Building Lean Systems, Part 1

Building Lean Systems Part 1 The important lean thinking tools to promote flow              5s Flow Chart the Process Value-Added and Non-Value Added Activities Takt Time Average Labor Content- Minimum Required Manpower Mixed Model Scheduling One Piece Flow Cellular Layout Standard Work Pull Replenishment: Placing a Cap on WIP Point-of-Use Material Storage Mistake Proofing and Method Sheets Continuous Improvement and the Pursuit of Perfection 3 5S: A systematic Process for Organizing the Workplace Japanese Definition English Example Seiri Tidiness. Throw Away Rubbish. Sorting Items are classified as Necessary, Unnecessary (disposed of immediately), Red tag (auctioned for anyone to claim as necessary). No claim  discarded Seiton Organization. Retrieve in 30seconds Storing Arrange items in order so that they can be picked up easily. Visual information about what & how much should be stored in a spot. Tools are hung on boards, with a silhouette (shadow box) of the tool painted. Drawers have Styrofoam cutouts of the items to be stored. Seiso Cleanliness. keeping the area clean, and organized. Sanitizing Individual Responsibility. Not just sweeping the floor and cleaning up leaks and spills. Checks for malfunctioning machinery or loose parts on machines. If machines are kept clean, oil leaks will be discovered before a equipment failure. If aisles are clean, accidents are minimized, etc. Seiketsu Neatness. Standardizing Standards by which personnel must measure and maintain personal and environmental "cleanliness." What the normal condition should be. How an abnormal condition should be corrected. Visual management; by colorcoding and standardization of colors for easier identification of problems. Personnel are trained to detect such problems using one or more of their five senses and to correct them immediately. Shitsuke Discipline Sustaining Do 5S Activities Daily and continually 4 Origin of Takt Time  German engineers helped Japan build aircrafts in 30s. Takt is a German word for a musical meter. Customer demand dictated the pace of operations on the shop-floor. Takt Time links the customer demand (external) to production resources (internal) Demand is 20 .policies/day. Available time is 400 minutes/day. Compute the takt time.  Takt Time = Available Time per Period Demand per Period Takt Time = Available Time per Period 400 = = 20 minutes 20 Demand per Period There are four sub-processes; Distribution (data gathering/ data entry, Underwriting (risk analysis), Rating (computing the premium), and Policy writing Distribution Underwriting Rating Policy Writing Operator 1 14 mins Total Operator 2 22 mins Operator 3 6 mins. Operator 4 12 mins 54 5 Load Balancing?        An operator can not be overloaded. Apply time studies to lower the time or breakdown the task. Loading each operator close to 100 percent may lead to infinite queue if the workload is highly variable (negative). Keep operators loaded close to 100% to motivate them to find creative ways to reduce their cycle time to takt time (positive). If the operators are underutilized, work expands to fill the time available (negative). takt time goes down when demand increases. Then some operator may become overloaded. Subdivide tasks more finely, to load each operator close takt time. However, that would uniformly underutilize each operator. A better alternative is to have the first two operators loaded with tasks that add up to the takt time, leaving the third under-loaded. 6 Takt Time is a Measure of External Demand  The third operator could help if the others fall behind. S/he could be located at the end of the cell to perform material handling. Distribution Underwriting Rating Policy Writing Distribution Operator 1 14 mins Total Operator 2 22 mins Operator 3 6 mins. Operator 4 12 mins Operator 1 18 mins Total 54 Underwriting Operator 2 18 mins 54 Balance 18 Rating & Policy Writing Distribution Underwriting Rating & Policy Writing Operator 3 18 mins. Operator 1 17 mins Total Operator 2 19 mins Operator 3 18 mins. 54 7 Takt Time is a Measure of External Demand       If each operator is paced to takt time, over production will be automatically limited. Limiting overproduction prevents frequent stops and starts that inhibit a smooth flow. It's best to buffer variation with capacity, not inventory. It is incorrect stating that a machine has a takt time of five minutes. Takt time is a measure of external demand; it has nothing to do with machine capacity. Takt is the time that we have (market oriented) to produce a flow unit, not the time we need (capacity oriented). Enterprise should match its (internal) resources to meet the (external) customer demand. Takt time applies better to a flow shop, may not be very relevant in job shop, but still useful to determine the number of operators. Takt time could be reevaluated if the demand exceeds the set production rate for 5 consecutive days (Run Test). Distinguish between noise and real trends.   If we change it too frequently  Chaos If it is not flexible, and we cannot change it  Missed opportunities, Inventory buildup 8 Internal vs. External Takt Time Takt Time allows to smooth external demand variation Demand Production 130 120 110 100 90 80 0 5 10 15 20 25 30 Day 9 Average Labor Content Average labor content is the minimum number of workers to sustain operations. Demand percentages for Hungama, Inc., Tasks RUNS RAPS RAINS RERUNS Jobs/Day 4 12 6 18 % of Total 10% 30% 15% 45% Operation times for Hungama, Inc. in (Minutes) RUNS RAPS RAINS RERUNS Distribution 58 50 44 28 Underwriting 43 40 23 19 Rating 72 65 68 75 Policy writing 67 0 55 50 240 155 190 172 Total Labor Available time per day is 400 mins. Available Time 400 Takt Time = = = 10 minutes Demand is 40 per day. Demand 40 10 Average Labor Content k Average Labor Content = ∑ (% of Model i )(Total labor content for Model i ) i =1 Average labor content = 0.10 (240) + 0.30 (155) + 0.15 (190) + 0.45(172) = 176.4 min Average Labor Content Minimum Manpower Reqirement = Takt Time 176.4 Minimum Manpower Reqirement = = 17.6 = 18 10 ALC for Distribution = (0.10 x 58) + (0.30 x 50) + (0.15 x 44) + (0.45 x 28) = 40 minutes. Since Takt time is 10 min, the minimum number of operators allocated to Distribution ALC TT MLR task will be 4. (40/10 = 4) Distribution Underwriting Rating Policy writing Total 40 28.3 70.7 37.5 176 10 10 10 10 10 4 3 7 4 18 11 Practice: Pleasant Valley Health Clinic The Pleasant Valley Health Clinic treats patients with respiratory illnesses. It classifies patients according to four different types of respiratory problems (commonly referred to as Diagnostic Related Groups, or DRGs): Bronchiolitis (BRO), Pneumonia (PNE), Pharyngitis (PHA) and Sinusitis (SIN). The average number of patients treated per day are summarized below. The clinic works two shifts, from 7:00 am to 3 pm and from 3 pm to 11 pm. During a shift, the staff are provided a half hour lunch break and two rest breaks of 15 minutes each. Patients / Day Fraction of total BRO 15 PNE 24 PHA 25 SIN 36 0.15 0.24 0.25 0.36 Each patient typically requires 4 process steps: Check-In (includes weigh-in, blood pressure check, etc.), Evaluation (by a physician), Testing (X-Rays, administering of respiratory instruments like Pulse Oximeters, etc.), and Assessment (diagnosis and future scheduling). The average task time for each process (in minutes) is given below: 12 Pleasant Valley Health Clinic: Task Durations Time (mininutes) Check-In Evaluation Testing Assessment Work Content BRO 30 20 45 15 110 PNE 30 15 40 15 100 PHA 30 10 15 10 65 SIN 30 12 15 10 67 Aggregate 30 13.42 25.5 11.95 80.87 Tasks 1, 3, and 4 are typically handled by RNs. Task 2 is handled by a physician. For simplicity, we assume that the arrival rates of patients are constant through both shifts. Average Work Content = 80.87 minutes. Daily demand; BRO: 15, PNE: 24, PHA: 25, SIN: 36. A total of 100. Time available in a day: 2 shift @ 8 hrs less 0.5 (lunch) - 0.5 (2 breaks) = 14 hours = 840 minutes Takt time = Time Available / Daily Demand = 840/100 = 8.40 minutes / request Min. # of RNs required = 80.87/8.4 = 9.627  10 13 Takt Time for Pleasant Valley Health Clinic Average Work Content = 80.87 minutes. Daily demand; BRO: 15, PNE: 24, PHA: 25, SIN: 36. A total of 100. Time available in a day: 2 shift @ 8 hrs less 0.5 (lunch) - 0.5 (2 breaks) = 14 hours = 840 minutes Takt time = Time Available / Daily Demand = 840/100 = 8.40 minutes/request Min. # of RNs required = 80.87/8.4 = 9.627  10 14 Mixed Model Sequence for Volpens Model Monthly demand Blue Pen 24 Red Pen 14 Yellow Pen 10 Blue Shell 6 Red Shell 8 Yellow Shell 6 68 Total Ratio to Total 0.352941176 0.205882353 0.147058824 0.088235294 0.117647059 0.088235294 0.088235294 Min # in the sequence 4.00 2.33 1.67 1.00 1.33 1.00 11.33333333 3 Times 12 7 5 3 4 3 34 Smallest possible sequence length = 1/0.09 = 11.11 Choose a 11 unit sequence; adjust every two cycles. Note: A mixed model sequence is used to intentionally vary work content and component requirements. 15 Mixed Model Sequence For Volpens Seq. # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Model Desc. Blue Pen Red Pen Blue Pen Red Shell Blue Pen Yellow Pen Blue Shell Red Pen Yellow Pen Blue Pen Yellow Shell Blue Pen Red Pen Blue Pen Red Shell Blue Pen Red Pen Seq. # 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Model Desc. Blue Shell Red Pen Yellow Pen Blue Pen Yellow Shell Blue Pen Red Pen Blue Pen Red Shell Blue Pen Yellow Pen Blue Shell Red Pen Yellow Pen Blue Pen Yellow Shell Red Shell 16 One Piece Flow Process 1 60 units Process 2 60 units Process 4 Process 3 60 units 60 units Reduce lead time by reducing WIP Move products between workstations Average lead time = WIP/Throughput What is the average lead time for the system above, if throughput is 100/week? 2.4 weeks 17 One Piece Flow What is the average lead time for this system? Process 1 1 unit     Process 4 Process 2 1 unit Process 3 1 unit 1 unit One piece could mean a pallet, a box etc. Is not practical in every situation One-piece flow may require relocation of the people/equipment. A process layout (grouping operations by function) must be replaced by a product layout (arranging operations in the order of flow.) 18 Batch Process For Volpens, Ltd. Cap Assy Pen Assy WIP WIP Label Press Production Scheduler Raw Material Flow Materials Information Flow Peel& Stick Test, Pack & Ship Inspect Finished Goods 19 Takt Time for Volpens, Ltd. Monthly Demand = 68 No. of days per month = 16 Daily Demand = Avail. Time/Day = Takt Time = 20 Manpower requirements for Volpens Ltd.  Pessimistic times for the current activities  Cap Assembly: 25 seconds  Pen Assembly: 17 seconds for pens, 5 seconds for shells  Label Making: 28 seconds  Peel & Stick: 16 seconds  Test,Pack,Ship: 15 seconds 21 Manpower requirements for Volpens Ltd.  Note that activities 3, 4, 5 are not performed for shells. Also, activity 2 is minimal for shells. The only activity done, for all items, is cap assembly.  The time for activity 3 includes an allowance for changing coils; excluding this allowance, a pessimistic time will be 23 seconds. Use this number for your calculations. 22 Minimum Manpower Required for Volpens, Ltd. Monthly Demand for Pens = 48 Monthly Demand for Shells = 20 Total Monthly Demand = 68 Percentage Demand for Pens = Percentage Demand for Shells = 23 Minimum Manpower Required for Volpens, Ltd. Activity Pens ( Cap Assembly Pen Assembly Label Making Peel & Stick Test,Pack,Ship %) Shells ( %) Ave.Time/Unit _____________ Total Labor Content per Unit: Takt Time per Unit: Minimum Manpower Required = 24