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mouldchina · 1 year

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Do You Know How to Heat the SMC Mould?

SMC(sheet molding compound) mould has excellent corrosion resistance, soft quality and easy engineering design, flexible and other advantages. Its mechanical properties can be compared with some metal materials, and the products manufactured by it have the advantages of good rigidity, deformation resistance, and wide temperature range. SMC molds require heating channels instead of cooling channels in injection molds. Normal heating systems are steam, oil, electricity or high pressure water. The working temperature of SMC mold is usually 140 degrees to 160 degrees. When designing the temperature system, it is necessary to keep the mold surface at a close temperature. Molds with uniform temperatures will fill more easily and produce parts with less warpage, improved dimensional stability and a uniform surface appearance.

In the process of mold processing, different mold materials and shapes will affect the heating method, and different heating methods will also have different effects on the performance and processing efficiency of the mold. This article will introduce in detail the common mold heating methods, their respective characteristics, applicable scenarios and their impact on SMC molds.

Electric Heating

Electric heating is a mold heating method commonly used at present. The electrothermal effect occurs on the surface of the mold by electrification, thereby heating the mold. It can be achieved by heating rods, convection heating and other different ways. Electric heating has the advantages of simple operation, fast heating speed, uniform and stable heating temperature, high temperature control accuracy, and no need to wait for heating or cooling time. It is suitable for mold heating of all materials. At the same time, electric heating can also realize the control of different temperature regions through the adjustment of heating elements, so as to realize different processing schemes and patterns. However, electric heating has a relatively large demand for electricity, and the cost of using an electric heater is also relatively high.

Electric heating is often used for heating plastic molds, especially for molds that require high precision, such as SMC molds. Compared with traditional heating methods, electric heating can control the mold temperature more precisely, so that the manufactured molds are more accurate and the shell quality is higher.

Steam Heating

Steam heating means that steam is transported into the mold through pipelines for heating. The temperature control of steam heating is more precise, and the heating speed is relatively fast. Steam heating is suitable for molds with complex and irregular shapes and needed temperature is not too high. However, steam heating requires a complete steam pipeline and supporting equipment. This method is more energy efficient than electric heating, but relatively consumes more energy. Steam heating is a commonly used mold heating method. Its basic principle is to use the heat energy of high-temperature and high-pressure steam to contact the mold, thereby increasing the temperature of the mold to meet the processing requirements.

This heating method has the following characteristics:

1. Uniform heating: Steam can be evenly distributed on the surface of the mold, so that the entire mold is heated evenly, avoiding thermal stress caused by excessive temperature gradient.

2. Efficient and safe: The steam heating speed is fast and the efficiency is high. At the same time, because there is no open flame in the steam heating process, it has higher safety.

3. Precise temperature control: When steam is heated, sensors can be used for real-time monitoring and adjustment, so as to achieve precise temperature control.

Steam heating is widely used in plastic molds, die-casting molds, rubber molds, etc., and can also be used for preheating and annealing of metal molds.

Oil Heating

Oil temperature heating, also called heat conduction oil heating. It means that the electric heating tube is placed in the heating oil tank, and the high-temperature heat transfer oil is used to transfer heat to the mold for uniform heating and maintain a certain temperature range. This method is easier to control the temperature, can achieve precise temperature control, and heat evenly, so as to ensure that the mold will not be damaged due to excessive temperature. Heat conduction oil can transfer high-speed heat and heat up quickly, so it is suitable for some bigger and complex shapes molds and molds that require high temperature heating. At the same time, heat conduction oil heating can also maintain the flatness of the mold surface during mold making and processing, avoid problems such as slack and cracks, and make the mold surface deform more uniformly, and it is not easy to appear towering and uneven. However, oil temperature heating also has some disadvantages, for example, the heat transfer oil needs to be replaced frequently during operation, and the heating speed is relatively slow.

The above are common heating methods, and the selection of different mold heating methods depends on factors such as mold material, shape and processing requirements.

As a professional SMC mold supplier, MDC Mould have experienced engineers, imported equipment, precise processing flow, years of research in SMC mold design and SMC mold technology, and a supporting SMC mold trial line to ensure that SMC molds can meet customer needs from initial design to subsequent mass production.

#smc mold #smc mould #mold heating #Oil Heating #Steam Heating #Electric Heating

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plasticmouldinjectionmold · 1 year

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Key points of scanner shutter injection mold design

Maximum size of scanner shutter product is 121.80 mm * 88.86 mm * 25.77 mm, average thickness of plastic part is 2.70 mm, the material of the plastic part is PC+ABS, shrinkage rate is 1.005, weight of plastic part is 18.35 grams. Technical requirements of plastic part are that there must be no defects such as peaking, unfillling injection molding, flow lines, pores, warpage deformation, silver…

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#injection moulding #moulding #plastic injection mould

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taizhouswymould · 3 years

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Design Summary Of Injection Mold For Electrical Fan Mold

Injection molding can produce a large number of parts with high precision and complex cavity shape. When using injection molds, analyze the mold flow of plastic parts, and select polypropylene molding process parameters to design molds and cavity injection molds. According to the average shrinkage rate of polypropylene, the molding size is calculated and made into an electrical fan mould .

Raw material analysis of plastic parts. Plastic varieties: PP (polypropylene). This crystalline material has low moisture absorption and excellent fluidity. The overflow value is about 0.03mm; the molding shrinkage rate is large, and it is easy to produce shrinkage holes, dents, and deformation. The heat capacity is large, and the molding mold must be equipped with a temperature control system that can be completely cooled; the appropriate mold temperature during the molding process is about 80°C and not less than 50°C. Otherwise, defects such as poor gloss on the surface of the plastic parts or welding marks will occur. The too high temperature will cause warpage and deformation. Mainly used in the automotive industry (PP used mainly with metal additives: mudguards, ventilation ducts, fans, etc.), household appliances (dishwasher doormats, dryer ventilation ducts, washing machine frames, and covers, refrigerator door mats, etc. ), consumer products (lawn and garden equipment, such as lawnmowers and sprinklers).

Analysis of the dimensional accuracy of plastic parts: The main factors affecting the dimensional accuracy of plastic products are the shrinkage of the material and the manufacturing error of the mold. The results show that the shrinkage rate of PP is 1.0%~2.5%, S = 1.75%.

Surface quality analysis of plastic parts: The outer surface of plastic parts requires low roughness, smooth surface and low inner surface requirements. The surface roughness readings of PP that can be obtained by different processing methods are 0.1 to 1.6 μm. Since there is no special requirement for the indicated roughness, to facilitate the actual processing, Ra = 0.8μm can be selected in the manufacturing process.

#Electrical Fan Mold

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darkfurypolice · 3 years

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Why thin wall cup mould so expensive?

Why thin wall cup mould price is so high? General speaking, thin wall cup mould are using better steel, hot runner, better cooling, better venting and better demolding effectiveness.

The thin wall cup mould runs on high speed machine which needs withstand high pressure during cup molding, so the mould moving plate and fixed plate thickness are thicker than common mould. There need many interlocks inside the thin wall mould to ensure accuracy and pillar support to avoid deform and eccentric. The plastic airline cup mould need use high hardness steel, high-wear and high-erosion with HRC 55 or above. This means thin wall mould steel cost is higher.

The hot runner design is larger than the common plastic moulds, and at the same time, need limit the melt residence tome to prevent the resin degradation. When the mould is mult-cavities, the gating balance is much higher than that of common molds. Which means thin wall cup mould hot runner cost is higher.

Thin-walled products do not withstand the large residual stresses due to heat transfer irregularities like traditional wall thickness parts. In order to ensure the dimensional stability of the product, and to control the shrinkage and warpage within an acceptable range, it is necessary to strengthen the cooling of the mold to ensure the cooling balance. Which means need better cooling design to enhance the cooling effect, adding high conductivity metal inserts where necessary to accelerate heat transfer, like BeCu beryllium copper. The cooling cost is higher than common moulds.

Due to the short filling time and high injection speed, it is very important to fully exhaust the mold, especially the exhaust in the flow front gathering area, to prevent air trap. The air is usually discharged through mould cores, rams, ribs, studs, and parting surfaces.

The airline cup walls and ribs are very thin, they are very easy to damage, and the shrinkage in the thickness direction is small, the ribs and other small structures are hard to separate, to avoid sticking, there need use more ejector pins when thin wall injection molding.

In a word, thin wall mould structure is more complicated than common moulds. That’s why the thin wall cup mould is so expensive.

Cutlery mould exhaust problem

In the process of producing cutlery mould, sometimes will have unfilled parts, air bubbles etc, this is caused by air exhaust.

1. The source of air in the injection cutlery mold.

(1) The air contained in the gating system and the mould cavity. (2) Some raw materials contain moisture that is not removed by drying, and they are vaporized into water vapor at a high temperature. (3) Air generated by decomposition of some unstable plastics due to excessive temperature during injection molding. (4) Air formed by volatilization or chemical reaction of certain additives in plastic raw materials.

Poor exhaust of the knife and fork mold will bring a series of hazards to the quality of the plastic parts. The main performance is as follows:

(1) In the injection molding process, the melt will replace the air in the cavity. If the air is not discharged in time, the melt filling will be difficult, resulting in insufficient injection volume to fill the cavity.

(2) Excluding the unsatisfactory air will form a high pressure in the cavity and penetrate into the plastic inside under a certain degree of compression, resulting in quality defects such as pores, voids, tissue sparseness, and silver streaks.

(3) Due to the high compression of the air, the temperature in the cavity rises sharply, which causes decomposition and burning of the surrounding melt, causing local carbonization and charring of the plastic part. It mainly occurs at the junction of the two melts at the gate flange.

(4) The air is not well removed, so that the melt velocity entering each cavity is different, so flow marks and fusion marks are easily formed, and the mechanical properties of the plastic parts are lowered.

(5) Due to the obstruction of air in the cavity, the filling speed will be reduced, the molding cycle will be affected, and the taxation efficiency will be reduced.

Distribution of bubbles in plastic parts

(1) The bubbles generated by the accumulation of air in the mould cavity of the cutlery spoon are often distributed on the opposite part of the gate.

(2) Bubbles generated by decomposition or chemical reaction in the plastic raw material are distributed along the thickness of the plastic part.

(3) The bubbles generated by the vaporization of residual water in the plastic raw material are irregularly distributed on the entire plastic part.

Injection molding is a process in which a molten plastic is injected into a closed mold having a relatively low temperature through a nozzle under high pressure. Both thermoplastics and thermosets can be injection molded. It can be used to make various box-type packaging buckets and pails, such as various pails boxes and small boxes mould. For box-type packaging containers, China bucket mold manufacturers will consider the following aspects in bucket mould structural design.1. The wall thickness of the

bucket mould

The design of the wall thickness mainly considers three aspects: one is thickness; the other is uniformity; the third is gentle transition.1 Thickness: The wall thickness of the bucket is mainly determined by its use, plastic type, structure and so on. For thermoplastics, generally not less than 0. 6mm, often choose 2~4mm; for thermosetting plastics, because of its poor fluidity, the thickness is larger, the small pieces are 1. 6~2. 5ram, the large pieces are 3. 2 ~ 8mm, the maximum is no more than 10mm.2 Uniformity: The uniformity of wall thickness has a great influence on the quality of the bucket. If the thickness difference of a bucket is too large, the shrinkage will be uneven, causing defects such as deformation and crack. Therefore, the structure should be designed with an equal thickness structure.3 Smooth transition: In some buckets, some parts must have different thicknesses due to structural requirements, such as the bucket turning point. At this time, a gentle transition should be adopted to avoid the sudden change of the section.2. Improve stiffness of the bucketThe plastic is relatively flexible, the bucket is made of poor rigidity, and the turnover box type container sometimes has a large load capacity, so various measures for improving the rigidity should be adopted in the structure.1 Add reinforcement: Reinforcement can enhance the strength and rigidity of the container. The basic requirements for the ribs are: the number should be more, the wall thickness should be thin, the height should be short, and the slope should be sufficient. The bottom of the rib should be a circular arc transition. The direction of the rib should be consistent with the flow direction to improve the plastic. toughness;2 Improve the shape: the box-shaped bucket is mostly rectangular thin-walled parts, which are easy to be deformed. Various reinforcement measures should be taken to slightly extend the four side walls of the bucket to improve the rigidity; it is a strip shape on the side wall to prevent distortion. Enhancement; edge reinforcement at the edge of the bucket to prevent deformation of the mouth; bottom reinforcement at the bottom of the bucket designed in a corrugated, arched shape.3 Reasonable support: The bottom area of the box-shaped bucket is large, but it is unreasonable to use the whole bottom surface as the support. Because the bottom is slightly curved, it is not flat. Therefore, the surface support should be changed into a line support or a point support, and the convex side support (ie, the line) Support); raised foot support (ie point support); the height of the protrusion is generally 0. 3 ~ 0. 5mm.4 Corner: The corner is the intersection of two faces or three faces. Regardless of the shape of the bucket, the intersection of the faces must be rounded, which can greatly improve the rigidity of the bucket and improve the plastic filling model. Sex, and can disperse stress and reduce deformation.3. Demoulding slopeIn order to facilitate the demolding of the molded part, a suitable draft angle must be considered when designing the bucket. The draft is too small, the demoulding is difficult, and the surface of the bucket is damaged; if it is too large, the dimensional accuracy is affected.The draft angle varies depending on the shape of the plastic part, the type of plastic, the mold structure, the surface roughness, the molding method, and the like. Generally speaking, the commonly used slope of the plastic part along the demolding direction is 1o~1.5o, and the minimum is not less than 0.5o.

Household molds are a form of fungus. There are many different types, and they can occur both indoors and outdoors.

Molds produce spores, which spread by floating around in the air. Mold spores are present in all indoor environments. There is no way to prevent spores, and they can persist in conditions where mold itself cannot grow.

Mold spores thrive in environments that are moist and warm, so when they land on a damp spot, they begin to grow.

Molds can grow on a variety of different surfaces, including fabric, paper, wood, glass, and plastic. As they grow, they may digest the material they are growing on.

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operonstrategist98 · 4 years

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IV Set Manufacturing

IV Set Manufacturing Medical devices assume a huge function in the conclusion, therapy, and checking of a few ailments. Medical clinic gear is carefully intended to keep up thorough wellbeing norms to guarantee the most extreme prosperity of patients. You will get best IV set manufacturers in Pune.

It is a mixture set that is utilized to manage intravenous treatment, wherein a fluid substance is conveyed legitimately into the patients’ vein. It gives clinical faculty an energetic and viable intends to convey liquids and drug during ailments, for example, lack of hydration, electrolyte lopsided characteristics, particular medicine conveyance, or for blood bonding.

When it comes to CDSCO medical device license process, Operon strategist makes the lengthy process easy and smooth with the best technical team working for you, along with excellent assistance, timely responses and affordable fees structure.

In any case, the sort of organization relies on the rate and kind of mixture, and the sort of arrangement holder utilized. These are also disposable infusion sets. An IV Set Manufacturing ought to consistently be custom-made to the patient and the arranged treatment methodology.

Types of

IV Set Manufacturing

Most imbuement sets are comprised of PVC material to guarantee high quality, simplicity of fixing, protection from sanitization techniques, and are moderately more affordable. In view of the motivation behind utilization, the IV implantation set is separated into two kinds:

Microdrip set

This mixture set is utilized for pediatric patients and explicit grown-up patients who require a little, intently controlled portion of IV arrangement as it conveys a little amount with each drop.

Macrodrip set

This set implants enormous amounts of IV arrangement at quick rates as it conveys a huge amount with each drop.

IV Set Manufacturing is isolated into two fundamental classifications dependent on the liquid sort. One is for moving blood and the other for giving non-blood items, for example, saline. There are different varieties of these two center sorts. Yet, the essential segments of an IV mixture set that stay consistent over the entirety of its varieties are:

Long sterile cylinder

Connector

Dribble chamber

V-track regulator

Spike

Looking Forward To Setup IV Set Manufacturing Facility ?

Operon strategists are the best regulatory Consultant. Contact us for all types of medical device consulting services and we will be always there to assist you.

Different Kinds of IV Sets

While IV sets are all used for similar reasons, there are a variety of different types of IV sets available depending on the specific therapeutic need.

Filtered IV Sets

Filtered IV sets have a small micron filter inside of them that is used to remove any potential contaminants from IV products. The filtration protects the patient that is receiving the infusion by filtering out any particulate matter, bacteria, or air emboli in the medication or solution.

It also protects the patient from phlebitis that can be caused by particulates or bacteria in the medication. Filtered IV sets are used with a wide variety of medications and the filters are available in a number of sizes. Filter sizes get as small as .22 micron for filtering out bacteria up to a 5-micron filter that filters larger particles.

Vented IV Sets

Vented IV sets, also known as vented IV tubing, are ideal for hard plastic or glass containers. Vented IV sets have a small vent that can be opened and closed to allow for air to enter and displace the fluid as it leaves. The fluid will not flow from a rigid IV container unless it is vented.

Non-Vented IV Sets

Non-vented IV sets are just the opposite of vented IV sets – they don’t have any vents in the tubing. Non-vented IV sets work great with flexible plastic containers like the Home pump Eclipse.

Non-vented tubing must also be primed to rid the tube of air. Non-vented tubing allows a vacuum to be created within the plastic IV bag so that it can collapse as it is emptied.

Gravity Tubing

Gravity tubing, or gravity administration sets, rely on gravity and flow rate regulators to infuse medicine into patients. Gravity infusion rates can be set in drops per minute, which will equate to the milliliter per hour infusion rate.

One example of gravity tubing is our dial-a-flow tubing. With gravity infusion, the bag is hung on a pole above the patient, and gravity creates the pressure required to deliver the medication.

The spike is penetrated / fitted into a sterile container containing a pre-filled IV arrangement. The trickle chamber permits the liquid to stream each drop in turn and makes it simple to see the stream rate. The long sterile cylinder with a V-track regulator helps control the stream rate. The IV set has a connector that can be joined to the entrance gadget. The Y-sets, T-sets, and V-sets are distinctively formed three-way connectors that permit an extra implantation set to be associated onto similar line for conveyance of anti-infection agents or different consistent liquid dribbles.

IV Set Manufacturing Process:

IV set manufacturing process is a cycle comprised of four phases; Filling – Pressurizing – Cooling – Remolding. These four phases legitimately decide the framing nature of our items. These four phases are a nonstop cycle. When complete we can duplicate items in groups.

We affirm the crude materials; our center is no contamination all through the way toward bundling.

Turning on the warming switch, and deliberately set the temperature of each segment.

To get into self-loader or full-programmed working state.

Utilize the vernier calipers to check the size of needle.

Imperfection in the appearance, for example, a silver staining or a weld mark.

Innovative inquiries, for example, a flying edge, shrinkage or paste lack.

Execution questions, for example, a warpage or embrittlement

Get together beginnings with a framework check for any issues or deformities with the gathering through the needle machine and the gas gracefully framework. We turn on the Main force flexibly of the get together machine and guarantee the crisis power gracefully is dynamic. We draw in the needle coat, center bar, elastic plug and infusion needle into each fortification. We turn on the vibrating container to change the taking care of speed.

Individual components are manufactured by molding process by use of molds on various molding machines. All these components are sub assembled in different subassemblies such as Drip chamber Assembly, Clamp & Roller Assembly, Male luer assembly, Y connector sealing with rubber tube.

Drip Chamber, Disc Filter, Airway spike, Airway cap and spike protector are assembled to make Drip chamber sub assembly. This is done on Drip chamber assembly machine. Clamp and rollers are assembled on special automated machine.

Male luer lock connector and plain stopper is sub assembled to make Luer assembly. Y connector and tube are sealed to make Y connector sub assembly. Above subassemblies along with tube are assembled on final assembly machine to make final product. IV Set Manufacturing is then packed and sealed on automatic packing machine. Fully packed pouch is then sterilized in sterilization plant.

IV Set Manufacturing

Machines:

Machinery used:

Injection molding machine

Set of molds for various parts like Drip Chamber, Airway spike, Airway cap, spike protector, clamp, roller connector, male lure lock.

Sealing machine

Automatic packaging machine

Blister Packaging machine

Sterilization Plant

Scrap Guiding machine

Weighing scale

Water Pump

Air Compressor

Chilling Plant

Testing Equipment

Electrical Fittings & Socket

All the components are manufactured by molding process.At that point they are sub gathered in various subassemblies, for example, Drip chamber Assembly, Clamp and Roller Assembly, Male luer get together, Y connector fixing with elastic cylinder. All these subassemblies are then gathered alongside tube in programmed get together machine.

Raw materials used for

IV Set Manufacturing

Raw material used for manufacturing of IV Sets is listed below:

Sr.No

Name of the raw Material

1.Polypropylene

2.Highly kink resistant non-Toxic Medical grade PVC Tube

3.HDPE

4.Packing Material

5.Non toxic grade PVC

6.Filter (Nylon +HDPE)

7.Printing Ink

There are a large number of infusion therapies available for people with different diseases. Therapies include blood component stimulating factor therapy, chemotherapy, hydration therapy, pain management therapy, and total parenterals nutrition. IV Set manufacturing does amazing things and can help people get their medication placed directly into their bloodstream. While it is a process, it can help a person feel a lot better once it’s over.

Reference – https://www.medonegroup.com/aboutus/blog/everything-you%20need-to-know-for-infusion-therapy

#ivset #ivsetmanufacturing #Manufacturing Facility

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plasticmouldinjectionmold · 2 years

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How to solve three major factors that lead to warpage of plastic parts

Warpage of plastic parts means that shape of injection product deviates from shape of mold cavity. It is a common defect in injection product and has a great influence on the appearance quality and performance of injection products. With development of plastics industry, degree of warpage deformation is one of important indicators for evaluating quality of plastic parts, it has also received more…

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#injection moulding #injection moulds #moulding #plastic #plastic injection moulds

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keikamechas-blog · 6 years

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Deformation of Plastic Products

Causes of Warping Deformation of Plastic Products

The deformation, bending and twisting of injection molded products are mainly caused by that the shrinkage rate of the flow direction during plastic molding is larger than that of the vertical direction, so that the shrinkage ratio of the parts is different and warped, and it is inevitable in the injection molding. There is a large internal stress remaining inside the piece to cause warpage, which is a manifestation of deformation caused by high stress orientation.

Therefore, the mold design determines the warping tendency of the part. It is very difficult to suppress this tendency by changing the molding conditions. Finally, the problem must be solved from the mold design and improvement.

This phenomenon is mainly caused by the following aspects:

Mold

The thickness and quality of the parts should be uniform.

The design of the cooling system is to make the temperature of each part of the mold cavity uniform. The pouring system should make the flow symmetry avoid the warpage caused by the different flow direction and shrinkage rate. Appropriately thicken the split runners and main runners which are difficult to form. Eliminate the density difference, pressure difference, and temperature difference in the cavity.

The transition zone and the corner of the workpiece should be sufficiently rounded and have good mold release properties, such as increasing the mold release margin and improving the polishing of the die face. The ejector system should be balanced.

The venting should be good.

Increase the wall thickness of the part or increase the anti-warpage direction, and strengthen the rib to enhance the anti-warping ability of the part.

The material used in the mold is not strong enough.

Plastics

The crystal type has more chance of warping deformation than the amorphous plastic, and the crystal type plastic can be used to correct the warpage deformation by using a crystallization process in which the crystallinity decreases as the cooling rate increases and the shrinkage rate becomes smaller.

Processing aspects

The injection pressure is too high, the holding time is too long, and the melt temperature is too low. The speed is too fast, which causes an increase in internal stress and warpage.

If the mold temperature is too high and the cooling time is too short, the parts during demolding will be overheated and the deformation will occur.

Reducing the screw speed and back pressure reduces the density while maintaining a minimum charge to limit the generation of internal stress.

If necessary, the mold which is easy to warp and deform may be soft-shaped or demolded and then annealed.

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plastic-mold · 3 years

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PMMA （Acrylic）injection molding supplier from China

PMMA （Acrylic）injection molding

Are you interested in finding a supplier and designer of Acrylic(PMMA) injection molding products for you who has a good reputation of being both reliable and cost-effective (as low as $ 0.3 per piece in some cases) with their products? Topworks Plastic Mold is an Acrylic injection molding company in China. We specialize in Acrylic molding and can therefore help you if you are looking for an injection molding company in China that deals with Acrylic plastic parts.

PMMA injection molding We have a wealth of experience in designing, tooling, and manufacturing Acrylic injection molding products at competitive prices worldwide. As a result, Topworks is able to offer the best standards of quality. Hence, we are proud to be one of the few companies that can provide products from conception to reality, utilizing our wide range of PMMA injection molding services, creating Acrylic parts, manufacturing, and delivering Acrylic injection parts. No matter if you're working on a concept or a work-in-progress, we make every step of the process in the Acrylic injection molding simpler.

What is Acrylic(PMMA) injection molding?

Acrylic is also called polymethyl methacrylate (PMMA). Due to the defects, such as low surface hardness, easy scratching, low impact resistance, and poor molding fluidity, the modification of PMMA appears a lot. Such as copolymerization of methyl methacrylate with styrene and butadiene, mixing of PMMA with PC, etc. The flow of PMMA is worse than that of PS and ABS. The melt viscosity is sensitive to temperature changes. In the molding process, the melt viscosity is changed mainly from the injection temperature. https://www.youtube.com/watch?v=5PHkIec5_X0 PMMA is an amorphous polymer with a melting temperature of more than 160 ° C and a decomposition temperature of 270 ° C. - DRYING PMMA has a certain degree of water absorption, which reaches 0.3-0.4%, while injection molding must have a humidity below 0.1%, usually 0.04%. The presence of water causes bubbles, streaks, and reduced transparency in the melt. Therefore, drying treatment is required. The drying temperature is 80-90 DEG C with a time of more than 3 hours. Injection molding can use recycled materials 100% in some cases, and the actual quantity depends on the quality requirements, usually over 30%. Recycled materials should avoid foreign materials; otherwise, transparency and the properties of finished products will be affected. - Injection Molding Machines PMMA has no special requirements for injection molding machines. Because of its high melt viscosity needs a deeper spiral groove and a nozzle with a larger diameter hole. If the product's strength is required to be high, low-temperature plasticization shall be adopted with screws of a larger length-diameter ratio. In addition, PMMA must be stored in a drying hopper. - Mold and Gate Design The mold temperature can be 60-80℃, the diameter of the main runner should match the internal taper, and the best angle is 5-7. If the PMMA molded product with 4 mm wall thickness is to be injected, the draft angle should be 7, the diameter of the main runner should reach 8-10 mm, and the overall length of the gate should not exceed 50 mm. For products with wall thickness less than 4 mm, the diameter of the runner shall be 6-8 mm. For products with wall thickness greater than 4 mm, the runner diameter should be 8-12 mm. The depth of the side gate, tab gate should be 0.7-0.9 T(T is the wall thickness of the product), and the diameter of the pinpoint gate should be 0.8-2 mm; a smaller size should be selected for low viscosity. Vent slots are within 0.05 depth and 6 mm wide, and the demoulding angle is between 30'-1, cavity side: 35'-1 30. - Melting temperature Shoot to air: from 210℃ to 270℃, depending on the information provided by the supplier. Re-track, the backseat, make the injection machine nozzle away from the main runner bushing, and manually do plasticizing injection molding, which is the way to shoot to air. - Injection temperature The fast shoot is available, but multi-stage injection, such as slow-fast-slow, should be used to avoid high internal stress. Slow injection speed is used for thick parts. - Residence time If the temperature is 260℃, the residence time should not exceed 10 minutes at most, and if the temperature is 270℃, the residence time should not exceed 8 minutes.

How to solve PMMA injection crack?

Acrylic molded parts are usually subject to warpage, deformation, bubbles, cracks, sinks, flash, weld lines, burns, silver streaks, spray lines, and other defects during injection molding. What solution should we adopt when warpage occurs? Cracking is a common defect in plastic molding, and the main reason is due to stress deformation. There are mainly residual stress, external stress, and stress deformation caused by the external environment. - Residual Stress The residual stress is mainly caused by the following three factors, i.e., overfilling, ejection, and metal insert. Residual stress due to overfilling, the solution can be mainly started from the following aspects: Due to the minimum pressure loss of the sprue gate, if cracks are mainly generated near the gate, the multi-point distribution of point gates, side gates, and tab gates can be considered. Ensuring that the resin does not decompose or deteriorate, appropriately increasing the resin temperature can reduce the melt viscosity and improve the fluidity. At the same time, it can reduce the injection pressure to reduce the stress. In general, stress is easy to occur when the mold temperature is low, and the temperature should be appropriately increased. However, when the injection speed is higher, even if the mold temperature is lower, which can reduce the possibility of stress. Too long injection and pressure holding time will also lead to stress, and it is better to shorten it appropriately or switch pressure holding for Th times. Amorphous resins, such AS PS resin, ABS resin, PMMA resin, etc., are more prone to residual stress than crystalline resins, such as polyethylene, polyoxymethylene, etc. When demoulding, due to the small draft angle and rough mold core surface, the ejection force is too large, resulting in stress and sometimes even whitening or cracking around the ejector pins. It can determine the reason by carefully observing the location of cracks. When metal parts are embedded during injection molding, stress is most likely to occur, and cracking is likely to occur after a period of time, which is extremely harmful. This is mainly because the thermal expansion coefficients of metal and resin are very different, resulting in stress. With time, the stress exceeds the strength of the gradually deteriorated resin material, resulting in cracks. In order to prevent the cracking caused by this, as a rule of thumb, polystyrene is basically not suitable for metal insert molding, and the metal inserts have the least influence on nylon. As the thermal expansion coefficient of glass fiber reinforced resin material is small, it is more suitable for inserts. In addition, preheating the metal insert before molding also has a good effect. - External Stress The external stress here is mainly caused by stress concentration due to unreasonable design, especially at sharp corners. R/7 "-0.5-0.7 is preferable. - External Environment Chemicals, water degradation caused by moisture absorption, and excessive use of recycled materials will degrade physical properties and produce cracks. Read the full article

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plastic-mold · 3 years

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PMMA （Acrylic）injection molding supplier from China

PMMA （Acrylic）injection molding

What is Acrylic(PMMA) injection molding?

How to solve PMMA injection crack?

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