THE MAGIC OF CALCULATING TAKT TIME

The Imbalance of Production

“We going to be short of meeting of our shipment this afternoon”. “I think we need to schedule overtime for this weekend as our production cannot keep up with the demand.” “Why do we have so much inventory of XURABB-4847BH in the warehouse? I counted and we have 2 weeks of finished goods inventory being stored there. Why did we make so much when we are missing shipments to other customers?”

Are these familiar statements you’ve heard from your scheduler, plant manager, or supervisors? These people are like the conductor of a group of musicians. They follow your instructions to be in rhythm with the flow you are trying to achieve, otherwise the music will sound bad, offbeat, or imbalanced. Your production may have a production imbalance problem and the key to solving it is using a formula called Takt Time. Every one of the above statements has a somewhat sad result. The response being, “Our system failed to meet customer demands. 

Another response or result from not achieving customer demand is an irate or unsatisfied customer. It’s doesn’t matter the type of business you have; you failed the customer and likely on a path to lose future business. How did that happen? What went wrong in the process? Why are we in the situation that we are in today? The answer lies within your process and scheduling. Do you really know how much you need to produce each shift or is it based upon an archaic forecast of years of customer orders? Are you sure what you make today, you will sell tomorrow? Well, just take a walk into your finished goods warehouse and then you will find your answer.

Defining Customer Demand

Customer demand is providing the customer what he wants, in the quantity he wants it and when he wants it. Simple. Think of a Subway Shop. You go in, look at the menu, identify what you want, place your order for type o bread, cheese, heated or not, category of meat, and all the extras toppings and dressings that follow. Your sandwich is literally made directly in front of your eyes, wrapped and placed at the cash register for your payment within 2 minutes unless you wanted it heated, just how you ordered it. Why can’t your production follow the same model? Who says it can’t? The days are long gone when sales forecasts run the shopfloor. You run the shopfloor or your process by utilizing firsthand, up-to-date information that the customer provides. 

What is Takt Time?

Another way to describe customer demand is defined as Takt Time. Takt Time is the time within which you should produce one part of product, based on customer demand consumption. Takt Time defines the rate which material and product flow through the value system.

To run faster than Takt Time anywhere in the value system stream is overproduction, resulting in excess inventory. To run slower than Takt Time creates the need for accelerated production, overtime, and expedited shipments

Takt Time = Available Time/Customer Requirements        

Impact of Process Variation or not following Takt Time

Process variation impacts Takt Time which likely increase system costs. CEO’s, CFO’s, and Operation/Plant Managers are not happy when system costs go up or out of control.

Another way to describe customer demand is defined as Takt Time. Takt Time is the time within which you should produce one part of product, based on customer demand consumption. Takt Time defines the rate which material and product flow through the value system.

Variation affects available time:

• Breakdown (major downtime) – how much production is lost when your equipment breaks down? (Minutes, hours, shifts, days, etc.)
• Changeover (time to change equipment over to make another product) – How much time is spent changing over equipment to produce a different product? This is a form of time loss created by inefficient changeover.
• Interruptions (minor downtime) – How many times during a shift are operations stopped due to small mechanical, electrical or IT problems, lack of inventory, incorrect inventory, part fit problems, etc.
• Late starts – What happens when everyone doesn’t show to work on time or after breaks? How much production time is lost?

Variation affects customer requirements:

• Scrap – How much product is thrown away each shift due to poor processing, poor quality of product, employee error? How much time was spent on the product at the point of scrapping it?
• Rework – How much time is spent reworking a product including adding new, disassembly, or adjusting for quality approval? How much time should be spent on reworking a product before it becomes unreasonable to rework?

The Magic of Calculating Takt Time

Process variation impacts Takt Time which likely increase system costs. CEO’s, CFO’s, and Operation/Plant Managers are not happy when system costs go up or out of control.

Another way to describe customer demand is defined as Takt Time. Takt Time is the time within which you should produce one part of product, based on customer demand consumption. Takt Time defines the rate which material and product flow through the value system. Here’s an example of the equation filled out using one, 8-hour shift with a total of 2 –15-minute paid breaks. Customer order is 1174 parts per shift.

The magic of Takt Time is like the work of a magician. You notice what the results are, but you do not notice “the magic” or what the process is not showing you. The above calculations tell us that a perfect, shippable product must be produced every 23 seconds within your shift in order to meet your customer demands. That means you have absolutely no mistakes, no downtime, no one showing up late, no reworks, no scrap, and that nothing interrupts your process throughout the day. So how often do you think that happens in the real world? Your world? The MAGIC is really being able to identify the things that are affect your available time and affect the quantity of customer orders produced in your shift. By calculating takt time, you expose the weakness in your system which in many cases you didn’t know existed. Maybe you realized for the first time, although your customer forecast is defined in stone and passed around to various departments to deploy, none are aligned to each other, each are working in their own cubicle and because of this, the reality is your forecast cannot be meet by system performance as operational variance exists which identify many processes to exceed takt time.

You need to be trained in understanding how to observe a process and how to identify waste within a process to make this beneficial to creating a better system and especially one that meets the daily demands of your customer.

Expanding upon the same example, this process has 5 different workstations which requires an employee to load and unload parts to/from a machine. The complete process for each workstation in time is shown against what the customer requirement is to make product, or takt time.

Do You See a Problem?

Hopefully, the very first thing you noticed was that 2 of the workstation cycles times exceed the takt time. That means if your process continues as is, without some form of change, you will always have a problem meeting the customer requirements on your shift. Operations A and C simply cannot perform to customer demand as designed. What else do you notice? Did you notice that Operation D is waiting for Operation C to complete its work? Operation B also waits on OP A. but to a lesser extent. Operation E, although below takt time has plenty of time to complete the work received from D and still meet the takt time. Bottom line is that takt time will never be achieved unless Operations A and C are modified or revised in such a way as to be able to perform their total process at or below 23 seconds. This graph shows an imbalance in workstations workload or cycle time.

Now several things can be the driver behind why one operation’s total cycle time is greater than another.

1. The equipment cycle time itself.
2. The sequence of steps to complete the process steps
3. The unidentified waste within the process
4. The variation among the people who conduct the work.

We can almost come to agreement that the equipment cycle time meets takt time, after all manufacturing engineers who specify the equipment are experts in knowing how many pieces of equipment are needed to meet the customer order, be in one or multiples of the same equipment. But in rare cases, the engineer has miscalculated, and the process will suffer until more equipment is ordered and placed within the process. So, we can ignore #1 most of the time. Whenever you observe multiple machines in the process producing the same product, you have witnessed the genius of the process engineer in calculating machine output to match or exceed customer requirements.

For #2, the sequence of steps may be excessive from a cycle time concern. Ask if the work has to be done in this workstation before the work is passed on or can the work be rearranged to do other steps later or earlier to achieve increased performance. If not, move the item downstream for the next workstation to complete the work to help balance the work cycle. 

#3 is where an understanding of the 7 wastes is important. You need to observe the waste in the process and if things can be changed by study, change them. Think about the Subway Shop model. The worker has all the necessary items if from and next to him to complete the work with few steps and minimal reaching. The layout of the work is important to minimize the waste of motion. Are all steps required or can the next workstation perform some of the work and still achieve a cycle time equal to or below takt time.

Finally, #4 becomes a real HR issue. After all, all people are hired to do a job regardless of gender, size, strength, etc. as it is the employer’s job to design the work for all people to do. If you accept this to be true, then all people are equal. But in reality, people are skilled differently, in mind, strength and dexterity, therefore people work at different paces. The process engineer is to design the process to a standard that satisfies a multitude of personnel in a manner that allows quantity and quality of work to be achieved safety and without severe stress or strain. Example: Bill outperforms Sally 2 parts to one. If the process is designed for the slower individual, production is literally cut in half because it is proven it can be done at a pace 2x as fast. 

Using Takt Time to Rebalance the Process

Before a rebalance starts, let’s define what cycle time is. Cycle time is the time the machine, the operator, or combination of both, it takes to completer the work task. The Total (Manual) Operating Time per piece does not include any wait time and based on average person. The average of Bill and Sally is 1.5 parts (Bill = 2 and Sally = 1). 

The Machine Cycle Time is the total operational time of the machine including loading and unloading of the part, be it mechanically, by robots, or by a human.

Using lean principles, you observed personnel were waiting, using excess motions or steps to complete their work. In modifying the workstation with the employee’s input, (Note: This is extremely important) you retime the work to discover the work can be done in the time shown by the yellow bars above. The gray area represents waste in the process. Notice in this example, each workstation has elements that are identified as waste OR work that can be performed in other workstations.

Now that you have rebalanced the operations by eliminating wasteful steps and/or by adjusting work elements to be completed downstream, the new graph shows a much more balanced workload across all 5 processes, not perfect, but much closer in cycle time to each other. The key is also to see all operations are below takt time which allows the revised process of operations to meet the customer need with approximately 5 seconds to spare. This spare time is a factor of safety to ensure your operations will have a good chance of meeting the customer demand each shift even if hiccups occur. Secondly, it also suggests that if the customer increase their orders, the operations are designed to handle a lower takt time, close to 18 seconds by this graphic display.

You’ve done an excellent job in performing your Magic!

Please send your comments or questions to pverschaeve@surefoundationsllc.com