The judgement of plastic product aberration

When molding plastic products, its product colors and materials has a direct touch its mainly manifested in the following aspects:

1. The color relations with incoming plastic granule. Due to the product raw material plastic material batch change frequently, and each batch of raw material Material, were inconsistent aberration phenomenon, such as some incoming slant blue color, has the processing slant red color, and so on, so we in the acceptance of incoming (sample) must sample product contrast aberration with customer's original sample and luster. Only in color and luster completely in line with and without other problems when the material can be thought of as good.

Relationship. 2. The color and material tube temperature used material aberration with the feed tube temperature relationship which were as follows; Feed tube at the higher temperature, a partial value red color, b value big yellow, L value little darker. But there are also in the process of forming phase for special case, so in molding should also to match the die temperature in debugging off color problem. Mould temperature, the higher the L value into negative dimmed, a, b.

3 colors and material drying temperature care generally speaking, the color and material drying temperature also has relatively direct contact: such as PC/PA transparent material, drying temperature too high and the time is too long, the color will be become yellow or black, forming the product transparency. Such as ABS material, drying temperature too high or too long, will lead to poor products change yellow and sex. We in front of the molding products must be in 3 to 4 hours before starting the preliminary drying to dry materials will be not too long time and too high temperature baking, so as to avoid product color run, as a result of product aberration And bad. But when molding material tube temperature is too high there will be some phase should be quality problem,, such as product performance, product package (poor exhaust) wind and so on. So I have aberration when molding products mainly come from raw materials incoming problem, method of control can only play an auxiliary role.

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Problem Cause incomplete filling of plastic products and solutions

A meaning: after the melt into the mold cavity does not fill completely, causing plastic parts shortage of material.

Second, Causes and Remedy:

①, improper selection of equipment: When sorting equipment, melt glue machine must be greater than the amount of molten plastic products, plastic parts by weight of the machine can only account for 85% of the total amount of melt.

②, feed shortage: the charging port if there is "bridging" phenomenon, may be appropriate to increase the screw injection stroke, increasing the feed rate.

③, raw illiquid: improved die casting system stagnation defect, a reasonable set of pouring glue position, expanding gates, runners and injection spout sizes and use larger nozzle, an appropriate increase in raw material temperature.

④, gating system design is unreasonable: gating system design, pay attention to the gate balance, the weight of the plastic parts of each cavity is proportional to the gate, the cavities are filled simultaneously, gate locations to be selected in the original wall parts, sub-runner balance design layout can also be used.

⑤, mold exhaust bad: check cold material cavity, or location is correct, for deep cavity mold, should be added to the exhaust vent in the trenches and less injection site, the clamping surfaces can be opened Deep 0.02 -0.04mm, 5-11mm in width exhaust ducts, vents should be provided in the final filling of the mold cavity. Also in the process of operation, by increasing the die temperature, reducing the injection speed, gating system to reduce resistance, and to reduce the clamping force.

⑥, mold temperature is too low: the mold must be preheated to the required temperature before starting the process, if the mold temperature does not rise up, check the mold design is not only reasonable waterway.

⑦, the injection pressure is insufficient: the length of the injection pressure is close to a positive relationship with the die, injection pressure is too small, short filling length, filling the cavity dissatisfaction, which can slow down the plunger forward speed through proper injection ting long time to improve injection pressure.

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Analysis of the solution injection flow lines

Flow marks (Flow Lines) definition:

Linear traces of the molded article surface, this trace shows the direction of flow of melt glue. Injection molding machine

1. Injection pressure and dwell inadequate

Injection pressure and holding pressure is insufficient condensed skin pressed against the mold surface, leaving in the direction of flow of melt glue sink marks. Increase injection pressure and holding pressure, condensate layer can be pressed against the mold surface until the product setting, free from the generated flow marks.

2. The residence time (Residence Time) improper

Plastic tube inside the residence time is too short, melt glue temperature is low, even if we manage to fill the mold cavity, when packing or plastic can not be compacted, leaving in the direction of flow of melt glue sink marks. Plunger tube material for the ratio (Shot-to-Barrel Ratio), should be 1 / 1.5 and 1/4 between.

3. Cycle time (Cycle Time) improper

When the cycle time is too short, plastic tube inside the heating less, melt glue temperature is low, even if we manage to fill the mold cavity, holding pressure still can not leave the plastic melt adhesive pressure to stay in the flow direction of sink marks, cycle time fully extended to plastic melting temperature high enough to melt glue so that the flow direction generated by the appropriate without sink marks.

4. Tube temperature is too low

When the tube temperature is too low, melt glue temperature is low, injection pressure and holding pressure is insufficient condensed skin pressed against the mold surface, leaving in the direction of flow of melt glue sink marks. Improve the material temperature, injection pressure and holding pressure condensate layer is pressed against the mold surface until the products stereotypes, not by the generated flow marks. Material temperature setting can refer to the material manufacturer's recommendations. After the feeding tube, middle and front nozzle (Rear, Center, Front and Nozzle) in four districts, later setting forth the material temperature should gradually improve, every forward one area, increased 6C. If necessary, sometimes the material temperature of the nozzle area and / or the front region of the set and in the same area.

5. Nozzle temperature is too low

 Plastic absorption heating zone (Heating Bands) in the feed tube heat release caused by rotation of the screw and the plastic molecules frictional heat generated by the relative motion, the temperature is gradually increased. Feed tube in a heating zone of the last nozzle, this should melt adhesive material to achieve the desired temperature, subject to moderate heating, in order to maintain the best condition. If the nozzle temperature is set high enough, because the nozzle and mold exposure, taking too much heat, melt temperature will drop, injection pressure and holding pressure is insufficient condensed die face pressed against the skin, leaving the melt glue in the flow direction of sink marks. Increase the nozzle temperature. Usually the nozzle zone temperature set lower than the front region of high temperature 6C °

Mold

1. Mold temperature is too low

Mold temperature is too low will cause the material temperature drops too fast, injection pressure and holding pressure is insufficient condensed skin pressed against the mold surface, leaving in the direction of flow of melt glue sink marks. Increase mold temperature, maintain a high melt temperature, injection pressure and holding pressure condensate layer is pressed against the mold surface until the products stereotypes, not by the generated flow marks. Mold temperature can be set from the proposed value starting material manufacturers. Every incremental adjustments may be 6C, plastic injection 10 times, after forming in stable condition, according to the results and decide whether further adjustments.

2. Gate (Sprue), runner (Runner), or / and gate (Gate) small gate (Sprue), runner (Runner), or / and gate (Gate) is too small, the flow resistance to improve , if the injection pressure is insufficient, advance melt glue wavefront will become increasingly slow, plastics will become increasingly cold, injection pressure and holding pressure is insufficient condensed die face pressed against the skin, leaving the melt glue in the flow direction The sink marks. In CAE (such as C-MOLD) on your computer to different melt adhesive delivery system (including the sprue, runners and gates) filling simulation analysis to identify the ideal sprue, runner and gate size ( including the length and cross section of dimensions such as diameter, etc.), it is feasible way.

2. Venting inadequate

inadequate venting will make melt glue filling blocked, before melt glue wave can not be condensed in the mold is pressed against the skin surface, leaving in the direction of flow of melt glue sink marks. Each section of the flow channel at the end began to exhaust, so you can exclude a large number of air before pouring into the mold cavity. Cavity exhaust but can not be overlooked. Parting surface opposite the gate, consider adding vents, corresponding to the product at the end of the blind hole, consider adding exhaust ejector pin. CAE (such as C-MOLD) simulation melt glue filling, can help us quickly find all possible at the end of the filling (Last Filled Area), which is required to increase the vent areas. Figure claims vary, foolproof. Installation of a vacuum system, was evacuated before filling and when filling, it is an effective method of exhaust. For some bite flower decoration products face words, this may be the only exhaust recipe.

Plastic

1. Illiquid

Flow length of the wall thickness ratio (Flow Length to Thickness Ratio) large cavity, shall be easily flowing plastic filling. If the plastic flow is not good enough, moving further and further slow melt glue, the more slowly the more cold, injection pressure and holding pressure is insufficient condensed skin pressed against the mold surface, leaving in the direction of flow of melt glue sink marks. Materials manufacturers depending on the particular design, can provide professional advice: In principle no burrs, selection of the most free-flowing plastic. 2. Using forming lubricant (Molding Lubricant) improper lubricant content is generally less than 1%. When the flow length to thickness ratio, the lubricant content must be appropriate to improve to ensure that the condensate is pressed against the mold surface until the products stereotypes, not by the generated flow marks. Increase the content of the lubricant, and shall be agreed upon after the material manufacturer.

Operator

1. Bad habits

Operators too early or too late switch forming machine door, will make molded inconsistent results. When the feeding tube heater due to heat loss irregular attempt to replenish calories, plastics uniform temperature easily, and have cold spots (Cold Spot) produced, injection pressure and holding pressure is not easy to cold near the surface of the skin is pressed against the mold on the left in the direction of flow of melt glue sink marks. Usually it should continue to educate the operator, so that we understand the trouble forming cycle inconsistency may bring, and understand the importance of maintaining good habit forming operation. Proper rest shifts, the operator can be prevented due to not following the physical, mental concentration, and cause errors. Using robots (Robots) and other automated molding cycle is to keep a consistent road.

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Plastic Injection Molding Manufacturer CNMOULDING Benefits Clients by Cutting Sales Costs

By taking advantage of Internet, CNMOULDING gets the edge in supplying the most cost-effective plastic injection molding products to customers from all over the world. Now CNMOULDING is providing an array of first-class products and services in automotive, home appliances and electronics

 Plastic injection molding products has been widely used in many industries and CNMOULDING promises customers direct benefits through its easy and definitive consumer approach module. The company's objective to become the "one stop shop" is facilitated through its 2000 sq meters workshop in China.  Powered by world-class infrastructure, a large and adroit workforce and a solid management team, the company has become a trusted supplier of plastic molds for many European and North American based companies. Furthermore, CNMOULDING claims to be the only China plastic molding injection company that offers complete cost analysis and full transparency to prospective buyers.

Company insiders indicate that the biggest plus of working with CNMOULDING is in the direct method of approach that the company adopts. As a top plastic injection molding manufacturer, CNMOULDING has earned its fame though innovation, quality control and cost-down.  According to their reports, CNMOULDING picks up direct consumer leads from the Internet and then tries to establish direct contact. Company officials have also, on several occasions, shown why the conventional way of marketing through trade shows is becoming obsolete. The company plans further expansion and the owners indicated that they are bringing more innovation in the manufacturing process to accelerate production and reduce downtime.

CNMOULDING has also made an elaborate effort to keep their price structure transparent for their international clients. While most similar companies would make every effort to conceal the numbers, CNMOULDING promises to give their clients a sneak peek into the pricing and profit structure.

The CEO of CNMOULDING recently addressed the local press. He laid great emphasis on the sales team of the company: "Most companies tend to carry out their sales through salespersons who exhibit an acute lack of product knowledge. At CNMOULDING, our sales manager deals with all the sales and effectively communicates the messages in and out of the company. We also make it a point to adhere to transparent pricing."

About the company

CNMOULDING is a leading direct plastic injection company based out of China. The company caters to both the Chinese and international markets.

More information about the company is available at www.cnmoulding.com

How Additive Manufacturing Is Making Injection Molding Cooler

Plastic part manufacturers are always looking for ways to reduce cycle time and get more productivity out of their injection molding machinery. One of the longstanding constraints in injection molding production has been cooling time. Removing parts from the mold before they have cooled induces warping or shrinking. But wait time works against productivity.

Another constraint has been cooling channels drilled straight through the metal blocks of injection molds using CNC machining. While coolant is passed through the channels to cool the mold and draw heat away from the part after it has been injected, the efficiency of that cooling process is limited by the conventional straight-line drilling that's used for the channels.

But if those cooling channels could more closely conform to the shape of the part, the cooling process could become more efficient and faster. According to Tober Sun, manager for the technical research division at software provider Moldex3D, a typical production cycle for a plastic part is 30 seconds to a minute, but cooling takes more than half of that cycle time.

Thus, he says conformal cooling has emerged as a practice, which is being aided by advances in additive manufacturing. With a conformal cooling channel design, the toolmaker can use an additive process to lay down the mold one layer at a time, fashioning the cooling channels along the way and curving them to any desired shape.

According to plastics consultant Robert A. Beard, “a typical cycle-time reduction range for a properly engineered, conformally cooled mold is 20% to 40%.” Such savings can lead to much greater productivity, especially in high-volume plants producing millions of parts.

Many industry observers associate conformal cooling with laser sintering, in which a solid object is printed by melting metallic powder using lasers. Sun told Design News that he prefers the broader term “additive manufacturing,” because of the widespread perception that sintered molds are not as strong as machined molds.

“It's not really sintering anymore. I prefer to call it remelting,” as it produces a solid metal object, he said. Sun stresses that additive manufacturing technologies are now handling very strong and durable materials, such as stainless steel and titanium, which compete well with machined molds. “Strength is no longer an issue,” he contended.

Sun recognizes that the added design effort and the use of additive technologies will increase the cost of mold development. But injection molds are expensive to start with, as they usually cost anywhere from $30,000 up to $1 million. The true economic concern shouldn't be the comparative cost of conformal molds versus traditional molds, Sun insists, but the trade-off between the added cost of the conformal mold versus the savings in cooling time on the production line. “The mold is quite unique and expensive, but you are using that single mold to make millions of parts. So it's important to increase the efficiency of that mold.”

Gate type-film gate-mould design

Film gate as shown in figure 6-19, also known as flash gate, thin film gate like circular runner, but used in flat edges of plastic parts, it has a flat gate, the gate width can jumper the whole or part of the cavity cavity edge. Film gate is suitable for pressing LiSu pieces, and often used in large, flat plastic parts

Film gate F as shown in figure 6-19, also known as flash gate (flash gate), thin film gate like circular runner, but used in flat edges of plastic parts, it has a flat gate, the gate width can jumper the whole or part of the cavity cavity edge. Film gate is suitable for pressing LiSu pieces, and often used in large, flat plastic parts, in order to keep the minimum of the warp. Film gate size is small, the thickness is about 0.25 ~ 0.63 mm, width is about 0.63 mm

                                     6-19

Automatic removal of gate Automatic removal of gate and mold actions, during ejection plastic parts cut gate. They are applied to: y avoid removing gate secondary processing. Y to maintain uniformity of cycle time

Y minimize gate marks. Automatic removal of gate includes the following types: needle gate, the latent type gate and hot runner gate, and the valve gate.

(1)  needle gate Pin gate (pin gate) as shown in figure 6-20, usually applied to three board mould, the runner system located in a component model online templates, cavity plastic parts meet the main parting line. The gate with a back taper Angle direction parallel to the template through the middle template. When open cavity of main parting line, the small diameter end of the needle gate from plastics tore off, then open the port can be parting line out port waste. This system can also open port parting line first, then using assistive devices off port waste. Needle gate used most often in a single plastic parts more into the water, in order to ensure symmetrical filling, or shorten the length of flow channel in order to ensure the parts of the holding operation. The typical needle gate 0.25 ~ 1.6 mm in diameter.

(2)   submarine gate the latent type gate Latent type gate (submarine gate) or is called the tunnel gate (tunnel gate), chisel gate (chisel gate), as shown in figure 6-21, used in the two plate mold, below the parting line, the end of the passage between the cavity and processing a tilt the cone of the tunnel. Ejection parts and runner, gate will be separated from the plastic parts. Typical latent type gate is 0.25 ~ 2.0 mm in diameter, runner from coarse to fine, until become globular endpoint. If parts of the functional area has the characteristics of large diameter of the needle, it can be connected to the latent type gate, to reduce processing costs. If the needle features occur in the hidden surface, also can not remove him. To multiple submerged in cylinder inside the gate design, can replace the disk gate, and have the function that automatically remove the gate, to the periphery of the molded parts roundness than disk gate parts of roundness is poor, but also can also accept it.

6-20 Pin gate                       6-21 Latent type gate

(3) hot runne the hot runner gate The hot runner gate (Hot - runner gate) or is called thermal probe gate (hot - the probe gate), as shown in figure6-22, usually from electrothermal vertical sprue and heat flow transmitted directly melt into the cavity, to produce plastic parts without a runner. Control the pressure maintaining cycle in plastic parts near the gate of solidification. When the template is opened, a fairly high temperature plastic tear from the cavity.

(4) Valve gate valve type gate valve type gate (Valve gate) as shown in figure 6-23

, in the hot runner gate increase a needle bar, in order to close the gate before gate solidification.

It can be applied in larger gate without gate trace. Because of the holding period is controlled by needle bar, valve type gate can get better the holding period and the stable quality of plastic parts.

(5)The side gate automatic gate design Side of the gate in the general design is not automatically take off a gate, if the product and the runner design into different time out, can realize automatic gate effect.

(6) take the bottom gate Take the bottom side gate of gate of improvement, products suitable for a particular shape. 1), in the case of side gate is not permitted.

2) and avoid the fluxion phenomenon; Backoff delay needle

3) in addition to the hard PVC, suitable for most of the products.

(7)The fan gate The fan gate is the improved side gate, its width increases with the decrease of depth. 1), suitable for large flat type shape products

2), the plastic into the cavity is flat, reduce the production flow and clamp water lines.

3), suitable for any except hard PVC plastic,

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Injection mold principle

Plastic injection mold is given to the shape and size of the molding member. Although the structure of the mold and performance of varieties of plastic, shape, and configuration and the type of plastics injection molding machine may be different and changing, but the basic structure is the same. Die mainly by gating system, molded parts and structural parts of three parts. Gating system and molded parts which are in direct contact with the plastic part, and with the plastics and products change, the mold is the most complex and the biggest change, the most demanding part of the process finish and accuracy.

Gating system refers to the plastic from the nozzle portion of the cavity before entering the flow path, including the main channel, cold-slug, diversion channel and the gate and so on. Forming part refers to the shape of the various parts constituting products, including dynamic simulation, the fixed mold and cavity, core, forming rod and exhaust ports and so on. A typical mold structure as shown.

Sprue

   

  It is mold injection machine nozzle connected to a shunt or cavity section channel. Sprue concave top to the nozzle convergence. Sprue inlet diameter should be slightly larger than the diameter of the nozzle (O.8mm) to avoid overflow and prevent the interception of convergence between the two are not allowed to occur due. Imported products according to the size of the diameter, usually 4-8mm. Expanding the diameter of the main channel at an angle of 3 ° to 5 ° should be within in order to release the flow channel thereof is superfluous.

Cold slug

    

It is located in the main channel at the end of a hole to trap shoot between the ends of two injections of mouth generated by cold material, thereby preventing the diversion channel or gate blocked. If cold material once mixed with the cavity, then the system is easy to produce products in the internal stress. Cold slug diameter of about eight a lOmm, depth of 6mm. In order to facilitate mold release, normally borne by the bottom of the release lever. Top release lever should be designed to zigzag trench subsidence hook or set up in order to successfully pull the sprue superfluous matter when stripping.

Shunt

It is a multi-slot die cavity connecting the main channel and each channel. In order to melt each cavity is filled with equal speed, diversion channel on the mold arrangement should be symmetrical and equidistant distribution. Runner-sectional shape and size of the plastic melt flow, and ease of mold release products has an impact. If the feeding amount in equal flow, it places the smallest cross-section of the flow path resistance. But because of the cylindrical flow channel surface area is small, the cooling of the shunt superfluous material adverse, and this shunt must be opened on the two halves of the mold, both labor-and easy alignment. Therefore, regular use of the trapezoidal or semi-circular cross-section of the runner, and the opening on one half of the mold with a release lever. Channel surface polished to reduce flow resistance must provide faster filling speeds. Depends on the size of the plastic flow channel variety, size and thickness of the article. For most thermoplastics, the shunt section width does not exceed 8m, up to 10 a large 12m, special small 2-3m. Under the premise of meeting the needs of the cross-sectional area should be minimized to avoid increasing the shunt Warts and extend the cooling time.

Gate

It is on the main road (or shunt) and the cavity of the channel. Sectional area of ​​the channel can be with the mainstream channel (or shunt) are equal, but are usually reduced. So it is the smallest part of the whole system, the cross-sectional area of ​​the flow path. The shape and size of the gate great impact on product quality. The role of the gate is: A, control the material flow velocity: B, due to the injection can be stored in this part of the condensate and prevent melt back earlier: C, so that the melt by strong shear by increasing the temperature , thereby reducing the apparent viscosity to increase flowability: D, easy separation of products, and the flow channel system. Gate design shape, size and position depend on the nature, size and structure of the article of plastics. The gate of the cross-sectional shape is generally rectangular or circular cross-sectional area should be small and the length should be short, not only based on the above effects, but also because larger than the small gate easy, and it is very difficult to reduce the large gate. Gate location should generally be selected in the products do not affect the appearance of the thick places. Gate size should be designed to take into account the nature of the plastic melt.

Cavity

It is the mold space molded plastic products. Component as constituting the cavity collectively referred to as molded parts. Various molded parts are often specific names. The molded article constituting the shape of the concave part called a die (also known as the female mold) to form the internal shape of the article (such as holes, slots, etc.) is referred to as core or convex mold (also known as the male mold). First, the overall structure of the cavity to be determined according to performance, the geometry of products, dimensional tolerances and use requirements designed plastic molded part time. Second, to select sub-surface, the gate and the vent mode position, and release according to the determined structure. Finally, press the control product dimensions of each part of the design and determine the combinations between the various components. Plastic melt with high pressure into the cavity, so the molded parts to be reasonable selection and check the strength and stiffness. To ensure the smooth plastic surface appearance and easy stripping, where contact with the plastic surface roughness Ra> 0.32um, but also resistant to corrosion. Molded parts are generally by heat treatment to improve the hardness and corrosion-resistant steel manufacturing.

Vent

A groove which is open in a mold outlet, and for discharging the original gas into the melt. When the molten material into the cavity, the original is stored in the cavity from the melt into the air and gas must be discharged through the exhaust port to die at the end of the stream outside, otherwise it will make products with holes, bad splices, filling dissatisfaction, even accumulated compressed air due to high temperature and the product burns. In general, both exhaust holes provided in the cavity of the melt flow at the end, may be provided on the mold parting surface. The latter was set up at the side of the die deep 0.03-0.2mm, wide shallow groove 1.5-6mm's. Injection, the vent does not have a lot of melt leakage, because the melt is cooled and solidified in where the channel blocked. Never open position toward the exhaust port operator, to prevent accidental discharge wounding melt. It will also use the top of the bar with the gap with the top of the hole, the top block and the stripper plate and with the gap cores like exhaust.

Structural parts

  

  It refers to the various parts constituting the mold structure, including: orientation, ejection, core pulling and genotyping of various parts. As the front and rear plates, after deduction templates, pressure plate, bearing columns, guide posts, stripper, stripping pole and the return pole and so on.

Heating or cooling means

   

  This is to make the melt solidified in the mold shape of the device for thermoplastic male and female mold is typically a cooling medium passage, and by circulating cooling medium to the cooling purposes. Pass into the cooling medium and the structure of an article with the type of plastic and the like, cold water, hot water, hot oil and steam. The key is uniform cooling high efficiency, uneven cooling products will directly affect the quality and size. Should be based on the thermal properties of the melt (including crystallization), the shape of the article and the mold structure, consider selecting the arrangement of the cooling passage and the cooling medium.

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