Analyze phase

• Takt time

Takt time is a very important concept because takt time is the rate at which the company should produce parts in order to meet the customer demand.

The purpose of takt time is to identify the maximum time available to produce a part in order to meet the customer demand.

To calculate the takt time we should have two main inputs: customer demand and time availability

The formula to calculate takt time is

𝑇𝑎𝑘𝑡 𝑇𝑖𝑚𝑒 = 𝑇𝑜𝑡𝑎𝑙 𝐴𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒 𝑇𝑖𝑚𝑒 𝐶𝑢𝑠𝑡𝑜𝑚𝑒𝑟 𝐷𝑒𝑚𝑎𝑛𝑑 The concept of takt time should not be confused with:

Lead time: is the time horizon difference between order recipient and the client getting their final product

Cycle time: is the time spent to process the customer order from all aspects Takt time: the maximum time, to comply with orders to meet customer demand goals.

The customer takt is the value stream rhythm, the takt time is based on the average customer demand. This is the heart rate driving the production system. The takt time concept entails working at a constant peace.

The sheet in figure 16 should is filled; the schedule time, elapsed hours, lunch or dinner time, mandatory break time, number of days the shift runs, and lastly entering the part number and demand rate.

The daily available time is 14 hours, the daily customer demand is

calculated by dividing the total customer demand over the days available per year, so 2944/235 = 12.5 is the customer demand, which is round to 13. Then the takt time formula is applied to calculate what the takt time is.

The process is repeated 3 times for 1,2 and 3 shifts and of course the takt Figure 16, Takt time calculation procedure sheet

As illustrated in figure 17, the implementation of takt time methodology, should move the production form a monthly target with a non-stable path, to a daily target with a stable path.

Once the takt time is defined, it should not be changed for at least 4 months.

• Operations bar chart

The operation bar chart identifies the real capacity of the operations and the can lead to the placement of a standard work to the process to maintain smooth part flow. It is the process of plotting the manual, automatic,

walking, and set-up time for each operation as it concerns to the flow of the material.

Figure 17, Process stability moving to takt time approach

In figure 18, first the measurement is identified from the time observation phase, the takt time is reported in the sheet (the three straight lines in the graph), and finally the bar chart is plotted.

Carefully observing the operations bar chart for the star part number, it is noticed that for 1 shift takt time the turning/milling machining operation takes more time than the takt, unfortunately it cannot be changed because the activity is a machining activity, so the CNC program runs in 50

minutes, and cannot be reduced.

• Capacity analysis

The capacity analysis is crucial to understand the real situation; the goal is to meet the takt time, so this analysis assesses the ability of the resources (people, machines and equipment) to meet the target (finishing the

operations before reaching the takt time).

Capacity analysis identifies any type of constrain the process may face, where the areas of excess capacity exists and the potential areas where

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110

Turning/Milling/ Dentatura Deburring/Marking Grinding Washing Visual Inspection

Time (minutes)

Operation Number

Operations Bar Chart PN: 15****-1

Manual internal Automatic (machine time) Manual external

Figure 18, Bar chart for the new machining cell

It also shows what the maximum process capacity is for each machine and determines the number of machines ideally required to perform the

process.

In figure 19, the capacity analysis for the grinding machine is analyzed.

The analysis starts with the part number, description, material, then the machining time and volume. The volume row (7^th row) is the

multiplication of volumes and time, dividing by 60 the sum, the total time needed is calculated.

AWCT, is the weighted average cycle time, it is calculated as the sum of volumes multiplied by machining time then divided by the sum of

volumes. Note that the calculation should take into consideration the uptime at 98%, and the planned load at 95% as convention. Then finally the number of machines required is calculated.

Figure 19, Grinding machine capacity analysis

Figure 20, Turning machine capacity analysis

The same concept also is applied to the second turning machine, and in figure 20 the calculations are illustrated.

• Operator loading chart

It is the graphical tool that helps creating continuous flow in a multi-stage operation phase by distributing elements of the operator's work in relation to takt time. The operator loading chart is used to compare operator’s actual task cycle time to the process takt time.

The procedure is simple, by plotting each operator physical time to do the activity (standard work combination sheet totals for manual, walking and waiting time) and compare the numbers with the takt time.

In figure 21, the operator loading chart illustrates the comparison between the takt time for 1,2 and 3 shifts with the manual, walking and waiting time, all summed together. In this case there is only one-line operator, and this is the reason why there is only one bar (which represents the line