德语
1. What are the major systems for molds?
Pouring → ejection → cooling → molding → exhaust.
2. What issues should be paid attention to during mold design?
(1) The wall thickness should be as uniform as possible, and the mold release slope should be large enough;
(2) The transition part should be gradually, smoothly transitioning to prevent sharp corners;
(3) Gate: The runner is as wide and thick as possible, and the gate position should be set according to the shrinkage and condensation process, and if necessary, the refrigerated material well should be added;
(4) The surface of the mold should be smooth and have low roughness (preferably 0.8);
(5) The exhaust hole and groove must be sufficient to discharge air and gas in the melt in a timely manner;
(6) Except for PET, the wall thickness should not be too thin, generally not less than 1mm.
3. What are the common defects in plastic parts?
Glue missing → cloak → bubbles → shrinkage → weld marks → black spots → stripes → lift up → layering → peeling.
4. What are the structures of the mold frame?
Panel → Board A → Board B → Square iron → Guide column → Thread pin plate → Thread pin fixing plate → Bottom plate.
5. What are the basic forms of the parting surface?
Straight → Incline → Curved surface → Vertical → Arc surface.
6. What are the mold processing machinery and equipment?
Computer gong→Lathe→Milling Machine→Grinding Machine→Drilling Machine.
7. What is touch-through and what is interlude?
The male and female mold fitting surface parallel to the PL surface is called the through-through surface, and the male and female mold fitting surface not parallel to the PL surface is called the insertion surface.
8. What is the occipital position?
The edges of the shell-like plastic parts are often opened and have notches, which are used to install various accessories. The pillow-strength part formed here is called the pillow position.
9. What is a crater?
The shape of the glue-reduced part at the root of the BOOS column reflected on the mold after the volcanic eruption is called the mold crater.
10. What is ranking?
The product layout on the mold is called ranking.
11. What is glue position?
The cavity of the product on the mold is called: glue level.
12. What is bone position?
The tendons on the product are called: bone positions.
13. What is column position?
The BOSS column on the product is called: column position.
14. What is virtual position?
The gap on the mold is called: virtual position.
15. What is buckle position?
The hook used for connection on the product is called a buckle.
16. What is the material level?
The wall thickness of plastic products is also called flesh thickness.
17. What are weld marks?
The line formed when two strands of plastic meet is called a weld mark.
18. What is a jet?
After the plastic enters the mold cavity from the plastic inlet, it forms a curved and folded snake-like flow mark called a jet.
19. What is undercut?
The part of the product that cannot be directly demolded from the front and rear molds is called undercut.
20. What is Dingbai?
When ejecting, the mold force required is large and the ejection pin is not strong enough, causing the product to be partially ejected. Viewed from the front of the product, there is an obvious white mark called ejection white, which is also called the ejection nozzle.
21. What is the factory’s mold design process?
The customer provides product drawings → analyzes the product → confirms the plastic type → confirms the mold material → converts the engineering drawing → multiplies and shrinks to make a mirror image → perfect the assembly drawing → order the mold base → order the mold core material → draft → 3D mold splitting → determine the runner/gate mode → refer to the ranking diagram for structural design → dismantle the insert → correct the 3D → produce the project drawing "including: mold core/insert/mold base/parts" → make a BOM → proofread and review.
22. What are the glue feeding methods?
Direct gluing → Overlap gluing → Side gluing → Circular gluing → Sheet gluing → Latent type → Point gluing → Horn type gluing → Fan-shaped gluing.
23. Classification of molds?
Molds can generally be divided into plastic molds and non-plastic molds. Non-plastic molds include: casting molds, forging molds, stamping molds, and die-casting molds. Plastic molds are divided into injection molding molds, blow molds, compression molding molds, transfer molding molds, extrusion molding molds, thermoforming molds, and rotational molding molds according to different production processes and products. Molds can be divided into three categories according to the different types of gating systems: large nozzle molds, thin nozzle molds, and hot runner molds.
24. What is a pouring system?
The plastic flow channel from the injection machine nozzle to the mold cavity is called the gating system. The gating system includes: main channel, branch channel, gate and cold well.
25. What is elastic deformation? What is plastic deformation?
An object deforms under the action of an external force. When the external force disappears, the object can return to the deformation before deformation, which is called elastic deformation. When the external force disappears, the object cannot return to the deformation before deformation, which is called plastic deformation.
26. What are the positioning methods of male and female molds?
There are two types of positioning methods for the front and rear molds: one is: template positioning, the other is: mold core positioning.
27. Planning of mold size?
Each company has different standards for planning mold sizes, but the common standards are as follows: molds with 15-30 series mold bases are classified as small molds, molds with 30-50 series mold bases are classified as medium molds, and molds with 50 or above mold bases are classified as large molds.
28. What is reverse engineering?
Reverse engineering is a high-speed three-dimensional laser scanning machine that accurately and quickly scans existing samples or models to obtain their three-dimensional contour data. It then performs curve reconstruction with reverse software, conducts online precision analysis of the reconstructed surface, evaluates the structural effect, and finally generates IGES or STL data, based on which rapid prototyping or CNC machining can be carried out.
What you should know about UG plastic mold design
First of all, after we get a product, don't rush to separate the mold. The most important thing is to check the product structure first, including mold drafting, thickness and other molding issues. Of course, these may be difficult for someone who is just engaged in mold structure design.
Because they may not know what products are more suitable for mold design. This does not matter, it is just a process of daily accumulation. After you have analyzed the product's draft, wall thickness, and undercuts in the mold ejection direction, you basically already know the direction of the mold parting surface and the location of the gate. Of course, these still need to be confirmed with the customer.
Some people say that after I analyze the product structure, I can start designing the mold. The answer is of course NO. In order to avoid detours during design, some items that affect the mold structure must be confirmed.
The specific contents are as follows:
1. If the tonnage and model type of the injection molding machine used by the customer is not confirmed well, you will not be able to confirm the entrance diameter of the sprue bushing and the diameter of the positioning ring of your mold, the size and position of the ejection hole, the depth that the injection molding machine can extend into the mold, and even the size of the mold base, closing height, etc.
You have worked hard to design a mold structure that uses an oil cylinder to pull the core, and you feel a sense of accomplishment. However, when the mold reaches the customer, it cannot be produced because the customer only has an electric injection molding machine and no additional neutrons. I guess you will feel like crying without tears.
2. The coding mode of the customer's injection molding machine is generally commonly used: pressure plate coding module, screw coding module, hydraulic coding module, magnetic coding module, etc. After this is confirmed, you will know whether you need to design die screw vias or die slots when designing the mold.
3. We just analyzed the problem points of the product, as well as the product clamping line, product material and shrinkage rate. Don't take it for granted that the plastic shrinkage rate of PP must be 1.5%. This must be confirmed with the customer. You must know what grade of material they ultimately use for production, whether any modified materials have been added, etc.
When possible, it is best to be familiar with the assembly relationships of the product and its uses, etc. This information will be very helpful for future mold structure design. Because after understanding these, you will know which are the appearance surfaces and which are the non-appearance surfaces, where the draft angle can be increased at will, and which places cannot be changed.
It even includes the structure of some products. If you understand the actual assembly relationships and uses of the products, you will know which undercut structures can be eliminated or changed to another simple form. We must keep in mind that the process of making molds is a process of simplifying complex problems.
I often see some people being proud of how complex a structure they have made. I think that is very ignorant. Because many product engineers may have designed some unreasonable structures due to their own experience. If they cannot correct them as a downstream process, they may never think that the design is okay. Then the progress of our product engineers will be very slow.
4. Mold water circuit external parameters, oil circuit external parameters, circuit external parameters, and gas circuit external parameters.
Only after understanding the customer's requirements before designing can you predictably design the water, oil, and gas circuits. Don't work hard to design the mold and later find out that the customer needs to connect the oil circuits in series inside the mold. If you make any changes at that time, you will probably be exhausted because you have finally arranged the water circuits, ejector rods, screws, etc.
The design sequence of these four circuits is generally to ensure the oil circuit first, because the oil circuit must be distributed in a balanced manner, especially the mold structure that requires the cylinder to be ejected. If the oil circuit is unbalanced, the ejection movements of the cylinder will be sequential, and the ejection may be unbalanced.
Of course, a gear oil separator can also be used, but that is more complicated. The second is the water channel, because the water channel must ensure the cooling effect, and uneven distribution will affect product quality and mold life. Finally, there are the air circuit and the circuit. The order of placement on the mold is: the circuit closest to the TOP direction, then the water circuit, the air circuit, and the oil circuit connector at the bottom.
5. Other unfinished matters. With this information in hand, we can start designing the mold.
The first is mold splitting, which is probably everyone’s favorite process. Because it gives me a sense of accomplishment to separate the molds. The principle of pulling the parting surface is that simplicity is the best. If it can be stretched, do not scan it or use other advanced commands.
Secondly, when drawing the parting surface, you must have an overall view, try to simplify the parting surface, and do not make it messy. If it is not a precision mold, those 0.1~0.5 insertion positions that can be avoided must be avoided.
In addition, the parting surface must follow a principle, which is to follow the product trend as much as possible.
Only in this way will the parting surface be beautiful. As a digression, when learning 3D software, you must remember to understand the principle of each command, then you will know when to use that command. Many times the important thing is not that you don't know how to use the software, but that you don't know how to learn and use the software. Experienced people can use the same command in many flexible ways, which is most obvious in UG.
In a word, what matters is the idea, not the tool itself. When making the parting surface, you only need to know that the angle of the insertion surface is as large as possible, the area of the collision surface is as large as possible, and the pulled-out pillow is as wide as possible. You have to fully consider whether the master in charge of flying molds in the workshop will scold you after the actual mold is made from the parting surface you are drawing now. If you think you won't get scolded, then OK, keep going. When you do get scolded in the future, these will be your experiences.
When making the parting surface, you must consider the arrangement of the slider and the inclined roof, because those also involve changes to the parting surface. The typical slider structure is a trigonometric function relationship. It's okay to do the math yourself, but make sure that the angle of the inclined guide column is not too large, and try to keep it below 30 degrees.
The principle for selecting inclined guide posts is to be as thick as possible, and don’t be too stingy, because the inclined guide posts have to bear force. In addition, sliders also have many variant structures.
For example, uphill slider, downhill slider, inner pumping slider, oil cylinder pumping, front mold slider, slider with slider, slider with reverse top, slider with inclined top, etc. These special structures make full use of the trigonometric function relationship. The purpose is to realize the demoulding of the product undercut and the normal opening and closing action of the mold. The calculation formula of the slider is introduced in detail in major forums, so I won’t go into details here.
The second is the inclined roof. The inclined roof is more flexible, but the angle of the typical inclined roof should not be too large. Try not to exceed 15 degrees. Of course, you can do it at 20 degrees, but the lifespan will be difficult to guarantee, and the movement will be very unsmooth. The specific principles refer to trigonometric functions and theoretical mechanics. The shape of the sloped roof has many evolved forms.
For example, uphill sloped roof, downhill sloped roof, crooked neck sloped roof, large sloped roof with sloped roof, large sloped roof with round rods, small sloped roof with hanging platform, sloped roof under the top block, sloped roof on the slider, sloped roof on the sloped roof, sloped roof with reverse roof, etc.
All these structures have one purpose, to use trigonometric functions to make the inverse of the product. This shows how important it is to learn trigonometric functions! Therefore, all kinds of special structures are thought up by people. You can give full play to your imagination.
No matter what kind of structure you can think of, if you think about it, go for a bold design. Maybe you will have a new invention. But after the design, you must verify the relationship of the trigonometric functions, that is, actually simulate the opening and closing action of the mold, and consider whether there will be any problems during injection molding, etc.
As we talked, we separated the molds. Next is the ranking of mold structures. These contents must be sorted out in advance. Different types of mold structures should be selected according to the actual situation of the product.
For example, two-plate mold, three-plate mold, hot runner, IMD, IML, two-color, stacked mold, etc.
All mold structure types are designed to achieve mass production of products. When choosing a mold base, we must fully consider the 4 points just mentioned.
After selecting the mold base, we must consider the mold assembly. The principle of assembly is to simplify processing, save materials, and facilitate product molding.
Such as exhaust and so on. If you think there are particularly thin areas on the mold, you must set them out separately to make them easier to replace in the future. When inlaying, the strength and processability of the inserts, as well as the designability of the waterway in the future, should be fully considered. After the mosaic is completed,
Just add standard parts. The principle of adding standard parts is to focus on the key points first and then the local parts, and try to arrange them as balanced and symmetrical as possible. Generally, the ejector rod must be added first. When adding the ejector rod, the arrangement of the waterway must be considered. Under normal circumstances, priority should be given to the arrangement of the ejector rods, and then the waterway should be roughly designed.
Then adjust the waterway ejector according to the actual situation to balance the two. The principle of adding ejection is to tighten the place where the holding force is strong. In addition, it should be added to the flutes, platforms, edges and other strong structural parts of the product to avoid white ejection or unbalanced ejection.
The principle of the drainage path is the principle of ejection, because generally speaking, the place where the product has a strong holding force is the hot spot of the product, and the part that needs to be cooled needs to be strengthened. This contradiction needs to be adjusted. As for whether to use a push rod, a push block or a push plate, specific issues need to be analyzed in detail.
This should be analyzed based on the structural characteristics of the product. For example, if the product is easy to stick to the front mold, you must consider whether to add an undercut to the rear mold, or add an ejection to the front mold. These are natural things, but many friends do not think about the comprehensive reasons.
That is because the product structure was not fully analyzed and the state of the product during the injection molding process was not actually considered. This is the crux of the matter. After adding the ejector water channel, all that's left are the messy standard parts. Just try to consider symmetry and balance when adding them.
After the entire set of mold design is completed, the following inspections must be made. The first is the draft analysis of the insert to see if there are any undercuts. The second is the interference inspection of each part of the mold. The most important thing is. Today's 3D software has this function, which is very convenient.
Then there is the simulation of the opening and closing movements of the mold. As long as the simple mold is not too clear, it must be simulated in practice. In addition, it is the machinability of each part of the mold and the assembly process of the mold. Don't work hard to design an ingenious structure. The theoretical calculation is no problem. After the processing is completed, the result is that it cannot be installed or is difficult to assemble.
At this point, I can congratulate you. The general process is over. In fact, mold design is a matter full of contradictions. If you want a perfect design, the mold cost will be high. If you want a simple design, the product may need to be modified or the strength and service life of the mold will be affected.
So there are no absolutes in mold design. As long as you find that balance point, the mold you design will be successful. Therefore, the structure designed by others may not be suitable for you. As long as the above mold design points are followed, it is estimated that everyone can design a more reasonable mold structure.
Source: Kunkun in the mold industry, Bilibili
Note: All pictures in the article are reprinted online, and will be deleted if infringed!
