1 a fundamental principle of tps produce to demand 1.make only what is needed when it is needed....
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A Fundamental Principle of TPS
Produce to Demand
1. Make only what is needed when it is needed.
2. Base production and planning on Takt Time.
3. Develop flexible production lines. When demand changes, the line changes. Usually, labor changes to maintain labor efficiency.
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Produce to Demand…Takt Time
1. Takt Time is the pace at which the customer is buying a particular product.
2. Takt time is not how long it takes to perform a task. It is customer demand, not cycle time.
3. Takt time is calculated by taking the available time to work and dividing it by the demand for that period of time
4. Takt time cannot be reduced or increased except by a change in sales or the available time to work
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Takt Time Formula
Productive Time Available per period
Number of Required Units per period
Time available per Shift (8 hours)
Breaks (2 at 10 minutes each)
Lunch
Productive Time Available =
480 minutes
-20 minutes
-20 minutes
440 minutes or 26,400 seconds
Example: Productive Time Available Calculation
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Takt Time Formula
Productive Time Available per period
Number of Required Units per period
Units = 72,000 units ordered per month = 1,200 Units Required per Shift
60 shifts per month (3 shifts x 20 days)
Example: Number of Required Units Calculation
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Takt Time Formula
Productive Time Available per period
Number of Required Units per period
Takt Time = 26,400 seconds available per shift = 22 seconds / unit
1,200 units required per shift
So…the line should make one unit every 22 seconds to meet customer demand.
Example: Takt Time Calculation
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123 seconds = 5.59 or 6 operators required
22 seconds
Example: Operators Required Calculation
Number of Operators Required Formula
Sum of Manual Cycle Time
Takt Time
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Labor Efficiency Formula
(Sum of Manual Cycle Time / 3600seconds per hour) x Demand per Shift x100
Current Manning x Available Hours per Shift
Total manual time to make one unit
Demand per shift
Current Manning
Available hours per shift
123 seconds
1,200 units
7 direct operators
7.3 hours (440 minutes)
Example: Variables
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(123 seconds / 3600 seconds) x 1,200 units per shift x100 = 70% labor efficiency 7 operators x 7.3 hours per shift
Example: Labor Efficiency Calculation
Labor Efficiency Formula
(Sum of Manual Cycle Time / 3600 seconds per hour) x Demand per Shift x100
Current Manning x Available Hours per Shift
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26,400 seconds per shift = 1,553 unit capacity per shift
17 second cycle time bottleneck station*
Example: Capacity Calculation
Line Capacity Formula
Productive Time Available (seconds)
Bottleneck Station Cycle Time* (seconds)
*Bottleneck Station Cycle Time = Machine C/T + Manual Load / Unload C/T
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1,200 units per shift x 100 = 77%
1,553 units per shift
Example: Performance to Capacity Calculation
Performance to Capacity Formula
Actual Line Output (units) x100
Line Capacity (units)
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Examples: Operational Availability Calculation
Operational Availability (Formal TPS Definition)
Actual Output (units) x100
Demand (units)
1,080 units per shift x100 = 90%
1,200 units per shift
1450 units per shift x100 = 120%
1200 units per shift
under-production over-production
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Examples: Rate of Operation Calculation
Rate of Operation Formula
Demand (units) x100
Capacity (units)
1,200 units per shift x100 = 77%
1,553 units per shift