Seven Tips for Quick Die Change
Brief Introduction of SMED
SMED, Single Minute Exchange of Die, “instant exchange of die in one minute”, usually called quick die change or quick production change, is a fast and effective operation switching method. This concept points out: All transitions or star-up can and should be less than 10 minutes. That’s why there is the term “single minute”, it is also called single minute rapid mold change and rapid operation conversion.
In fact, it is a method used to continuously improve the difficulty of rapid equipment adjustment, shorten the line change time to the shortest as much as possible, and even realize instant line change. It can quickly switch an ongoing production process to the next production process.
The main purpose and benefit of SMED is to reduce the time waste of work operation and the number of products in progress. Thereby increasing the switching number, realizing small batch production, increasing the flow rate and shortening the production cycle. At the same time, it can meet customer requirements without additional inventory.
In the process of implementing SMED, there are seven recommended techniques for reference.
Recommended Techniques for Quick Die Change
Tip 1: Parallel operation
The so-called parallel operation refers to two or more people jointly engaged in the switching action. Parallel operation is the easiest way to immediately obtain the effect of shortening the internal operation time.
It may take an hour to complete the switching action by one person slowly. If two people work together, they may complete the action in 40 or 20 minutes. Then the entire switching time is reduced from the original 1 hour to between 20 minutes and 40 minutes. The labor time required in parallel operations may increase, remain unchanged, or decrease. But this is not the focus of consideration.
Because the other effects obtained by shortening the switching time are far greater than the labor cost, which is easily ignored by ordinary people. When engaging in parallel operations, the coordinated actions between the two must be practiced skillfully, especially safety. And make sure no accidental injury caused by negligence.
Tip 2: Do not move your feet
The switching action is mainly by hands, and don’t move or walk unless necessary. Therefore, to reduce movement, the needed tools, molds, cleaning, etc. for switching must be placed on a special trolley. Besides, they must be sorted in order to reduce the search time.
Molds or moving lines for switching items must also be designed in a way that is easy to enter and exit. And the sequence of switching actions must be rationalized and standardized.
Tip 3: Special props
The so-called tools are general-purpose appliances. Props are special-purpose appliances. Just like the playing cards used by the magician’s performance, they are specially designed. If you buy ordinary playing cards at a stationery store, it will be more difficult for the magician to perform some wonderful magic. So the tools used by magicians are called props, not tools.
The mold-switch action is to use props and not tools as much as possible. Because props can improve the efficiency of switching, and shorten the switching time. In addition, the measuring instruments should also be made into props. And block gauges or grid bars should be used instead of measuring scales or meters to measure the reading values.
The most important point is to try to reduce the types of props, in order to reduce the time to find, pick and put into the game.
Tip 4: Remove screws
When switching actions, screws are the most common method used to fix the mold. The use of screws is of course necessary, but the action of fixing and unfixing screws usually takes up a lot of time.
If you observe carefully, you will find that the screws abusing is common. For example, originally only four screws are enough, but six are used. There are too many screw turns and it takes time. The screw, the real function of tightening is only the last lap. Therefore, the best countermeasure for improvement is to eliminate the use of screws.
For example, you can use bolts, pressure rods, mold clamps, card sockets, shaft cam locks, positioning plates, etc. to replace the use of screws.
Tip 5: Set at a turn
Limited to certain conditions, when bolts and screws must still be used, try to reduce the time for tightening and removing the screws. The goal of improvement is to be able to achieve the locking function without removing the bolts and screws. The main method can be tightening or loosening with only one rotation.
For example, the C-shaped opening washer can be placed under the nut. After the nut is loosened one turn, the C-shaped washer can be removed from the opening. When tightening, the reverse operation is performed, and the tightening can be achieved by only one rotation. In addition, methods such as gourd holes can also achieve this purpose.
The second method is to fix the height of the locking part. The overly high locking part should be cut down to the standard height. While the overly low locking part can be added with a pad to achieve the standard height.
After the height of the locking part of each mold is standardized, the tightening part of the nut will not change. This can reduce the number of rotations for locking and loosening. And of course, it also reduces the switching time.
Tip Six: Skillful machine operator
Due to different products, the different molds or working conditions must be changed. That’s why the switching actions are necessary. Therefore, adjustments must also be made and new standard operating data must be set again.
The adjustment action for the machine data usually takes about 50% – 70% of the entire switching time. The skillful machine operator is the key point to save this time .
Tip 7: Preparation beforehand
The necessity of Preparation
Preparation is a work that belongs to outside operation. If the external operation is not done well, it will affect the smooth progress of the internal operation and make the switching time longer.
For example, if the external work is not fully prepared, during the internal work, we may not find the required props or the mold is wrong, defective, etc. Then, it is necessary to temporarily stop to find the props or repair the mold. And that will cause the internal work time to become longer.
How to standardize the preparation work
Therefore, the action of external work should also be improved and standardized. Set up a special cart for mold change. Then, put all the required molds, props, mold change schedules and related equipment on the trolley to reduce individual searching and transportation.
The place where the mold is placed should also be clarified. And the storage place should be marked with a meaningful number. The storage of utensils, instruments, and props should not be placed by function, but should be placed in special boxes made of different products or molds.
Set up a checklist to assist in checking whether the equipment required for inspection is complete. In addition, compile a standard switching procedure table, and distinguish operations and implement grouping.