Muri (無理)
Muri means overburden, beyond one’s power, excessiveness, impossible or unreasonableness. Muri can result from Mura and in some cases be caused by excessive removal of Muda (waste) from the process. Muri also exists when machines or operators are utilized for more than 100% capability to complete a task or in an unsustainable way. Muri over a period of time can result in employee absenteeism, illness, and breakdowns of machines. Standardize work can help avoid Muri by designing the work processes to evenly distribute the workload and not overburden any particular employee or equipment.
Standard Work
The Toyota Production System defines standard work as the current best practices for performing a process. The term current is important becuase is indicates that the standard can (and is) updated as improvements to the process are found. Standard work exists to be changed, or improved upon.
Virtually anything can benefit from standardization. Within the manufacturing business standard work can be applied to safety, equipment setups and tool changes, inventory restocking, preventative maintenance and of course the process steps to produce the finsihed goods. One can also apply standard work instructions to warehousing finished goods and the loading and unloading of delivery trucks. Even office activities such as quoting, order taking, purchasing, schedule/planning and accounting can all benefit from standard work instructions.
The best standard work instructions are visual rather than written text. If you've ever assembled a piece of furniture from IKEA® you have seen a visual example of standard work. These types of instructions make what is complex very simple and they don't rely on the users language skills.
TAKT
Takt time is used in manufacturing to set the average time interval between the start of one production unit to the start of the next unit. By measuring the time between the completion of units workers can know if they are producing products at the right cadence. If the time between completions is greater than the takt time, you are behind on your schedule, if it is shorter you are ahead of schedule and in jepoardy of overproduction one of the 7 wastes of muda.
The formula for takt time is simple. Takt Time = Time available for production / Customer Daily Demand.
For example, let's say you have 8 employees all working an 8 hour shift. This equates to 7.5 hours (of working time) per person. 8 x 7.5 = 60 (hours).
60 (hours) x 60 (minutes) = 3600 minutes of manufacturing time.
Assume the customer demand for the product is 700 units per day. By dividing the 3600 minutes by the 700 units you get a takt time of 5.14 minutes per unit. 3600 / 700 = 5.14
By calculating takt time, and measuring your output (cycle time) and displaying both metrics to your workers you will see an amazing improvement in output.
Work Cells
Simply put a workcell is an arrangment of resources in a manufacturing environment in such a way as to improve the quality, reduce the cost and improve the speed of a given process. A well designed work cell limits the amount of movement (motion) a worker must make. Ergonomics play a key role in designing a workcell along with takt time. Additionally the cycle time of the equipment balanced with takt time can help establish the proper workcell configuration.
Production Leveling
Production leveling is key to keeping your factory or process under control and avoid burnout in your employees and overtaxing your machines. It is very rare for customer orders to arrive in the quanities that are optimum for production. In almost all cases some type of production leveling is needed. Production can be leveled by volume or by product. While these approaches are closely related, there are some key differences. When leveling by volume the approach is to produce at the long-term average demand while keeping a finished goods inventory to account for the variablilty of the demand. By using the differences in change over times and smaller batches, leveling by product can be achieved. This leveling is often augmented by the user of visual scheduling to communicate the production plan to the factory.
Total Productive Maintenance (TPM)
Total Productive Maintenance utilizes the equipment operator as the first line of maintenance for the machines. TPM is a holistic approach to maintenance that serves to reduce breakdowns/slowdowns, defects and creates a safer workplace by reducing accidents due to machine failures. By training and empowering workers to clean and maintain their own equipment a sense of ownership becomes pervasive on the factory floor. It is important to engage the factory maintenance department in the training and with a robust preventative maintenance program to address issues discovered by the operators and recorded on their daily cleaning and inspection checklists.
Overall Equipment Effectiveness (OEE)
Overall equipment effectiveness can dramatically affected by TPM. OEE is the act of measuring manufacturing productivity of you machines against the standards of availabilty, performance and quality. OEE begins by knowing your planned production time.
The first metric of Availability subtracts any unplanned stops, for equipment failures or material shortages, and planned stops, for tool changeovers, from the planned production time.
Availabilty % is expressed as Planned Production time / Time lost due to Availability.
The second metric of Performance accounts for anything that runs at less than maxiumum speed. This includes slow cycles and small stops. Defective materials, jams and misfeeds as well as machine wear can contribute to performance loss.
Peformance % is expressed as Planned Production time / Performance time lost
The third and final metric of OEE is Quality. As the name implies this takes into account the parts that are manufactured with defects or that don't meet quality standards. These parts often require rework.
Quality % can be expressed as Planned Production time / Quality time lost.
By measuring your Overall Equipment Availability (the average of the 3 measurements) you can gain insights into issues that can rob your production of efficiency causing employees to work overtime and threatening your on-time deliveries to your customers. If your OEE is not 100% you have room for improvement.