machine and also for the operator. Instruction are executed in time - PowerPoint PPT Presentation

Machining on CNC machines is controled by a NC code. NC code is a list of instructions for the machine and also for the operator. Instruction are executed in time order. NC code must have a specific format so that the control system of machine is able to read it.

 The tool in machine is moving in workspace.  The position of the tool is given by coordinates.  We are using different coordinate systems.  If we set some coordinates in NC code, the machine moves the tool to the specified place.

 Basic is orthogonal system Z Y X

Z axis is usually axis of spindle a X axis is the working axis, or the longest! Z Y X

Z axis is usually axis of spindle a X axis is the working axis – diameter!!! X Z

 To set the position we can add rotation along the axes. Second set of coordinates Z U,V,W resp. P,Q,R etc. C Y B X A

 Refernce point – a specific point on machine with given coordinates. Not always in the workspace of machine.  A special command G98

 Tool is moving to specific coordinates with given speed.  On its way it may enter the material and perform machining

Ways how to define a movement a) Absolute programing – position is in all point expressed as a distance from zero- point b) Incremental programing – position is expressed as a change from last postion

2. 3. 1. Absolut Incremental   G90 X0 Y0 Z50 G91 G0 X15 Y70 Z50 G0 X15 Y70 Z0 2. G1 X15 Y70 Z0 G1 X0 Y0 Z-50 G1 X25 Y70 Z0 G1 X40 Y0 Z0 3. G0 X25 Y70 Z50 G1 X0 Y0 Z50 G0 X0 Y0 Z50 G1 X-45 Y-70 Z0 1.

Structure and form of NC code is standardized by international standard - ISO 6983 – Numeric control programs formating Differences between different control system manufacturers and differences between versions.

Lines (blocks) Words Word has a meaning and value part S 1500

ISO is standardized code (G – code) Some manufacturers devoloped their own standard for NC code – native standard Mazak – Mazatrol Heidenhein – iTNC Siemens - Sinumeric

 Heading lines Definition of relation between coordinate system of CNC machine and program, type of programing, work mode, working conditions  Program body Cutting and non-cuting moves, main program and subprograms, tool changes  Ending lines Tool return to home point, change to first tool, coordinates reconstruction

Subprograms  A link to another then the following line is entered into main programm.  This subprogram is executed.  After finishing this program we return to main program a we contiue until end of main program(M30)

 Manual/Hand programing  Shopfloor programming  Automated programing

 Editors are used. Program is written manually (by hand) line after line.  Used for simple parts (but complex too)  Toolpath is exactly defined  Program can be adjusted to save time  Can use canned cyles  Can be parametrized  Used in mass production

We need to know the functions: (many more function exist) Movement functions: G00 rapid movement G01 linear interpolation/movement G02/03 circular interpolation G40 diameter compensation off G41 diameter compensation on /right handed G42 diameter compensation on /left handed Support and help functions: M06 tool change M03/04 spindle start CW/CCW M05 program stop M30 program end

Specilzed editors Predator G-code editor G Wizard Mikronex

Somewhere in between manual and  automated Uses cycles with parameters  We have to edit these  parameters manually But the NC code  is generated automatically No postprocessing 

Control system use – programming on machine - No costs (together with machine) - Fast use (macros) - Time waste (program x work) - Comfort (on machine x in office with PC) - Shape limitations Heidenhein

 Work with the „ sequential NC code preparation “  Uses CAM (Computer Aided Manufacturing) software  For all parts including complex shapes  We dont need to compute the toolpath  We need correct postprocessor

Partprogram – workpiece, Partprogra material, cutting conditions, tools … m Procesor – according to Proces technology or CL data – virtual toolpaths on virtual machine CL-data Postprocesor – „ translator “ for the specific CAM- control systém -machine combination Postproces NC code – toolpaths of a or real tool on a real machine NC- kód

is Computer Aided Manufacturing (machining)  From simple 2-axis turning up to multiaxis machining  Feature or technologically oriented  Special types of CAM for special purpose Live presentation

2D – just in two axis - turning 2,5D – two axis, but in layers – not simultaneously 3D – three axes simultaneously multiaxis 4D – four axis - one rotary axis (rotary table) 5D – five axis - maching (two rotary axes)

CAM software uses „ Strategies “ Strategy – is a general plan how to move the tool durign machining Continual development Roughing – offset, raster (Zig-Zag method) plunging Finishing strategies – pencil milling, streaming, rest material maching

NX (Siemens PLM software) Catia (Dassault systémes ) – both 10% market share PowerMill, FeatureCAM, ArtCAM (Delcam company) ,InventorCAM (Autodesk) Wildfire – Pro/Ingineer (PTC) – 5% EdgeCAM, SurfCAM, SolidCAM, MasterCAM, OneCNC, ESPRIT, GibbsCAM

Simulation is used to control generated toolpaths for following reasons: - Colisions - Undercuts (or rest material) - Postprocesing check

NX

 We can do complex shapes, no need to calculate control points  We can use simulation and verification  We can change the tool easily But  We need postprocessor  Expensive (SW, computer, learning …)  Program is always longer (again expensive)

Projects - Common – same tasks for all - Individual – own selection of part and individual work on it. Evaluated. Test – from theory of programming and use of CAM software