In article 1 you have seen the difference between cost reduction and increase of output, whereby the increase of output brings the biggest financial result. You have seen that OEE is the internationally accepted measure for the output.
You have also seen how OEE is the multiplication of Availability, Performance and Quality. In article 2 you have seen the 6 steps to define where you stand and where problems are.
Below is a list of the 6 big losses.
|Six Big Losses||OEE Category||Examples||Comments|
|Unplanned Stops||Availability Loss||Tooling failure, unplanned maintenance, overheated bearing; Motor failure||There is flexibility on where to set the threshold between an unplanned stop (availability Loss) and a small stop (Performance Loss)|
|Setup and Adjustments||Availability Loss||Setup/Changeover, material shortage, operator shortage, mayor adjustment, warm-up time||Tis loss is addressed through setup time reduction programs such as SMED (Single Minute Exchange of Dies)|
|Small Stops||Performance Loss||Component jam, minor adjustment, sensor blocked, delivery blocked, cleaning/checking||
Typically, only includes stops that are less than 5 minutes and that do not require maintenance personnel
|Slow running||Performance Loss||Incorrect setting, equipment wear, alignment problem||Anything that keeps the equipment from running at its theoretical maximum speed.|
|Production defects||Quality Loss||Scrap, Rework||Rejects during steady state production|
|Reduced Yield||Quality Loss||Scrap, Rework||Rejects during warm-up, start-up or other early production|
Source: Vorne Industries
Attacking these problems requires working on improving the status of your equipment as well as the methods how these machines are used. Bringing the machines into an optimal state is one, to keep them there is another. That requires all personnel working with the machines taking tasks to keep them in that state. That again means that the operators must take on new tasks and that the operators and management must develop standardized procedures allowing to train everyone to do the job in the same way and to track what is being done.
The structure of that work is shown below.
There is a basis, 5S and there are 8 pillars of TPM all leading towards continuous improvement of the performance of your production line. Beware, that no machine or production system can work without people. It’s the PEOPLE that make your line perform bad, good or excellent.
The mentioned 5S method comes from Japan and consists of:
You create a clean workplace clean, with all tools at hand and no superfluous material around.
We suggest following these steps to implement the 5S:
It may be useful to use the Kaizen method of continuous improvement. You may find improvements in sorting, you may add other tools, you may change procedures. Keep your 5S up to date
Based on this the 8 aspects of Total Productive Management are implemented. There is no sense in reorganizing things when the workplace is in disarray, therefore the 5S is the first step. First, we will go over the 8 aspects and then we will give tips how to proceed.
The goal of all your activities is to reduce the down time to 0 and to reduce the quality losses to 0. Having achieved that you would end up with an OEE of 100%. This is an extremely difficult goal, but at the same time it will serve forever as goal.
All ACTIVITIES ARE TARGETED AT 0 + 0
|Pillar||What Is It?||How Does It Help?|
|Places responsibility for routine maintenance such as cleaning, lubrication and inspection in the hands of the operators||
|Schedules maintenance tasks based on predicted and / or measures failure rates||
|Quality Maintenance||Design error detection and prevention into production processes. Apply root cause Analysis to eliminate recurring sources of quality defects.||
|Have small groups of employees work together proactively to achieve regular incremental improvements in equipment operation||
Early Equipment Management
|Directs practical knowledge and understanding of manufacturing equipment gained through TPM towards improving the design of new equipment||
Training and Education
Fill in knowledge gaps necessary to achieve TPM goals.
Safety, Health, Environment
|Maintain a safe and healthy working environment||
TPM in administration
|Apply TPM techniques to administrative functions||
To keep the equipment in optimal condition, it is necessary to execute a continuous maintenance, independent from the technical staff (Autonomous Maintenance). I have seen operators taking machines apart and put them together again. To what level you can go depends on the team of operators.
Once the operator sees the production line as his baby, AM will come automatically, and generally the operators will be pushing for taking more responsibility, doing more than before. This results in having knowledgeable operators that are simultaneously maintenance personal on the line. No time lost waiting for help, they can do it themselves and feel pride in it. Management must assure that they see this result also in the paycheck, at the same time reducing the personal turnover.
Based on OEM manuals and the history of breakdowns of your equipment you can set up a schedule of maintenance activities that prevent breakdown during production.
As production stops generally have a high cost, mostly it is in the end cheaper to replace a part before it causes an unplanned stop.
Example: Electrical heaters in a flow wrap machine may break down. Looking into the history you may calculate that they last at least 600 Hours, so the Meantime Between Failures (MTBF) is 600 hours. It is advisable to replace them every 600 hours, thus eliminating a possible break down and production stop. This work can be done in the time the equipment is stopped, for example when cleaning of part of the system is planned
The cost aspect of planned maintenance is very well shown in this graph.
Source: Nestle continuous excellence
The maintenance cost as usually reported only involves the direct cost of Maintenance personnel and spare parts. The cost of stops in the production are not calculated or reported. This graph shows (as an example) the cost of breakdown time, minor stoppages and speed losses. You also may include the wasted product (rework) and packaging material losses. Only then you see the real cost of break downs.
Preventive maintenance will increase the labour cost (or may even reduce it as emergency work generally is not as efficient as well-planned work). There will be an increase in cost of spare parts and probably consumables, but there will a tremendous reduction in down time and losses in bad product and lost packaging material.
It is advisable to make a list of all parts that have failed and define their MTBF. Based on that, combined with the production and cleaning schedule you may develop an excel table that shows which part is to be replaced when. This may also serve purchasing to assure availability of these parts.
There is another aspect of planned and unplanned maintenance. In order to define whether it makes financially sense to do certain planned maintenance (that is replacing something before it breaks down). If you do not replace the part, it will break down during production and cause an unplanned stop, lowering your OEE. If that part is expensive, but it takes little time to replace, you may decide to use it till it breaks. The time to repair is defined as Mean Time To Repair, MTTR.
If the cost of a part is high, and the MTTR is low, you may decide to use it till it breaks. It is vital though to have the replacement in stock and best, close to the machine. At the same time, it is necessary to assure that the repair can be executed quickly. (best is by the operator him/herself avoiding waiting time for maintenance personal.)
List all possible wear parts and define of each the MTBF and the MTTR as well as the cost of the part. Based on this, take decisions which items to include in your planned maintenance schedule.
There is another measuring dimension. MTBF and MTTR concern a specific part or specific event. If there are many items on a line that have a certain MTBF, it will result in frequent stops of the line, each time due to something else. Therefore, we measure the Mean Time Between Stops (MTBS)
Use this dimension to measure interruptions. Set goals to get the average over 10 Minutes, then increase the goal little by little. 0+0 means that MTBS is infinite. Again, an unachievable goal, but a good measuring to report how the line is doing as a total.
Quality Maintenance is establishing and maintaining zero-defect conditions.
We must switch from controlling the outputs of our processes (the quality of our products) to controlling the causes of quality (the process and equipment conditions themselves).
This means that we must dig deep to find the real root cause of a problem and change settings, procedures of even equipment to make sure that this cannot happen in the future. This is especially valid in machine building and other complex systems.
You will find a more production-oriented approach in Focused Improvement.
This is a process that involves operators, maintenance and management. In meetings the failures are discussed and solutions are sought. It may result in small changes in the equipment (change the position of a sensor; change a guide etc.) or may require the involvement of the OEM to make modifications to the equipment.
Or it results in changes in the procedures. The team must develop these. Once decided on a modified procedure, make a good description and instruction, train all persons on the line.
This is a Kaizen process of continuous improvement. This never stops. Due to wear of equipment or changes in the product, new problems may arise. Kaizen is the process of small steps. Single out one issue and solve it, then tackle the next. Don’t try to do all at the same time. Prioritize the items on your list and re-evaluate frequently what is at that moment the biggest problem.
This concerns the purchase of new equipment. The input of operators is valuable in order to formulate the requirements. The experience from Autonomous and preventive Maintenance must be part of the equipment selection and purchase process. Not Purchasing decides (they are price oriented) but operations (TCO, Total Cost of Operation) must have the biggest say in that
As mentioned before, the people on the line will make or break it. Therefore, training of the operators and the maintenance staff on the equipment is essential. The OEM training is step 1, but the developed procedures for maintenance and best practices in production must be formalized and trained.
Training should be theoretical (what is the idea behind the design) and practical (on the machine and during production)
At the same time, management must learn and understand the implications of TPM. Making the operator the owner of the line means that changes cannot be made without involving them. Management cannot simply decide if they want to achieve 0 + 0. This is a team job whereby everyone is an equal partner, although some-one must decide priorities and what’s next.
As there will be changes in personal (0 turn-over is impossible), procedures must be developed how to bring new operators to the same level of knowledge. This investment is the one with the biggest pay back, and no money should be saved there.
Each accident has a high human cost and a high financial cost in production. Therefore, 0 accidents must be the goal. If the equipment has dangerous spots, operators should report them and engineering or the OEM must make changes.
There are dangerous procedures too. These must be brought into the Group, and changes must be elaborated that become part of the standardized procedures.
Simplify administrative procedures to a minimum. Administration should never be an obstacle in improving the performance of the line.
An example could be that it is forbidden for the purchasing department to change the supplier of packaging material without a written consent that the new material has been tested and approved by production. The goal of purchasing is to reduce cost but changing packaging material may cause huge negative effects. This may be seen as an attack on the authority of purchasing, but here the principle “penny wise, pound foolish” rules, and material specifications do not tell how material performs on a packaging machine. Therefore, the savings in changing a packaging material may result in an increase in cost. The savings are Purchasing’s credit and the operational cost increase are production’s fault. Make purchasing co-responsible for the TCO. They carry the blame when changing packaging material. Enlarge their focus from saving pennies to the whole picture: how do we make more money.
This leaves for the day to day operation on the line the following key activities:
In the next article I will show the practical side; how to define where to start; how to make a plan, make cost estimation; Examples of 5S and Autonomous Maintenance.
Leading image by Monkey Business Images/Shutterstock.com