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Technical University - Sofia

IMS I

Course Work

Sava Savchev 221206016

143B

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Contents: Task...3 1. Production analysis..4 2. Determining type of production.4 3. Determining type of process...4 4. Selecting a billet...4 5.Milling operations.6 5.1. Choosing milling machine...6 5.2. Face milling...6 5.3. Side milling9 5.4. Thread milling..12 6. Drilling.15 7. Total servicing time.18 8. Price.19 9. Operation sheet...20 10. Reference...20

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Task: Body

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1. Production analysis Designing such kind of body requires to be very precise in material

shaping because of the high density of the used material. In order to have fast and high quality production, it has to be chosen minimum amount of types of machining according to the required operations.

2. Determining the type of production 2009 has 257 working days(8 working hours a day). We must

make 50 000 bodies a year. First we should find our type of production using the coefficient k:

60 257 84 50000 0.62 We find that our production is mass.(mass production k=1-2) In order to calculate the time limit for production of the whole lot

of 50 000 bodies, the following formula has to be used:

50 000257 8 24 ; 124 0.042 2.52 min .

3. Determining the type of processes Operation1 Selecting a billet

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Milling:-face milling (cutting off the billet);

-shoulder milling; -thread milling;

3 Drilling

4. Selecting a billet In the course work we have to choose the right material in order to have high strength, low cost and low machining expenses. The material for this part must have high yield strength, so we choose Aluminum alloy 7075 T6 with ultimate tensile strength of 503MPa. The billet is of flat type with dimensions 63.5x127 mm and

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length 116 mm. This billet is only for determining the required time for the operations because of the almost exact dimensions.

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5. Milling Operations 5.1. Choosing Milling Machine The material of the body and the big length of the cuts require milling machine with higher power. That is why we choose X.Mill 900 B with the following specifications:

Travel x-axis 800 mm; Travel y-axis 500 mm; Travel z-axis 550 mm; Table 1050x500 mm;

Power 15 kW; Spindle speed 8000 rpm;

5.2. Face milling First thing that has to be done is to cut the billet in order to reach the exact dimensions of the body. In order to do that there must be done two facing operations: 63.5 mm 54 mm and 127 mm 120 mm. For the operation we choose:

Tool: CoroMill Century Arbor R590-100Q32A-11M

Maximum ap depends on the type of the insert.

Parameter Value Dc 100 mm l1 50 mm

dmm 32 mm No. of teeth zn 6

Kr 90

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Insert: R/L590-110504H-NL

a) First we should mill to 120 mm, because then the second facing

will have smaller length. In order to decrease the power we will cut in two passes each with half of the working engagement (58 mm):

ap = 7 mm - depth of cut; ae = 58 mm working engagement; L = 63.5 mm length; Dc = 100 mm cutting diameter; zn = 6 number of teeth;

hex = 0.2 mm (Coromant); Vc = 325 m/min cutting speed (Coromant);

Kr = 90 fz = hex = 0.2 mm; HB = 150 hardness Brinell; K = 2.2 (Coromant); The given cutting speed is for HB = 130, so we will have to multiply it with coefficient taken from the Coromant catalogue and for hardness bigger with 20 units it is equal to 0.91: Vc = 325x0.91 = 300 m/min;

1000 955 ; 1146 / min ;

0.055 3.3 ;

Parameter Value max ap 10 mm

iW 11.5 mm la 11 mm bs 2.2 mm r 0.4 mm

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100 000 10.2 ; For the second pass the data will be the same, so we can say that the first face milling will be done for approximately 6.6 seconds.

b) For the second facing we will use the same tool and insert, which makes the parameters almost the same. The only difference is in the depth of cut and the length. Otherwise we will have the same cutting, spindle and feed speed.For this face milling again we will make two passes in order to have smaller power consumption.

ap = 9.5 mm; ae = 58 mm; L = 120 mm;

n = 955 rpm; vf = 1146 mm/min; K=2.2;

0.11 6.6 ;

100 000 13.9 ;

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For the total time we must again multiply by two, because the second pass is the same and we can see that the total machining time for the second facing is 13.2 seconds.

5.3. Side milling Specific instruction for this operation is the fixing of the detail,

which must be 45 according to the tool in order to have the right dimensions.

In order to make the right choice for the tool and the insert we must calculate simple geometric problem:

A 17 mm

B 17 mm C As we can see the triangle is right with angles 45-45-90. If we draw

the altitude from the angle which is 90 , it will also be a meridian for ABC. From the Pythagorean theorem we find AC:

17 17 24; 12 Altitude is also equal to 12 mm.

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Tool: CoroMill 331 Bore with keyway N331.32 160S40RM

Insert:

N331.1A-04 35 05H-PL

ap = 12 mm; ae = 22 mm; L = 24 mm; zn = 6; hex = 0.1fz = 0.1 mm(Kr=90); K = 2.7; Vc = 380 m/minVc = 380x0.91=346m/min(HB=130+20);

1000 1102 ; 882

;

Parameter ValueDc 100 mmap 12 mm

No. of teeth zn 8 Kr 90ar 25

Parameter Value iW 9.5 mmla 4.6 mm bs 0.2 mm r 0.5 mm s 3.5 mm

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0.027 1.6

100 000 6.3 This is the time for one of the side millings. Because they are four we have to multiply four times Tc and we find the total machining time to be Tc = 1.6x4 = 6.4 seconds.

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5.4. Thread milling In order to do threads we can use also milling. It is cheaper and faster than to do it with special machine. Coromant offers wide variety of thread milling tools which will satisfy our task. a) Our first thread milling is the two holes (top and bottom) with dimensions:M12x1.25. Tool: CoroMill Plura R217.14C095125AK26N

ae = 25 mm; ap = 25 mm; Dc = 9.5 mm; zn = 4; Vc = 280 m/min, but adjusted for too life 240 min Vc = 56 m/min ; fz = 0.65 mm; L = 25 mm; Dth = 12; K = 2.2;

1000 1877 ; 4880

;

Parameter ValueDc 9.5 mmap 26.2 mm

No. of teeth zn 4 l1 40 mml2 80 mm

Pitch 1.25dmm 10

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1016 ;

0.025 1.5

100 000 13.9 The total machining time for the two thread holes is 3 seconds.

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b) The second thread milling must be with dimensions:M6 Tool:

CoroMill Plura R217.13C048000AC10N

ae = 18 mm; ap = 18 mm; Dc = 4.8 mm; zn = 3; Vc = 280 m/min, but adjusted for too life 240 min Vc = 56 m/min ; fz = 0.65 mm; L = 18 mm; Dth = 6; K = 2.2;

1000 3715 ; 7244

;

1450 ;

0.012 0.72

Parameter ValueDc 4.8 mmap 22 mm

No. of teeth zn 3 l1 21 mml2 57 mm

Pitch 0 dmm 6

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100 000 10.33 The total machining time for 12 holes of this size is Tc =0.72x12=8.6 sec.

6. Drilling We have to drill two big holes with diameter 40 mm. This cant be done with milling tools and we have to have special drilling devices. Machine: BO 90 CNC

travel x-axis = 700 mm; travel y-axis = 510 mm; travel z-axis = 800 mm

table size = 630x630 mm; spindle speed = 6000 rpm;

power = 11 kW;

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Tool: CoroDrill 880 3xDc 880-D4000C6-03

Insert: 880-07 04 06H-C-GR

Dc = 40 mm; ap = 116 mm; Kcx0.4 = 1000; zn = 2;

Kr = 88; fn = 0.15; Vc=300m/min; fz=0.075;

L=116 mm;

1000 2500 ; 375

;

.

1300;

2000 1

860 ;

Parameter ValueDc 40 mm

No. of teeth zn 2 l1s 175 mml3s 124 ml4 120 mm

D5m 63 mm

Parameter Valued1 4 mmiC 12.35s 4 mmr 0.6

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240 1000 9.6 ; 0.5

2 1949 ;

0.31 18.6

The total machining time for the drilling of two holes is 37.2 sec. This is the last operation of shaping the body. As we can see it is the slowest. This is because of the big length of the holes. After we finished calculating the operations we can see the body in its final shape:

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7. Total servicing time Milling: 1.Face milling - 127120 2 times(2 passes): - time for fixing the detail 0.20 min - approach of the tool 0.004 min - face milling 0.11 min Total servicing time for the first facing 0.354 min 2.Face milling 63.554 2 times: - time for fixing the detail 0.20 min - approach of the tool 0.004 min - face milling 0.22 min Total servicing time for the second facing 0.424 min 3. Side milling 4 times: - fixing the detail (45) 0.30 min - approach of the tool 0.004 min - side milling 0.108 min Total servicing time for the side milling 0.412 min 4.Thread milling M12x1.25 2 times - fixing the detail 0.20 min - approach of the tool 0.004 min - thread milling 0.05 min Total servicing time for the 1st thread milling 0.254 min

5.Thread milling M6 12 times - fixing the detail 0.20 min - approach of the tool 0.004 min - thread milling 0.144 min Total servicing time for the 2nd thread milling 0.348 min

Total time for milling = 1.792 = 1.8 min

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Drilling 40 2 times - fixing the detail 0.20 min - approach of the tool 0.004 min - drilling 0.62 min

Total servicing time for the drilling 0.824 min

Total time for drilling = 0.824 min

Because the milling and the drilling machines will be working together, we choose the longer time 1.8 min, which in our case is the so called bottleneck. So the making of the product is much faster then it has to be. This gives us the opportunity for even more tool life considerations, workers time for rest and etc. 8. Price Material cost for one body is 66.65$, which is only useful material. We have to make 24 bodies per hour and we have two workers one worker on each machine. Their salary is 1$ per hour. One piece weight 3.14 kg and the volume of the all body is V=439000 mm3 with density 2.81 g/cm3. From this we can find: Salary expenses: 2$/24=0.08$ per body; Price for one body: 66.65$ + 0.08$=66.73$;

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9. Operation sheet

Operation

No.

Name of the

Operation

Machine tools

Cutting tools

Cutting Speed

[m/min]

Feed

[mm/rev]

Depth of cut

[mm]

Passes Tc

[min]

Total Time

[min]

1 Face

milling X.Mill 900

B

CoroMill Century

Arbor R590-100Q32A-

11M

300 0,2 7 2 0,11 0,354

2 Face

milling X.Mill 900

B

CoroMill Century

Arbor R590-100Q32A-

11M

300 0,2 9.5 2 0,22 0,424

3 Side

milling X.Mill 900

B

CoroMill 331 Bore with keyway

N331.32 160S40RM

346 0,1 12 2 0,108 0,412

4 Thread milling

X.Mill 900 B

CoroMill Plura

R217.14C095125AK26N

56 0,65 18 2 0,005 0,254

5 Thread milling

X.Mill 900 B

CoroMill Plura

R217.13C048000AC10N

56 0,65 25 12 0,144 0,348

6 Drilling BO 90 CNC

CoroDrill 880 3xDc 880-D4000C6-03

300 0.15 116 4 0,62 0.824

10. Reference www.knuth.de

www.coromant.sandvik.com Manual for exercises in machine building technology G.Getev,

A. Georgiev - publisher Tehnika Sofia, 1980