Many mold designers take a product and start to rush into mold. In fact, don't rush to split mold after getting a product. The most important thing is to check product structure, modification of product tolerance and draft. Some products will also have a step difference. When you have processed parting surface of product in the early stage, structure and position of gate can be basically determined. Of course, these are ultimately confirmed with customer.

 

Some mold designers may ask, is it possible for me to start designing mold after I have analyzed product structure? Answer is of course not. If you want to avoid trouble to make changes in the design, then you must understand customer's requirements for mold.

If this confirmation is not accurate, you can't confirm entrance diameter of mold's sprue sleeve and locating ring, size and position of ejector hole, even size of mold base, and even height of mold, etc. You have worked hard to design a set of mold structure and also have a sense of accomplishment, but mold can not be produced when delivered to customer. If thickness of mold is not compatible with customer's injection molding machine, customer will not accept the mold you designed.

 

It is not taken for granted that plastic shrink rates of ABS must be 0.5%. This must be confirmed with customer. It is necessary to know what grades materials are ultimately used for production, whether or not to add any modified materials. When conditions permit, it is best to be familiar with assembly relationship of product and use of product, etc. This information is very helpful for future design of mold. Because only by understanding these, you know which ones are appearance and which are non-appearances. Which areas of draft angles can be increased and which areas cannot be changed. Even including structure of some products, if you understand actual assembly relationship and use of product, you will know which reverse structure can be canceled or changed to another simple form. It is important to keep in mind that process of making a mold is a process of simplification of complex problems. I often see that some people are proud that they have finished a complicated structure. It is very ignorant. Because many product engineer may design some unreasonable structures due to their own experience. If you can't correct them as a downstream process, they may always think that their design is okay. Then progress of our product designer will be very slow. As shown in figure below, position of slanted top where product designer doesn’t consider carefully, must be put forward by our mold designers.

Only after understanding customer's requirements before design, you can have a predictable design waterway. You have worked hard to design a set of mold, but you will find that customer needs to add other standards inside mold: date stamp, lettering insert, exhaust inserts. At that time, if you change it again, it is estimated that you will be tired and half dead, because your waterway, ejector, and screws are all already in layout.

First is parting mold. This process is estimated to be a process that everyone likes. Because of sense of accomplishment. Principle of parting surface is simple, that is, parts that can be stretched out is not scanned, or other advanced commands are used. Secondly, when you want to parting surface, you need to have a big picture and try to simplify parting surface. If it is not a precision mold, those 0.1~0.5 insertions can be avoided. In addition, parting surface must follow a principle, that is, try to follow product trend. Parting surface that was made in that way will be more conducive to fitter master fitting mold. When using UG software, it's important to remember principles of each command, so you know when you can use that command. Many times it's not important that you don't know how to use software, but you won't learn to use software. Same command, experienced people will have a variety of flexible usage, which is the most obvious in UG. In a word, important thing is idea, not the tool itself. When doing parting surface, you only need to know that angle of insertion surface can be large, area of collision surface can be large, and width of occipital can be wide. It is necessary to fully consider actual mold of parting surface that you are do now is finished in the future, master who is responsible for fitting mold in the workshop will not be jealous of you.

 

It is also necessary to consider layout of slider and lifter while making parting surface, because those also involve modification of parting surface. Typical slider structure is a trigonometric function relationship. This is fine if you can calculate it more times, but make sure that angle of oblique guide column is not too large, try to achieve 25 degrees or less. Principle of inclined guide column is that it can be thick, not too small, because inclined guide column must be strong. In addition, slider is also divided into many variegated structures, such as upper inclined slider, inner suction slider, cylinder pumping, front mould slider, slider with reverse ejector, slider with lifter, and so on. These special structures make full use of trigonometric function relationship, purpose is to achieve demouding of product buckle, normal opening and closing of mold.
Followed by lifter, lifter is more flexible, but angle of typical lifter is not too big, try not to exceed 15 degrees. Of course, you have to do 20 degrees, life is hard to guarantee, and movement will be very smooth. Specific principle refers to trigonometric functions and theoretical mechanics. There are many evolutions for shape of lifter, for example, slanted lifter, large lifter with a round bar, small lifter with a splicing platform, lifter under top block, lifter on slider, and so on. All of these structures target on one purpose, using trigonometric functions to make product's undercut. This shows how important it is to learn trigonometric functions!
As for various special structures, people think of it. You can make full use of your imagination. No matter what kind of structure, you can just think about it. After thinking, go to bold design. Maybe you have a new invention, but after designing, it is necessary to verify relationship of trigonometric function, which is to simulate opening and closing of mold under actual simulation, and to consider whether there will be problems during injection molding. Next step is layout of mold structure. These contents are to be sorted out in advance. According to actual situation of product, different types of mold structure are selected, for example, two-plate mold, three-plate mold, hot runner and so on.
All mold structure types are designed to be able to achieve mass production of product. When choosing a mold base, we must fully consider considerations just mentioned.
After selecting mold base, we have to consider inlay of mold. Principle of inlaying is to simplify processing, save materials and facilitate product molding, such as exhaust. For parts where you feel that there is very thin on the mold, it must be set separately and easy to replace in the future. When inlaying, consider strength and workability of insert, designability of waterway in the future. After inlay is finished, it is necessary to add standard parts. Principle of adding standard parts is kay parts first, then local parts, and try to arrange balance symmetry. Generally, it is necessary to add on ejector parts first. When adding mold ejector pins, it is necessary to consider layout of waterway. Under normal circumstances, it is necessary to give priority to layout of mold ejector pins, then generally design waterway, and adjust waterway ejector according to actual situation to balance these two. Principle of mold ejector pins is to add to the place where holding force is strong. In addition, it should be added to bone position and place where strength structure is better, so as to avoid whitening or imbalanced ejector.
Actually principle of waterway is principle of ejector. Because in general, place where product is tight is also hot spot of product and part where cooling needs to be strengthened, This contradiction needs to be adjusted well. As for whether to use a ejector, a top block or a push plate, specific analysis is needed. This should be analyzed in combination with structural characteristics of product. For example, if product is easy to stick to front mold, it is necessary to consider whether to add reverse buckle in back mold, or to add ejector to front mold. These are natural things, but many mold designers will not think comprehensively. Why? It is because there is no adequate analysis of product structure, and there is no practical consideration for state of product during injection molding process. This is the key to problem. After eject waterway has been added, the rest are some messy standard parts. You should consider symmetrical balance when adding. After design of the whole set of molds is completed, following checks must be done. First is draft analysis of inserts to see if there is any undercut, followed by interference check for various parts of mold, which is the most important. and interference check of the parts of the mold is the most important. Then there is simulation of mold opening and closing action. If mold is not too clear, it must be simulated. In addition, machinability of various parts of mold and assembly process of mold. Please do not work hard to design a clever structure, theoretical calculations are no problem. After processing, result is that it can not be installed (especially structure of tunnel slider), or poor assemble.
General process is over. In fact, molding design is a matter of contradiction. If you want to design a perfect one, cost of mold will be high. If you want to design a simple one, you may have to change product or strength of mold, and service life will have an impact. So molding design is not absolute. As long as you find a balance point, mold you designed is successful. Therefore, structure designed by others may not be suitable for you. As long as you follow above molding design points, we can design a more reasonable mold structure.