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  • Background

    Estimated to be worth around 29 billion dollars per an-num, the eyeglasses lens market comprises three main segments: single vision lenses (correct eyesight for either shortsightedness or long-sightedness), bifocals and mul-tifocals. A staggering billion lenses are sold globally every year. Statistics show that about 4 billion people world-wide require vision correction, while only about 1.6 billion of them already own a pair of glasses, indicating a high growth potential.

    The market share of multifocals is on the rise, due mainly to the rise in the standard of living, greater aesthetic awareness and the increase in the older population world-wide. The continual development of the market is driven mainly by the increase in the population over 45 years of age, most of whom are characterized by presbyopia, a natural condition in which the eyesight of the elderly gradually weakens.

    In the competitive world of spectacles, the delivery lead time to the optometrist stores is a critical parameter in the customers satisfaction both for the optometrist and the patients themselves. Nowadays the average lead time for a pair of glasses is between 4 and 8 days (the manufac-ture lead time varies by lens type and complexity). Clearly, a company which will be able to consistently deliver lenses to the optometrist store within 2 days or less will achieve a considerable competitive advantage.

    So how can Lean help us shorten the lead time?

    The Lean approach is a way of working which focuses all resources on performing the minimum of those specific value-added tasks which achieve what the customers want (value), when they want it and at the cost and the quality they expect.

    Over the last 30 years, thousands of companies worldwide have been assimilating the Lean method. Implementa-tion of Lean is extremely effective toward shortening lead times, since it focuses on activities which yield value to the customer and significantly reduce those factors which delay the material flow, such as in process inventory or overproduction.

    However, Tefens research done recently, shows that merely 40% of the Lean transformations around the world truly succeed in achieving a Lean culture of continuous improvement. The main reason for that is insufficient emphasis on the corporate culture and on building intra-organizational capability to lead processes of continuous improvement. In other words, these projects focus mostly on Lean tools and methodologies implementation and give very little attention to building employees skills and training and for enhancing change management processes to achieve employees buy-in.

    Copyright 2013 Tefen Management Consulting. All rights reserved.

    A clearer focus on value enhancement

    Lean 360 in the Eyeglasses Lens Sector By Rotem Greener and Lior Ben Ari

  • Copyright 2013 Tefen Management Consulting. All rights reserved.

    To close this gap, Tefen has developed its own lean method a holistic approach known as Lean 360.

    This approach is based on 4 work streams all of which are handled in parallel:

    Tools and methodologies:1. Assimilation of Lean 6 Sigma tools and methodolo- gies 2. Optimization of the organizations resources 3. Reduction of quality and waste losses4. Improvement of material and information flow5. Improvement of inventory planning and management processes

    Culture Re-Design & Capabilities Building1. Management of change and formation of corporate culture together with executive staff and the entire workforce2. Creation of a common language and building capabili- ties throughout the workforce while assimilating a culture of excellence and continuous improvement3. Provision of tools and knowledge, training of managers, change leaders and specialist leaders

    Management infrastructure 1. Assimilation of performance management routines and cross-organizational communication processes2. Setting up a system for ongoing performance measure- ment and evaluation

    Value Stream Management1. Adaptation of the organizational structure to the opera- tional needs and processes 2. Focus on building an effective operational synergy among all units within the value chain

    The Lean 360 approach formed the basis for the following case study, aimed at dramatically improving the customer delivery lead times.

    Case study

    One of the leading companies in the lens market fore-casted a substantial growth in the worldwide demand, requiring preparations for a considerable growth in output. The company also wanted to position itself as a top level service provider, while retaining a high standard of product quality.

    Tefen was requested to assimilate the Lean 360 method in the companys labs worldwide, in an effort to improve the product quality, service level, and output, while also enhancing employee skills and developing a continuous improvement process for the various processes within the company.

    The project runtime was about six months and covered three stages:

    Diagnostics identification of the status quo and potential opportunities

    Planning analysis of the findings and construction of a plan for assimilation of improvements

    Implementation in which quick wins were assimilated first

    Tools &Methodologies

    Culture Re-Design& Capabilities


    Value Stream



    Phase 1 Diagnostics

    Organizational Survey Observations Data collection Interviews Finding analysis Value Stream Mapping Continuous flow measurement Maintenance analysis

    Phase 2 Planning

    Design: KPI Management routines Visual management tools Future continuous flow Lean- 6 sigma training Change management plan Change agents recruiting TPM autonomous

    maintenance design

    Phase 3 Quick Wins

    WIP reduction Line balancing Standard work Communicating lines performances Layout improvements OEE measuring Implementation:

    Continuous flow Visual management TPM

  • Copyright 2013 Tefen Management Consulting. All rights reserved.

    DiagnosticsThis stage aimed to identify improvement opportunities in the four Lean 360 work streams. To gain an in-depth understanding of the company conduct and to achieve maximum cooperation, about 20 employees were divided into work groups with a detailed work plan down to the daily level. These work groups included staff and manag-ers from all departments, who underwent training in Lean-6 Sigma methodologies. The training was delivered at this early stage in order to build up their ability to lead similar processes, end-to-end, in the future.

    Results: gaps in flow of materials and information; weak performance management

    A wide-ranging attitude survey, which was distributed to all employees, showed that staff felt the widest gaps existed in the flow of material and information, performance man-agement and continuous improvement.

    These results were supported by interviews, observations and measurements, showing a 20% ratio between the

    process time and the lead time and a high variance in the lead time.

    Additional findings1. A high level of in-process inventory, increasing the lead time 2. Imbalance in the production line in some of the stations, the cycle time was higher than the takt and in some stations, the opposite (as can be seen in the chart)3. Inadequate management of machines and OEE (Overall Equipment Effectiveness) long wait times for materials at most of the machines, lack of real-time production stoppage documentation and structured processes for analyzing the production losses 4. The efficiency of the workforce was not optimal there was a high proportion of Non Value Added activities. This finding was mainly due to the imbalance in the work between the stations, a large amount of manual movement of materials and a non-optimized layout, which did not support lean material flow 5. High percentage of rejects (more than 5%) analysis of the data indicated that about 50% of the rejects were the result of superfluous hand contact with the lens, which could be partially prevented by reducing the amount of manual handling and streamlining the material flow6. Non-optimized maintenance management: a. Only some of the machines had a preventive maintenance program b. Most of the malfunctions were not documented c. Line employees had very limited knowledge of how to handle machine malfunctions and on how to carry out preventive maintenance

    The analysis of managerial infrastructure found a non- structured set of KPIs and a very poor level of manage-ment routines for monitoring the performance at the daily, weekly and periodic level.

    Constant reduction of losses

    Flow of materials and information







    Capacity building



    Focus on Service


    2,00 3,96































    ch s



    e tim


    cycle time takt batch size


    Line balancing chart - cycle time & batch size of each station compared to takt time

  • Designing the futureAt this stage we wanted to take advantage of all of the opportunities for improvement which were found in the diagnostics stage. In order to achieve a high level of in-volvement among the factory staff, a change management team was set up (se