Straighten is focused on organising the workplace to reduce waste. To do this we must clearly understand the frequency of use of each item. When this is understood we can decide where items should be placed and make the workplace visual.
To decide where items should be placed, we should first understand the flow of the area and look for evidence of waste. We consider 7 types of waste
Do we need to move items to different locations for work to be done. If so, we could move the items closer together.
Inventory is cash tied up in the business. The longer that cash is tied up in inventory, the greater the risk of obsolescence. In addition, high cash demand for inventory increases the cash gap, stifling growth.
Waiting is `wasteful at the best of times, however, what must be tracked is waiting at bottleneck resources. Bottleneck process steps are rate-determining and limit output already If they are waiting it is impossible for the process to recover lost time.
Production of more than is needed is a waste since it consumes time and resources, potentially taking them away from orders that the customer is waiting for. Adding stock to warehouse where it may become outdated is also an increased risk
Processing items more than necessary, or duplication of effort are clearly wastes or resources. Duplicated processing or elongated processing times reduce capacity and add to costs.
Making something incorrectly will result in either rework or replacement. Replacement means that item took twice the materials expected, rework means it took far more labour than expected. If the item escapes from the organisation and reaches the customer, it will result in complaints and possibly loss of custom.
Understanding the flow of materials and work in the business can be accomplished using a spaghetti diagram. These are created by tracing the movement of work on a floorplan. Similarly a physical process map can be used by placing post-its for each step on a floorplan, connecting the dots and calculating the distance travelled. The diagrams can then be analysed for waste, congestion or any other problems that may contribute to ineffectiveness in the process.
Having identified the problems a new process layout can be created to eliminate as many of the problems as possible.
Some things we use daily, some weekly, some monthly and some rarely. Clearly they don’t all need to be here right now. Using the information from 1S about what is needed, decide how often items are used. Daily use items should be at the workstation. Items that are needed on a weekly basis should be close by, and as the usage gets less frequent the item can be further away. Items that are used infrequently can be in storage.
Now we know what is stored and how often it is used, we can place things to make the workplace visual. In a visual workplace, it is obvious where to go to find what they need, where to return it and what needs to be done. Item recoil is the hardest thing to build into the system. How can we ensure that itens are returned to their correct storage location? There are many ways, using colour, shadow boards, labelling, and floor markings.
As with 1S, 2S must be repeated every 3 to 6 months to ensure routines are maintained and that the arrangements remain cinsistent with process and business needs.