1. SMED is the basis of leveling

1. leveling production

there is an effect in the supply chain called' bullwhip effect', which means that a small change in demand of end customers will be gradually amplified in all links of the supply chain. From the overall situation of supply chain, this phenomenon is the main reason that directly leads to inventory waste and excessive production waste.

the reasons for this effect include:

1) mass production, such as low switching ability of high-speed equipment and excessive processing batch

2) using data of direct customers instead of data of end customers

3) lack of ability to respond to real demand, such as long manufacturing cycle and inflexible manufacturing system

4) some information systems will enhance this effect

. Excessive processing batch

2) Using the data of direct customers instead of the data of end customers

3) Lack of responsiveness to real demand: for example, the manufacturing cycle is long and the manufacturing system lacks flexibility

4) Some information systems will enhance this effect

From the level of leveling, It can be measured by EPE (product interval time) index:

EPE=EPE = product type/switching times

The technical route to achieve leveling includes four stages:

Stage 1: Establishment of production flow, mainly for layout optimization and production line design, so as to establish the physical basis of flow and realize basic rectification. At the same time, the standard operation is established to make the 4M stable. Then through SMED, the switching ability between products can be improved to support the flow. Finally, the effect to be achieved is that a single production unit and process form a flow, stability and flexibility.

stage 2: internal logistics, which drives internal logistics and information flow through supermarkets and material distribution, and realizes process synchronization through Kanban and Junjo. Through the leveling and pulling plan, the goods are gradually pulled forward from customers to form a pull, avoiding internal manufacturing waste and realizing leveling.

stage 3: external logistics

(2) smed

the concept of smed was invented by Japanese Shigeo Shingo (しんごしげぉぉ), whose value lies in helping to lay a solid foundation for leveling, and in improving production capacity and equipment.

In 1969, it took 4 hours for Toyota 1111t punch to change dies, while Volkswagen only took 2 hours. Taiichi ohno wants to catch up with the public. It took Shigeo Shingo six months to separate the internal mold exchange from the external mold exchange, and gradually improved all the operation contents and procedures in each step, and the final time was shortened to 1.5 hour.

Ono continued to ask him to shorten the time to 3 minutes. At first, Shigeo Shingo thought it was impossible, but he soon came up with a new method to shorten the debugging time. After several months, this goal was achieved. Under the challenge of Shigeo Shingo, it took Ford only 1.2 minutes to replace the mold. This was a great achievement in 1986. However, Xinxiang is still not satisfied, and the challenge is completed within 11 minutes. A few months later, Ford reported that the replacement time had been shortened to two and a half minutes.

With the development of technology and the deepening of improvement, die changing has made a further breakthrough. At present, the fastest way is OTED (Die Changing at One Touch)

To implement SMED, the definition of die changing time must be made clear first. Usually, die changing time consists of two parts, namely, switching time adjustment time. Its specific definition is' the total time from the last product to the first product and normalization.'

In the process of implementation, many enterprises only pay attention to the switching time and ignore the adjustment time. From our counseling experience, the adjustment time is actually more critical and longer.

First, the method of introducing SMED

1. Selecting the pilot: It is suggested to start with the pilot, rather than fully implement it. The role of the pilot is to focus, achieve rapid breakthroughs in a short period of time and set a benchmark.

2. establish a team: establish an inter-departmental promotion team, which generally includes: technology, equipment, molds, quality, production, logistics, etc. At the same time, it is necessary to consider the role of team leader when promoting, and generally choose the strong person with open mind, familiarity with processes and communication skills as the organization.

3. Determine goals: Set short-term (3 months), medium-term (half a year) and long-term (1 -3 years) goals according to the SMART principle. General enterprises can shorten the mold changing time by 51% through the improvement of methods, and can shorten it by 81%-91% through further technology, equipment and mold improvement.

4. Start implementation: observe, analyze and improve with SMED method

(1) The first round of improvement can be started with improvement week, in order to quickly form a breakthrough effect in a short time, and appreciate the essence of improvement as fast as lightning and temper the team in the process of improvement.

(2) In the process of improvement, we should pay attention to different types of mold changing and set corresponding targets to avoid one size fits all. It is also necessary to strategically select some types of switching as priority improvement, and generally, the one with the largest mold changing time * mold changing times is the priority improvement object.

III. Introduction of SMED method

(1) Research on the current situation of die changing: record the whole process of die changing by video, and then record all steps and time in the analysis table of die changing in the meeting room.

At the same time, it is necessary to observe the operator's moving line to form the spaghetti diagram. An excellent moving line has three typical characteristics:

1. The moving line is simple, and there is no long-distance walking and detour

2. In the process of changing the mold, people do not need to drill in and out of the equipment

3. After changing the mold, the clothes will be kept clean, and the body will not be dirty because of changing the mold

. People don't need to drill in and out of the equipment

3. Clothes will be kept clean after mold changing, and people won't be dirty because of mold changing

In this step, it is also necessary to record the preparation of tools, logistics, parts and so on, and insufficient preparation is a significant problem in the process of mold changing.

(2) Distinguish between internal and external die changing: distinguish between internal and external die changing based on the basic definition. Attention should be paid to the distinction between external mold exchange (front external mold exchange and rear external mold exchange) and internal mold exchange (preparation, mold exchange and adjustment), which is very important for improvement.

(3) the transformation from internal mold changing to external mold changing: this step is the key step to effectively shorten the mold changing time. During the implementation process, the team needs to effectively ask questions and think about each step, and whether it can be converted into early completion. Specifically, there are the following aspects for reference.

1. Heating and cooling in advance: injection molds often encounter such problems

2. Cleaning in advance and cleaning afterwards: injection molds and die-casting molds have such problems, and it is time-consuming to stop the machine for cleaning during mold changing, and the cleaning effect is not good. It is best to open the mold online for cleaning and do a good job of preservation.

3. die height uniformity: this kind of problem usually exists in both stamping dies and injection dies, and the fundamental reason for its formation is that the problem of die replacement is not fully considered when the product is introduced, and there is a height difference in the dies. As a result, the height needs to be adjusted during the mold changing process. If the mold height can be unified, the mold changing time can be greatly shortened

4. Reduce waiting problems, such as waiting for driving, forklifts and finding tools. This kind of problem was originally supposed to be external mold changing, but due to the lack of effective arrangement and preparation, it changed to internal mold changing. Need to be improved. In the process of mold changing, the best way is to completely eliminate the problems such as traveling crane and forklift, and the best solution is to design a turnover trolley or a translation trolley without using traveling crane or forklift at all, because this kind of handling tools always has the problem of being occupied, and it is difficult to maintain the improvement results only by coordination.

5. Lock in advance and install in advance: If some molds need to be installed with oil pipes, water pipes and additional devices, they can be installed before changing molds to avoid downtime.

It is important to pay attention to the role of the team in the implementation process, and only after full discussion and thinking can we put forward good countermeasures. It is best to discuss each specific step in the process of implementation with reference to the Form for Die Change Analysis.

(4) Shortening of internal mold changing time: After the previous step is advanced to a certain extent, it is necessary to further shorten the mold changing time, and it can be further shortened by improving tools, equipment, molds and processes. Specifically, we should make breakthroughs in the following aspects.

1. Reduce the locking time of bolts and screws.

the screw bolt is the natural enemy of quick die changing, and it should be improved from the angle of screw bolt-free. Such as electromagnetic locking and hydraulic clamping.

it can also be changed into quick lock and quick release device.

when bolts and screws must exist, they can be improved from the aspects of types of bolts and screws, and unified to fewer specifications and types as far as possible (for example, external hexagon is more difficult to be damaged than hexagon socket head bolts)

Locking tools can also be further improved, such as manual wrenches can be changed into electric tools, pneumatic tools and booster rods, which can speed up locking. However, at the same time, it should be considered that the tool has the function of torque setting, so as to avoid the damage of bolts and screws caused by uneven locking or excessive locking.

2. Simplify adjustment and avoid adjustment

Adjustment includes positioning adjustment, parameter adjustment and program adjustment, which need to be analyzed and improved from two aspects

. Positioning adjustment can be realized by establishing auxiliary positioning devices

. Adjustment can also be realized by completely changing the action function of equipment, such as the positioning mode composed of multiple cylinders, which can be designed as long as the tooling is changed. There is no need to adjust the cylinder

. Shortening the adjustment time is often related to the equipment accuracy, and TPM must be done in daily life to ensure the equipment accuracy

. Parameter and program adjustment is often related to the equipment accuracy and mold accuracy, so it is necessary to improve its accuracy and stability from these two aspects. At the same time, the parameters should be recorded and stored in the equipment, and even edited and called off-line.

3. Completely eliminate the problem of finding and placing: combine with 5S and visual management

4. Quickly remove and load the mold: forklift and forklift are not only easy to wait, but also difficult to remove and load for a long time. The best way is to use the mould changing trolley, or to get off in translation.

5. parallel operation: through reasonable division of labor, what one person completes can be changed into two people working at the same time, which can further shorten the time of internal mold changing.