Simulation Study Of Flexible Manufacturing Systems Engineering Essay

This paper presents the consequences of a simulation survey of a flexible fabrication system on the simulation package WITNESS. The system here includes two fabrication cells. First cell is holding two indistinguishable turning machines and 2nd holding one milling machine. A conveyer system is used for the entry of the parts in the fabrication system and besides at the issue for transporting the finished parts to the shop. An AGV based stuff managing system is used to reassign the parts from entry to the issue and through the machines. The effects of the figure of AGVs and the velocity of the AGVs on the public presentation of the fabrication system are studied. Machine use and the figure of parts processed are taken as the public presentation steps.

A FMS can be defined as the aggregation of production equipments, logically organized under a host computing machine and physically connected by a stuff handling system. The term flexible fabrication system is by and large used to bespeak a broad assortment of machine-controlled fabricating systems. A FMS consists of the undermentioned elements-

The fabrication industries deal with continually altering and progressively complex merchandise demands every bit good as mounting force per unit area to diminish costs. To run into this challenge, Flexible Manufacturing systems must be more robust, reconfigurable, adaptable and more flexible.

FMS is designed to unite the aim of high productiveness of mass production system and the flexibleness of occupation store production. FMS is used for the mid volume and mid assortment of merchandises production system.

Flexibility: Flexibility in FMS can be defined as the capacity to run efficaciously and expeditiously under altering market and technological production conditions.

Flexibilities in FMS can be of the undermentioned types [ 11 ] , [ 12 ] , [ 13 ] , [ 14 ] : –

Machine flexibleness: Capability to accommodate a given machine in the system to a broad scope of operations and portion manners.

Production flexibleness: The scope or existence of parts manners that can be produced on the system.

Mix flexibleness: Ability to alter the merchandise mix while keeping the same entire production measure ; i.e. , bring forthing the same parts merely in different proportions.

Product flexibleness: Ease with which design alterations can be accommodated. Ease with which new merchandises can be introduced.

Routing flexibleness: Capacity to bring forth parts through surrogate workstation sequences in response to equipment dislocations, tool failures, and other breaks at single Stationss.

Volume flexibleness: Ability to economically bring forth parts in high and low entire measures of production, given the fixed investing in the system.

Expansion flexibleness: ( Ease with which the system can be expanded to increase entire production measures.

Literature Review

Prakash and Chen [ 5 ] presented the consequences of simulation survey of a flexible fabrication system. The nowadayss the consequences of a simulation on FMS dwelling of six machining centres capable of executing a assortment of undertakings, an automated guided vehicle based stuff managing system and a individual input, individual end product storage retrieval system connected to the fabrication system by conveyers. They analyzed FMS by simulation on SIMAN IV simulation package and studied the effects of assorted parametric quantities ( figure of AGVs, velocity of AGVs, scheduling regulations ) on the public presentation of the FMS. The survey was towards the public presentation rating of the system under different programming regulations, assorted conditions of AGV handiness different processing times and different layout of the fabrication system. Mohamed [ 1 ] studied operations planning and scheduling job in FMS under different burden schemes, due day of the month assignment and portion type reachings and analyzed the consequence on mean flow clip, average tardiness, average earliness, and system use. The consequences presented that the overall system use was higher for a certain type of lading schemes and the reconciliation of the system was better achieved by some other loading schemes. Kumar and Sridharan [ 2 ] analyzed the public presentation of the Part Launching Rule ( PLR ) and Tool Request Selection Rule ( TRSR ) in FMS when the system portions the tools between the machines. The public presentation steps evaluated are average tardiness, conditional mean tardiness and intend flow clip. Based on the analysis of the simulation consequences, the best possible programming regulation combinations for portion launching and tool petition choice have been identified for the three scenarios. Sidhartha R Das and Cem Canel [ 3 ] proposed an algorithm for scheduling batches of parts in the FMS. The method used is Branch and Bound method which solves big size jobs in a sensible clip. This paper presents an algorithm to work out the FMS planning job of scheduling batches of parts holding sequence dependent apparatus clip ( SDST ) in a multicell FMS exhibiting flowshop features. It has been shown that the clip to work out a job of big size ( holding more figure of machines and batches ) can be reduced by the Branch and Bound method. This was used to minimise the makespan by altering the figure of machine cells and figure of batches. Yildirim et Al. [ 6 ] used the unreal nervous web to accomplish the ends of direction in a production system. Back Propagation Artificial Neural Network ( BPANN ) is used to accomplish the certain public presentation steps of the production system when the system is non used to its full capacity. The consequences present the use of the production system under different programming regulations for the assorted constellation of the production system. Kosturiak and Gregor [ 4 ] studied the simulation in FMS and proposed some experience and recommendations for effectual simulation application. This paper presents how the betterment steps can be evaluated utilizing simulation and a Taguchi program of experiments. The influence of assorted control schemes on the fabrication system parametric quantities is demonstrated. The simulation in the fabrication system analysis has been proved to be an indispensable tool. It besides has been shown that how the fabrication cost can be reduced through the usage of simulation. Angelo et. Al. [ 8 ] presented a survey to choose the statistically important variables and to find the comparative impact on system public presentation. The paper presented a method for supervising three types of workss public presentation: Daily Output, Lead Time, Work-in-Process. In this paper, by using an appropriate computing machine simulation theoretical account and by following convenient statistical tools, such as design of experiments, the relationship between the system ‘s technological public presentation and the important factors regulating the procedure kineticss has been investigated. Tunali [ 9 ] nowadayss a simulation theoretical account of a job-shop type FMS developed to look into how the public presentation of scheduling determinations ( i.e. , average occupation flow clip ) is affected by the usage of flexible or prefixed portion procedure programs in instance of a machine dislocation state of affairs. It has been shown that leting the parts affected by a machine failure to be scheduled on to jump machines helps to cut down the possible negative effects on average occupation flow clip. Yan et.al [ 10 ] presented the New Extended Stochastic High-Level Evaluation Petri Nets ( ESHLEP-N ) , which show that these are more suited for patterning and simulation of flexible fabricating systems. The consequences presented that the throughputs of the rescheduling can increase on an norm by 6.48 % as compared with those of non-rescheduling. It besides has been shown by comparing between simulation consequences and the experiment 1s under the indistinguishable experiments conditions and processes that the comparative mistakes between both are less than 3 % .

Development of theoretical account for the survey:

The theoretical account for our survey shown in fig. 1 consists of the undermentioned equipment and accoutrements: –

Two parts types ( P1 and P2 ) are to be processed ( batch size assumed is 2 for both the parts )

For portion P1 inter reaching clip is 20 and for portion P2 the inter reaching clip is 15

Two indistinguishable turning machines ( rhythm clip 15 units )

One milling machine ( rhythm clip 8 units )

An AGV base stuff handling system ( capacity two parts at a clip )

Two conveyers ( C1, C2 ) , one for the entry of the parts in the system and the other for the issue of the finished parts

Buffers at the appropriate topographic points

The theoretical account developed here for our survey consists of two indistinguishable turning machines and a milling machine holding rhythm times of 15.0 and 8.0 severally. The parts enter in the system through the conveyer C1 and so loaded on to the AGV at the lading path T5. The capacities of the AGVs are to transport two parts at a clip. The parts are so transported to the terminal of path T2 where the parts are unloaded in buffer B4 from where the parts are sent to the turning machines and turning operations are carried on both the parts. After the turning operation the parts are pushed to the buffer B3. The parts are so loaded on to the AGV on path T4. Then the parts are transported by the AGV up to the terminal of the path T8 and unloaded in the buffer B5. When the milling machine is free the parts are transferred to the milling machine for the milling operation one by one. After milling operation the finished parts are pushed to the buffer B6 from where two finished parts are loaded on to the AGV waiting for the parts to be loaded and carried at the terminal of the unloading path T6. Here the parts are unloaded on the issue conveyer C2. Conveyor C2 carries the finished parts to the buffer B2. Thus the rhythm of the fabrication system is completed.

Premises:

The undermentioned premise are made for the survey of the simulation:

The parts arrive in the system at a fixed interval of clip

The portion geting foremost, enters foremost in the system.

The AGVs based stuff managing system considered operates like consecutive entree stuff managing systems ; the flow form of parts from machine cell to machine cell is similar to that of a flow store.

The burden and unloading clip of the parts on to the AGV and from the AGV is neglected.

The indexing of the conveyer is adjusted such that the parts are non accumulated on the conveyer.

Fig.1 Simulation theoretical account of the fabrication system in WITNESS

Experiment:

The survey is done for the probe of the public presentation of the system with the alteration of the figure of AGVs and the velocity of the AGVs. The other variables are kept changeless.

The fabrication system modeled for the survey is simulated on the WITNESS simulation package and run for a period of 500 units.

First the figure of AGV in the system is taken one. The velocity of the AGV is increased maintaining all other parametric quantities changeless. The consequences are obtained for the public presentation parametric quantities.

After altering the velocity of the AGV in stairss, the Numberss of AGVs in the system are increased and the velocity of the AGVs is besides changed in stairss.

Consequences:

The system considered here was run on the WITNESS simulation package for a period of 500 units for each observation.

The undermentioned observations were made: –

Case I – when the first reachings of the two parts are at different times i.e. portion P1 arrives at clip 1.0 and the portion P2 arrives at clip 0.0.

At low velocity as the figure of AGVs are increased from 1-2, the idle clip of the Turning Machines is reduced significantly ( halved from 67.00 to 34.00 % ) and the figure of parts processed on these machines besides increase from 11 parts to 22 parts i.e. the parts processed are doubled.

Further with the addition of AGVs from 2 to 3 the idle clip of turning machines is once more reduced significantly ( from 34.00 % to 16.80 % ) but the figure of parts processed on the turning machines are non doubled ( figure of parts processed addition from 22 to 27 merely ) .

When the Numberss of AGVs are increased farther from 3 to 4, we observe that there is no alteration in the idle clip of the turning machines and besides the figure of parts processed remains the same.

We conclude that the machine use increases to a certain bound with the addition in the figure of AGVs. But when this is increased beyond a certain bound the machine use becomes optimal and farther addition in the figure of AGVs will merely do these AGVs unutilized in the system and with the addition of cost of the stuff handling system above a certain bound will merely increase the cost of the system with no addition.

Same consequences are observed in the instance of milling machine.

We besides observe that when the velocity of the AGVs is increased the impact of the velocity is more in instance of the certain figure of the AGVs. From the tabular array 1 it can be seen that the machine use is increased from 66 % to 81 % with the addition of velocity of AGVs when the figure of AGVs are 2. But when the figure of AGVs are less or more than 2, the velocity of the AGVs is non that much important.

So in this constellation of FMS we find a stuff handling system with two AGVs, as the most efficient system and the velocity of the AGVs besides need to be taken at higher side.

Case II – As can be observed from the consequences presented in the tabular arraies 2 and 3 when the first reachings of both the parts P1 and P2 are at 0.0 the machine use clip is reduced. When the figure of AGV is one the decrease in the machine use clip is less at the lower velocity of the AGV but this decrease is more at the higher velocity of the AGV.

The lessening in the machine use clip is more in the instance of more figure of AGVs. After a certain figure of AGVs there is no lessening in the machine use and it becomes changeless.

Table – 3

Sl. No.

Speed

Decrease in Machine use

AGV -1

AGVs – 2

AGVs – 3

AGVs – 4

1.

5

0.0 %

2.0 %

12.0 %

12.0 %

2.

8

0.5 %

3.7 %

12.0 %

12.0 %

3.

12

0.0 %

8.0 %

12.0 %

12.0 %

4.

16

2.6 %

10.4 %

12.0 %

12.0 %

Table 1

First portion reachings are at: –

P1 at 1.0

P2 at 0.0

Turn MACHINE 1 & A ; 2

AGVS-1

Speed

5

8

12

16

% Idle

67.00

63.50

61.00

58.40

% Busy

33.00

36.50

39.00

41.60

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

11

12

13

13

AGVS-2

Speed

5

8

12

16

% Idle

34.00

26.60

21.73

19.00

% Busy

66.0

73.40

78.27

81.00

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

22

24

26

27

AGVS-3

Speed

5

8

12

16

% Idle

16.80

16.50

16.33

16.25

% Busy

83.20

83.50

83.67

83.75

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

27

27

27

27

AGVS-4

Speed

5

8

12

16

% Idle

16.80

16.50

16.33

16.25

% Busy

83.20

83.50

83.67

83.75

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

27

27

27

27

Milling Machine

AGVS-1

Speed

5

8

12

16

% Idle

64.80

61.60

58.40

58.40

% Busy

35.20

38.40

41.60

41.60

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

22

24

26

26

AGVS-2

Speed

5

8

12

16

% Idle

32.80

24.25

19.50

16.52

% Busy

67.20

75.75

80.50

83.47

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

42

47

50

52

AGVS-3

Speed

5

8

12

16

% Idle

15.40

14.95

14.70

14.57

% Busy

84.60

85.05

85.30

85.42

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

52

53

53

53

AGVS-4

Speed

5

8

12

16

% Idle

15.40

14.95

14.70

14.57

% Busy

84.60

85.05

85.30

85.42

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

52

53

53

53

Table 2

First portion reachings are at: –

P1 at 0.0

P2 at 0.0

Turn MACHINE 1 & A ; 2

AGVS-1

Speed

5

8

12

16

% Idle

67.00

64.00

61.00

61.00

% Busy

33.00

36.00

39.00

39.00

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

11

12

13

13

AGVS-2

Speed

5

8

12

16

% Idle

36.00

30.30

29.73

29.40

% Busy

64.0

69.70

70.27

70.60

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

21

23

23

23

AGVS-3

Speed

5

8

12

16

% Idle

28.80

26.5

28.33

28.25

% Busy

71.20

71.50

71.67

71.75

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

23

23

23

23

AGVS-4

Speed

5

8

12

16

% Idle

28.80

28.50

28.33

28.25

% Busy

71.20

71.50

71.67

71.75

% Filling

0.00

0.00

0.00

0.00

% Emptying

0.00

0.00

0.00

0.00

% Blocked

0.00

0.00

0.00

0.00

% Cycle Wait Labor

0.00

0.00

0.00

0.00

% Apparatus

0.00

0.00

0.00

0.00

% Setup Wait Labor

0.00

0.00

0.00

0.00

% Broken Down

0.00

0.00

0.00

0.00

% Repair Wait Labor

0.00

0.00

0.00

0.00

No. Of Operationss

23

23

23

23

Decisions:

The present paper presents the consequences of a simulation survey of flexible fabricating systems. The simulation is performed on the simulation package WITNESS. The system is presented diagrammatically and the consequences are presented in the signifier of tabular arraies and charts.

The simulation in this paper confirms that the figure and velocity of the AGVs can be increased to a certain bound beyond which the efficiency of the system is non improved

Further we can widen our survey by adding more figure of machines to our system and choosing some regulation for the parts to be processed. The AGVs constellation can be set for the different types of FMS and some algorithm can be formed to happen the optimal solution to the job