The Waste of Overprocessing
Overprocessing is one of the seven wastes of lean manufacturing (or 7 mudas); Overprocessing is adding more value to a product than the customer actually requires such as painting areas that will never be seen or be exposed to corrosion.
The costs of the waste of Overprocessing
By adding work that is not required, Overprocessing costs you money with regards to the time of your staff, the materials used and the wear on your equipment. These costs can amount to a considerable sum over a period of time, they will also reduce your efficiencies as the operators that are Overprocessing could be performing other value adding tasks that the customer is willing to pay you for.
Causes of the Waste of Overprocessing.
Overprocessing as one of the seven wastes is caused by having unclear standards and specifications, many operators will try to do the best job possible and will not always be aware of what truly adds value to the product or even the end use. They will therefore often expend time polishing and finishing components that do not require it.
Another issue is the one of non-standardized working practices, unless you have standardized working then you will have differences in methods between different shifts and different people.
The most common issue is to do with design, often designers specify tolerances that require precision machining when in reality looser tolerances that could be produced by significantly less expensive methods could be employed.
Examples of wastes of Overprocessing
- Painting areas that will never be seen or be affected by corrosion.
- Over polishing an area that does not require it.
- Tolerances that are too tight.
Within a company that I used to work in many years ago, we produced rubber components for the automotive industry, we cut these components to length (anywhere from 1M to 3M) with a tolerance of +/- 1mm. These then had to be measured and documented on SPC charts to ensure that capability was maintained. Engineers worked hard on trying to design machines that could cut these products to the tolerances required.
These products were then joined together end to end to form a circular seal, this in use was stretched around another component; stretched far beyond its actual length at rest like a rubber band.
The tolerance was a joke and the measuring also, as long as the piece of rubber was at least 10%-20% smaller than the final component it would work fine in operation. The measurements conducted were also a sham as the operators could either stretch or compress the components to get any measurement they wished! All of this is relative to the waste of Overprocessing.
How to eliminate or reduce Overprocessing
To prevent the waste of overprocessing there are a number of simple steps that can be undertaken, as part of your initial 5S implementation instigate the use of Standard Operating Procedures (SOP) to provide written instructions for all of your employees. This is extremely easy in today’s age of digital cameras and word processing packages.
These SOPs will ensure the standardization of methods across shifts and personnel, combined with on the job training they are an highly effective way to improve the quality of your product as well as ensuring the reduction in Overprocessing. These SOPs combined with quality standards can also help with regard to clarifying specifications and acceptance standards.
Review designs with techniques such as value engineering and value analysis to identify opportunities to remove tolerances that are too tight.
Examine your process routes, are you using expensive processes where there are simpler cheaper methods?
Remove Wastes to increase Profits
By working on your Muda, Mura and Muri you prevent the occurrence of waste within your business, waste that adds no value to the product and is purely a cost to you. Every penny saved in your costs is added to your profit, so if you want to realize the benefits of lean manufacturing then you need to implement lean and reduce the seven wastes;
The waste of Overproduction is the production of product before it is required or in too great a quantity.
The waste of Defects is parts or services that do not meet specifications.
The waste of Transport is transportation of product from one place to another.
The waste of inventory is the raw materials, work in progress and finished stock within your company.
The waste of waiting is the time spent inactive waiting for work to arrive or to be told what to do.
The waste of Motion is the excessive movement of people or machines within the work cell.
The waste of Resources in not using your electricity, gas, water and any other resources in an efficient manner.
The waste of untapped human potential is not involving and respecting your employees.