## How would you define the cycle time for a material

## How would you define the cycle time for a material

*HOMEWORK

1)

a)How

would you define the cycle time for a material handling system.? What are the

components?

b) What is the traffic factor ?

How it effects to material handling systems?

Explain.

c)

What is the worker efficiency in a material

handling systems? Why it is important?

Explain.

d)

What are the decision variables in a material

handling system and how are they related to demand that the system isserving?

2)

The chart below indicates the material

movements between departments in a batch production environment. The distances

in meters and load frequencies are given as # of times per day time. AGVs

(Automated guided vehicles) are used to transport materials between

departments. They move at an average speed = 175 ft/min (loaded) and 250 ft/min

(empty). Loading time per delivery is 2 min, unloading time is 1 min, and

anticipated traffic factor = 0.90. Use an availability factor = 95%. Determine

the number of trucks required under each of the followingassumptions:

a) The AGVs never travelempty

b)

The AGVs travel empty a distance equal to their

loadeddistance.

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3)

In a facility, in order to deliver pallet loads

of parts between work cells, 8 forklift trucks are used. Average travel

distance loaded is 520 ft and the travel distance empty is 410 ft. The trucks

are driven at an average speed of 440 ft/min when loaded and 616 ft/min when

empty. The load handling time is 2 min and the unload handling time is 1 min.

If the traffic factor for the system is 0.85, worker efficiency is 0.95 and

availability is 100%, what is the maximum hourly delivery rate of the 8

forklifttrucks?

4)

An AGVShas an averageloaded

travel distanceper delivery620 ft. The average empty traveldistance is not known.Required numberof deliveries per

hour50. Load and unload timesare

each 0.5 minand the AGVspeed = 130 ft/min. Anticipatedtraffic factor

= TF and availability= AF. Developan equation that relatesthe number

of vehicles requiredto operatethe system as a functionof the averageempty traveldistanceLe.

5)

Majorappliancesareassembled

onaproductionlineattherateof60perhour.Theproductsare moved

along the line on workpallets

(one productper pallet).At the final workstationthe finished products

are removedfrom the pallets. The pallets

are then removedfrom the

line and deliveredback to the front

ofthe linefor reuse. Automated

guided vehiclesare usedto transportthepalletstothefrontoftheline,adistanceof600ft.Returntripdistance

(empty)totheendof

the line is also 600 ft.Each AGVcarries five pallets and travelsat a speed of 145 ft/min(either loaded or empty).The palletsform queuesat

each end of the line,so that neitherthe productionlinenortheAGVsareeverstarved

forpallets.TimerequiredtoloadeachpalletontoanAGV=

15 sec; timeto releasea loaded AGVand movean

empty AGVinto positionfor loadingat the end of the line

= 12 sec. The same timesapply

for pallet handlingand release/positioningat the unload station locatedat the front of the productionline. Assumethe traffic factoris 1.0 since therouteisasimpleloop.Howmanyvehicles

areneededtooperate

theAGVsystem?

6)

Given

the demand level faced by the company marketing department andproduction planning department stated that the required production rate is 80

units/hr for acertain product. It

is planned to have an assembly work content time of 2 hr of directmanual labor. It is to be produced on a

production line that includes fiveautomated

workstations. The remaining manual stations will each have one worker. It isexpected that 9% of the cycle time will be

lost due to repositioning at the bottleneck station.If the balance delay

(1 â Balance Efficiency) is expected to be0.05.

b)

Determine the cycletime

c) Determine the number ofworkers

d) Determine the number of

workstations needed for theline.

7)

An automotive assembly plant in Bursa is

expecting to have a demand for thenew model that can be satisfied by a capacity of

320800 units annually. The plantwill

operate 52 wk/yr, 2 shifts/day, 5 day/wk and 8 hr/shift. Itwill be divided intothree departments: (1) body shop, (2)

paint shop, (3) trim-chassis-final department.

The body shop uses robotic arms

for welding operations while the paint shop coatsthe bodies using static electric painting. Both of these

departments are highlyautomated.

Trim-chassis-final has no automation: There are 19 hr of direct labor content

oneach ear in this third department,

where cars are moved by a continuousconveyor.

b)

Determine hourly production rate of theplant

c)

Determine number of workers and workstations

required in trim-chassis-final ifno automated stations are used. The average

manning level (average number oflabor

per workstation) is 3, balancing efficiency is 95%, and a repositioning time of0.1 min is allowed for eachworker.

8)

A moving belt line is used for a product whose

work content time = 35min. Production rate = 52 units/hr The length of

each station = 1.90 m, and manning levelis

1. Itis expected that the

balance delay will be about 0.12 or slightly higher.Uptime reliability = 98%. Time lost for repositioning each

cycle is 6sec.

a)

Determine the number of stations needed on theline.

b)

If the tolerance time were 1.5 times the cycle

time, determine the belt speedand

spacing between parts fur thisline.

9)

A manual assembly line is to be designed to

make a small consumer product.The

work elements, their times, and precedence constraints are given in the tablebelow. The workers will operate the line

for 400 min / day and must produce 300 product

/ day. A mechanized belt moving at a speed of 1.25 m/min will transport

theproducts between stations. Because of the variability in the time required

to performthe

assembly

operations, it has been determined that the tolerance time should be1.5 times the cycle time of theline.

b)

Determine the ideal minimum number of workers

on theline.

c) Use the Kilbridge and Wester

method to balance theline.

d) Compute the balance delay for

your solution in part(b).

e) Determine the spacing between

assemblies on theconveyor.

f)

Determine the required length of each workstation

to meet the specificationsfor the

line.

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10)

Solve the above problem with Ranked positional

weight method and updateyour

answer.

11)

Now suppose element 5 has a cycle time of 2

minutes and can not be brokendown

into smaller pieces. Offer a solution to this problem and solve problem 4 withyour newapproach.

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