Final - JIT Systems Flashcards
JIT
Just-in-time manufacturing: to produce only what is needed, when it is needed
JIT inventory, JIT purchasing, lean manufacturing
JIT philosophy
Eliminate all waste i the organization
JIT system
a management system that aims to improve the manufacturing or service process by eliminating waste
Origins of JIT systems
In 1950s, Toyota realized there were all kinds of waste in the production process because of how little capital and space Japan had, forcing them to minimize inventory
Felt that inventory hides problems. For Toyota, improving performance meant reducing inventory.
waste
anything other than the minimum amount of resources that is essential to add value to the product
Examples of process waste
scrap, non-value-added cost, wrong tools/equipment
Examples of over-production waste
extra inventory, inappropriate use of resources
Examples of inventory waste
storage, capital costs
Examples of product defect waste
interrupted flow, lost capacity, wait for replacements
Examples of waiting time waste
unplanned, planned queue, waiting for other parts in batch
Examples of methods waste
searching for tools, poor layout, walking
Examples of movement waste
material handling, receiving, storing, retrieiving
How can managers improve the pull system?
reduce the variability associated with supply and demand
pull system
coordination between process -> improving means eliminating the need for large inventory (which is a major issue in automobile manufacturing)
work cells
Eliminating worker inefficiency = increasing worker productivity
highly utilized multifunctional workers operating a number of different machines
Cellular facility layout
work is moved within a cell (mostly U shaped) according to a prescribed path (as opposed to assembly lines typical in traditional automobile production)
Flexible machines
automated, general purpose machines with quick setup times
cell
grouping of products based on similar requirements
Should a company implement work cells if employees need to constantly tend to the product?
No, because work cells only work if the workers don’t need to be at the same step in the product all the time (they rotate between steps)
push system
each workstation produces according to a schedule and ‘pushes’ its completed work to the next workstation (aka the traditional approach to production by building inventory)
pull system
each workstation requests, or ‘pulls’ items from the previous workstation only when needed
What are the benefits of a pull system?
Overall: Improves coordination between processes by force
Prevents overproduction and underproduction
Kanban system
Visible production control system which authorizes the production or movement of the next batch of material only when needed
Works the same way as a fixed-quantity inventory system: Order quantity (Q) is equal to reorder point (R)
What are kanbans NOT?
Not schedules!
MRP vs. Kanban
schedule vs. cue
complex vs. repetitive
higher-level vs. shop-level control
production lot
aka batch; the typical amount of items produced in one session
true or false: compared to a large lot size, a small lot size is harder to achieve between-process coordination that’s required for the pull system
false; easier because there’s less room for error/steps involved (my assumption)
What are the benefits of small lot sizes?
Better coordination
Better material handling
Reduce average inventory levels
Reduce inventory space
Avoid buildup of defective items
Flexibility in reacting to problems
What does each ‘kanban’ container represent?
Production or order lot size
What are the 4 different types of supply variability?
lot size, machine breakdowns, quality, suppliers
preventative maintenance
periodic inspection and maintenance designed to avoid breakdowns (as opposed to breakdown maintenance)
necessary due to small inventory and high automation
work environment: five S’s
there are 5 S’s that make up a work environment (don’t need to know what they mean, just that they exist). Seiri, seiton, seiso, seiketsu, shitsuke.
Stuff like cleanup, workplace organization, discipline, etc. Basically JIT systems prioritize preventative maintenance and workplace organization to be effective.
Why are consistently high quality products necessary in JIT systems?
Due to the small inventory
Why do facilities and equipment need to be kept in good working order (maintenance) in JIT systems?
Because machine downtimes are waste. Fixing is also waste.
Empowerment
authority given to workers to stop the production line if a problem occurs
Andon lights typically used to signal issues.
Why do JIT systems focus on fixing quality problems at the source?
Because it’s not easy to coordinate between processes if product quality is poor.
Ex. Workers might not have enough good quality items to continue work, or time might be spent on fixing defective items
poka-yoke
devices that are designed to prevent mistakes/defects from happening
What do standard parts and modular design of products help with?
reducing variability
Why are reliable suppliers important for JIT systems?
So that deliveries are on-time and frequent. Must build long-term, close relationship with. few suppliers.
What sourcing method of suppliers is best in JIT?
Single-sourcing: entire family of parts provided by one supplier to minimize time etc. between deliveries (prevent bottlenecks)
prefer physical proximity but not necessary
JIT II
Supplier working in the manufactuer’s plant.
What are the pros and cons of a supplier establishing a relationship with a company employing a JIT system?
Pros:
- Guaranteed, steady demand
- Advanced notice of volume changes
- Minimal design changes
Cons:
- Lots of requirements
- Competitive vs. cooperative dilemma
- All eggs are in one basket
JIT systems are most successful in which industries in relation to demand?
Industries that have a relatively consistent demand due to JIT being effective with minimal demand variability
Kanban systems can absorb +/- what % of demand variability through manipulating the number of kanbans?
10%
True or false: the fewer the kanbans, the less production there is
true
How can worker cells deal with changes in product mix and volume?
Volume adjustment by a number of workers
Volume adjustment by integrating or separating cells
However, can only do so to a certain extent
Uniform loading
Arrange daily production in the same ratio as monthly demand
Always have some quantities of each product and steady demand on components
If a company implements a JIT system, what changes would be expected? (7)
Reduced Inventory > safety stock
Cells > assembly lines
Pull > push manufacturing
Zero defects > defect toleration
Quick setup times > toleration of set up times
Emphasize team-oriented employee involvement > IC contribution following manager instructions
Suppliers as partners > independent entities
Why do JIT systems lead to shorter cycle times?
Because batch sizes are smaller
What are some benefits of JIT systems?
REDUCE: inventory, space
IMPROVE: quality, process
PEOPLE: Better use of HR, supplier relations, employee engagement, productivity
SHORTEN: cycle time, lead time
PROCESS: increased machine utilization, greater flexibility, more product variety
Limitations of JIT (aka issues)
- All key elements must be present and integrated for system to work well i.e. work cells, suppler variability, pull system, lot size (smaller), machine breakdowns, fewer suppliers, increase quality
- Must balance technical and behavioural aspects
- Each org must mould a JIT system to suit its own environment
- Requires fundamental change in the org
JIT systems are not suited for companies that have..
Very high or low volume, unique products
High fluctuating demands or true make-to-order products
What are the pros of job specialization for management?
Readily available labour
Minimal training
reasonable wage
high productivity
What are the cons of job specialization for management?
High absenteeism
High turnover rates
high scrap rates
grievances filed (i.e. unsatisfied workers)
What are the pros of job specialization for workers?
Minimal credentials
minimal responsibilities
minimal mental effort
reasonable wage
What are the cons of job specialization for workers
Boredom
little growth opportunity
little control or initiative
little intrinsic satisfaction
just a cog in the wheel :(
what are three types of alternative job designs?
job rotation, job enlargement, job enrichment
job rotation
shifts workers to different jobs to increase understanding of the total process
job enlargement
expansion of the job through increasing the scope of the work assigned (more horizontal)
job enrichment
expansion of the job through increasing the worker responsibility (more vertical)
method analysis
a type of work measurement that studies how a job is done; typically a document outlines how job is done and what is expected to be evaluated
time study methods
sets a standard time based on timed observations of one worker over several cycles to measure work
what do time study methods help with?
helps to reduce variability time in the production cycle and determine how long it takes to do each task
