THE ADVANTAGES OF INTELIGENT APPROACH TO MACHINING PRESENTED THROUGH PROCESSING TECHNOLOGY DESIGN DEVELOPED BY I-MACHINING

The modern day effi cient machining requires a new approach to designing machining technology, which enables the complete engagement of all technological machining parameters, like cutting speed and cutting feed depending on the work piece material, characteristics of the machine and tools and volume of the material removed from the machined zone. Controlling physical quantities, which appear in the process of cutting, enables us to achieve faster machining processes when compared to current high speed machining technologies (HSM) and at the same it increases productivity. This approach to machining requires the CAM software intelligence to make decisions in real time and optimize tool path, in order to keeping the constant cutting tool force during whole machining process. This type of approach was used while designing machining for “heat exchanger”with the help of imachiningtechnology within SolidCAMsoftware for programing of CNC machines.Where by reduced the machining time for 36% in accordance to conventional machining and made a total savings of 45.33%.


INTRODUCTION
Imachining technology represents an implemented set of experiences and data in SolidCAM software for designing of machining technology, on which the basic algorithm for creating of optimum tool path is based, Figure 1. Based on the integrated information about tool, workpiece material and geometry and machine capability, imachining technology automatically synchronizes the cutting speed, cutting feed, cutting depth, milling width, chip thickness and chip shape while creating the executiveg codefi le for programing of CNC machine. Synchronizing the cutting conditions is present during the total tool path depending of the tool involvement degree, i.e.Side step value, Figure 2. In this way we can create perfectly smooth and tangential tool path, which avoid the overuse of the tool and eliminate air cutting, implicating productivity increase and tool wear reduction, Figure 3.

Imachining technology advantages
The research of current designing machining methodology has shown that there is an incomplete and inadequate control of tool path leading to tool overuse and a large number of air cutting in most cases. That is the reason for the development of advanced generation of designing machining for fast material removal with built -in intelligence, the so called imachining technology which enables the completely automatic tool path control and cuttingconditions based on the machining parameters. The user does not have to have a wide technological knowledge, because it has already been integrated in the technological base it self. It is just necessary to choose the machine andappropriate tool based on workpiece material. Namely, the integrated

Imachining technology disadvantages
In order forimachining technology to work properly, we have to input empirical data in the technological base kept in two tables connected with appropriate relations based on which the algorithm optimizes the tool path. It is necessary to defi ne machine characteristics, like the power of engine drive, effi ciency, the max spindle speed and max Side step. The current data on material require only the value of Ultimate tensile material strength Rm[MPa], Figure 6.

Figure 6: Technological base of selected machine and materials
Current algorithm does not take into consideration other machinability parameters, but the user could manually modify other values as necessary in technological material base. The earlier versions used as basic machining parameter the value of unit power necessary to remove 1cm 3 material. Because of the complexity of calculating the value of this parameter, today's program package version was upgraded and requires the

PROPERTIES OF MACHINE, TOOLS AND WORKPIECE MATERIAL
The example material we used was titanium alloy Ti6AI4V, with the following properties,   For the machining of this particular example of heat exchanger we used milling machine Mazak FH4800, with the following properties,

PREPARATION OF EXECUTIVE GCODE FILE FOR PROGRAMING OF CNC MACHINES
Besides enhancing productivity in machining, imachining technology simplifi es the process of defi ning technological operations and reduces the number of tools required for the production of parts because it enables machining with lower tool diameter. This leads to shorter preparation period for executive g code fi le for programing of CNC machines. The user is required to choose the machine which would be used in the machining process and workpiecematerial from technological imachining base and the most suitable Tool for the part in specifi c, Figure 9. Software automatically calculate the maximum cutting depth based on the length of the tool cutting edge and workpiece geometry, which is later adjusted to fi nal product geometry, by machining, fi rst, the deepest zones, and then tool is lift-ed higher in accordance with demanded surface roughness(Scallop). This is an inverse process (Step-Up) of geometry scanning procedure considering the previous CAM high speed machining (HSM) processes, Figure 11. The user has the freedom to defi ne machining aggressiveness depending on the clamping conditions and workpiece stability, cooling possibility and tool condition, during which this technology synchronizes all cutting condition in every tool path point, Figure 12. This enables fast and simple adjustment, as well as fi ne tuning of the tool path to the current cutting conditions and processing new executive g code fi les for programing of CNC machines. During this technology testing, we have done machining with several different setups and we have come tofollowing conclusions: Number of the cutting edges:fi rst of all, the cutting tool been used by three with different number of the cutting edges and of the SECO-JABRO SOLID series. Apparently, we have used the tool with two, three and four cutting edges. Two cutting edges made good machining but the machining time was too big. Machining with four cutting edges caused high cutting speed, and this is not well demonstrated in the processing of this material because of high temperature in machining zone. We have concluded the three cutting edges of the tool is the best solution for this case.

Number of axial contact points(ACP):
We have concluded that the number of contact points of tool spiral and workpiece directly affects the increased vibration occurrence. The integrated algorithm, based on the diameter, number of tool cutting edges and tool helix angle, calculates the number of contact points and warns the user about the possibility of vibrations occurring. This way user could choose a tool of different geometric properties or change cutting depth in order to reduce vibration during machining, Figure 13.

TOOL PATH IN IMACHINING TECHNOLOGY
Imachining technology is unique in its tool path shape in which are achieved. Integrated algorithm adjusts the tool path to workpiece geometry and create spiral tool path with changeable Side step and separates islands if it is necessary, Figure 14:

IMACHINING TECHNOLOGY DEVELOPMENT TENDENCIES
SolidCAMCompany is working on developing advanced models of this technology for complete automation of machining preparation process, when the user would be able to choose one of three possibilities given to him while creating tool path: Minimum machining cycle time -this option might be used when a certain part is machined with cheaper tool on high performance machine, due to short delivery deadlines, Longest tool working life -users would be able to decide for this option in order to keep the current tool, due to the tool storeroom shortage, up to the date of the delivery of the fi nal part or product, Lowest cost -algorithm would fi nd the right balance between machining time and tool working life by using data fromtechnological base on tool cost and machine working hours.
In collaboration with cutting tool manufacturers, ISCAR Company among others, new tool series are being developed with adjusted cutting part tool geometry and increased number cutting tool edges (6-12). These will farther increase productivity and Tool life.

CONCLUSION
Imachining technology represents unique and revolutionary machining technology on the market of CAM software; it enables manufacturing cost reduction and increases productivity among materials diffi cult for machining. Application of SolidCAMimachiningtechnology in machining of the mentioned heat exchanger we have managed to save 36% of machining time, when compared to standard HSM machining, Figure 15. When machining of lighter materials time savings are smaller but not venial. This technology development enables companies dealing with machining services to accept tasks which they were unable to fulfi ll due inexperience and insuffi cient knowledge in the material machining area.