Industries are struggling for efficiency where it is necessary to generate and meet a demand for a product in the market, optimize their processes to reduce errors, improve quality, eliminate waste, reduce costs and risks and maximize productivity, consequently, profitability.
Not only competition between industries, but the increase in customer requirements, both for quality and delivery time, lead industries to seek solutions and methodologies to make them more efficient. Among them, the most well known and successful model is Lean Manufacturing.
A Brief History of Lean Manufacturing: In the second decade of the twentieth century, the production model online, created by Henry Ford, worked very well, but only for the manufacture of nearly identical products. When the market started to demand varieties of products with different specifications, the model did not respond as well. This led industries to regress in the manufacturing model to produce different product models, which again filled the factory floor with machines, increase production time and stock.In 1930, Toyota executives analyzed this situation and created a model that would serve both the flow of processes (which optimizes production) and production diversification (which meets market demand). There was born the Toyota System of Production or Lean Manufacturing.
The losses can be classified into eight large groups, they are:
1. Loss due to overproduction.
2. Waste of material waiting in the process.
3. Waste of transport.
4. Waste of processing.
5. Waste in the operations.
6. Losses due to production of defective products.
7. Stock losses.
8. Waste of knowledge and skills of employees.
1)LOSSES DUE TO OVERPRODUCTION: Overproduction is one of the biggest sources of waste and is the most difficult to eliminate. There are two types of overproduction: the quantitative and the anticipated.
- Quantitative overproduction: occurs when it is produced beyond what is requested, in other words, more than a batch of economic output. For example, a customer places an order of 480 pieces and the manufacturer decides to produce 580 pieces. At the end of the process the surplus will be in stock.
- Overproduction by anticipation: occurs when the company decides to manufacture the product prior to its request. Example: a factory decides to anticipate its production for 45 days, soon there will be an anticipated consumption of manpower, raw material, energy and physical space necessary for the storage of this material for 45 days.
The main consequences of overproduction for organizations are:
- Intermediate stocks;
- Long lead Time;
- High cost of storage;
- Difficulty in identifying and managing materials, etc.
- Low commitment to quality; In view of this, the Toyota Production System teaches us that we must produce only what is necessary, enough to meet the needs of use and processing. The causes of overproduction are related to failures in productive processes, such as:
- Calculation error in determining demand and production planning;
- Low level of equipment reliability, which leads the company to produce more than necessary;
- Long setup period (preparation of machines and equipment on assembly line).• More setup time leads the company to produce more to compensate for the time the machine or assembly line stands still;
- Quality deficiencies in manufacturing processes, which leads to waste and rework;
In order to minimize losses due to overproduction, the following actions can be implemented:
- Carry out adequate demand sizing as well as realistic analyzes of the market and consumption. In other words, production must be “pulled” by consumption and not “pushed” by consumer offer.
- Implement maintenance systems (preventive, predictive and corrective) and Total Productive Maintenance – TPM for the purpose of increasing reliability and performance;
- Raise the level of quality in the processes;
- Implement a rapid tool change system, etc.
2) WASTE OF MATERIAL WAITING IN THE PROCESS: Occurs when the purchased material is left waiting for its processing. When part of the material has been processed, the rest awaits the availability of the equipment to finalize its processing.
There are basically three types of loss per wait:
1.Loss due to process waiting: a batch is waiting for the processing of the previous batch until the operator and the equipment are available;
2.Loss for batch waiting: occurs when the processed parts of a batch are waiting to process the remaining batch before they can move to the next operation. Example: a batch of 2000 pieces begins its processing and is in the first piece, after being processed it is the waiting of the remaining 1999, because only with the complete batch it is passed to the next operation.
3.Loss due to operator wait: occurs when the part has to wait for operator availability.
Main causes of material waste waiting in the production are:
- Production bottlenecks;
- Layout not suitable for production processes;
- Lack of synchrony in production;
- Production batch greater than the consumption needs.
Procedures for waste reduction:
- Reduction of production bottlenecks;
- Planning and definition of the appropriate physical arrangement to improve the production flow;
- Implementation Study Tools times and methods;
- Sizing production batches so that they are as small as possible.
3) WASTE OF TRANSPORT: Transport losses are related to the movement of goods throughout the process (from receiving to shipping) and generate costs and do not add value to the product. Therefore, such waste should be reduced by eliminating movement between the lines or other areas of the process.
The main causes of transport waste are listed below:
- Unnecessary and unplanned movement;
- Inadequate transportation systems;
- Inadequate factory layout.
To eliminate this type of waste:
Move the material as little as possible with the maximum possible capacity;
- Mechanize and automate transport to reduce costs and increase productivity;
- Improve the layout: approximate stock of material from the workstations and processing steps; eliminate against material flow, facilitate access to the supply areas.
4)DESPERDÍCIO DE PROCESSING: Occurs when the processing is below the ideal state or when unnecessary actions are taken so that the product reaches the specifications of the project.
Causes of main processing losses:
- Errors in the sizing of machines and equipment;
- Errors in product project that cause unnecessary additional operations during production;To minimize processing losses, the manager can take the following measures:
- Improve methodology and process parameters;
- Use engineering and value analysis to focus on product project to simplify product structure while maintaining functionality and quality.
Edson Miranda da Silva Manager of Quality, Productivity and Sustainability.