Cnc machining nm09/2
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- Practical exercise 12 — section 7
- First off part measurements
- Review questions — section 1
- Review questions — section 2
- Review questions — section 3
- Review questions — section 4
- Answers to exercises — section 4 — exercise 1
- Answers to exercises — section 4 — exercise 3
- Answers to exercises — section 4 — exercise 5
- Answers to exercises — section 4 — exercise 7
- Section 4 — Exercise 8 — slotted base plate
7.4 MachiningSimple shapes resulting from motion of one axis at a time can be machined by manual control of the machine through the handwheel and axis selector switch. Actual positions can be displayed relative to the start position to easily allow accurate distances to be traversed. More consistent motion may be obtained through the MDI function which then places the machine under programmed conditions. Some machines will allow several blocks of MDI to be entered resulting in a 'one shot' program with most functions available but usually excluding canned cycles. Other machines will only accept one MDI block at a time, still without canned cycles and the like. Another disadvantage of MDI is that each command must be correct, no trialing is possible and pressing the feed hold will defeat the MDI block (or program). The third method used for machining is the execution of a properly prepared program, carefully trialed and checked.
7.5 ProvingProgram proving (or trialing) is the careful and concentrated execution of the program by various means in order to eliminate all errors that could cause machine or tool damage or spoiling the workpiece before actually machining the part under automatic cycle conditions. The technique used may differ from one machine to another even from one person to another, but the result of trialing must be a knowledge that the program is as close to 100% operational as can be ascertained. Use such methods as:
Finally, and only when it appears the program is 100% correct on all counts, cut the part and check sizes to determine if all offsets are set to allow tolerances to be achieved. 7.6 EditingIf the program results in many alarms during the graphic display, it is probably wise to move off the machine and carefully check the print out, correcting faults at the program preparation area, rather than perform involved editing at the machine. Any editing, be it simple or involved will alter the execution of the program and therefore program re-trialing may be necessary before safe and sure execution of the program is proved. 7.7 MachiningThere occasionally comes a time during machining when something goes wrong; perhaps a cutter chips or breaks, an insert comes loose, the part moves during heavy machining the coolant falters to a dribble, there is a general failure etc. In any situation like these, it is advisable to stop the machining process temporarily, if not totally and immediately. In other situations, such as cutter dulling, the machining process can be nursed to completion by using the override controls. It should be noted, that if the spindle is slowed with a G94 command active (feed/minute) the effective chip load on the cutter increases, but if a G95 command (feed/revolution) is active, the feed slows proportionally. In either case, feed can be overridden independently of the spindle. Some controls have only one override control for all axis motions, and will usually be effective in all modes that is, cycle, single block, dry run, jog (or manual), feed and rapid traverse. Other controls will override rapid motions only if the single block switch is on, while others again have separate override controls for feed and rapid motions and may also have a jog rate switch marked in feed rate per minute values, which can be advantageous if machining in the jog mode. The hand wheel (manual pulse generator, or MPG) works independently of any override controls, is effective on only one axis at a time and can be switched to different sensitivities -usually 0.001 mm, 0.1 mm to allow precise positioning. The effect of pressing the emergency stop button may be different between one control and another. The emergency stop on some controls switches everything off, including the control itself, but most will cause all motions and miscellaneous functions to cease. Some machines may require re-homing after an emergency stop, but most won't. After an emergency stop, power must be connected again to the machine via the reset button before the machine can be moved, and if the reason for the emergency stop was tool breakage, the motion directions must be chosen with a view to minimising any further damage to the tool or work piece. The cause of the damage should be determined before the program is restarted, in case the cause was program related. After reset and damage repair, the block search function can be used to restart the program at any point providing that block has a sequence number. The use and effect of block search and program restart will be different on different controls; some process the program while searching, which slows up the procedure on long programs, but results in all modal conditions being set and active at the block searched to. Other controls ‘jump’ straight to the block required with only the default modal conditions active. In this case all necessary modal conditions must be entered through the MDI function before restarting the program. Possibly the most successful way to restart a program is to block search to a tool change command -from there all necessary modal conditions will be commanded in the program for that tool. Another advantage is that the wrong tool cannot be in the spindle for the sequence required, although any machining already completed will be re-executed, and that may cause a problem on parts having a fine tolerance, or where tapped holes will be re-tapped. Some controls allow subsequent block searching (once the tool is in position and running) to bypass machined sections without a loss of modal conditions. A program can be written with easy and accurate restarting in mind by judicious use of sequence number and perhaps skip block commands. Practical exercise 12 — section 7Note: This exercise must be done under the supervision of your teacher. Refer to the drawing NM09 -Exercise 12 and prepare the material for machining.
First off part measurementsReferring to the drawing of the part that you have machined, measure at least five features specified by your teacher and fill in the chart below. Under supervision of your teacher modify the tool offsets necessary to correct any errors in the part dimensions.
Exercise 12
Answers to questionsReview questions — section 1
Review questions — section 2
Review questions — section 3
Review questions — section 4Question 1
Review questions — section 4Question 2
Review questions — section 4Question 3
Review questions — section 4Question 4
Review questions — section 4
Answers to exercises — section 4 — exercise 1
Answers to exercises — section 4 — exercise 2
Answers to exercises — section 4 — exercise 3
Answers to exercises — section 4 — exercise 4
Answers to exercises — section 4 — exercise 5
Answers to exercises — section 4 — exercise 6
Answers to exercises — section 4 — exercise 7
Section 4 — Exercise 8 — slotted base plateSample program millingShown below are all of the dimensions required to complete the part program as a functional example of a Machining Centre Program %MPF 1
N05 (PR0GRAM PRACT1CE) N10 G71G90 G17 G40 G94 N15 G00 Z0 D0 N20 G54 X0 Y0 N25 G55 X0 Y0 N30 (////) N35 M19 N40 M00
N45 (L0AD 10mm END M1LL) N50 T01 D01 N55 F600 S3000 N60 (///) N65 G00 X-10 Y45 N70 G00 Z10 M03 M08 N75 Z-2 N80 G01 X30 N85 X-10 N90 G00 Y65 N95 G01 X35 N100 X-10 N105 G00 Y100 N110 X30 N115 G01 X60 Y70 N120 Y20 N125 X90 Y-10 N130 G00 X110 N135 G01 Y25 N140 X90 N145 Y33 N150 X115 N155 X-10 N160 G00 Z40 M05 M09 N165 (////) N170 G00 Z0 D0 N175 M19 N180 M00 N185 (REM0VE LAST T00L) N190 G53 X0 Y0 N195 M02 Section 4 — Exercise 8 — slotted base plateSample program millingShown below are all of the dimensions required to complete the part program as a functional example of a Machining Centre Program %MPF 1
N05 (PR0GRAM PRACT1CE) N10 G71G90 G17 G40 G94 N15 G00 Z0 D0 N20 G54 X0 Y0 N25 G55 X0 Y0 N30 (////) N35 M19 N40 M00
N45 (L0AD 10mm END M1LL) N50 T01 D01 N55 F600 S3000 N60 (///) N65 G00 X-10 Y45 N70 G00 Z10 M03 M08 N75 Z-2 N80 G01 X30 N85 X-10 N90 G00 Y65 N95 G01 X35 N100 X-10 N105 G00 Y100 N110 X30 N115 G01 X60 Y70 N120 Y20 N125 X90 Y-10 N130 G00 X110 N135 G01 Y25 N140 X90 N145 Y33 N150 X115 N155 X-10 N160 G00 Z40 M05 M09 N165 (////) N170 G00 Z0 D0 N175 M19 N180 M00 N185 (REM0VE LAST T00L) N190 G53 X0 Y0 N195 M02 Section 4 — Exercise 9Practice program turning Locating pin N10 (MATERIAL 57 DIA X 160 LONG M.S.) N15 (TOOL T01 – 80 DEGREE ROUGHING) N20 (T00L T05 -30 DEGREE F1N1SH1NG) N25 G90 G95 N30 G96 S180 N35 G40 G00 X300 Z300 T0101 N40 (T00L T01 R0UGH1NG) N45 G50 S2500 M42 N50 G00 Z108 M03 M08 N55 G01 X-1.6 F0.15 N60 G00 Zl09 N65 X5l
N70 G01 Z5.1 F0.3 N75 X57
N80 G00 Z109 N85 X45
N90 G01 Z18.1 N95 X51
N100 G00 Z109 N105 X39 N110 G01 Z79.7 N115 X41 Z78 N120 Z18.1 N125 X45 N130 G00 Z109 N135 X33 N140 G01 Z84.2 N145 X39 Z79.7 N150 G00 Z109 N155 X27 N160 G01 Z88.7 N165 X33 Z84 N170 G00 Z109 N175 X21 N180 G01 Z93 N185 X27 Z88.7 N190 G00 Z109 N195 X19 N200 G01 X25 Z106 N205 G00 X300 Z300 T01N240 X20 Z107 N245 Z93 N250 X40.01 Z78 N255 Z18 N260 X50
N265 Z5 N270 X60 N275 G40 G00 X300 Z300 T0500 N280 M05 M09 N285 M02 % Directory: file -> view view -> Western Europe after wwii view -> Author study: paul fleischman view -> Qpa1 7ela study Guide view -> Arctic Oil/Gas Neg view -> November 1970 Approximately 150,000-500,000 deaths Bhola Cyclone Bangladesh view -> Grade Level: 6 Unit of Study: Caribbean glce view -> Citation: Duffield, Katy view -> Table of Contents Lesson # view -> Chinese Wind Energy Disad Download 0.53 Mb. Share with your friends:
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