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Rework

 

Rework - is the effort put in for correction of defects in a non-conforming product. Rework could be done during or after inspection and is additional cost to the organization. Reduction of rework is one of the key focus area in Lean Six Sigma.

 

 

An application oriented question on the topic along with responses can be seen below. The best answer was provided by Mohan PB on 24th October 2017. 

 

 

Question

Rework is considered a wasteful endeavor.  However, in some processes, zero rework is impractical or undesirable. Please explain the outlook for business excellence by taking examples of few such processes. 

 

Note for website visitors - Two questions are asked every week on this platform. One on Tuesday and the other on Friday.

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Frida Kahlo, the Mexican painter once said, “Nothing is absolute. Everything changes, everything moves, everything revolves, everything flies and goes away”. The first part of this statement is applicable to all subjects, including, “Rework”. While, “Rework” is traditionally considered a waste, in the following situations, “Rework” may be less unwanted.

1

Innovation

By definition, innovations or the first attempts at it cannot give exactly the desired results. Unsuccessful innovations are required to eliminate failure modes and rework leads to a marketable product

2

Product Development

When factors outside the control of the organisation change, like tighter laws, rapidly evolving customer requirements etc., rework is almost mandatory to sell the product

3

IT Coding and Development

Especially when large applications are developed over a period of time, the circumstances under which decisions related to development would have been taken would have changed with time. While under the set of then prevailing conditions, the decisions would have been correct, in the present circumstances, the same decisions may warrant review. Upon review, if these decisions are found to be not appropriate to the current circumstances, then they may need to be changed and the work impacted may need to be redone. This is preferable to trying to avoid rework and ending up releasing a poor application with known issues.

4

IT Testing

As part of testing a unit or a module of an application, if say Mixed case incorrect input is not detected as an error by the code, it is advisable to rework the code to further increase its robustness

5

Ignorant Market

When no one including the potential users know what they need, the only way to create and supply what is needed is by experiments, testing the market with prototypes, feedback on failures and rework

6

Painting or creating other works of art

Perspectives are available only after creation of the entire work of art or atleast part creation. Rework for improvement is the route to the success of that work of art

7

Cooking

When testing the soup to be served at the beginning of a huge dinner, if the soup is found to be too salty, rework in the form of dropping a few quartered potatoes over a simmering flame is essential to de-salt the soup and make it consumable

8

Wine making

Wines are known to get better with age. If a wine has not been sold after the targeted ageing (say) ten years, its price may further increase as in the additional waiting time the wine would mature more and thus become better. This additional ageing is a kind of preferred rework.

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Rework, as would many verbs that begin with “Re”, signifies that there has been a related preceding activity. In the industrial world, rework is immediately associated with poor Quality and efficiency. Most lean programs aim to reduce wasteful efforts, of which Rework is one.

The most common reason for a rework could be because of limitations of the process capability, due to which a percentage of products will fall outside certain specification limits.

It may not be desirable to go for zero rework always. The decision to improve the process capabilities to reduce the rework will have to be based on certain considerations viz. Investment cost, tenure of the business, the cost of rework etc.

Sometimes, it could be a result of an assignable variation that ended up with non-conforming parts by the time the process could be restored within its limits.

 

Let’s also consider the following different examples that denote activities that arguably fall within the definition of “Rework”

 

1.     Post shipment reworks:

  • Many a time Product recalls happen based on field failures or based on information about some possibilities of  reliability issues realized after a product has been shipped. We have seen even major auto manufacturers recalling vehicles for certain part replacements.
  • Many software products have the practice of providing update patches to overcome bugs or deficiencies on already launched products

 

2.     Customized products:

  • Certain products require the customer to perform trials / evaluation, only after which the corrections will be made before the final release. Popular example is how a tailor provides a ‘trial’ session for the customer, based on which the dress may be reworked before the final stitches.
  • Several “made to order’ products are subjected to a site inspection by the customer and some reworks may be performed. Some times for complex products say “a special production equipment”, the final requirements may get clarified after the product has been built to a certain extent.
  • Important documents, books etc. are subject to ‘proof reading’ and edits before the final print is done.
  • For the above kind of situations, attempting to avoid rework fully, may prove costly.

 

3.     Avail automation benefits:

  • Today’s world we have automated methods of data recognition and capture, which greatly speedens the process, but will have to go through manual verification and edits to reworks some errors.
  • We would have seen the fast billing method in supermarkets using bar-coding technology. However, occasionally this could fail on certain products, which forces the billing agent to do a manual keying.
  • For above kind of situations, the benefit of automation exceeds to cost / effort of limited rework.

 

4.     Not fully certain about outcome of the process:

  • Certain medical treatments are changed or modified based on the reaction of patients, and this could vary from patient to patient.
  • A method called progressive evaluation is used for Training processes, where based on the scoring pattern of the recipients, the training process may have to be reworked.

 

5.     “Made for each other” parts:

  • Certain processes need the product to be fitted upon its counterpart to decide the kind of rework to be done. Eg. Gears need to be lapped with the mating part; engine valves need to be polished based on the seating with the engine base.
  • A dentist reworks a dental crown to final dimensions after placing and checking on the patient’s gum
  • These parts are made for each other and need to continue to operate together

 

6.     Unpredictable market expectations:

  • Sometimes a finished product may have to be modified to suit the varying taste of market. For eg. The change color of a consumer durable product.
  • Rework may also happen on the design of a product that has been launched – This could be an ongoing change to incorporate market feedback or changing needs.

 

To conclude, the term “Rework” does imply a job being not done ‘right the first time’. However, the scope and type of improvement efforts will have to be decided appropriately based on the situation

 

 

                            

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The processes where, I understand, zero rework is impractical or undesirable are the process concerned with

  1. design (mostly related to product features) 
  2. software design and development.

 

Rework done to fix bugs /defects/rejects i.e. as a correction measure is a “waste”. The aim should be to produce “First time correct”.

 

But Rework might be needed to:

  • Add features and functionalities that were intentionally left out in previous versions. Sometimes it is recommended to get a base product (minimal features) out (to minimize “time to market”) and then go back and rework to add additional features that were left out.
  • Enhance features and functionalities to satisfy the “Excitement needs” of customers.

From a Business Excellence perspective, some of the rework initiatives could be driven by a understanding of the Voice of Customer, and Voice of Business.

 

Example:

 

(1)    Car manufacturers constantly rework their designs to provide customers with new features better/more efficient engines and so on.

A rework on the engine design to improve its efficiency is “desirable” ( it is more of a continuous improvement activity to improve the engine performance) , but a rework on the shop floor if it produces defective engines is a “Waste

 

(2)    An initial version of an ERP software may be designed only with Financial Accounting & Controlling, Supply Chain modules. In the subsequent versions the architecture might be reworked to include other modules like Human Resource Management, Production Planning, Sales and Distribution and so on.

 

(3) Based on business requirements, there might be a need to integrate and connect a software product with other software products. This would require an architectural rework.

 

It should be noted that the amount of rework needs to be properly understood, the cost to benefit ratio should be analyzed before taking a rework decision.

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No system can be 100% correct.  Normally when we talk about rework, everyone thinks of the bad quality of the product/service that the service provider provides which will impact its reputation and credibility.  

 

Rework creates additional effort to be put in, to course correct the mistakes/defects that have happened.  Often its conveyed as a waste, because more often than not, the defects raised are due to either a missing step, or to a deviation from the right way of doing or doing things wrongly or doing less than what is needed, etc..,. So doing rework for addressing these category of issues, which should have happened in the first place, is a waste of time and effort.  But there are cases, where rework would be a mandate due to the nature of the work being done across industries.

 

Let us take some examples across industries to prove this

 

Manufacturing Industry

In manufacturing industries, say for instance, Telecom sector, there could be a Rework unit as part of a Production department.  For instance, there could be a quality issue in a product or in a process. The Rework unit will look into the quality issue. If it is a product issue, it could be say a component failure.  

 

Movie Industry

Invariably in almost every movie, when it is about ready to be moved to the theatres, the Censor board blocks some dialogues or scenes from that movie. This results in as a rework for the movie’s production unit , in editing the movie and then show the movie to the censor board and then upon the board’s approval, release the movie to the theatres. Hence here Rework is very much prevalent and is the only option. If certain scenes or dialogues are not removed as requested by the board, that may warrant a legal action against the producer or director of the movie.

 

IT Industry

In a typical agile project, depending upon the business needs of the customer, the product/service needed can keep changing dynamically. Accordingly the design needs to be robust.  So refactoring of the design/code can help to achieve the objectives. Sometimes if refactoring is not suffice to support the business needs, then rework effort will be needed.

 

Note: Refactoring is about restructuring the existing code without changing its External behaviour.

 

Conclusion: 

Thus we have seen here how rework effort does make a difference for various type of works across industries and we see how Zero Rework effort is not possible in some cases and not desirable as well in some other cases.

 

 

 

 

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Rework is usually considered as a waste. In fact Cost of Rework is considered as Cost of Poor Quality and a lot of emphasis is laid on minimizing, if not altogether eliminating rework.

However, there are some methodologies where some amount of rework is inevitable due to the iterative nature. Take Joint Application Development (JAD) for example. In this methodology, the vendor and customer collaborate to create the product. First the design team of the vendor creates a prototype, which is shown to the customer. The customer reviews/tests the prototype and provides feedback on how it can be improved. In this process, some part of the prototype would have to be dismantled and rebuilt. In other words, some amount of rework is inevitable.

However this method is superior to having the design team spend a far greater time on design simply to avoid a small amount of rework. Even that is not guaranteed as the minds of the designers and customers work differently.

The benchmark should be whether the cost of prevention is lower than the cost of rework + cost of failure. If that is not the case, it might be better to incur the failure and rework, rather than over-engineer the product by trying to prevent defects!

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Though zero rework should be the mindset in the pursuit to business excellence its extremely important to trade off this decision with Return On Investment provided by such high quality outcome. Overall output is influenced by cost, quality and time. It’s an important conversation that is needed with customer on how we tradeoff between these three in the context of their importance to customer. When time becomes critical then zero rework may not be feasible, and cost will go high as well.

Rework acceptance also boils down to criticality of the output and where does it fit in. Like in case of pace maker that is implanted in to body would expect to be manufactured with lower rework compared to an office printer which is not similarly critical. Space shuttle would be one another critical area that would need perfection as outcome. Otherwise there is no need to compromise on cost to just to get zero rework outcome. Also in case of mobiles it may not make sense to wait for perfection until you reach to market only to realize that your version is outdated, it may make sense to go in to market with at best quality and then strive to rework on improvising the version so that you may not lose on marker hold.

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For an organization target should be to reach as near to zero rework as possible instead of zero rework.

Because to accomplish zero rework , we will require huge capital investment which includes all the modern technology and machines that will produce product within the specification limits all the time.

Cost of product will increase which at the end will affect their market share.

Some reworks are always acceptable, when that product, process is not a critical function of the product.

Taking an example of a sensor which was not functioning properly, and after doing some maintenance it started working again.

Now imagine this sensor is too be used at two different places.

1.       In Aeroplanes

2.       In a local manufacturing machine.

In this case the reworked sensor should not be used in aeroplances, but that sensor can be used at a local manufacturing machine.

Taking another example of a food industry. There are various parameters on which a product is accepted by quality representative.

One of them is metal pass. if the machine detects that there is slightest of chance that there is metal in the product it will not be allowed by quality representative. We need to do rework in this product. Because it affects the human health directly.

There is another parameter of length of the product, if there is slight variation in the length of the product, we may not rework that product instead we will pack in a lower grade of product.

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Examples of Rework/ Useful Rework >> In Hospitality(where my experience lay most) Rework has hardly been of value; as far as when one is on Stage i.e Guest Service area.

 

But, Yes, at a Product Development stage Eg : Creating a New Offering : Could be a Physical Facility - New Restaurant / a Dish / a Service Offering, "ReWork" tends to happen irrespective of the effort to "Get it Right First Time". Thought it might incur some incremental cost or Cost overrun, it helps in developing something Unique/ Best in Class/ Benchmark. It's could be 1) A New Age Restaurant like None 2) a Fusion Dish never offered before or 3) A New Bouquet Butler Service Design offering etc. 

 

Usually where ART / Component of Art is involved, such "Rework" is found to be inevitable, essential & beneficial !!

 

Thank you :)

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Definition of Rework as understood generally: To make change to “something”, especially to make it more up to date.

Definition of Rework as per Six Sigma: Is a Quality assurance method that focusses on improving rejects at the end of a process (Inspection) with the goal of delivering only acceptable products and Service to the customer.

The first though that comes to mind, with the word “rework” , associates with “Waste” as rework is extra <effort, time, cost> and hence Rework is taken as an unwanted evil and not acceptable at all. However, what can be taken from the above two definitions is that, rework is the activity to correct any product or service, which is not up to the intended standard, before it is delivered to the end customer. There are some processes in which zero rework is not practical and also not desirable.

Let us take the example of a Burger outlet in the Modern QSR industry. The production area is a line assembly unit, where the Patties are kept in frozen state, the Buns are kept ambient temperature and the Sauces & Salads are kept in Chillers in conducive temperature to retain their “freshness index”. The said items are the basic build-up of a burger. All the said items are highly sensitive to their storage temperature and hence are volatile.

As a normal process the order for a burger or different varieties of burgers are passed on to the kitchen multiple action takes place simultaneously to assemble the final product in a defined structure / alignment of the said items. - - The Buns are toasted,

- The bun is dressed with the sauce, then ,

- The chilled Salads and then the Fried Patty which is Hot.

 

The purpose of this order also systematic-

>The Bun is toasted, so that the caramalized surface becomes more or less non-porous

> The  Sauce is dispensed on the toasted surface to ensure that the sauce does not seep into the Bun 

> The salad  Chilled salad is placed on the sauce to ensure that the Hot patty does not directly touch the Sauce, which can melt it down to a thin consistency,

> The salads also provide a crispy texture and enhances the body / bulk of the burger and also complements the taste of the final product .

> The Patty is placed above the salads and is hot and is the main component of the burger.

 

 Patently, the process is simple and the training for storage, alignment and dressing and assembly of the burger is extensive. However,  Given the Volatility of the products & the chances of incorrect order of assembling  & error in fulfilling “special” order requests ( like No chilli sauce, Less onion, More lettuce etc) , there are so many aspects that can generate a defect in the product. The product can have a quality issue or an arrangement issue or a out of spec issue as well. So, Zero defect is almost impossible. Though following the DMAIC methodology can reduce such defects expecting zero defect is not practical. In this case, a level of inspection becomes a necessity.  

 

There is normally a person who is assigned the responsibility of checking the product “Feel” before passing it on to the service counter for final service to the customer. Any defect that is visible or felt by this seasoned person, in quality or product build up, is corrected and Wrapped in a Butter paper sheet at this station itself for final presentation to the customer.

This way the restaurant avoids not only raw wastes , as all the raw products are used effectively and not wasted, but also complete waste, which would have happened if the customer had to spot a defect and return it, ensuing a replacement which is an additional cost. In the food business Food cost control is a revenue driver and this final step in the process is of great importance and value add, though it is technically a rework.  This then becomes an integral part of the process – A Rework Loop . It is a situation , as is above ,where a step in a process is repeated in order to correct a defect- also known as backtracking. Rework lopps are work that needs to be done repeatedly. This is more often seen in processes where large amount of work move back in the process to be fixed- It is better to fixed station instead- Like in the case above. Here Zero rework is not desirable at All!!

 

When the above is applied as an analogy to many “On The Floor” Production Processes, This can be a part of the quality control procedure as the problem detected was corrected. The Rework here , thus, avoided any “DEFECTIVE WORK” which could have come back from the customer, i.e. found to be defective AFTER it had left the production unit.

In a warehousing process, this can be a part of the quality control procedure and the  problem found can be fed back into the systems and the procedure and the person that did that work can be reviewed to detect & confirm what was the cause of the defect and what needs to be done for preventive action. Thus the business owner will not only review the existing work procedure but also the inspection procedures that allowed a defective item to be shipped. A complete layout for the improve state of DMAIC.

Likewise, The Rework loop is also seen in critical processes like healthcare and space research. The result of the the rework loop is that Defectives are avoided. Defectives in Critical Processes can cause Great harm to the repute of the business and supervened cost of litigations, cost of brand rebuilding and Immediate loss of sales & business!!

 

 

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Rework is generally considered wasteful endeavor however for products that perform non-critical functions or products produced in masses at very low cost, rework may not be worthwhile (scrapping may be easier) or rework may be acceptable.

Products that are related to health like pacemakers have to be done right first time. In such cases rework is undesirable. 

For certain industries like software industry zero defect is impractical and cannot be achieved. The cost to reach near zero defect is exponentially high and not justified against the risks associated with defects leaked.

Products like nails – produced in masses, low cost of manufacturing and sale may be perfectly ok with scraping rework items and not create extraordinary processes to ensure zero rework as the cost may be far more than the saving from reduced rework. Again here it is impractical and undesirable.

Finally the decision on what level of rework is acceptable and necessary is driven by cost of poor quality to intended user (hazard, risk associated), cost of rework (to fix identified defect), ability to fix the defect effectively like a fresh product without introducing other defects.

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Rework is considered a wasteful endeavor. However, in some processes, zero rework is impractical or undesirable. Please explain the outlook for business excellence by taking examples of few such processes.

 

Rework means redoing or repeating the process, when it is rejected in its first opportunity given, which involves extra human effort, time, cost and diverse risks. This might be due to failure of the design, defect / error, changes suggested, poor communication or poor coordination between the supplier and customer. This will also have a huge impact on the product delivered to customer and their satisfaction scores, organization’s reputation, performance metrics of the organization.  Rework often results in other such wastes like delays, waiting time, motion/transportation, etc. “Do it first time right” is the concept we will have to apply in reducing the rework cost.

 

Zero Rework is impractical:

·         When the defect / error is identified, the rework is mandate to satisfy the customer. For Eg. In medical coding organization, the coder codes the chart and it is being audited by the QC and corrected the chart before sending it to client. In such instances, to please the customer and provide him error free chart, rework is necessary, where it requires additional human intelligence/ robotic technology of correcting the error. This requires additional man power, extra investment in building additional intelligence and to strengthen the gate way of defect free zone in the organization and time.

·         When the changes suggested by the client / end customer in the product, rework is done. This is also called customization of the product. According to the customer’s preferences, certain products are redesigned and given to client to improve customer satisfaction scores. For Eg. In case of buying a flat, customization of features like paint color, extra wall coating, extra interiors, etc will be suggested by client and rework is inevitable by the builders.

·         When the design requires rework due to multiple delivery modes, rework / repeating the process is not avoidable. For eg. In publishing industry there will be different template for print and web delivery for which the input codes has to be reworked according to the deliverable.

·         When there is poor communication or poor coordination between supplier and customer, rework is inevitable. For eg, In manufacturing when the supplier misses to clarify the specification used by customer to indicate the dimensions of the product leads to rework to meet the requirements of the customer.

 

Few more examples,

·         In Software development, certain aspects of the output will be visible only after execution of the program. In such cases there exists possibility of rework to re-align with the desired outcome.

·         During survey, when the person conducting the survey is not able to map the answer from questionnaire with the factors under consideration for predictive analytics the author reworks on the questionnaire to get expected responses.

·         In marketing industry, the executive has to explain the specification and uses of the product being sold multiple times to a customer while pitching the product to convince the customer to buy the product which is also a rework for the executive.

 

Conclusion:

Rework is definitely a waste. At the same time, rework is important when the error / defect is identified. Also to delight the customer, in certain cases like product redesign, etc, rework is inevitable. It is a difficult and additional cost/ time/ man power involved process. Though there are challenges, to keep up the customer in tight with organization, rework is an important and considerable activity.

 

Thanks

Kavitha

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Hello,

 

My view on processes where Zero rework is impractical or Undesirable would apply mainly to manufacturing process,

 

  • where the cost of "Rework" is higher than manufacturing a "New" product - For example a small component of an electronic device like LED bulb or such similar products where a dismantling to fix it is costlier than reworking to fix it ( I am not a industry expert however, this is an apt example I could think of)
  • FMCG manufacturing of products especially with foods, daily consumables where the variation in the look and feel of products is not critical in comparison to the desired purpose of the product. In such situation it is not desirable to "Rework"  to ensure "uniformity" of the product.

 

Based on cost/benefit analysis, TAT for rework are the key metrics that needs to be studied to arrive at a conclusion on impracticality or undesirableness of rework should be taken.

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In some processes,  zero rework is impractical,  it will affect the business Excellence.  It depends on the cost of rework.  If it is more than the cost of part then there is no use of doing rework.  If I talk about manufacturing industry,  parts which are used in inner side of the car are if deep draw and have wrinkle in most of the cases.  According to standard wrinkle not allowed but after seeing and verifying location,  how is it going to effect the quality of final car,  although rework is needed to remove wrinkle but we can do straight pass so it will save our cost because there will not be any need to do scrap those part.  We can not ignore wrinkle in inner parts due to part profile and it will come in all parts but we can't do rework for whole or scrap so based on quality point of view we take decisions to save cost. 

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zero rework is impractical or undesirable in some situations. If we take pharma production as example some cases like

 

1. As per the market requirement and forecast if a particular product "A" was manufactured and packed for USA and the requirement got changed after packing the product that the same product "A" is urgent in Canada. Repacking of the product as per the canadian regulations has to be done. And repacking is allowed as per GMP practices if the written procedure for repacking is followed. Then again the product has to be repacked and sent to canada to meet the market requirement. In this case zero rework is impractical because if we doesn't meet the Canada requirement we may loose the market share and the business will get effected.

 

 

 

 

 

 

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Interesting question but difficult to answer as i am not able to think of those situations where zero rework is impractical or undesirable. May be stage show rehearsals kind of situation is one of such situation where 'rework' would be required. As far as manufacturing industry is concerned this concept may be applicable to those processes which involves craftsmanship or artistic work, where there is always some scope of improvement. In other words any of those situations and processes which need perfection and where there is always some scope of improvement will always require rework. Such situations may be sports or games, scientific invention, development of better products etc. In these processes concept of 'zero rework' is not applicable.

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Reworking is the process of rectifying mistakes made during manufacture so that a product meets requirements. It could be as simple as affixing a new label, or as extensive as welding additional material, heat treating and re-machining. Deciding whether to scrap or rework is not straightforward.

For eg, A Flash in the plastic part can be easily reworked & removed . But if the same flash had been stuck in the past and send to the customer it may cause serious effects.. A Flash in the car engine may cause serious functional problems...

Rework might add additional cost & manpower, but it prevents more damages at customer end

Thanks, M.Karthik

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This question challenged us to go beyond what we have frequently heard in most Lean and Six Sigma discussions, which is that Rework should be avoided or reduced or eliminated, where possible. The contributions show how this group is open to evolving ideas.

 

"Nothing is absolute. Everything changes, everything moves, everything revolves, everything flies and goes away” - Frida Kahlo. The first part of this statement is applicable to all subjects, including, “Rework". Very creatively mentioned by Mohan PB, who has also supported his answers with diverse examples. This is the chosen best answer for this Monday's question.

 

Other answers also cite some examples, which are worth a read.

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