شنبه ۲۲ اسفند۱۳۸۳

تولید به هنگام

Just-In-Time ـJIT     

Just-In-Time production is a philosophy rather than a clearly defined method to control production. What most managers consider to be JIT, originated at Toyota where it is referred to as the Toyota production system. This system is still evolving as computer integrated manufacturing technology and information systems are integrated with it. The details of Toyota’s system are provided by Monden in his book the Toyota Production System: an integrated approach to just-in-time (1993). From 1973 when the Toyota system began to be widely adopted in Japan (due to the oil shock) until 1983, JIT received a limited amount of attention in the United States. With the publication of Robert Hall’s book Zero Inventories (1983), the concepts and practices of JIT received wide acceptance and adoption by many firms. JIT is defined as a philosophy of waste reduction, not a limited set of practices. Schneiderjans (1993) has examined all of the literature about JIT and has determined that there are eight key principles.

JIT principles:

1.    Seek a produce-to-order production schedule.

2.     Seek unitary production.

3.     Seek to eliminate waste.

4.     Seek to continuous product flow improvement.

5.     Seek product quality perfection.

6.     Respect people.

7.     Seek to eliminate contingencies.

8.     Maintain long-term emphasis.

At first glance, most of these principles may seem to oppose JIT`s philosophy of waste elimination. But, they actually do promote waste elimination. By seeking a produce-to-order system, a firm is able to eliminate the waste of finished goods inventory, because the product is sold when completed. By seeking unitary production a firm eliminates the waste of both work-in-process and finished goods inventory. A side effect of this is that a firm using unitary production is able to respond to customer changes much more quickly, since the lead times are shorter. Because there is no buffer of inventory in the system, unitary production reveals problems that might be hidden by the inventory. The third principle is to eliminate waste by using only the minimum amount of equipment, materials, and human resources required. Seeking continuous product flow improvement eliminates idle time. Under this principle all activities that are not required for work are eliminated. By seeking perfect quality, JIT eliminates waste by building 100% perfect products. Respect for people involves workers in the production control, giving them the authority to insist on perfect quality. By eliminating contingencies, managers reduce inventory, which reduces waste. A long-term emphasis is required since JIT`s benefits can take a long period of time to mature.

        It is important to understand that JIT is not an inventory reduction system. It is a system that focuses on the elimination of waste in all of its forms. It is sometimes thought of as stockless production, because it uses much less inventory than other systems. But, it still requires inventory. The level of inventory does provide a good measurement of how effectively waste is being eliminated. In this way, inventory is analogous to a thermometer. A thermometer tells the temperature, but it does not create the temperature. The level of inventory in a system tells the observer how effectively waste has been eliminated. The reduction of waste did not eliminate the waste. Inventory is often used in a system to hide problems or to hide waste. Inventory is like the level of water in a stream, which allows a boat to float safely over the rocks and other obstacles. If we remove the rocks the boat can safely float in a lot less water.

       It was only possible to operate with fewer inventories after the problems creating the waste in the system were eliminated. Inventory is an effective measure of waste in the system, because the level of inventory in the system is the combined outcome of all the system components. If the quality of the system is poor, then there is additional inventory to compensate for the bad quality, so bad parts will not shut the system down. If the process used in the system is defective, then additional inventory is needed to accommodate the problems such as an extended flow time. The product design greatly influences inventory. The design of a product determines how many components there are in a product and also determines how easy it is to manufacture the product. Maintenance certainly influences the level of inventory, as machines, which are not maintained appropriately, break down more frequently and consequently more inventory is needed to protect against breakdowns. The employees` motivation makes a difference in the level of inventory in a shop as the employees can help solve problems if they are motivated to do so.

Total Productive Maintenance

Total productive maintenance (TPM) has evolved over the past 30 years to ensure equipment reliability at low cost. TPM emphasizes zero breakdowns and zero defects. It supports the philosophy of JIT to eliminate waste. TPM uses all the tools that have evolved over the past 100 years to improve equipment reliability, but it organizes the maintenance process so that it becomes a continuous learning process for everyone involved in it. For example, TPM is a set of techniques to manage breakdown maintenance, preventive maintenance, and predictive maintenance. It applies the scientific method to the management of these programs and to the management of equipment. The goal of TPM is to create an environment in which people and equipment can deliver exactly what the customer requires without waste. TPM actually creates a new system for equipment management. It depends on autonomous teams and on cross-functional teams for its employment.


نوشته شده توسط مهدی نیاجلیلی در 21:40 |  لینک ثابت   • 

دوشنبه ۱۰ اسفند۱۳۸۳

انواع مشتری

به نام خدا




قبلا در مورد ارزش نوشتیم و اینکه ارزش توسط مشتری تعیین میشود. حال به بررسی انواع مشتری میپردازیم.





هر مشتری دارای معیار های مخصوص به خود برای ارزش گذاری کالا و خدمات است، بر این اساس مشتریان به سه گروه عمده تقسیم می شوند:


1- برای گروهی، کالا و خدمات دارای ارزش ذاتی است.


2- گروهی دیگر براساس نحوه کاربرد آن کالا و خدمات آنرا ارزش گذاری می کنند.


3- گروه سوم بر اساس روابط استراتژی بین دو سازمان.





خریداران کالاها: commodity buyer


این دسته از خریداران دقیقا می دانند که چه می خواهند و چگونه از آن استفاده کنند و در این شرایط آنها نیازی به توضیح بیشتراز جانب فروشندگان ندارند.


این گروه از خریداران به دو دسته کلی تقسیم می شوند:


دسته اول: مایل به پرداخت وجهی بیشتر از حد نیاز نخواهند بود. برای اینکه سازمان مورد نظر این گروه از مشتریان خود را از دست ندهد، لازم است که کلیه هزینه های اضافی را از زنجیره عرضه بیرون بکشد، به هر روشی که می تواند.


دسته دوم: مایل به دسترسی به امکانات به ساده ترین شکل ممکن هستند. در این مواقع شرکت ها با فراهم اوردن امکاناتی چون خرید اینترنتی قادر به جلب رضایت انها خواهند شد.


فرض کنید من یک خریدار هستم، وقتی سفارش یک لنز طبی را می دهم، شما به عنوان یک فروشنده تنها با پایین آوردن قیمت محصول خود، ساده تر کردن راه های سفارش گیری، تحویل در منزل و قبول برگشت از فروش در صورت عدم رضایت مشتری، قادر به ایجاد ارزش در سازمان خود خواهید بود.



با تشکر از توجهتون. خوشحال میشیم نظرتون رو در مورد این مطلب بدونیم.

نوشته شده توسط مهدی نیاجلیلی در 21:5 |  لینک ثابت   • 

سه شنبه ۴ اسفند۱۳۸۳

six sigma



There is a common word, which says that “Quality attract customers and Invention

distinguishes you from others in competitive environment “. Six Sigma is a very

structured quality improvement methodology and TRIZ is an inventive one; by

applying both of them together, inventive problem solving tools can be used for

quality improvement and the highest degree of quality can be achieved with inventive

quality improvement methodology.


1- What is Six Sigma?

Six Sigma is a structured methodology used on any repetitive process, procedure or

transaction. Statisticians at Motorola developed this methodology in 1980s. The basic

premise of Six Sigma is that there is a cost to poor quality, because poor quality

causes lost sales and lost business opportunities. Improving quality through the

reduction of defects lead to greater customer satisfaction. Reduction of defects leads

to reduced costs, and increased customer satisfaction lead to increased revenue. So the

primary goal of Six Sigma is to improve customer satisfaction, and thereby

profitability, by reducing defects and increasing “The degree of quality”. The degree

of quality can be measured from one or more critical outcomes from a business

process; everything that the customers are interested in comes as a product. Defects

may be related to any aspect of customer satisfaction: high product quality, schedule

adherence, cost minimization and etc. In other words every process, procedure or

product has an opportunity to be executed correctly, any opportunity that occurs

which does not meet customer requirements is called “defect”.


2- What is the success of Six Sigma methodology:

For increasing the degree of quality a specific metric is needed, a key aspect in the

success of Six Sigma methodology is the use of Sigma metrics as a measure of

customer quality and process efficiency, the term “Sigma” refers to measure of

variation. Specifically, sigma is a statistical measurement of the capability of a

process, procedure to meet customer requirements., it should be noticed that customer satisfaction is usually quantified in terms of a target and limits.

The success of Six Sigma is due to three major points:

·  Top-Down commitment and involvement of the organization

·  Proven methodology with tools base on TQM

·  Data-Driven using statistical techniques.


3- Six Sigma Job Plan:

The Six Sigma job plan consists of five phases: Define, Measure, Analysis, Improve

and Control.

Ø Define: The Define phase is concerned with the definition of project goals,

and the identification of issues that need to be addressed to achieve the higher

(better) sigma level.

Ø Measure: The goal of the Measure phase of the Six Sigma strategy is to

gather information about the current situation, to obtain baseline data on

current process performance, and to identify problem areas.

Ø Analyze: The goal of the Analyze phase is to identify the root cause(s) of

quality problems, and to confirm those causes using the appropriate data

analysis tools.

Ø Improve: The goal of the Improve phase is to implement solutions that

address the problems (root causes) identified during the previous (Analyze)


Ø Control: The goal of the Control phase is to evaluate and monitor the results

of the previous phase (Improve).

At the macro level each of these phases answer the following questions:

Ø Define: What is important to the customer? Or what are our defects?

Ø Measure: What is our current performance versus what is important for the


Ø Analysis: What cause variations from target for the customer?

Ø Improve: What improvements will place us on target with minimal variation?

Ø Control: What controls will keep us there?

we are looking forward to seeing your comments. 

نوشته شده توسط مهدی نیاجلیلی در 23:43 |  لینک ثابت   • 

دوشنبه ۳ اسفند۱۳۸۳

مثالی از اتلاف

به نام خدا


حتما تاکنون اسم مودا رو شنیده اید. مودا همون اتلاف است. در اینجا مثال جالبی از اون و تاثیر بدش بر روی سیستم میزنیم.


وجود کارگران، تجهیزات و تواید اضافی، نه تنها هزینه ها را افزایش میدهد، بلکه منجر به بروز اتلافهای مرتبه ی دوم (Secondary Wastes) نیز میشود. برای نمونه، وجود کارگران مازاد (به عنوان اتلاف مرحله ی اول)  ، منجر به انجام کارهای غیر ضروریی میشوند که به نوبه ی خود بر میزان مصرف انرژی و مواد خام می افزایند. اتلاف ناشی از مصرف انرژی و مواد خام اضافی، یک اتلاف مرحله ی دوم محسوب میشود.


از میان تمام اتلافها بزرگترین اتلاف همانا موجودی اضافی است. وقتی موجودی اضافی داریم، باید آن را در کارخانه انبار کنیم و برای نگهداری آن مجبوریم در کارخانه انبار بسازیم و کارگرانی را برای حمل کالا به این انبارها استخدام کنیم و چه بسا مجبور شویم برای هر کارگر یک گاری حمل نیز تهیه نماییم.


همچنین در چنین انباری، به افرادی برای مدیریت موجودی و جلوگیری از زنگ زدن قطعات نیاز خواهیم داشت. هرچند با و جود آنها هم برخی از کالاها همچنان زنگ خواهند زد و خراب خواهند شد. به همین جهت افراد دیگری لازم خواهند بود تا قبل از خارج کردن کالاها از انبار، آنها را تعمیر کنند. همچنین باید کالاهای موجود در انبار به طور ادواری، انبارگردانی شوند. و این خود نیازمند کارکنانی دیگر است و وقتی موجودی به سطح معینی رسید، دیگر خرید رایانه ها برای کنترل آن ضروری به نظر خواهد رسید.


اگر نتوان موجودی را به طور کامل کنترل کرد، لاجرم کمبودها پدیدار خواهند شد. عده ای فکر میکنند این کمبودها بر اثر پایین بودن ظرفیت تولید ایجاد شده اند. در نتیجه ظرفیت تولید را افزایش میدهند و  تجهیزات جدید میخرند که خرید آنها باز هم بر موجودی اضافی می افزاید.


و متاسفانه چنین چرخه خبیث اتلاف سازی، در گوشه و کنار فضاهای تولیدی مخفی شده و از دید پنهان میماند. برای جلوگیری از بروز چنین اتلافهایی فقط و فقط یک راه وجود دارد: مدیران و سرپرستان باید عمیقا درک کنند که اتلاف چیست و چرا بوجود می آید.


کتاب سیستم تولید تویوتا TPS اثر تا ایچی اوهنو




                                                                    لینکهای مربوطه:

                                                                       مودا چیست؟



با تشکر از توجهتون. خوشحال میشیم که نظرتون رو در مورد این مطلب بنویسید.

نوشته شده توسط مهدی نیاجلیلی در 23:16 |  لینک ثابت   •