To the Die :
- Standard shut height & feed height.
- Improved alignment.
- Reduce & Standardize attachment points.
To the Facility :
-Quick action pneumetime.
-Simplified iron hand adjustments.
- Dual die trucks.
- Hydraulic clamping upper die.
-Roller track in press bed.
In 1950 in Mezda Plant at Hiroshima, the setup time for 350, 750, 800 tons processed was reduced by more than 50%. This was based on observation of all activities and dividing it into two parts.
The concept was born in TOYO KOGYO. But name SMED was given in Toyota. In 1969, Toyota 1000 ton press needed 4 hours for setup. Folks wagon did in 2 hours. Management desired it to be reduced – and it was reduced to 90 minutes but management wanted it to be 3 minutes. This could be done by converting internal setup to external.
SMED is based on years of practical experience.
It is a scientific approach to setup time reduction that can be applied in any factory to any machine.
The distribution of time (average) on the 4 steps in sequence as under :-
TIME
Step 1 : Separating internal and external setup. This can be done by production study, sampling, interviewing worker, supervisor, etc., or video taps.
Step 2 : Converting internal setup to external setup. Normal setups can be reduced by 30-50% at stage 1. Re-examine all steps to see if any step is wrongly classified and find ways to convert them to external setup e.g. preheating.
Step 3 : Streamlining all aspects of setup operations. To achieve SMED it is necessary to streamline all the operations and for this elemental analysis will have to be carried out.
At Toyota bolt maker setup of 8 hours was reduced to fifty eight seconds.
At Mitsubishi internal setup of six arbor machine was 24 hours and was reduced to 2 minutes and forty seconds.
A processes is a continuous flow from Raw Material Stores. An operation is an action performed by machine or equipment on raw materials, intermediate or finished products. Production is a network of operations and processed.
Manufacturing process can be divided into four phases –
Storage - Raw Materials
Finished Products
Waiting for a process – an entire lot waits because work on previous lot is not complete.
Waiting for a lot – when first item is being worked on rest must wait for their Turn.
Internal Structure of Operation consists of –
A. Preparation and after adjustment. These are performed once before and after each lot is processed or setup operation.
B. Principal Operations -
In essential operation we can have the four phases – work, inspection, transportation and storage.
If order is for 300 pieces and we produce only 300, there may be defectives and supply of good pieces will be less. So add 10% to take care of this or produce 300. If only 20 are defective, 10 are left over. These are kept in stores in anticipation of repeat order. This is excess inventory.
If the produce goods before they are needed or order is received. This is excess anticipated production
Diversified, low volume production – problem. Therefore produce small variety large volume and stimulate demand e.g. voluswagan
One time orders are difficult problems but repeat orders are not so much of a problem. The number of setups are reduced by combining the lots into one. This creates waste due to production not needed immediately.
For diversified production – more setups needed frequently. But some elements can common or similar. By focusing on common or similar setup elements, by classifying these elements and by choosing the right machine for each task, it is possible to reduce setup difficulties dramatically.
For small lot – consider
The problem is not diversified – low volume production but multiple setups involved and small lots.
a. Setup time 8 hours :
c.Setup time saved by changing lot size from 100 to 1000 – setups reduced from 10 to 1.
Setup time Setup time
4 hours 4 x 9 = 36 hours
8 hours 8 x 9 = 72 hours
Large lot production has advantages and disadvantages as follows.
Advantages :
- Since Setup time
---------------------------ratio is low
Total operation time
Apparent operating hours are reduced.
-Reduction in setups and setup times and increase in work rate.
-Large inventory helps load smoothening.
-Large inventory help as cushion in case of defects, machine breakdown, rush orders.
Disadvantages :
-Large inventory, less capital turnover rates fall.
-Inventory does not add value and occupies space.
-Inventory needs storage equipment and records rationalization waste by computerizing records.
-Longer load times and discarded items delay for new orders.
-Sell extra stock as scrap when model changes.
-Deterioration of stock due to rust, etc.
The concept is right lot does not talk of reducing setup times drastically. If four hours setup is reduced to 3 minutes –
Reduction in man hours is only 3%. If 9 setups are reduced, savings are 27 minutes. But rate will increase tremendously, inventories will be cut down. Then nobody will ask the question of economic lot size with SMED this EBQ has disappeared. If 24 hours later supply is there, not need to store and storage banks.