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About Mathi

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  • Birthday 07/22/1978

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    Mathiazhagan Kaliyaperumal
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  1. Y= f(x), from this mathematical expressions, we could understand the output of Y depends on functions and the input factors. In six sigma context, Y is the desired outcome or results that you need from a process ,X- represents the inputs, I.e factors that need to create a desired outcome (Y) f is the function , the way of process carried out to transform all Xs into the outcome. Say example; Y = Instant Coffee X = (Hot water, instant coffee powder, sugar, Milk, utensils, Man) f = Process of coffee making Therefore, Instant coffee Y = f (Hot water, Instant coffee powder, Sugar, Milk, Man, Utensils) To have a good coffee, we must ensure that the all Xs are in prescribed condition If the input Xs are not meeting the requirements, obviously we shouldn’t get a good coffee. However, I don’t think all Xs inputs are equal importance, the vital few may have a stronger influence should have understood and manage them correctly to have a consistent and predictable results from the process Simply, control the inputs to control the output. Though the process carried out in controlled condition, there will be an uncertainty in the process. So we must consider the error factors in the process, and we have to make sure how well our controlled actions produce the desired or expected results. The other way round, though we provide all Xs as per the requirements, the person who makes the coffee is not knowing how to prepare the instant coffee, we won’t get a coffee as we desired. Hence, hand-to-hand, the process and input variables have to be controlled to have a desired output, otherwise it will be a conventional output, but not as expected or as desired The underlying message is, don't correct your process until you correct your input materials and don’t correct your input materials until you correct your process
  2. Y = f(x) formula to describe the relationships between the CTQs and the process variables that impact CTQs. The following tools can be employed during the various phases of six sigma process Phase Process activities / Tools Output Measure Understand the process Process Map- as is QFD Histogram Run Charts Process inputs X variables and outputs Y Variables Analyze Identify the sources of variation Process Map Brainstorming Fish bone diagram FMEA SPC on X’s and Y’s MSA on X’s Why Why Analysis Identified sources of variation that impact the output(y) Validate causes Hypotheses testing Multi -vari analysis Correlation and regression analysis Chi-square test 1-t test 2-t test Paired T test Potential X’s critical to the process output (Y) Improve Determine the variable relationship y=f(x) DOE Regression analysis ANOVA Simulation Scatter plots Relationships between input x and output y Establish process operating specifications New process capability Cost / benefit analysis Optimum process tolerances
  3. This answer to the question is considered the manufacturing process environment, variable and normally distributed data No two products or characteristics are alike, because any process contains many sources of variability. Differences are always presents in the products or characteristics; What is process? A process is a set of activities that converts an input into desired output. A set of inputs are Men, Materials, Machines, Methods, Measurements and Environment. Though there is a control in input parameters (4M + 1E), the actual performance of the process can be measured through the process output. When we measure the output of the process and we can clearly see that there is a part to part variation. So variability is an inherent properties of every process and we accept the variability within specification. Some sources of variation in the process cause short-term, piece to piece variations e.g backlash in the machine, Spindle run out and its fixturing or the accuracy of journal entry. The other sources of variation cause changes in the output only over a period of time. e.g tool wear, temperature increases in the process. The measured individual values form a pattern that can be described as a distribution. The distribution shall reveal the process characteristics such as; · Location ( Central tendency) · Spread ( Variation) · Shape However, process control aims to maintain the location to a target value with minimal variability A goal of a process control system is to make predictions about the current and future state of the process. A process said to be capable when the output of the process meets customer / drawing specifications. And, a process said to be stable / statistical control when the output of the process has less variations and produces the predictable outputs over a period of time within control limits Causes of Stable Process Variation: In any production process, regardless of how well its designed or carefully maintained it is, a certain amount of variation will be existed in the process. When inherent and natural causes present in the process, then it often called the process is in stable or control. This causes called as common causes or chance causes. Some other kind of variations may occasionally be present in the output of the process and it changes the process to “out of control”. For examples, improperly adjusted toolings, operator errors or defective input material etc., such variability is generally large when compared to the chance causes, and it usually an unacceptable level of process output. This causes often called “assignable causes or special causes” A process that is operating in the presence of assignable causes is said to be an “out of control process” Let us take µ0 and s0 is a stable process mean and standard Deviation, time at t1 an assignable causes occur, the process mean will shift to µ1> µ0. At time t2 another assignable cause occurs, resulting in µ = µ0, the process standard deviation will shift to s1>s0. When other assignable causes occur, the process mean and sigma will be in out of control limits. Assignable causes which shifts the process mean and /or increase the process standard deviation.A Control Chart is a tool for monitoring process stability or process control relatively for longer periods of time. Assuming, there is no probability error (type I and type II) of the control chart, eventually the right control chart deployed to study the variability and stability of the process, the following are the few causes to make the process unstable but not limited to; · Control limit have been miscalculated or misplotted · The measurement system has changed( e.g different appraiser or instrument) · The measurement system lacks appropriate discrimination · Mixed lot of input materials · Tool change / Fixture change / Set up · Wrong loading · Voltage fluctuations · Over control or Tampering ( take action when action is not necessary for the process) The change events to be recorded in the control charts and if any outlier due to this changes and it can be omitted, provided other data points are stable. To interpret the subgroup ranges or subgroup averages, the R Chart to be analyzed first because it shows piece to piece variability. For any process, the process must first be brought into stable (statistical control) by detecting and acting upon special causes of variation. Then its performance is predictable, Process capability can be assessed. In order to test the special causes, I-MR chart to be made and following interpretations will help us understand the presence of special causes; Test 1 : One point more than 3s from the center line ( mean) Test 2 : Nine points in a row on the same side of the center line Test 3 : Six points in a row, all ascending or descending Test 4 : 14 points in a row, alternating up and down Test 5 : Two out of three points more than 2s from the center line ( same side) Test 6 : Four out of five points more than 1s of center line ( same side) Test 7 : 15 points in a row within 1s of center line ( either side) Test 8 : Eight points in row more than 1s from center line ( either side) Causes of incapable Process: Process capability is often termed “output of the process meets customer specification”. When discussing process capability, two contrasting concepts to be considered; · Process Capability · Process Performance Cp, Cpk, Pp, Ppk are the indices which used to measure the process capability in short term and long term respectively The output of a stable process can be described by its statistical distribution. The statistics are estimates of distribution location (center) and spread relative to the customer requirements. A shift in process location, an increase in process spread or combination of these factors may produce the parts outside the specification limits. Process capability study is an activity to evaluate the processes and machines are capable to produce the parts as per the customer specification. The following are the possible causes could make the process incapable not limited to ; 1. Special cause variations in the process 2. Limitation of machines / process 3. Part to part variation and center shift (Spread & Location) 4. Poor Fixture and tool design 5. Selection of measuring instrument ( 1/10th of tolerance) 6. Design weakness ( selection of tolerance) A perfect state of process control is not possible in a production process. The aim of process control is not a perfection, but a reasonable and economical state of control.
  4. The following Japanese words related to “handling of manpower” in production process according to the organizational requirements; Shojinka: This is the Japanese word that originated from the lean manufacturing principles of Toyota. When we translate from Japanese to English, it gives direct meaning of “Various people”, shortly it can be “Vary people". i,e Flexible manpower lines maintain productivity with fluctuating demand. Shoninka: It means “Manpower saving”, by providing machines / equipment in order to free one or two operators: Shoryokuka: It means “ labour savings” partial removal or combining two operations by automation to support the process Productivity = outputs/ inputs i.e it is a measure of efficiency of production line. More often the Shojinka is defined as having to main categories; first, the workers are multi skilled and they can perform in multiple workstations at a time in a production line. The second is, the line should be designed in a way to accommodate or vary people based on the fluctuating customer demand. In simple words; Shojinka can be defined as “ability of a production line can be balanced when the production volume goes up or down" Demand Vs Supply: Shojinka techniques developed based on the Demand Vs Supply and no excess production as they considered as an inventory by deploying flexible machines and man powers. Capacity planning is the process of determining the production capacity needed by an organization to meet changing demands for its products. The capacity is normally developed based on takt time: Takt time: Available production hours per day / customer demand per day (Generally it is calculated on annual basis with full speed of line capacity). When the demand fluctuates, the organizations have some broad questions; · How to absorb the fluctuations in demand that will occur over next 12 months? · To what extent should inventory be used for this purpose · Can demand fluctuations be met by varying size of workforce (Shojinka?) · Why not absorb the fluctuations by changing activity rates and varying work hours( overtime) · Why not outsource to maintain a stable work force and let suppliers change activity rates to absorb demand fluctuations? · Will the organization lose orders if doesn’t meet all demands? Should the organization adopt this policy? Each of these choices determine the moves of the organizations. The organizations will adopt basically three strategies of planning to managing supply · Chase strategy: - when demand fluctuates, the organizations should adjust the capacity to match the demand as close as possible. E.g seasonal business demand like sale of apparels during festivals · Level strategy: - a firm maintain constant capacity over a period of time, irrespective of fluctuations in demand; e.g When more investment or skilled labour required, this strategy will apply · Mixed Strategy: Individual firms devise infinite combinations of the above strategies based on the situation. Shojinka is suitable to apply when organization adopts chase strategy. Flexible manpower line: The production line is designed in such way to meet the changing production requirements: Before designing of any production capacity, the following parameters to be considered; Takt time : Net production time / Customer demand Cycle time : Net production time / No.of Units produced No. of stations / Operators: Cycle time ( Work content) /Takt time In the competitive market, the organization has to prepare some strategy to prevent the business loss and shojinka is a solution for the flexible manufacturing; Calculating Manpower / machines: The following formula will help us to determine the manpower / machine requirements to meet the demand; Overall cycletime / Takt time = Manpower / machines Cycle time is the sum of the processing time to complete one unit of assembly Examples: Case: 1 Overall cycle time: 240 secs Takt time: 80 secs No of manpower = 3 So, we can use the manpower formula and assign no. of operators based on the demand Case: 2 When demand goes down, we can remove the manpower and he can be used in other machines/ assembly lines; Overall cycle time : 240 secs Takt time : 120 secs No of manpower : 2 When the demand low, we reduce 30% manpower and two manpower will produce the output to meet the low demand. Shojinka demands employee training, multiskilling to manage / operate different machines / practical standard operating procedure in place for flexible manpower line. Advantages of Flexible manpower line: · Avoid overproduction · Better usage of capacity · Smooth material movement · Kaizen culture Disadvantages of Flexible manpower line: · Design of production process is complicated as the forecast are not realistic · Require high skilled operator · Not suitable for small, medium size industries Conclusion in my purview: At the present time, most of the industries look for outsourcing when the demand peaked up. The peak demand may not be long-lasting, as the demand lows they withdrawn the order from the supplier. This will affect the supplier relationship in long term. However, organization should design flexible manpower line to the peak volume and if the demand is lower, the assigned manpower can be used in another production area, provided if they are competent. But practically it is complex in real time production situation. Industries, normally extend their work hours to meet the peak demand and cut off the extra hours if the demand goes down. If the forecast is realistic, the cell design is flexible to manpower, Shojinka is a best tool to apply.
  5. Focused Area Lean Wastes Closed MITT Relationship Business Processes & Manufacturing Processes - C-Complexity- It describes the business processes and its interaction between processes. The process should be as simple as possible with minimum lead time to complete the processes. Complicated processes consume more times and they need highly skilled employees to perform the processes. It is a kind of managerial process waste as well as manufacturing process. Ex. CAPEX Approval. It is a tedious process and the approval takes in every desk more than one month, this entire complex process may halt the entire project and lead to project delay This is the unique waste addressed by Boeing, however this can be well addressed in our 7 waste reduction methodology under "Exessive motion". By designing optimized process will avoid motion and complexity of process. People Motion: Operators/Processes motion waste is frequently caused by a badly organised work processes, unsuitable equipment and poor working conditions.Ex. Taking any items from left side and move to right side for any processes, instead keeping the item at right side. It is also consider 8th waste of under utilized talent / skills L -Labour - Reduce peoples walking / motion from one place to another place for collecting raw material, tools, and other accessories for manufacturing process. Need to be deployed right people according to the nature of job and people's skills to perform the task to meet the organizational objectives/ goals. Both concepts are addressing this requirements as a waste and that has to be reduced Production Over Production: Product what customer wants or willing to take. Produce something and kept as an inventory is an one of the waste. The inventory cost will go up when they kept as a finished product , because the cost of production completely loaded on the finished product O-Over production: CLOSED MITT also demand to produce the parts as required. Producing parts sooner, faster or excess quantity will be considered as a waste In practical, when there is no pull system from customer, we need produce parts and kept ready for customer order. This is the situation where more lead time to procure the parts from supplier either fom domestic or overseas. For a batch production company this waste can not be eiminated. Space utilization S-Space: Using space is a cost to the company. If the floor space can not be utlized effectevely, the overheads will go up. This is well addressed in CLOSED MITT and missing in traditional 7 wastes Most of the companies are, presently not focusing on effective usage of floor space. A proper layout system help to design and use the floor effetively Energy conservation It is not mentioned in traditional seven wastes, but indirectly it has addressed through overproduction, over processing and transportation E-Energy : This is a waste does not get neary any attention like running machine idly, unnecessary lightings, fans, leaks from air connectors etc This is adding up company overheads and affect the bottom line of the company, CLOSED MITT addressed this waste in their process Rejection prevention Defects : In manufacturing terms, defects occur when the product has something wrong with it, such as not meeting the drawing requirements. Any manufacturing company, defect prevetion is the paramount in their operational control processes D-Defects: Do it right the first time. Rework and rejection are adding their cost to the company as a watse Both system are well addressed as this is a one of the important wastes Material consumption It is directly link to the "defects"waste M- Materials: It is a unique waste identified in Boeing waste reduction process. It can be a replacement of rejected parts and exessive material used to complete a production process.Look for effective way of raw materials usage Material storage Inventory: Inventory is a waste in form of storing excess raw material, WIP and finished products. All this costing up to the company by means of inventory carrying cost, storage space and handling / preservation cost Idle Materials: It is a another name of inventory. It is also saying another wastes like Non moving stock, Slow moving stock, idle material for next processess. Inventory is addressed well in both system Time management Waiting: Waiting involves que of manpower, machines for next processes, like waiting at airport for an hour to get board on. Waiting also a waste at customer point of view to receive the parts from the seller Time: Time is another non-renewable resource, but it is vague. Wasted manhours / machine hours can be considered as a waste appropriately. But not sure time can be considered as waste Material movement reduction Transportation: Unnecessary movement of material and people between processes. This can be considered as a waste. Transportation: Unnecessary movement of material and people between processes. This can be considered as a waste. Eg, Forklift moving one place to another place is time and energy consuming process in manufacturing process Process Design Overprocessing: Design the optimum process to achieve the customer requirements at minimum cost. Say example surface roughness is 0.8 Ra, choose the best process to achieve it, rather than designing conventional process of grinding. It costs up the production cost When the process is being designed as simple and effective, we may address the energy and complexity in closed MITT 7 wastes and closed MITT.xlsx
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