed to generate numerical control (NC) data are traditionally targeted toward specific mechanisms and are obtained via specific methods, normally resulting in complex algorithms. In order to resolve this problem, this paper proposes an instinctive method to convert cutter location (CL) data to NC data for non-orthogonal table-type 5 axis machines. The rotational angles of the two rotational axes can be easily derived from the tool-orientation vector, and the coordinates of the three linear axes in the NC data can be easily derived from the rotational angles and coordinates of tool position. Even more, this method enables the development of a generic algorithm for the rotation mechanism of any 5-axis CNC milling machine.

Technical concept of patient-specific, ultrahigh molecular weight polyethylene orbital wall implant

IntroductionThe authors have been using patient-specific implants since 2006 and are constantly looking for new reconstructive materials, in order to create precise implants for orbital reconstruction. Such materials should be biocompatible and stable in the human body, as well as easy to machine and form into complex 3D shapes. Biocompatible ultrahigh molecular weight polyethylene (UHMW-PE) has several unique properties including high impact strength and a low friction coefficient that result in self-lubricating and thus non-sticking surfaces after processing. AimTo present the concept of a patient-specific, UHMW-PE orbital wall implant. Materials and methodsThe material used to manufacture the orbital implant was UHMW-PE converted into a solid block of medical polymer from a powder material. A delayed treatment unilateral orbital fracture case was chosen for reconstruction with patient-specific orbital wall implant. On the basis of computerized tomography, a virtual model of both orbits was prepared. The injured orbit was significantly enlarged due to dislocation of its walls. The 3D model of the facial skeleton was symmetrically divided into two parts. This resulted in two models – left and right orbit, then the uninjured orbit was superimposed onto the contralateral side. As a result two surfaces were created; the outer surface (taken from the injured orbit) was used to design the outer surface of the implant, and the inner (taken from the uninjured orbit) for the inner surface. By combining both these surfaces it was possible to determine the unique shape and thickness of the UHMW-PE implant that would allow for accurate reconstruction of the orbit. Following this, the CAD model was transferred to CAM software and a numerical code for a 5-axis milling machine was generated. The manufactured implant was sterilized in gas plasma and used to reconstruct three orbital walls. ResultsThe thickness of the manufactured implant ranged from 0.2 mm to 1.5 mm and was successfully inserted via transconjunctival approach. The lower, medial and lateral walls were reconstructed. The correct position of the right eyeball was re-established by moving it upward and medially, which resulted in enophthalmos and diplopia correction. The described method features several advantages: accurate reconstruction of the original shape of the orbit, precise modification of local implant thickness during design of the CAD model, structural globe support combined with a thin implant, the possibility of repairing large orbital floor defects, corrections using scissor/scalpel during surgery are relatively uncomplicated, low level of morbidity, smooth edges and gradual, controlled variations in implant thickness between different regions. Disadvantages: changes to the curvature of the implant cannot be made during surgery, implant may require fixing with screws to be stabilized during the early phase of healing, long time required to design and manufacture implants (pre-op) and also UHMW-PE implants are radiolucent and cannot be imaged using X-rays. ConclusionUHMW-PE appears to have numerous advantages as a material for precise reconstruction of the orbits. Such patient-specific implants are durable, can even be used to reconstruct very thin walls, do not exhibit the high degree of morbidity typical for autogenous bone grafts and result in restoration of vision function.

NC Post-Processor for 5-Axis Milling Machine of Non-Orthogonal Type

It is important in practices and engineering applications to study the post-processor of 5-axis milling machines with non-orthogonal structure. A special type of 5-axis milling machines was studied in this paper, in which the axis of the rotary table is fixed at 45° to the spindle. Based on analysis of its structure and kinemics, the post processing algorithms were deduced in detail, including calculation of the table rotary angle and the motion coordinates of the spindle. The post processing algorithms provide the mathematic foundation for development of the CAD/CAM soft ware.

Study on Cutter Radius Compensation Methods for 5-Axis CNC Machining

The numerical control (NC) program files need re-generating if there is any tool dimension change or tool wear for multi-axis machining. If the tool is replaced to adapt this change there will be increased cost. To solute this problem, 3D cutter radius compensation method for 5-axis computer numerical control (CNC) machining is deeply researched. Taking five axes linkage machine tools of X, Y, Z, B, C form with rotary tables B and C as an example, coordinate transformation matrix (CTM) and the cutter compensation vector for 3D cutter radius compensation are derived. The discrimination methods for path joint pattern (PJP) are given. A controller with 3D cutter radius compensation function for 5-axis linkage CNC machine tools is developed based on this method. The controller is allocated to a 5-axis milling machine tool and experiments are done. The proposed algorithm is demonstrated using a practical example.

Optimum process parameters to produce green ceramic complex parts

The fragility of green ceramic compacts introduces considerable difficulties during green or bisque machining. This paper demonstrates methods developed to manufacture thin wall–thin floor, complex green ceramic parts to close tolerance. Hybrid finite element (FE)/mechanistic models were utilized in the development of the green machining process. An FE model was used to define cutting edge geometry and machining parameters that would reliably produce crack free parts. Mechanistic model was used to direct cutter path generation of a 5-axis milling machine having a large axial depth of cut, and to prevent edge chipping. The optimized cutter path eliminated any need for hand work before densifying the machined part.

High-speed milling of large impellers

In the past, technical limitations have meant the high-speed machining of precision parts has been restricted to smaller, highly-dynamic machines. Challenging this, Sulzer Innotec has created large impellers for compressors on 5-axis milling machines.

Parametric tool correction algorithm for 5-axis machining

Today, 5-axes CAM systems generate tool paths as a sequence of tool postures, which define the position of the tool tip and the orientation of the tool axis. This tool posture data file is usually called CLDATA, because it stores the position of the Cutter Location. In current practice, if the tool correction problem arises on the shop-floor, or at the machining simulation level, it can only be solved by sending back the code to the CAM system for re-generation. This iterative procedure is slow and very inefficient. In this article, a data model is specified that stores machine independent and dependent information separately. Based on this segmented data model a general method is presented to solve the tool correction problem for 5-axis milling machines. The new data model and the provided algorithms allow us to solve tool correction and possible other setup problems on the shop floor level. The algorithm is developed for ball-, flat- and radius-ended tools and is valid for 5-axis milling machine with open kinematic chain.

NC tool path generation for 5-axis machining of free formed surfaces

This paper presents a ‘tool axis vector’ approach for machining sculptured surfaces. Such an approach is well suited for highly twisted, rolled, or bent surfaces. The tool paths are generated for a 5-axis milling machine. The proposed approach is based on tilt angle, cutting direction, and a vector normal to the cutting surface. Gouging is avoided by checking the interference between the cutting tool and the part surface. The algorithm also finds maximum path intervals that generate maximum admissible cusp height within the specified tolerance limits. Such an approach minimizes the tool path and machining time. The paper presents an example to illustrate the details of the algorithm.

Evaluation of cutter orientations in 5-axis high speed milling of turbine blade

Recently, the development of aerospace and automobile industries has brought new technological challenges, related to the growing complexity of products and the new geometry of the models. High speed milling with a 5-axis milling machine has been widely used for 3D sculptured surface parts. When turbine blades are machined by a 5-axis milling, their thin and cantilever shape causes vibrations, deflections and twists. Therefore, the surface roughness and the waviness of the workpiece are not good. In this paper, the effects of cutter orientation and the lead/tilt angle used to machine turbine blades with a 5-axis high speed ball end-milling were investigated to improve geometric accuracy and surface integrity. The experiments were performed using a lead/tilt angle of 15° to the workpiece with four cutter directions such as horizontal outward, horizontal inward, vertical outward, and vertical inward directions. Workpiece deflection, surface roughness and the machined surface were all measured with various cutter orientations such as cutting directions, and lead/tilt angle. The results show that the best cutting strategy for machining turbine blades with a 5-axis milling is horizontal inward direction with a tilt angle.

NC post-processor for 5-axis milling machine of table-rotating/tilting type

The free surface machining with more than three axes motion needs CAD/CAM system for the cutter location and orientation data. Since these data are defined with respect to the coordinate system of workpiece, they need converting for machine control commands in machine coordinate system, through processing so called a NC post-processing. Most commercial CAD/CAM software vendors provide these post-processors for each type of 5-axis machines. However, they may cause some erroneous operation during phase reverse process that is due to unsymmetrical operation limits about rotating axes. In this work, efficient algorithms for NC post-processing have been presented for typical 5-axis milling machine of table-rotating/tilting type. The first algorithm is for avoiding the interference between a workpiece and the machine tool during the process of phase reverse. The second is for better strategy of machine path, which needs fewer number of phase reverse processes.

Development of a 5-Axis Control Ultraprecision Milling Machine for Micromachining Based on Non-Friction Servomechanisms

The study addresses the development of a 5-axis ultraprecision milling machine to create tiny 3-dimensional workpieces as well as microstructures. 3-axis control ultraprecision milling machines allow microstructures on tiny workpiece surfaces to be manufactured; however it is difficult to create 3-dimensional workpieces such as very small heads, statues etc., which will be important in micromanufacturing in the future. Thus, a 5-axis milling machine consisting of three translational and two rotational axes has been developed benefitting from the use of non-friction servomechanisms. 5-axis micromachining was conducted to create a half cylindrical workpiece. It was found that the ultraprecision milling machine is accurate enough to machine tiny 3-dimensional workpieces.

Design and fabrication of end spacers for a 13 T Nb/sub 3/Sn dipole magnet

A 13 Tesla R&D dipole magnet is being constructed using Nb/sub 3/Sn superconducting cable. The four-layer "cosine-theta" magnet uses a wide cable (/spl sim/15 mm) that will undergo a 650 C reaction after each layer is wound. About 75 bronze spacers at the magnet "ends" separate the winding blocks in such a way that the stored strain energy in the cable is minimized and the integrated field harmonics are reduced. Wax prototypes of the designed spacers were made on a 5-axis milling machine. This method of rapid prototyping required no tooling and enabled us to produce a large number of different end spacers that can be physically inspected and repeatedly modified before final prototypes are made. Spacers were originally machined from wax billets which were later cast in bronze.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

New coil end design for the RHIC arc dipole

The racetrack-shaped coils for the RHIC arc dipoles are wound with 32 turns of flat cable interleaved in the curved ends with insulating material {"spacers"} of varying thickness. To simplify production, the number of spacers, about 64 in each coil end, was reduced by making some of them thicker, to about 23. A new computer program was written which gives a description of each turn closely resembling the turn as made. The output of this program is processed by newly written computer programs which change the parts descriptions into forms which are used by a computer-controlled, 5-axis milling machine. The solid spacers replace spacers assembled from laminations and improve the fit as well. The parts will be molded during production. The calculated harmonic content of the ends is compared with measurements on the first magnets built with the new ends.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Influence of surface shape on admissible tool positions in 5-axis face milling

Abstract The machining time of sculptured surface face milling on 5-axis milling machines can be reduced if the tool trajectory is fitted to the surface shape. To achieve this, an interactive graphic CADCAM programming system should be applied, the machined surface should be smooth and its curvatures should not change too rapidly. In the case presented here, it was shown that the maximum width of machined strip on the surface could be obtained if the tool moved on the surface approximately along the minimum curvature line. The maximum width of the strip depended in this case mainly on the difference of the surface main curvatures at the contact point.