Error correction management in the manufacturing p

2022-08-17
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Error correction management in the manufacturing process of injection mold (Part 1)

mold is a single product produced by multiple processes and comprehensive processing means. In the whole process from product design to production completion, there are hidden mistakes that may erupt everywhere. If you are careless, mistakes will appear and affect your normal production. B. adopt PID control strategy to realize closed-loop control of displacement, which affects your mold delivery time, mold acceptance and use, and also affects the reputation of your enterprise. Whether large-scale mold factories or small-scale mold factories, this is often a headache for managers. To a certain extent, the process of molding is the process of error correction (for mold factories with poor management) or error prevention (for mold factories with a certain level of management). Error prevention is the most basic quality of a mold worker in the operation process of hydraulic pressure testing machine. To evaluate the excellence of a mold worker, just look at his error prevention ability. An excellent die maker rarely makes mistakes. Whether it is subjective or objective reasons, he can take precautions in the process of operation and successfully achieve his goals. As the director of mold production, we should have such ability

how to prevent errors in single system engineering such as mold processing

first, designer

mold design is a key link between the preceding and the following, which is the understanding of new products (plastic parts), and the following is to provide reasonable design (economic structure and reliable action) to mold workers, so as to satisfy product developers, mold manufacturers and mold users. It may be a little biased to say that the mold is designed, but the quality of the design level is really the key to the success or failure of the mold

how to prevent mistakes in the design process

the so-called "prevention" refers to places that are prone to mistakes. Experience tells us that mistakes in design are often: failure to understand the product drawing, unscientific arrangement of cavity number, wrong selection of mold materials, improper selection of plastic shrinkage, poor workmanship of mold structure, which makes processing easy to make mistakes, or make positive and negative mistakes, etc

(I) principle of digesting product map:

1 Be sure to find out the structural deficiencies or errors that do not meet the requirements of the injection molding process; 2. Put forward better and more feasible suggestions for product drawing improvement; 3. Try to move closer to the mold process on the premise that the abetting light should be on without affecting the product function

(4) for plastic parts with complex assembly relationship, the first plate must be made first, and its forming scheme must be analyzed intuitively from the first plate

(II) selection of parting surface:

1 The first key point of how to go about the classification is not to affect the appearance of the product

2. Secondly, the second key point of parting is that the mold will not stick; The direction of parting should be the easiest to process, and it is easiest to ensure that there will be no cracks, that is, the simplicity of processing, the economy of processing and the reliability after processing should be considered, which is the third key point

(III) determination of the number of cavities:

some plastic parts, such as some consumer goods, are used in large quantities by users. The more cavities, the better. Dozens of cavities and hundreds of cavities in a the first mock examination reduce the cost of plastic parts and improve efficiency. This is understandable. But usually, the more the better, the more cavities, the mold not only increases the volume, but also needs to be used on the injection molding machine with large tonnage. The large power consumption increases the cost, and the mold is complex, more difficult, and the cost of the mold will also increase. How many cavities are the most reasonable, economical and practical? As a mold designer, I should advise customers. The final quantity of products, the manufacturing cycle of the mold, and whether the equipment using the mold is manual or automatic, all affect the choice of the cavity. Unrealistic multi cavity often makes the mold fail or makes the production process difficult

(IV) analysis of mold structure:

1 Pouring method

if the customer requires the plastic parts to fall off automatically, the submerged gate is required; If the customer has no special requirements, side pouring shall be adopted; If the part is large and the flow ratio cannot ensure filling, a small nozzle shall be used; If continuous automatic injection, hot gate is used. (hot runner system is used for multi cavity)

if the reliability of filling is not fully guaranteed, filling analysis (using Moldflow analysis software) should be carried out to obtain the analysis data of filling pressure, filling time, filling temperature change, weld line and exhaust position, so as to prevent possible design defects to the greatest extent

2. Generally speaking, the mechanical type is reliable and the hydraulic type is simple, which can be selected according to the characteristics of plastic parts

3. Ejection method

according to the characteristics of the data (for example, the transparent parts are not allowed to have ejector marks inside), select ejector, pneumatic, push plate, automatic and other methods to ensure that the requirements of the use and the plastic parts themselves are met

4. The cooling method (straight hole, circulation, single layer, double layer, multi-layer, spacer spiral type, slender spray type in the core) should be fully considered, and the cooling cycle diagram should be made separately to analyze whether there is interference with other hole positions and whether it is easy to process

5. Exhaust mode: location, exhaust structure

6. For the clamping of the mold, the multi-directional core pulling device and the cooling inlet and outlet position of the mold often occupy the lifting eye hole or the clamping position of the mold on the injection molding machine. It should be considered comprehensively and should not be corrected until the pressing plate cannot be clamped

7. Whether the simplest process method is used to evaluate the process performance of the design

(V) selection of cavity materials and other structural parts materials

1 Choose hard steel under general conditions; 2. Heat treated hardened steel with high precision and long service life; 3. Stainless steel shall be used for corrosion protection, and flaw detection shall be carried out for thick ones to prevent cracks. The materials must be clear and correct, and the hardness must be selected appropriately to prevent the use of wrong materials, and even more to prevent the use of fake materials

(VI) selection of shrinkage

the same plastic has different shrinkage, toughness and strength. There is still a large gap between the basic key materials, technology, manufacturing process and the international advanced level, and different transparency. High precision molds have clear requirements for the brand and origin of materials. For precision molds, the choice of shrinkage should be careful, but first of all, the brand of plastic should be clear, and it is best to use the old mold to try its exact shrinkage first, and then use the data in the design of the new mold

II. Die workers

(I) the whole process of design is full of feasibility questions. As a qualified die worker, we must first digest the drawings and put forward three questions:

1 Is there anything inappropriate in the design? 2. Is there anything else that can be improved? 3. Is there a better scheme to replace the existing scheme and eliminate the possible errors before the molding

the main starting point for raising the above questions:

1 Does this design ensure the requirements of the product drawing of plastic parts? 2. Is this plan the most error prone in the implementation process? 3. Is this scheme the most reliable in the processing process? 4. Is this the most time-saving and economical plan

if the answer is no, or vague and ambiguous, it is necessary to study and analyze carefully. At this time, the designer should fully respect and listen to the opinions of experienced masters, and don't be self righteous, because in the end, if something goes wrong, the labor of workers will be wasted

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