Subject: Techniques for Operational Efficiency Chapter: 1 – Systematic Problem Solving a nd Quality Check Tools Example of Problem in a company Ideal Situation * Customers are satisfied * Workflow is free of bottlenecks * Resources are utilized for maximum profits * Labor problems are minimized * Breakdown losses are reduced
Real Situation * High-level of rejections and cancellations due to faulty products * Over-use of raw material & scrap production due to faulty machinery * Labor force is dissatisfied and overworked
Factors responsible for different problems: Factors Problems Mate Ma teri rial al & Equ Equip ipme ment nt Over Over sup suppl ply y of raw raw mat mater eria ials ls and and lar large ge inv inven ento tory ry of of subsubstandard goods Machine Frequent breakdown, repairing and high maintenance costs Method Instructions for operating techniques missing, absence of inspection during process, and use of wrong techniques Labor Frequent strikes, careless attitude and over confidence Types of problems: Types Zero Problem
Examples of problems As a floor manager in boiler area of a pesticide firm, you have to solve the problem of recurring accidents The The produ roduc ction tion of spor sports ts goo oods ds in your your firm firm has been een augmented by 55% in order to meet the demand created by National Athletic Field You have have to solv olve the the probl roblem em of hig high inv inven enttory ory so so th that you can minimize inventory costs incurred by your firm
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Quality Check Tools
7 in number
1. Check-Sh Check-Sheets: eets: Used Used to gather gather and interp interpret ret data in in form of a list list 2. Graphs: Graphs: Used to represent represent accurat accurate e status status (Line / Bar Bar / Pie) 3. Histogram: Used to represent graphically the variations in a process (e.g. time) 4. Scatter Scatter diagrams: diagrams: Used to represen representt correlation correlation between between two variables variables (e.g. (e.g. frequent accidents and tired workforce) 5. Stratification: Used to group data to identify influencing factor (e.g. stratification of absent labor in different groups like sick leave, dissatisfied worker, family issues, weather conditions, etc) <<>> 6. Ishikawa Ishikawa / Fishbone Fishbone Diagram Diagram:: Used to represent represent cause cause of a problem problem (root (root cause analysis). Also called cause-and-effect diagram 7. Pareto’s Pareto’s Analysi Analysis: s: Used to to find most most vital vital cause of of a problem problem
Exercise 1.1: Which tool is used to resolve which problem? Problem The functioning of bottling equipment and canning equipment has to be monitored The most important cause of accidents in the factory has to be determined Data on the level of water table has to be depicted with respect to different factors The relationship between wages and productivity of labors in the factory has to be determined The variation in flavor of canned juices of different batches during the year has to be monitored
Tool Check-sheets Pareto’s Analysis Stratification Scatter Diagram Histogram
Exercise 1.2: Possible causes of spoiled juices
To improve operational efficiency of a process / unit, the problem has to be found by defining gap between real situation and ideal situation.
Chapter: 2 – Managing Resources Quality Circle (QC) Advantages of implementing QC Enables staff to participate in key decisions (Staff feels empowered and the • feeling of “us-versus-them” is removed effectively Enables streamlining of processes by implementing the solutions proposed in Quality Circles •
5-S technique for material / resource management: Seiri: Generates space, prevents unnecessary buying, • clarifies items in stock, reduces unnecessary maintenance of useless items and creates storage space Seiton: Allows the materials to be retrieved easily, • minimizes time taken to search and prevents unnecessary purchase Seiso: Helps identify problem areas such as leaks and cracks, improves • product quality, induces pride in employees and confidence in customers Seiketsu: Minimizes errors, improves quality through zero defect, inculcates • sense of pride among staff and ensures safe working conditions Shitsuke: Sustenance of well-managed / well-organized work place, regular • trainings to staff to maintain Standard Operating Procedures (SOP) Advantages of 5-S technique for material / resource management: Focus on effective workplace management Standardized work procedures Simplification of work processes Reduction of clutter and non-essential Activities Improvement in Quality, Efficiency and safety • • • • •
Exercise 2.1: Which 5-S technique is used by Pamela in which step? Problem Tool Pamela sorted all her clothes and other items, discarded Seiri unnecessary items and returned the borrowed items Pamela Put the dirty clothes in laundry hamper. She then Seiton categorized toys and books and decided where to place them Pamela arranged all her clothes in proper order. The top drawer Seiso was reserved for school wear, middle one for home wear, and the next for socks and handkerchiefs Pamela is so excited by how her room looks that she now Seiketsu regularly cleans her room, puts dirty clothes in laundry and arranges books and toys Pamela’s mom is very pleased with the way Pamela keeps her Shitsuke room now. Although she doesn’t supervise Pamela’s daily cleaning, however, she often shows her how to organize items in a room
Chapter: 3 – Statistical Process Control Statistical Process Control (SPC) – The use of statistical analysis to improve quality by reducing unwanted variations in industrial and management processes and process capabilities. Types of variations: Variations due to Random Cause – e.g., someone bumps your elbow when you are singing Variations due to Assignable Cause – e.g., all documents in your computer are changed into bar codes due to a virus attack •
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Random Cause Difficult to identify Large in number Economically expensive to rectify since they need fundamental process changes Insignificant variation per cause, and is considered inherent part of process Examples: Poor lightening, bad workbench conditions, bad maintenance, poor machine conditions, fluctuations, etc.
Assignable Cause Identified in operating conditions and can be statistically controlled Few in number Economically inexpensive Large amount of variation per cause Examples: faulty jigs and fixtures, poorly trained staff, defective raw material, etc
A process is capable (or under statistical control) when Assignable Causes have been identified and removed. SPC is used to: Decide exactly how much variation is allowed in a process Ensuring defect-free manufacturing / processing by reducing variations Measure the consistency of processes Keep processes under control • • • •
Tools for SPC: Control Charts: Used to graphically represent quantitative measurements of a process and minimize variations Two types of control charts: Control charts by variables Control charts by attributes • •
Interpreting Charts: Used to graphically control the variation in the process
In these charts there is a Center Line (CL) which represents the exact measurement of a variable required in a process. There are two more lines representing Upper Control Limit (UCL) and Lower control Limit (LCL). If a particular variation falls beyond the area between UCL and LCL, it is considered a major variation. The control lines are set at a distance of three-sigma above (UCL) and three-sigma below (LCL) the center line.
Out-of-Control Processes: A continuous upward pattern indicates that the process is deteriorating with time. A common reason may be wear and tear of machines.
A cyclic trend (peaks and valleys) indicate that the process faced variations due to random causes such as worker fatigue, shift change, etc.
Peaks and valleys outside the control limits indicate the poorly trained workers, defective materials and frequent readjustments of the machines
Another graph which is an outcome of wrong samples being picked up rather than wrong processes followed. Apart from improper sampling, biased measurement may also cause such a type of graph
Exercise 3.1: What can be concluded from appearance of the graph?
This shows that the operators of the unit are not trained properly Zone Tests: Zone tests are used to enhance the ability of the control charts to detect / study small shifts in the process. The dividing line of each zone is exactly one third the distance between center line and the UCL or LCL.
Nine points in Zone C or beyond: This pattern indicates that the process average has changed. It is a useful test to alert the quality control engineer to potential shifts in the process
Two out of three points in a row in Zone A or beyond: This pattern provides early warning of a process shift
[False-positive error rate = 2%] Four out of five points in a row in Zone B or beyond: This is also an early warning indicator for a potential process shift
[False-positive error rate = 2%]
15 points in a row in Zone C: A small variability than is expected based on the Control Limit points in the graph
Eight points in a row in Zone A or B or beyond in either side of the centerline: This test indicates that different samples are affected by different factors, resulting in bimodal distribution of modes.
A process which is in statistical control need not necessarily produce product or services that meet the design specification of a product or service. To ensure that the process is meeting design specifications, we need to measure the process capability by calculating two indices of process capability – CP and CPK CP calculates the capability of a process by measuring overall process performance considering both positive and negative deviations. CP = (USL – LSL) / 6 sigma Typical features of CP are: These have no upper limits This doesn’t take into account any non-centering of a process Non-centering reduces margin of safety • • •
CPK calculates the capability of a process by measuring clustering effect on the Upper and Lower specification limits. CPK = MIN [USL – x.bar / 3 sigma, (x.bar – LSL) / 3 sigma]
Exercise 3.2: Estimating Process Capability
Step 1: What is the CP of the machine? USL = 25 + 0.02 = 25.02 LSL = 25 – 0.02 = 24.98 Sigma = ? CP = (USL – LSL)/6 sigma = (25.02 – 24.98) / (6 * 0.01973) = 0.337 Step 2: What is the CPK of the machine? CPK = MIN [USL – x.bar / 3 sigma, (x.bar – LSL) / 3 sigma] = MIN [(25.02 – 25.01) / (3 * 0.01973), (25.01 – 24.98) / (3 * 0.01973)] = MIN [0.1689, 0.5068] = 0.1689 Step 3: Is the process capable of meeting specifications? (Yes / No) No, because process variation exceeds specification limits when CP < 1 Step 4: Is the process correctly centered? (Yes / No) No, because CP < 1
Variations are not only unproductive but also expensive. For an operation to be a success it is very important to eliminate or at least minimize the variations
Chapter: 4 – Total Productive Maintenance Total Productive Maintenance (TPM) is a continuous improvement strategy that involves an innovative approach to maintenance that improves and maximizes equipment effectiveness. Advantages of TPM: TPM works with full support of management and cascades down to lowest level TPM shows quick results but is not a quick one-time solution for all problems. TPM is proactive, as all employees are trained to anticipate problems that may arise, instead of reporting only when there is a breakdown TPM works well in small group of employees and allows greater participation / involvement, improved morale and development of those involved TPM increases equipment availability and quality and at the same time decreases production costs and industrial accidents. •
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Pillars of Total Productive Maintenance: Jishu-Hozen: Begin by cleaning, inspecting, lubricating a nd performing corrective action on the machinery (daily chores) [Adv: System fell in place] Kobestu-Kaizen: Used to handle chronic problems, done by finding route cause of the problem, suggest and implement the most effective solution, test it and display the results. [Adv: Losses dealing with breakdown, speed, defects, setup, etc were removed] Planned Maintenance: Corrective, preventive and productive maintenance involved. Replacement of unsatisfactory equipments, improvements in design weaknesses were made to achieve zero defects and maximize MTBF (Meantime between failures) Quality Maintenance: Checklists were used to maintain quality and train workers on TPM Initial Equipment Control: Education & Training: Office TPM: TPM was used not just to maintain machines and upgrade skills of workers, but also for improving office administration. The TPM Standards for office include: Uncluttered, paperless work desk • Automated office space, where files are easily available Short and to the point meetings Optimum inventory available Minimal and non-repetitive manual work Safety, Hygiene & Environmental Control: TPM Standards for zero accidents, zero diseases and zero pollution include: Preparation of safety manual Audits on safety and hygienic conditions Safety work permit system and upgrading the pollution control system Safety award scheme Campaign on awareness of safety and environmental issues Regular monitoring of accidents Environmental review Eliminating spills and leakages Tree plantation • • • •
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OPE = Overall Plant Efficiency (e.g., gone up by 1.5 times) OEE = Overall Equipment Effectiveness (e.g., gone up by 90%)
Exercise 4.1:
Steps for implementing TPM: 1. Announcement by Upper Management about implementation of TPM in the organization 2. Initial Education and propaganda for TPM 3. Setting up TPM Committees for TPM Pillars 4. Establishing basic policy and target and master plan for TPM Implementation 5. TPM kick-off events 6. Implementing all TPM pillar activities 7. Total application of TPM, monitoring implementation on continuous basis and raising its level. Exercise 4.2:
