week 5: assembly and automation Flashcards
cell assembly definition
single fitter at single bench
to increase production rate number of benches increases
cell assembly advantages
- flexible (add or remove cells)
- good accountability (single fitter assembles each product, easy to determine whose responsible for quality issues)
cell assembly disadvantages
-require more space
- redundant use of space
- require more assembly stores
- require more equipment
kitted assemblies
used in high variety, low volume productions ; necessary components loaded into a kit and kept with products
bench stores
used for smaller products with cheap components
assembly line definition
work for each product split into a number of packages - product goes through various work stations
what re the three types of assembly line
- fixed fitter lines
- moving fitter lines
- hybrid lines
fixed fitter lines (definition, adv/dis)
- single fitter lines (manned by single operator for small products )
- multi fitter stations ( multiple operators for large products )
- can also be for producing a single product or multiple
advantages :
- fast throughput times
- minimize tooling
- minimize stores
- allow fitter specialization
- high output and quality
- very efficient
disadvantages:
- low flexibility
- consistent demand needed
- difficult to balance
- typically on or off
moving fitter lines (definition, adv/dis)
fitters either walking or riding and the products stationary
advantages:
- high flexibility
- high product variation
- multiskilled fitters
- fast through put times
- minimise tooling
- minimise stores
disadvantages:
- multiskilled fitters
- difficult to manage
hybrid lines
combined moved and fixed
disadvantages;
- very difficult to balance
- large complicated lines
line balancing
ensures uneven workload, bottle necks and tock holdups re eliminated and smooth overall flow of components
what is a precedence diagram
identifies the ways a product can be assembled
- each task identified by an oval with time relation shown by arrows
line balancing methods
- intuitive ( use experience to divide work)
- mathematical model (objective to minimise number of workstations)
- heuristic methods (experience based methods used to reduce need for calculations e.g rank positional)
rank positional weight
1) calculate each elements positional weight
2) construct rank positional weight table of elements
3) assign unallocated element with highest available rank to first available station
4) assign next highest
5) continue process
automation goals
- integrate various aspects of manufacturing system to improve quality and uniformity minimising cycle time
- Improve productivity to reduce costs by better control of production
- Improve quality by using repeatable processes and thus reducing variance
- Reduce human involvement, boredom and thus potential for human error
- Raise the level of safety, especially in hazardous environments
- Economise space by arranging machines, material handling etc more efficiently
