Material Handling System(AGV)
Material Characteristic
Routing
Layout
Physical State(solid, liquid, gas...)
Size(ex: volume, length, width)
Weight(ex: weight / pc , weight/unit volume)
Shape(ex: long, round, square)
Condition (hot, cold, dry, wet)
Safety Risk and Damage Risk(flammable, toxic, fragile, explosive)
Fix position
Cranes, Truck==>Large product size, low production rate
Process
AGV, forklift trucks==>Variation in product and process, low and medium production rate
Product
Coneyors==>Limited product variety, high production rate
Pick-up & drop-off location
Move distance
routing variation
condition along the route (surface, traffic, elevation)
Scheduling - timing of each delivery
Prompt delivery when required
Use of buffer stock to mitigate against late delivery
Unit Load Principle
It is the mass that is to be moved or otherwise handled at one time. In general, should be as large as practical for the material handling system that will move and store
Reason for using unit load
Multiple items handled simultaneously
Required number of trips is reduced
Loading/Unloading time are reduced
Product damages are decrease
AGV Management
Traffic Control
AGV Dispatching
Flow Rate
Move Distance
Quantity of material moved
Delivery Cycle Time
TC = Delivery cycle time(min/del)
TC = Tl + [Ld/v] + [Le/v] + Tu
Tl = time to load (min)
Tu = time to unload(min)
Ld = distance b/w load to unload
Le= distance b/w unload to load
v = vehicle velocity (meter/min)
Rate of Delivery
Availability(A) - proportion of total shift time that the vehicle is operational and not broken down or being reparied
Traffic congestion(Tf): blocking, waiting in queue
Efficiency(E) - of manual driver if any (worker efficiency)
AT: available time (min per vehicle)
AT = 60 x A x Tf x E
Rdv = rate of delivery per vehicle(del/hr)
Rdv = AT / TC
Number of Vehicle required
Rf: specified delivery schedule or total delivery requirements(del/hr per vehicle)
WL: workload (min/hr)
n = number of vehicle require
n = WL / AT or n = Rf/Rdv