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Looking for CNC Programming, CNC Machine Programming, CNC G-Codes, or Examples in pdf form to download and study? As great as the world wide web is, . Cartesian Coordinate System. 7. Machines Using CNC. 9. Programming Systems . Point-to-Point or Continuous Path. Point-to-Point Positioning. Fax: +44 (0) Email: [email protected] G and M. Programming for CNC. Milling Machines. COMPUTERISED MACHINES AND SYSTEMS.
N80 G03 X Popular in Computing And Information Technology. We act ually need t he nose radius t o be t angent ial t o t he part cont our at t he point where it is cut t ing, but m oving t he Theoret ical Tool Tip TTT along t he cont our does not ensure t his. Coordinat es in finish t urning are calculat ed wit h nose radius com pensat ion, and will t herefore not m at ch t he part coordinat es. When cut t ing a t hread, for every revolut ion of t he part t he t ool m oves axially by a dist ance equal t o t he Lead of t he t hread.
I n a single st art t hread t he lead is equal t o t he pit ch. When cut t ing a t hread, for every revolut ion of t he part t he t ool m oves axially by a dist ance equal t o t he Lead of t he t hread. Ex a m ple The following program segm ent cut s a t hread of 2 m m. G00 X The G76 canned cycle is com m only used because it can cut a t hread wit h m ult iple cut s at various dept hs by specifying t he pit ch, t hread dept h, et c.
G0 4 — D w e ll A dwell com m and result s in a t em porary st oppage of all axis m ot ions for a specified durat ion. The spindle m ot ion is not affect ed.
I t is t ypically used when t he t ool has reached t he final posit ion in an operat ion and needs t o st ay t here for a few spindle rot at ions t o obt ain good dim ensional accuracy or surface finish. For exam ple, in a grooving operat ion when t he t ool reaches t he bot t om of t he groove it needs t o st ay t here for at least one full revolut ion. Wit hout a dwell it would ret ract back inst ant aneously and result in a non- circular cross sect ion at t he groove bot t om.
Ex a m ple G04 X1. Spin dle r ot a t ion Spindle rot at ion is st art ed by specifying a spindle direct ion com m and and a spindle speed com m and. Spindle direct ion: This is specified by an M code. Spindle clockwise CW M Spindle count er- clockwise CCW M Spindle st op Spindle speed: The spindle speed is specified eit her as a const ant surface speed or as a const ant spindle speed.
Con st a n t su r fa ce spe e d This is com m anded by G96, and is always accom panied by a lim it ing spindle speed com m and G Exam ple: The second one com m ands a lim it ing spindle speed of RPM.
Con st a n t spin dle spe e d This is com m anded by G Const ant spindle speed is used in t hreading and drilling, while const ant surface speed is used in all ot her operat ions. Tool ch a n ge The t ool change com m and includes t he t ool num ber and t he t ool offset num ber of t he com m anded t ool. When t he com m and is execut ed, t he t ool changer causes t he com m anded t ool t o com e t o t he cut t ing posit ion. For m a t Taabb aa is t he t ool num ber bb is t he t ool offset num ber.
The t ool num ber and offset num ber m ust be writ t en wit h leading zeros. Ex a m ple T This m eans t ool num ber 3 and offset num ber 3. The second line is t he program num ber, writ t en as Onnnn. En d The last but one line is t he program end com m and M02 or M Block n u m be r s Block num bers add clarit y t o t he program. They can be om it t ed from all blocks or included in som e blocks only.
Quit e oft en block num bers are used only in t ool change blocks. The leading zero is opt ional. They can be operat ion nam es, t ool nam es, inst ruct ions t o t he operat or, et c. Com m ent s are insert ed wit hin bracket s. Wit hout com m ent s a program is j ust a m ass of alphabet s and num bers and you cannot figure out what each sect ion of t he program is doing.
A com m ent can be in a separat e block by it self, or aft er a set of com m ands, as shown below. Here G01 and F are m odal, and need not be repeat ed in every block. G01 rem ains act ive t ill it is changed by G The block aft er G00 has it , but here F need not be repeat ed.
The blocks can be writ t en as: G01 X G00 Z2. When you com m and t he t ool t o m ove t o a posit ion, you are act ually com m anding t he Theoret ical Tool Tip TTT t o m ove t o t he posit ion. When doing an operat ion like cont our t urning, you j ust program t he cont our according t o t he coordinat es in t he part drawing. This causes t he TTT point m oves along t he com m anded pat h. TTT m oving along cont our This is t he point on t he t ool t hat is used as t he reference point for det erm ining t ool offset s.
N e ce ssit y of TN RC As t he t ool m oves along t he program m ed cont our, t he point on t he t ool nose radius t hat is act ually doing t he cut t ing keeps changing. We act ually need t he nose radius t o be t angent ial t o t he part cont our at t he point where it is cut t ing, but m oving t he Theoret ical Tool Tip TTT along t he cont our does not ensure t his.
As a result , t he t ool leaves unm achined m at erial in som e areas P1 t o P2 in pict ure and digs int o t he m at erial in som e areas P3 t o P4 in pict ure. Tool pat h wit hout TNRC To get an accurat e cont our during m achining, an alt ernat e t ool pat h is generat ed such t hat t he nose radius is t angent ial t o t he cont our.
Com pe n sa t ion com m a n ds The com pensat ed t ool pat h m ust be eit her t o t he left or t he right of t he t ool pat h program m ed wit h t he coordinat es from t he part drawing. The direct ion of com pensat ion depends on t he direct ion of m ot ion and whet her t he t ool is cut t ing on t he inside or out side of t he part.
I n t he program you can specify whet her t he com pensat ion m ust be t o t he left or right , and t he cont roller det erm ines t he com pensat ed t ool pat h. The t ool nose radius t oo m ust be specified in a separat e area of t he m em ory. Program t o m ove along t he cont our in t he part red lines in t he pict ure indicat e rapid t raverse, and blue lines linear int erpolat ion. Su bpr ogr a m s A t ool pat h pat t ern t hat is repeat ed can be st ored as a subprogram and called m ult iple t im es.
Using a subprogram reduces t he program lengt h and program m ing t im e, and m akes t he program m ore readable. A subprogram looks like a norm al program , but is t erm inat ed wit h an M99 com m and at t he end inst ead of M02 or M I t is called from t he m ain program by a subprogram call com m and. For m a t Subprogram call: This com m and calls subprogram , 5 t im es. I f a subprogram is only called once, t he aaa param et er can be om it t ed.
The t ool pat h at each groove is: Move at rapid t o t he st art posit ion of t he groove in Z 2. Feed int o t he groove. Rapid out of t he groove 4.
Rapid sideways t o t he st art point of t he next cut. Rapid out of t he groove The program segm ent t o cut t he grooves would look like t his t he t ext in bracket s is com m ent s, and t his is exact ly how you can insert com m ent s in an act ual program: This segm ent can be put in a subprogram t hat is called 5 t im es from t he m ain program.
The m ain program and subprogram can be writ t en like t his: Main program: Ca n n e d Cycle s — sin gle cu t A single cut canned cycle execut es a sequence of m ot ions required t o perform a cut — rapid approach t o t he st art posit ion, cut t ing m ot ion, and rapid depart ure. A single block replaces 4 m ot ions - 1 cut t ing and 3 rapid. Operat ions norm ally involve t he rem oval of m at erial in m ult iple cut s, so t hese cycles are seldom used. The m ult i- cut canned cycles are t he ones generally used.
Tu r n in g cycle - G9 0 This cycle does a single t urning cut along t he part axis.
I n t his case: Use addresses U and W inst ead of X and Z. Use appropriat e signs wit h t he end point , since increm ent al coordinat es are specified wit h reference t o t he st art point.
Ex a m ple Raw m at erial is a cylinder of 80 diam et er. The end point can be specified by increm ent al coordinat es inst ead of absolut e coordinat es.
Fa cin g cycle - G9 4 This cycle does a single facing cut perpendicular t o t he part axis. Raw m at erial is a cylinder of diam et er. R m ust be specified wit h t he proper sign.
Th r e a din g cycle - G9 2 This cycle does a single t hreading cut. G92 X They are t herefore om it t ed in t he t hird block. Ca n n e d Cycle s — m u lt iple cu t A canned cycle is a single com m and t hat execut es a whole m achining operat ion t hat requires repet it ive t ool m ot ions.
The cycle t ypically consist s of a few blocks wit h dat a defining t he area t o be m achined and som e cut t ing param et ers. The coordinat es of individual t ool m ot ions are det erm ined aut om at ically by t he m achine cont roller and t he m ot ions are execut ed. An operat ion t hat m ay require t ens or even hundreds of blocks of program can be writ t en in j ust a few blocks. The cycle definit ion has t he part shape, dept h of cut , finish allowance and couple of ot her param et ers.
Param et er P has t he num ber of t he first block Ns and Q has t he last block Ne. Ex a m ple G00 X The t ool pat h defining t he shape bet ween t he blocks defined by P and Q m ust st art and end beyond t he raw m at erial. I n t his exam ple t he st art and end point s are point s P1 and P2 respect ively, 2 m m. Not e t he use of block num bers in t he program exam ple.
Block num bers are opt ional, need not be used in every block. Cont our definit ion and signs of finish allowances: I n t he cycle, t he area t hat is being m achined decides: The signs of t he finishing allowances U and W, and 2.
The way t he part profile is defined I n each of t he cases shown above, t he t ool is posit ioned at point P before calling t he cycle and t he part profile is defined from point A t o B. The signs of t he finish allowances U and W are as follows. Case 1 Out side- Right: Fa cin g cycle G7 2 This cycle generat es a part shape from a cylindrical raw m at erial, wit h cut s perpendicular t o t he axis.
Not e t hat t hese are t he reverse of t he point s in t he G71 t urning cycle. The signs of t he finishing allowances U and W, and 4. Pa t t e r n r e pe a t cycle G7 3 This cycle generat es a part shape from raw m at erial t hat is t he sam e shape as t he final part wit h cut s parallel t o t he along t he part shape. I t is used when t he raw m at erial is a cast ing or forging.
The cycle definit ion has t he part shape, dept h of m at erial t o be rem oved, num ber of cut s and finish allowance. I n t his exam ple t he st art and end point s are point s A and B respect ively, 2 m m. These are t he sam e as in t he G71 cycle. Fin ish t u r n in g cycle G7 0 This cycle does a single finish pass along a cont our t hat has t ypically already been rough t urned wit h a G71, G72 or G73 cycle.
Nose radius com pensat ion is aut om at ically act ivat ed in G The cycle can act ually be used t o drill m ult iple axial holes at various posit ions on t he radius, on a m achine wit h a C- axis and live t ools. The explanat ion here is rest rict ed t o drilling a single axial hole.
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