Waste

Peter Drucker, the father of the modern management theory, said: ... there is nothing so useless as doing efficiently that which should not be done at all. This can easily be regarded as the definition of Lean Manufacturing.

Traditional manufacturing systems impose continuous use of machines and people. If particular process steps are not properly balanced, this leads to the creation of inventory at different manufacturing stages. Inventory, like a river "hides" problems the company has to cope with. Usually, these problems include high failure rate, different cycle times, bad planning, low quality and staff dissatisfaction.

Lean Manufacturing focuses on the elimination of all waste generated during manufacturing processes. Such an approach radically changes the image of an enterprise. Inventory is either kept a minimum level or non-existent. Materials are supplied upon demand, based on the Kanban principles. High level of workplace organization and visualization thanks to 5S rules engage employees in the change and improvement process. Machine downtimes during changeovers are reduced to a minimum, so there is no need to produce large batches of materials.

Single Minute Exchange of Dies (SMED)

Single Minute Exchange of Dies (SMED) in other words means a changeover taking less than ten minutes. Although the term is quite intriguing, especially when it comes to machines where changeover takes several hours, it should be translated rather as an indication of the huge potential of reducing the time needed for changeovers.

Changeover is defined as the time period between stopping a machine after it has manufactured the last good piece from a previous batch and turning on the machine for manufacturing the first good piece from the next batch.

Changeover involves two types of procedures. These are external and internal procedures. External procedures include everything we do during a changeover without having to stop the machine. Internal procedures are everything we do after stopping the machine. This is one of the assumptions underlying SMED.

Very often Formula 1 pit crews are given as an example of an ideal changeover, where changing of tires is planned with surgical precision and lasts only a few seconds.

The changeover analysis process consists of 4 stages

Stage 1 – Differentiation between external and internal procedures This is best done by video recording the entire process. Next, a changeover map is created, where each observed action is identified and assigned an external or internal procedure status. At this stage you can already notice some procedures which, being evident losses, should be eliminated from the process, e.g., repeatedly returning to the same point. 

Stage 2 – Separation of external set-ups from internal set-ups At this stage you must decide what can be done while the machine is still producing items from the previous production batch. For example, you can collect all tools, dies, etc. required for the production of a new product batch. In this way after stopping the machine you are sure you have at hand everything needed for changeover. 

Stage 3 – Replacing an internal set-up with an external set-up Question every internal procedure to see whether it could be replaced with an external one. In other words, think how to do certain operations while the machine is still running. Define the “real functions and goals” of each step to encourage staff to generate ideas helping to eliminate, simplify or replace internal procedures with external ones. The separation of these procedures can often reduce the changeover/set-up time by 30-50%. 

Stage 4 – Differentiation between external and internal set-ups All machine parts should be self-locking. For example, you can use a system of openings and plugs/pivots to place a specific part in the machine. Flexible clamps or plugs/pivots in this case can be used to keep the part in the required position. All adjustments must be done in terms of value (that is, set-up in accordance with a given value) in contrast to quality adjustments (that is, carried out on the basis of a feeling, intuition or experience) in order to achieve repeatability. Consistent use of the same set-ups helps to avoid additional adjustments after line start-up.

OEE

OEE –the main indicator of progress in the implementation of TPM

OEE (Overall Equipment Effectiveness) is a measurement used in TPM to show how effectively machines are used.

What do we mean by overall equipment effectiveness? Many of us are familiar with the term performance, which usually means the number of items a machine or employee produces in a specific time period. OEE differs from performance in a number of aspects.

Overall equipment effectiveness means much more than just the number of pieces made per shift. When calculating the overall equipment effectiveness, performance is only one of the factors. Apart from performance, OEE contains two other factors.

Another element considered is availability, that is the difference between the potential  operating time of a machine/piece of equipment and the actual time required to manufacture a product. The third element, complementing OEE is quality, as a comparison between the number of pieces produced and the number of pieces that meet the customer’s requirements.

Why implement TPM?

TPM is a new approach to machine and equipment maintenance management. Equipment management according to TPM principles involves the prevention of quality errors, machine breakdowns and machine adjustments. TPM provides operators with considerably easier and safer work conditions. It is a continuous improvement  technique based on the cooperation of all company departments.

Goals of TPM

·      Strengthens the company by maximizing the effectiveness of the manufacturing system

·      Deals with the manufacturing system in a comprehensive manner and creates a concrete loss prevention system based on workplaces, and encompasses such elements as elimination of all accidents, defects and breakdowns

·      Everyone participates in TPM, starting from the management and ending on sho-floor staff

·      TPM applies to all company departments, from production to the construction office, sales and administration

Why implement TPM?

Nowadays equipment is becoming more and more automated and sophisticated, so there is no exaggeration in claiming that it is machines that create products. The role of people is to maintain equipment in such a technical condition as to ensure its proper performance- failure and defect-free. This is not possible, though, if machine maintenance is limited only to maintenance specialists, as it was common in the past. Total productive maintenance requires the involvement of machine operators and machine constructors, as well as the designers of the products themselves.

Six Sigma

Six Sigma is a systematic and very effective set of procedures strictly related to the implementation of proven quality principles and related techniques. Six Sigma aims for error-free business management. Sigma, a letter in the Greek alphabet, is used in statistics to measure process variability. Therefore, effectiveness in a company is measured by the sigma level of processes run therein. The majority of companies have accepted the level of three or four sigmas as a standard, although their processes generated from 6200 to 67000 defects per million opportunities! Six Sigma is based on proven tools which have been united into a logical pattern, allowing precise and reliable assessment of all deficiencies within an enterprise. The Six Sigma standard, namely 3.4 defects per million opportunities, is a response to the growing expectations of customers and the increasing complexity of modern products and processes.

The tools are introduced by means of a simple effectiveness improvement model, called DMAIC and consisting of 5 phases, namely: define, measure, analyze, improve, control

DMAIC may be described as follows:

Define improvement goals. At high level, the goals will be the strategic objectives of the company, such as higher return on investment or larger market share. At operational level, an increased productivity of the manufacturing department may be one of the goals. At the project level, a reduction in defects and increased productivity may be the goals. First of all, define the problem which you want to subject to 6 Sigma analysis.

Measure the existing system. Determine standards and formulas, to facilitate the process of monitoring progress in attaining the goals set in the previous phase. Begin by determining the current status of the problem.

Analyze the system or process to identify ways of eliminating discrepancies between the current impact of the system/process and the goals set. Interpret analyzes using statistical tools.

Improve the current system. Use your creativity to find new ways of doing things better, cheaper and faster. Apply project management or other planning and management tools to implement the new idea.

Control the new system or process. Introduce information about the improved system or process, regulations, procedures, budgets, operating instructions and other management elements.

5S

5S is a group of techniques for organizing the workplace. It is the foundation for changes and standardization upon which any improvement can be built. Although it is often referred to as housekeeping, it is much more than that. It is a method for systematic learning of discipline and standardization. Although the tools applied in 5S are very simple, many people, who come upon them for the first time consider them rather useless in the improvement of effectiveness. One can often hear statements such as: "we’ve been through this before”, “let’s focus on important matters first” or “it’s beyond my scope of responsibilities”. Such reasoning often leads to situations where we waste time on cleaning actions carried out solely in anticipation of important guests, instead of introducing more systematic solutions. 5S offers this methodical approach through consistent observance of the program’s rules. The 5S program consists of 5 simple rules that organize the workstation and workplace.

These are:

The first S – Keep you workplace in order.

The primary objective of this stage of implementing 5S rules is to eliminate items that are not needed. Remember that the word “eliminate” does not necessarily mean “discard”. In this case elimination means the removal of unnecessary items from the area where 5S rules are being implemented. You need to decide what is needed and should be kept, and what is unneeded and should be removed from the area but can still be useful in another company area, and what is absolutely unnecessary and can be discarded. The  basic technique used in removing unnecessary items is red tagging .

The second S – Keep your workplace clean. The aim of this stage in 5S implementation is to use cleaning-up for identifying irregularities and areas that require improvement. A clean workplace and keen observation help us spot any irregularities or areas we still lack control over.

The third S – Find a storage location for every item. Identify the locations and introduce quantity limits. The goal of this stage in 5S implementation is to determine a specific location for specific items stored in specific amounts, where necessary, and to identify these locations adequately.

The fourth S – Introduce principles for organizing your workplace. Present them in the form of standards. The aim of this stage in 5S implementation is the consolidation of the first three rules by setting model standards and procedures to be followed in a given workplace.

The fifth S – Sustain the set standards and improve them if necessary. The goal of this stage in 5S implementation is to sustain and enhance improvements by effective use of a schedule for checking whether workplace standards are observed and whether they meet current needs.

Kanban

Kanban is a critical tool in the “just in time” system, which manages the warehousing and manufacturing processes to supply customers with what they need, at the exact amount they need and when they need it.

The Kanban card is the main source of information signaling that a customer has ordered particular materials. When the supplier receives a Kanban card, this is the signal to launch production.

The Kanban card contains the following information: name of the product manufactured, number of products in transport bin, card number and details of the product supplier. The Kanban system significantly facilitates communication between product suppliers and customers, as it indicates what needs to be done in response to the demand.

The Kanban system is based on a supermarket concept. Customers pick items from the supermarket. Items produced by suppliers are transferred to the supermarket. Each bin (container, box, etc.) in the supermarket contains a Kanban card, which is handed over to the supplier, once the stocks finish. The supplier stores the Kanban cards on the production planning board. Each item included in the system has minimum and maximum levels set. Upon production launch, the card is attached to the bin, and after manufacturing the required items, it is transferred together with the bin to the supermarket. It is a closed-circuit process.

In Kanban systems, production instructions are directed downstream to the end operations, which respond to the instructions by “pulling” relevant materials from suppliers. Suppliers, on the other hand, in response to the Kanban cards replenish the supermarket stocks with the agreed supplies. That is why the Kanban system is often referred to as a “pull system”.

An average of 20-30% of items in every company can be serviced by the Kanban system. This 20-30% of the so-called renewable production (for some standard production) accounts for 70-80% of the turnover in terms of quantity. Thanks to Kanban, production planning for these materials can be practically eliminated.