At present, most of the home appliances exterior components are injection molding. Frequently occur in the process of injection molding, welding scar, gas marks, deformation defects such as; Highlights non-mark mould can solve the above defects. Let's take a look at 10 highlights non-mark injection mold design elements.
 
A principle, highlights non-mark injection
 
1. The higher temperature
 
Molding of the high temperature (80 ℃ to 130 ℃ or so), switch to cooling water after injection into the holding, the mold temperature dropped to 60-70 ℃. Higher mold temperatures under pressure forming is conducive to eliminate the internal stress of weld lines, flow mark, product, etc. So the mold need to heat treatment at work, in order to prevent heat loss, usually in the side and heat shield.
 
2. The cavity surface (generally for high specular level 2 or higher)
 
Highlights the mold to produce a product can be directly used for installed (assembly), without having to do any surface treatment. So it is very high to the requirement of mold steel and plastic material.
 
3. The hot nozzle of hot runner system
 
Each hot nozzle must take needle and independent airway, alone to be controlled by electromagnetic valve and time relay, realize time-sharing into glue, thus achieve the purpose of control or even eliminate welding scar, complex control way.
 
4. The heating mode
 
Heating of the die usually has a steam (hot water) heating and electric heating rod (tube) heating. Steam (hot water) heating mode is through specific temperature control machine to mold in injection molding process input steam (hot water), so that the mold growing rapidly; After injection with cold water cooling mold, mold cooling fast. Heating of the electricity and water heating temperature control machine, on the principle is the same, is the source of heat, electric heating is a secondary energy, heating water is three times the energy, according to the principle of electrical heating energy loss, high utilization and good energy-saving efficiency. Easy to use, so say: if it is flat (surface) product USES electric heating mode or real wisdom.
 
 
 
Graph: the steam heating 
 
 
 
Graph: heating rod heating 
 
 
 
Second, the mould material
 
1. The general requirements of the mould surface material available: NK80 datong (Japan), etc.;
 
2. Highlight requirements material selection: S136H (Sweden), CEANA1 (Japan), etc.;
 
3. NK80 can not quench processing; S136H should after rough machining hardening to 52 degrees; CEANA1 itself has 42 degrees do not need to quenching (suggest using the steel, because does not affect the subsequent processing or changes);
 
4. There is also a good choice in Germany ge Leeds brand: CPM40 / GEST80 
 
 
 
 
 
 
 
Figure highlights the mold
 
Third, die channel design
 
1. The waterway aperture size design
 
Waterway is 5-6 mm size of aperture; Water mouth by 1/8 or 3/8 of the tooth (mould), on the other side with 3/4 inch thread (the old connection); Pipe material with stainless steel tube; Now we change a into a FenLiuKou is to do the best in the mould, the interface can adopt diameter with DN25 connection, so less heat loss, easy operation, convenient interface.
 
2. Product surface design
 
Channel side away from the product surface generally choose 5-6 mm; Choose the big has influence to the mould heating time, choose the small have an effect on the strength of the mold. Channel parallel products surface need to average the well arrangement (precursor equidistant distribution center 15 mm) thermocouple should be designed in the middle of the two channel depth in more than 50 mm, less than 100 mm, depend on the mould structure and flexible control. Each mold PT100 is a match, maintain its accuracy, must put it into the mold cavity die within the kernel, and fixed. With the outside of lead to the mould, and then connected to the outlet temperature control machine.
 
3. The die channel connector design
 
Die channel connector must be designed in the mold up and down side or the back end; Operating side (stand) side channel is not permitted in the import and export or the pipe arrangement and avoid the pipe burst soup production personnel. Remember that!
 
4. The design of the mould in and out of the water
 
Mould using shunt board design in and out of the water mouth, water hot mould temperature control machine system has only one into a interface, in order to reduce excess water pipe connection, reduce unnecessary heat loss; And achieve the goal of * * and energy saving. Wrapped with insulation tape and corrugated pipe appearance, have the effect of heat preservation and * *.
 
5. The mould construction holes
 
Mould construction hole hole (don't), want to use plug plug, make sure don't leak leakage, method is to use copper wall first, and then with a taper throat teeth with high temperature resistant rubber seal; Specular mould for cooling waterway configuration is more exquisite (water hot mould waterway is common), good channel configuration not only can greatly improve the efficiency of injection molding, and also play an important role in improving the quality of its products. Highlights the mould waterway not only uniform but must be sufficient (enough).
 
So to mould heats up quickly; At the same time, using the extension pipe directly to the mold core water lead to not use sealing ring, can help to prevent long-term operation under high temperature, the sealing ring aging, also can reduce the maintenance cost of many of the mould. Worth a mention, highlights the mould delivery pipe must have a high temperature resistant material (250 ℃), corrugated pipe.
 
High pressure 1.6 Mpa bellows, in order to prevent the pipe burst of high temperature and high pressure. For circular products adopt circular water; For the strip products adopt parallel water channel. For highly divide a big product in the form of Wells; For special-shaped products and products to the 3 d water way.
 
Four, mould heat insulation system
 
1. The mould core design
 
Mould core fixed mould set or dynamic model with core to be emptied all around; Frame and framed core must have certain gap (see mold material thermal expansion coefficient, the single side 1 mm). To prevent the expansion of the frame to reduce the mold core in the frame of the contact surfaces, to minimize heat loss. Mold core and the frame of locking adopt bevel type or other similar way, front end USES the heat insulation effect of dust resin or other material (such as asbestos board).
 
2. The design of the frame
 
The detailed structure of mould frame and set core, frame of the cooling water is very important, to prevent heat transfer in mould kernel to the frame, near the guide pin location, configuration a circle water up and down
 
3. The guide sleeve design
 
Guide bush moving parts as far as possible with graphite materials or the guide pillar front avoid empty processing, cooperate with as long as the guarantee of 25 mm length is enough;
 
Five, the mold gate design
 
Mold runner design should as far as possible to reduce weld mark, and is advantageous to the exhaust and reduce shear. Adopting the heating water temperature control machine mould, the gate size to open a bigger one and try to use big gate into the glue, in does not affect the product function and forming efficiency, gate should try to shorten the length, width and depth.
 
1. The gate is too small
 
If the gate is too small, easy cause insufficient fill (short shot), apparent defects such as shrinkage depression, weld line, and the molding shrinkage increases.
 
2. The gate is too large
 
Around the gate is too large, the gate produced good residual stress, lead to produce deformation or fracture, and the gate removal processing difficulties, etc.
 
Had better choose a gate, unless the flow more than the actual limit. Diagram of the resin flow length, will provide in a certain shape under the condition of material flow length. Multiple gate often produce weld line and weld marks. In addition to the long, narrow products, using the single gate will ensure a more consistent materials, temperature, pressure distribution, in order to better cooperate.
 
Six, mold exhaust
 
As far as possible in the product around 10 mm apart for a while, evenly distributed open exhaust slot, depth of 0.15 mm; Products cover also need exhaust design in the middle.
 
Seven, the mold parting surface coordinates
 
Because highlights mould temperature has a great gap, so the cover with the demand is higher, at the same time to reduce the area of a face, there are 10 mm near the parting surface matching is enough.
 
Eight, heating rods (tube) highlights the mold design
 
1, up and down at the gate side should have electric heating rod (tube), coolant passages in general is 6 mm (better); Two hole center distance is 15-20 mm; Heating stick wall from a distance of 5 mm, surface at the center of the distance between two heating rods for 20 mm; Cooling water in the heating stick wall distance is 6 to 8 mm, conditional word with electric heating rod with best arrangement.
 
2, inner cavity water can use high temperature resistant sealing ring seal or using hard seal.
 
3, heating bar diameter is 4.92 mm, the mold design is 5 mm, assembly before heating rods with 5 mm thimble edge grinding the burr heating rods are removed.
 
4, mold using water in and out of the mouth with water vapor heating the shunt board design of the mould as (cooling water), because electric mold control system has only one into a water pipe.
 
Nine, highlights the mold for the product requirements
 
Highlights the mold is very strict with product structure, the light refraction effect is more sensitive to light products, the surface a slight defect will be found soon, so how to solve the problem of shrinkage is the chief problem of specular products. General products rib thickness is less than the main body of a thickness of 0.6 mm times will not shrink, or shrink small not easy to be found, negligible. But for specular products, such a request is not enough, still need the product the thickness of the rib reduce to less than the main body glue thickness 1 times, for the screw column type inclined roof structure must also do the crater of the volcano.
 
Ten, highlights the selection of plastic material
 
At present commonly used specular plastic material is ABS + PMMA and ABS + PC, PMMA, ASA, etc.
 
As commonly used casing material, ABS + PC products in terms of impact resistance, surface glossiness and hardness are better than HIPS, so in the production of high products, is usually selected highlights ABS material. If you need a weather resistance, can choose ASA, in terms of hardness may choose PMMA alloy material. The following specific said the ABS material. 
 
 
 
1. The melt viscosity of ABS on how to control?
 
ABS is amorphous polymers, no obvious melting point. Due to its brand quality is various, in the process of injection molding should be according to the different grades of formulating appropriate process parameters, generally above 160 ℃, 270 ℃ below. In the process of forming, ABS has good thermal stability, selection of range is larger, degradation or decomposition is not easy to appear. And ABS melt viscosity, its liquidity than polystyrene (PS), polycarbonate (PC), such as better, and the melt cooling curing speed is faster, generally in 5 ~ 15 seconds can be cold setting.
 
2. How the bibulous rate of ABS control?
 
Liquidity of ABS and injection temperature, injection pressure, injection pressure is a bit sensitive. Therefore, in the process of forming from the injection pressure, to reduce the melt viscosity, improve the filling mold performance. ABS because of the different components, different water absorption and the performance of the adhesive water, its surface adhesion and bibulous rate was 0.2% ~ 0.2% water, sometimes up to 0.3% ~ 0.8%, in order to get ideal products in shaping its dry processing, make the water content below 0.1%. Otherwise the surface will appear bubbles, silver and other defects. Usually plastic material need to add 1% metal powder can improve the effect of specular metal.