JOB SHOP Flashcards
Strengths?
* High fliexibility is the main feature Short-to-medium term.. - mix flexibility - volume flexibility - Product customization Medium-to-long term - Product innovation - Expansion (technological capacity& production capacity)
Strengths?
- Machine flexbility
- Material handling flexibility
- Alternative routing / technological cyles
Strengths?
Workers are more skilled in specicif technoloies leading to:
- Functional separation
- Knowledge transfer (faster and more efficient)
Why JOB SHOPS can introduce new products wtithout affecting the already existant ones?
It is possible due to:
- Machinery flexibility
- Material handling flexibility -> machines are decoupled
- Routing flexibility: Within the same department or between different departments.
Why Expansion Flexibility is easier in JOB SHOPS?
Because if market’s demand grows, it requires more production and techonolical capacity. So it entails the addition of new machines.
JOB SHOP is more flexible for introducion machines.
If makert’s demand increases in a JOB SHOP, its techonological capacity increases?
Increases both the production capacity (volume) and also the mix flexibility (variety of products).
WEAKNESSES?
- Limitation in machinery efficiency
- High Work In Progess (WIP)
- Quality of products is not constant
- High Lead Time (LT)
- Difficult to manage the production
- Low machine saturation / low utilization rate
On which does the JOB SHOP performance depend?
It depends on the PRODUCTION MIX variety of products to be manufactured :(
Why is it difficult to manage the production in a JOB SHOP? :(
Because it is difficult to calculate the production capacity since it depends on many aspects.
On which aspects does the Production Capacity depend?
- Mix of products to be manufactured
- There are alternative routings
- Materials handling is complicated
- Number of machines and their state: If there is a breakdown, there is a reduction in capacity within the department, but it is difficult to quantify it within the overall system.
- Technological features of the jobs: Different processing requirements within the same department.
Typical questions related to system design?
- How many machines do we need to meet demand?
- How many operators do we need to meet demand?
- Where are the bottlenecks?
- What happens if the production mix changes?
- What happens if a machine break downs?
- What is the effect of reducing setup times or lot sizes?
- What is the effect of adding another machine to the system?
Steps for the design of JOB SHOP?
- production Mix identification
- Routing definition
- Machine identification
- For each product type, calculate the total time of the operations that have to be done on the same type of machine.
Tij
5.Calculate the yearly workload NHi for each type of machine i.
6.Calculate the number of hours available for each machine-type i
7.Calculate the number of machines of type i necessary to manufacture the production mix, given the yearly demand - The number that has been obtained must be rounded up or down.
- Evaluate the number of shifts/day, computing the yearly costs adopting 1, 2 or 3 shifts/day
Design of JOB SHOP - Step 1?
Production mix definition
- Identify all the product types
- Estimate yearly demand for each product type
- Define the lot sizes for each product type
Design of JOB SHOP - Step 2?
Routing definition
Define the main routing for each product type
If possible, define alternative routings
Design of JOB SHOP - Step 3?
Machine identification
On the basis of routings, it is possible to identify all the machine types that are necessary to manufacture the production mix
