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DMFD 3333 – CNC TECHNOLOGY. DMFD 3333 – CNC TECHNOLOGY. PROCESS PLANNING/ PROGRAMMING PROCEDURE. DMFD 3333 – CNC TECHNOLOGY. GOAL - Completion of all instruction in the form of a program that will result in an error free, safe and efficient CNC machining. DMFD 3333 – CNC TECHNOLOGY.
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DMFD 3333 – CNC TECHNOLOGY PROCESS PLANNING/ PROGRAMMING PROCEDURE
DMFD 3333 – CNC TECHNOLOGY GOAL - Completion of all instruction in the form of a program that will result in an error free, safe and efficient CNC machining.
DMFD 3333 – CNC TECHNOLOGY All planning must be approached in a logical way and methodical way Decision: What task to be done? What goals?
DMFD 3333 – CNC TECHNOLOGY PROCESS • Study of initial information (drawings) • Material evaluation • Machine tool selection • Sequence of machining operation • Tooling selection and arrangement of cutting tool • Setup parts • Technological data • Determination of tool path • Program writing and preparation to transfer to CNC • Program testing and debugging • Program documentation
DMFD 3333 – CNC TECHNOLOGY PROCESS • Study of initial information (drawings) • Material evaluation • Machine tool selection • Sequence of machining operation • Tooling selection and arrangement of cutting tool • Setup parts • Technological data • Determination of tool path • Program writing and preparation to transfer to CNC • Program testing and debugging • Program documentation
DMFD 3333 – CNC TECHNOLOGY Study of Information (Drawings) Very important document where it physically visual the shape, dimensions, tolerances, surface finish and many other requirements such as number of parts and other secondary processes
DMFD 3333 – CNC TECHNOLOGY Material Evaluation • Typical material is raw and unmachined: billet, bar, plate, forging, casting etc • The size and shapes of the the material determine the type of fixturing • Machinability: charts for recommeded speed and feed for most common material
DMFD 3333 – CNC TECHNOLOGY Machining Sequence • Order of machining sequence. • Technical Skill and and machine shop experience is important. • The machining sequence must be in logical order. • Determine the shape of the part.
DMFD 3333 – CNC TECHNOLOGY Machining Sequence • Order of machining sequence. • Technical Skill and and machine shop experience is important. • The machining sequence must be in logical order. • Determine the shape of the part.
DMFD 3333 – CNC TECHNOLOGY Work Holding Devices
DMFD 3333 – CNC TECHNOLOGY The method of holding the parts to be machine on the machine so that: • Parts is correctly orientated • Dimension is not distorted • Locate part with respect to its datum • Proper locating and clamping ensures repeated products and accuracy.
DMFD 3333 – CNC TECHNOLOGY Work Holding devices for milling: • Vice • Angle plate • Direct clamping or fixtures • Chuck • Tomb stones
DMFD 3333 – CNC TECHNOLOGY VICE • Most commonly used for simple shape machining • Manually, air or hydraulically operated • Mount on table so that it is parallel to its x and y axis • Movable jaw should not be used as a datum as it moves
DMFD 3333 – CNC TECHNOLOGY ANGLE PLATE • For work that need to be held at 90o angle to the axis • L shaped cast iron or steel that has tapped holes or slots to provide for clamping purposes • Suitable for horizontal machining centre
DMFD 3333 – CNC TECHNOLOGY CHUCK Three jaw chuck used to hold cylindrical workpiece on machine table
DMFD 3333 – CNC TECHNOLOGY DIRECT WORK MOUNTING • Used to hold big or having odd shaped workpieces • Bolted directly to the table • Required ingenuity and expertise
DMFD 3333 – CNC TECHNOLOGY FIXTURES Used in the following cases: • The stock require some periphery machining • The stock is too large to be held by a machine vice • Not rectangular in shape.
DMFD 3333 – CNC TECHNOLOGY TOMB STONE Allow multipart to be held on any or all of its parts. Manual or power clamping can be used Held on rotating machine pallets so that each side could be represented. Increase productivity.
DMFD 3333 – CNC TECHNOLOGY MILLING PROGRAMMING
DMFD 3333 – CNC TECHNOLOGY TYPICAL PROGRAM O002 Program No N1 G20 Unit setting in different block N2 G17 G40 G80 G49 Initial Setting and cancellation N3 T01 Tool 1 in waiting position N4 M06 Tool 1 into spindle N5 G90 G54 G00 X.. Y… Z.. M3 TO2 T01 restart block T02 into waiting position N6 G43 Z2.0 H01 M08 Tool lgth offset coolant on N7 G01 Z… F… Feed to Z depth (….Cutting tool motion with tool 1)
DMFD 3333 – CNC TECHNOLOGY N33 G00 G80 Z2.0 M09 Clear above part – coolant off N34 G28 Z2.0 M05 Home in Z only coolant off N35 M01 Optional stop ---- N36 T02 Tool 2 in waiting N37 M06 Tool 2 in spindle N38 G90 G54 G00 X..Y.. S.. M03 TO3 T02 start block T03 in waiting N39 G43 Z2.0 H02 M08 Tool lgth offsett coolant on (N40 G43 G01 Z-…F..) Feed to Z depth …….Cutting motion with tool 2
DMFD 3333 – CNC TECHNOLOGY N62 G00 G80 Z2.0 M09 N63 G28 Z2.0 M05 N64 M01 …. N65 T03 N66 M06 N67 G90 G54 G00 X.. Y.. S..M03 T01 N68 G43 z2.0 H03 M08 (N69 G01 Z-…F….. ……..Cutting motion with tool 3 …
DMFD 3333 – CNC TECHNOLOGY N86 G00 G80 Z2.0 M09 N87 G28 Z2.0 M05 N88 G28 X.. Y.. N89 M30 %
DMFD 3333 – CNC TECHNOLOGY Preparatory Command • Identify as G codes • To preset or to prepare the control system to a certain desired condition or to a certain mode or state of operation
DMFD 3333 – CNC TECHNOLOGY Description and Purpose e.g. N7 X200 Y10 –end position of the cutting tool does not show coordinates are absolute or incremental, imperial or metric, rapid or feed… hence the block is in complete
DMFD 3333 – CNC TECHNOLOGY Example A N7 G90 X13 Y10 Example B N3 G90 N4 …. N5….. N6….. N7 G00 X13.0 Y10.0
DMFD 3333 – CNC TECHNOLOGY EXAMPLE C N3 G90 G00 N4 … N5 … N6 ... N7 X13.0 Y10.0 EXAMPLE D N2 G90 N3 G00 N4 ….. N5 …. N6 …. N7 X13.0 Y 10.00
DMFD 3333 – CNC TECHNOLOGY Will there be any difference in motion in all the example ?
DMFD 3333 – CNC TECHNOLOGY • NO – there is no change in G codes between block N4 and N6 • One G codes in a modal will replace another g code from the same group
DMFD 3333 – CNC TECHNOLOGY G CODES IN A BLOCK Several preparatory function may be used in a single block, providing they are not in a logical conflict with each other
DMFD 3333 – CNC TECHNOLOGY • Modality of G command N3 G90 G00 N4 X0 N5 Y20 N6 X15 Y22 N7 X13.0 Y10.0
DMFD 3333 – CNC TECHNOLOGY For a command to be a modal, it means it has to remain in a certain mode until cancel by another mode
DMFD 3333 – CNC TECHNOLOGY Conflicting command in a block It is impossible to have rapid motion and a cutting motion in one block e.g G00 and G01 - The latter will be used if accidentally used
DMFD 3333 – CNC TECHNOLOGY • Word Order in block G codes are normally programmed at the beginning of a block e.g. N40 G91 G01 Z-1 F200
DMFD 3333 – CNC TECHNOLOGY • GROUPING OF COMMAND Commands cannot be in the same block: G00, G01, G02, G03 Any G code from a given group automatically replaces another G code from the same group
DMFD 3333 – CNC TECHNOLOGY MICELLANEOUS FUNCTION
DMFD 3333 – CNC TECHNOLOGY M code – Miscellaneous function - machine function (not all)
DMFD 3333 – CNC TECHNOLOGY Machine Related Function Spindle rotation CW or CCW Gear range change Low/medium/high Automatic tool change ATC Automatic Pallet change APC Coolant operation ON or OFF Tailstock or Quill motion IN or OUT
DMFD 3333 – CNC TECHNOLOGY PROGRAM RELATED FUNCTION Control of machine function Control of the program function
DMFD 3333 – CNC TECHNOLOGY SPECIAL MDI FUNCTION Manual Data Input (MDI) – used to program from the controller – simple and repetitive process. M funcion cannot be programmed.
DMFD 3333 – CNC TECHNOLOGY M FUNCTION IN A BLOCK Only ONE function in a block Each M function is designed logically – also common sense