Blog about buying plastic mold, plastic injection molding parts from China Plastic Injection mold and molding companies, advantages and disadvantages buying plastic molds and plastic molding parts from China.

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Plastic Chair Mould

Chair mould

How Plastic Chair Mould Produces Comfortable Modern Seats

Plastic chairs are seen almost anywhere you lay your eyes on, from the busy cafes lining the city streets to the nooks of your own home. But did you even consider how these chairs even come to life?

The surprisingly simple answer is none other than the plastic chair mould, the tool that shapes the chairs you sit on every day

A plastic chair mold is not just a negative space. The people working in a plastic chair mould factory are like sculptors who transform molten plastic into the comfortable and functional seating solutions.

But what makes the plastic mold chair so beneficial in the first place? Read on to learn more about the hidden advantages of plastic chair moulds.

Efficiency Redefined: Mass Production for Maximum Comfort

Imagine a world where every plastic chair was hand-crafted. The cost and time involved would be prohibitive! The plastic chair moulds eliminate this hurdle entirely. The plastic chair mold allows manufacturers to generate identical chairs at high speeds that significantly cut down production time and overall costs. It results in a wider availability of affordable seating solutions for everyone, from owners of busy restaurants to budget-conscious families.

plastic chair mould

Consistently Strong for a Comfortable Foundation

A flimsy chair can be downright uncomfortable, not to mention that it can also pose a serious hazard to safety. A plastic chair mould guarantees consistent thickness of walls and overall structural integrity on all chairs produced. It ensures that users are always safe while offering a reliable foundation of comfort, whether you’re engrossed in a work meeting in the office or enjoying a leisurely lunch.

Design Delights: A Chair for Every Occasion

Not all seating needs are made equal. A plastic mold chair caters to this as it offers an amazing array of design possibilities. The designs of a plastic mold chair can be adapted to create the perfect chair for any purpose, from ergonomic office chairs with adjustable lumbar support to stackable bistro chairs for outdoor cafes. It guarantees that the level of functionality and comfort are tailored to the specific intended use.

Material Marvels: Choosing the Right Comfort Formula

A reliable plastic chair mould factory doesn’t only use a single type of plastic. Different materials can be chosen according to the desired balance of weight, durability, and comfort.

For instance, polypropylene or PP is a popular choice because it is easy to clean and lightweight which makes it a recommended choice for outdoor furniture.

On the other hand, high-density polyethylene or HDPE offers incomparable flexibility and strength, which is ideal for high-traffic areas such as schools and restaurants. This flexibility ensures the chair is crafted with the right “comfort formula” for the purpose it is meant to do.

Beyond Seating: A Mould of Many Uses

The plastic choice mould is not just used for traditional seats.  They can also come in handy for a variety of other functional and comfortable products, including beach loungers, children’s play equipment, as well as ergonomic seating components for wheelchairs.  This versatility makes them a valuable asset in a wide array of industries.

In order to buy high-quality plastic chair mold from your mold supplier, you need ask some follow question before ordering your chair mould.

1, The minimum lifetime of the plastic chair mold.

The normal standard of lifetime of the chair mould should meet up to at least 0.5 million shorts or even more, so the quality of steel is very important, some of injection mold companies offer the poor quality steel to save the money and offer the cheaper price to the customer, but when the customer has the mold at their factory, may haev issue after a few months, to keep good quality of plastic chair mould, we usually suggest our customers use 718H or P20  mold steel. this will make sure the mold can last at least 0.5 million without any problem

plastic table chair mold

plastic table chair mold

2, The cycle time of plastic chair mold during production,

This is another important for your Chair mould project,  and the simple question to all other custom injection mold, as you know short cycle time can produce more chair molding parts, this will increase your profits, to increase the cycle time we need to focus on two points, one is making good mold structure to the plastic chair mold, good structure can make the mold running smoothly, and another most important thing is the cooling, to reduce the cycle time cooling the number one key points, so when you buy any custom plastic chair mould from your supplier, you need to change the cooling channel design in the mold drawing, to make sure your mold maker has designed the perfect cooling in the mold, According to our plastic chair molding experience, for 1.8-2.5kg plastic chair mold running with perfect cooling water systems, the whole chair mold cycle time would be the 40s to 50s.

3, How to optimize the weight of the plastic chair molding part but the same strength.

When we start the plastic chair product design, we should analyze to make good strength with less weight, when you have a plastic chair project in hands, you need to change your competitive in advance, like the part weight and price, to make the min less weight but same strength of your plastic chair is the best way to help you win the market because less weight means less cost and fast cycle time. to improve this we have some suggestions, like to add some ribs under chair bottom ribs, when we make chair designs, we could check chair stacking in software to avoid future chair stacking problems.
Hope this information is enough for your reference. If you want to know more detail about this welcome to contact us,
If you have any custom plastic chair mold that is looking for a mold manufacturer to make this for you, you are welcome to send us your requirement for quotation,
We have over 17 years of experience in custom plastic chair mold manufacturing, We are one of top 10 mold manufacturers in China. We offer fluent technical English communication service ( this is very important to run your project smoothly), good quality, and competitive price,

 

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Cosmetics Injection Molding

The resin you decide on will have a dramatic effect on appearance. A filled resin won’t ever reach a highly-polished appearance, and the bucks you spend having the mold polished is going to be wasted. Different plastic resins are readily available to pick from during production. As an example, moldings produced from amorphous materials are much harder to trim than crystalline materials. Cosmetics Injection Molding calls for much of upfront engineering to create comprehensive tooling or molds. The mold may be made of one piece, in which case it’s sheared off the glass article, or it can be an open-and-shut device comprised of two parts, which enables the mold to be eliminated and reused. It is then clamped surrounding this, trapping the plastic while air continues to fill the parison into the design of your part.

If over one material is necessary, a multi-barrel machine is necessary. Various types of materials have their own bodily characteristics affecting trimming. When you compare the properties of HDPE and HMWPE with a cheaper low-density PE according to the stiffness-related demands of the final solution, it’s more economical to utilize the costlier materials since it’s possible to earn a container’s walls thinner.

Below are some of the Cosmetics packaging molding products we made before for your reference. If you have any requirements on the Cosmetics packaging injection molding products, you are welcome to send us an email.

A pump bottle is really a rather common packaging material employed for cosmetics and personal care solutions. Because glass is incredibly breakable, after the debut of plastic, plastic had been used to replace glass in certain instances. The plastic solidifies as it’s cooled within the mold. The method by which the molten plastic is injected into the mold could also recognize the kind of molding equipment.

In the event the resin choice is constrained, you may need to compromise on cosmetics. With each one of these choices for your plastics industry recruiter requirements, it’s a scary job to get someone that’s qualified to provide the type of service that you need. With over 500,000 suppliers, you’ll easily have the capacity to find the one that matches your requirements and requirements. Work is usually done in teams with different employees on the same level and direct supervision for big parts of the work.

A manufacturer offering over 1 option of the 3 types of blow molding procedure is ideal as you can discuss the most appropriate method by viewing the advantages and disadvantages of each. It will be mass-produced in a molding business in China to supply distinctive forms of storage for assorted products. You can find well-established companies out there which stand tall in the typical aspect. The cosmetics industry is among the biggest manufacturing industries on the planet. The cosmetics industry has converted into one of the very most lucrative industries that use plastic injection moulding. Correspondingly, concerning motion control, there’s no single major technology that fulfills the numerous requirements to an identical degree.

Maintenance isn’t the work of the mold maker. As there are plenty of types of Cosmetics Injection Molding equipment, each little equipment is, actually, among several diverse types and could be unique, on the basis of the combination of systems it possesses. Some injection molding equipment is identified in addition to which the pressure necessary to keep the many parts of the mold together is created. For this reason, you simply ought to select excellent machinery to make sure that your process can be as efficient as possible. Specify the type of machine and the unit will probably be factory programmed for that kind of machine. Run the equipment for a couple of cycles, and IMPACT II produces a theoretical type of the procedure.

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Micro Injection Molding

Micro Injection molding

What is Micro Injection Molding

Micro Injection molding ( micro-molding) is small & high-precision thermoplastic injection molding parts and components with tight tolerances ( 0.001mm to 0.005mm).  this type of micro injection molding parts is used in the medical industry, automotive, aerospace, and electronic industry, the microinjection mold is as same as standard injection mold that has sliders, lifter, but the precision and the tolerance are totally different.

Micro injection molding or Micro injection moulding that is the same meanings, No matter how you spell it, the micro-molding size is very small, from 2mm to 20mm, the most important thing to make good quality of micro molding parts is the tolerance and injection molding machine, must use high-speed injection molding machine and high quality brand of injection mold machines.

High speed injection molding machine for micro molding

Mold making and tooling

Sincere Tech has three high-speed Nissei injection molding machines with 80 tonnages to offer micro custom injection molding for automotive, medical, aerospace, communications, defense, and general industrial applications. We specialize in micro mold design, Engineering, Thermoplastics choosing, Moldmaking, trouble-shooting, and massive production,

With years of design and manufacturing excellence, our tradition of producing innovative solutions and world-class quality assures your product’s success. As a one-stop service custom plastic mold maker, we offer a complete range of value-added services to meet your needs:

  • Custom Molding of Precision Small Parts, Medical Device, and High Tech Industries
  • 3-D Modeling
  • Specializing in Tight Tolerance Molding can easy to meet a 0.003mm tolerance requirement.
  • Energy Absorbing Rubber
  • 3D parts/mold design, Engineering Services, and Mold Making
  • Secondary, Sub Assembly and Finish Work
  • The prototype, short and long Production Runs
  • Custom Compounding and engineering thermoplastics

Sincere Tech has a complete in-house mold factory for building new molds, repairing and maintaining existing molds.  In addition, we provide competitive mold making services and ship the mold to Europe and America.

Engineering and Mold Designs

Sincere Tech can provide complete design and engineering services, from part concept designs, to 3-D CAD models, to complete mold design, mold manufacturing until massive production. We can make recommendations regarding part designs and resins in order to minimize production costs and maximize part performance. We also build low-cost prototype molds and test the design prior to production.

If you have any micro injection molding project that looking for the best suitable supplier from China, contact us now, we will be one of the best options for you, we will offer you 100% satisfaction service.

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PE Injection Molding Technology

PE injection molding

Polyethylene is PE for short, which has the properties of softness, non-toxic, cheap, and easy to process. It is a kind of typical crystallographic polymer.

PE-LD has the lightest density in its own kind and is easy to ventilate and soak. It has good dielectric properties and chemical resistance properties, softness, elongation, impact force resistance. Its translucency is better than the middle and low LDPE but it has the bad performance of mechanical properties, which can apply for softness injection molding and extrusion molding. PE plastic mold molding

PE-HD also has good dielectric properties, abrasive resistance, and water tightness. In terms of chemical medicine resistance, HDPE is better than that of LDPE. It has a high softening temperature, bad performance in assembling cold and thermal, and low mechanical strength and heat deflection temperature. Therefore, HDPE is suitable to be used as the insulating medium materials for the high-frequency circuit.

Common points of HDPE & LDPE injection molding process:

High shrinkage rate than other plastic resins.

Crystallization tendency is bigger than others. Therefore, in the process of injection molding, the temperature of materials and mold temperature should be higher, and injection pressure should be lower (at medium or low speed and speed of fusing glue should not be too fast).

By changing the injection pressure: Influence of changing of the injection pressure on melt fluidity is obvious than that of feed cylinder temperature.

for PE injection molding The processing temperature of low-density polyethylene ranges from 160  to 220 Celsius degree and the high-density polyethylene is 180 – 240 Celsius degree, they both need lower temperature at feed zone to avoid the material cling to screw to block material feeding.

By Mold temperature: Mold temperature affects significantly the products of polyethylene. When the mold has a high temperature, melt cooling speed became slower and the product will get higher crystalline, hardness and rigidness will be improved. For the lower temperature of the mold and high speed of melt cooling, the product will have lower crystalline high transparency and presenting of flexibility. Accordingly, the internal stress and the anisotropy of shrinkage are also increasing, which can easily lead to warpage and distortion.

 

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POM Injection Molding Technology

POM plastic molding parts

What is POM injection molding?

POM injection molding or acetal injection molding, is a process for creating parts by injecting molten POM (Polyoxymethylene) material into a mold, where it cools and solidifies. POM is a thermoplastic polymer that is commonly used in precision parts such as gears, bearings, and electrical components due to its high strength, stiffness, low friction properties, mechanical and chemical properties, especially excellent rub resistance.

The POM injection molding process allows for the creation of complex and precise shapes with high dimensional accuracy and repeatability. POM (also called Acetal) is polymerized by formaldehyde and other raw materials, etc. POM-H (Polyoxymethylene homopolymer), POM-K(Polyoxymethylene copolymer) are thermoplastic engineering plastic with high density and crystallinity.

POM Injection Molding is a crystalline plastic with an obvious melting point. Once it reaches the melting point, the melt viscosity will rapidly decrease. When the temperature exceeds a certain limit or the melt is heated too long, it will cause decomposition. Copper is POM’s degradation catalyst, the areas contacting with POM melt should avoid the use of copper or copper materials.

POM injection molding

POM injection molding

Advantages of POM injection molding

POM injection molding offers several advantages over other manufacturing processes. Some of the main advantages of POM injection molding are:

  1. High strength and stiffness: POM is a highly durable and rigid engineering plastic that provides exceptional strength and stiffness, making it ideal for applications that require high strength and resistance to wear and tear.
  2. Excellent dimensional stability: POM has excellent dimensional stability, which means that it maintains its shape and size even under high temperatures or mechanical stresses. This makes it a popular choice for precision engineering and high-tolerance applications.
  3. Good chemical resistance: POM has good resistance to many chemicals, including solvents, fuels, and oils. This makes it suitable for use in applications where exposure to chemicals is expected.
  4. High heat resistance: POM has a high heat deflection temperature, which means that it can withstand high temperatures without deforming or losing its mechanical properties.
  5. Low friction and wear resistance: POM has a low coefficient of friction, which makes it an excellent choice for applications that require low friction and wear resistance, such as gears and bearings.
  6. Easy to mold: POM is easy to mold using injection molding techniques, which allows for the creation of complex geometries and intricate designs with high precision.
  7. Cost-effective: POM injection molding is a cost-effective manufacturing process that allows for high-volume production runs with consistent quality and minimal waste. This makes it a popular choice for mass production of plastic components.

Disadvantages of POM injection molding

Although POM injection molding offers many advantages, there are also some disadvantages to consider. Some of the main disadvantages of POM injection molding include:

  1. Susceptible to stress cracking: POM is susceptible to stress cracking when exposed to certain chemicals, such as strong acids, bases, and some solvents. This can result in premature failure of the molded parts.
  2. Limited color options: POM is naturally white, and it can be difficult to achieve vibrant colors during the injection molding process. This may limit the aesthetic appeal of the final product.
  3. High processing temperature: POM requires a high processing temperature during injection molding, which can result in higher energy consumption and longer cycle times.
  4. Poor UV resistance: POM has poor resistance to UV radiation, which can cause it to degrade and lose its mechanical properties over time when exposed to sunlight or other sources of UV radiation.
  5. Brittleness at low temperatures: POM becomes brittle at low temperatures, which can make it unsuitable for applications where low-temperature resistance is required.
  6. Environmental concerns: POM is not biodegradable, and it can take hundreds of years to break down in the environment. This may be a concern for applications where sustainability and environmental impact are important considerations.
  7. Tooling costs: The production of high-quality POM injection molds can be expensive, particularly for complex geometries and intricate designs, which can increase the overall cost of the manufacturing process.

Types of POM Plastic Injection Molding

Type Characteristics Applications
Homopolymer POM (POM-H) High crystallinity, excellent mechanical properties, may be susceptible to stress cracking Gears, pulleys, bushings
Copolymer POM (POM-C) Improved impact resistance and stress crack resistance Automotive parts, consumer goods
Reinforced POM Enhanced mechanical properties, such as strength, stiffness, and heat resistance Structural components, automotive parts, industrial machinery
Flame-Retardant POM Improved fire resistance Electrical connectors, building materials
Food-Grade POM Meets food safety standards Food processing equipment, containers, packaging materials
Medical-Grade POM Meets biocompatibility and sterilization requirements Surgical instruments, prosthetics, medical components
Conductive POM Improved electrical conductivity Electrical connectors, EMI shielding, electronic components
Low-Friction POM Very low coefficient of friction Bearings, bushings, moving parts
High-Temperature POM Can withstand higher temperatures Automotive under-the-hood components
Color-Pigmented POM Imparts color or opacity Consumer goods, automotive trim

Chemical Structure and Properties:

  • POM is a crystalline polymer composed of rehashing formaldehyde units. This chemical structure gives a few alluring properties:
    High Quality and Firmness: POM shows amazing ductile and flexural quality, making it appropriate for applications requiring strong mechanical execution.
    Dimensional Steadiness: POM has moo dimensional float and fabulous crawl resistance, guaranteeing exact resistances and long-term unwavering quality.
    Fatigue Resistance: The material’s weakness quality is tall, permitting it to withstand rehashed loads without disappointment.
    Chemical Resistance: POM is safe to an assortment of chemicals, counting aliphatic hydrocarbons, alcohols, and numerous solvents.
    Low Coefficient of Grinding: POM has an actually moo coefficient of contact, making it a great choice for moving parts and orientation.
    Good Wear Resistance: Its scraped area resistance is tall, guaranteeing long benefit life in applications subject to wear and tear.
    Excellent Machinability: POM is simple to machine, permitting for complex shapes and exact resiliencies.

Tips working with POM injection molding.POM INJECTION MOLDING

  1. Processing of plastic POM
    POM has low water absorption which generally is 0.2%-0.5%. Under normal circumstances, POM can be processed without drying, but the wet raw material must be dried. The drying temperature is above 80 Celsius degree, the drying time is above 2-4 hours which should be conducted according to the supplier’s datasheet. The utilization of recycled materials is generally within 20-30%. However, it depends on the species and final use of products; sometimes it can reach 100%.
  2. Selection of injection molding machine
    In addition to the requirement on the screw with no material banking zone, there is no special requirement on the injection molding machine; the general injection molding is available.
  3. Design of mold and gate
    During the POM injection molding process. The common mold temperature is controlled 80-90 Celsius degree, the diameter of flow channel is 3-6mm, the length of gate is 0.5mm, the size of gate depends on the thickness of plastic wall, the diameter of circular gate should be at least 0.5-0.6 times of the thickness of the products, the width of the rectangular gate is usually 2 times or more of its thickness, depth is 0.6 times of the wall thickness, stripping slope is  between40′ and 1-30.

Mold Exhaust System-air venting grooves for POM

POM-H the thickness is 0.01-0.02mm and the width is 3mm.
POM-K the thickness is 0.04 mm and the width is 3mm

  1. Melt temperature
    You can use air injection method to measure the temperature.
    POM-H   it can be set to 215 Celsius degree(190 -230 Celsius degree)POM-Kit can be set to 205 Celsius degree(190 -210 Celsius degree).
  2. Injection speed
    The common is middle speed which is a little fast, too slow speed is easy to produce corrugation, too fast speed is easy to produce ray lines and shear overheating.
  3. Packing
    It’s better to be lower for packing. Generally, it does not exceed 200bar.
  4. Dwell time
    If the device doesn’t have melt retention point,
    POM-H      In the temperature of 215 Celsius degree, the retention time is 35 minutes.
    POM-K     In the temperature of 205 Celsius degree, the retention time of 20 minutes will not have serious decomposition.

In the temperature of POM injection molding, the molt material cannot be stranded in the barrel for more than 20 minutes. POM-K can strand 7minutes in the 240 Celsius degree. If in the downtime, the temperature can decrease to 150 Celsius degree, if the downtime is for a long time, you must clean the barrel, turn off the heater.

  1. Downtime
    You must use PE or PP to clean the barrel, turn off the heater and push the screw frontier area, keep the barrel and screw clean. Impurities or dirt will change the superheating stability of POM (particularly POM-H). So after exhausting the halogen-containing polymer or another acidic polymer, you should use PE to clean up and then Play PM material, or it will cause an explosion. If you use improper pigments, lubricants or GF nylon materials, it will cause the plastic degradation.
  2. Post-processing
    For the POM products used in non-normal temperature, there are higher requirements on quality; it needs to make heat treatment.

The annealing treatment effect is checked by immersing products in a hydrochloric acid solution of concentration 30% for 30 minutes, and then uses eyes observing and determining whether there are residual stress cracks.

Application of POM injection molding parts

POM injection molding parts are used in a wide range of applications across various industries. Some of the most common applications of POM injection molding parts include:

  1. Automotive industry: POM parts are widely used in the automotive industry for applications such as fuel systems, engine components, and interior trim parts due to their high strength, stiffness, and excellent wear resistance.
  2. Electrical and electronics industry: POM parts are commonly used in the electrical and electronics industry for applications such as switches, connectors, and housing components due to their excellent dimensional stability and low friction.
  3. Consumer goods industry: POM parts are used in the manufacturing of consumer goods such as toys, sporting equipment, and household appliances due to their durability, resistance to chemicals, and ease of processing.
  4. Medical industry: POM parts are used in the medical industry for applications such as surgical instruments and medical devices due to their high strength, stiffness, and resistance to sterilization.
  5. Industrial machinery: POM parts are commonly used in industrial machinery for applications such as gears, bearings, and other components that require low friction and wear resistance.
  6. Aerospace industry: POM parts are used in the aerospace industry for applications such as fuel system components, valve seats, and hydraulic system components due to their high strength and resistance to wear and tear.

POM injection molding parts are used in applications where high strength, stiffness, wear resistance, and dimensional stability are required, making them a popular choice across a wide range of industries.

The injection molding processing technology of POM

The injection molding process parameter for POM material will depend on several factors such as the specific grade of POM, the design and geometry of the part, and the injection molding machine being used. However, here are some general guidelines for injection molding parameters for POM material:

  1. Injection temperature: The recommended injection temperature for POM material is typically between 170°C to 230°C (338°F to 446°F), depending on the grade of POM.
  2. Mold temperature: The recommended mold temperature for POM material is typically between 60°C to 100°C (140°F to 212°F), depending on the grade of POM and the complexity of the part.
  3. Injection pressure: The recommended injection pressure for POM material is typically between 60 MPa to 140 MPa (8700 psi to 20300 psi), depending on the grade of POM and the size and complexity of the part.
  4. Injection speed: The recommended injection speed for POM material is typically between 50 to 100 mm/s (1.97 to 3.94 in/s), depending on the grade of POM and the size and complexity of the part.
  5. Holding pressure and time: The recommended holding pressure for POM material is typically between 50% to 70% of the injection pressure, depending on the grade of POM and the size and complexity of the part. The recommended holding time is typically between 10 to 30 seconds.

It’s important to note that these are general guidelines, and the optimal injection molding parameters for POM material may vary depending on the specific requirements of the application and the processing conditions. Therefore, it’s important to consult with the POM material supplier and the injection molding machine manufacturer to determine the appropriate injection molding parameters for your specific application.

POM injection molding parts has been used in various of industry and has very sensitive molding process. Sincere Tech is professional in POM injection molding process, if you have a project that needs POM injection molding parts, contact us to get a price.

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Polystyrene PS Injection Molding

PS plastic molding

Polystyrene (PS, GPS) is commonly known as ordinary styrene hard plastic which is transparent and belongs to translucent plastic (with greater density than water, fragility).

The properties of PS include good optical performance 88%-92%, excellent electrical performance, easily molding and processing and good colorability. Its disadvantages include fragility, low temperature of heat-resisting, high requirements for processing and molding conditions (distinct Aging and great sensitivity to heat) weak acid resistance, easy to burn. If there is no fire source and it will burn continually with yellow color, thick black charcoal, blistering, and monosomy.

PS injection molding

Viscosity is sensitive to the velocity of shear. With the increase of pressure, melt viscosity decreases. Therefore, considering internal stress factors which are easy to produce, which means injecting into the cavity with high speed in the ideal molten state, the pressure should not be overloaded.

The processing temperature ranges from 176-260 Celsius degree and the melting point is 225 Celsius degree. Injection temperature of molding should not be too high, and the temperature of feed cylinder is distributed as low in the entrance, less high in the middle and the highest in the outlet, as well as twice high at the nozzle.

Time of mold opening can be a little early and adjust dwell time appropriately (Big gate products) as its solidification speed is faster than other plastics.

When demoulding, it should pay attention to clean the gate wire and should not drag out it in the way of mould closing by violence. For the production of usual internal stresses, it can be immersed in the sink (65-80 Celsius degree) for 1-3 hours after demoulding.

HIPS or IPS is commonly known as unbroken PVC, unbroken hard rubber or unbroken rubber.
Raw materials of MPS are not transparent, which are yellow or milky white and easy to be processed and colored. It has strong tenacity and greater impact strength of flexibility, similar to the high elastic rubber (injection pressure and molding temperature should be high).

SAN is commonly known as transparent and unbroken plastic, which has high softening temperature and shock temperature, high resistance to stress. Cracking, wear resistance, chemical stability, dry resistance, heat resistance, corrosion resistance, oil resistance are better, with stable size and easy molding.

Modified polymethyl methacrylate plastics have similar transparency with polymethyl methacrylate, good toughness and some certain impact-resistance temperature, abrasive resistance, poor chemical stability, dry resistance, heat resistance, corrosion resistance, oil resistance, stable size, and easy molding.

For the cooling rate, HIPS is slower than PS. It requires enough dwell pressure and dwell time, intensifying the heat exchange of mold and providing enough cooling condition.

 

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PET Injection Molding

PET plastic moulding

The injection techniques of poly terephthalic acid alcohol ester (PET)

The chemical name of PET is poly terephthalic acid alcohol ester, also called polyester. At present, GF-PET is used by most clients. PET injection molding parts are mostly used in the bottle preform products

PET has a good rheological property in molten condition and pressure has more effects on viscosity than temperature does. Therefore, we change the rheological property mainly from the pressure.

Plastic drying

Due to PET macromolecule contains an aliphatic base, it has certain hydrophilicity. The aggregate is very sensitive to water when it’s at a high temperature. When the water content exceeds the limit, the molecular weight of the PET will drop during the processing, so the product will be colored and become crisp. Therefore, we need to dry the material at 150 Celsius degree for more than 4 hours and 3 to 4 hours at 170 Celsius degree before processing. We can use air injection method to examine whether the material is completely dry or not. The proportion of recycled material is generally not more than 25%, and the recycled material needs to be completely dried.

Selection of injection molding machine

PET can only be stable for a short time after the melting point, and the melting point is so high, which needs to choose the injection system which has more temperature-control periods and less friction heat when plasticizing, and the product’s (the material which contains water) actual weight cannot be less than two-thirds of the amount of machine injection.

Mold and gate design

We generally use hot runner mold to design PET bottle preform. It is better to have an insulation board between mold and injection molding machine template. Insulation board’s thickness is about 12 mm, and can bear high pressure. There is enough exhausting effect for it so as not to appear local overheating or chipping, but the vent’s depth is generally not more than 0.03 mm, otherwise, it is easy to produce flashing.

Plasticizing temperature

It can be measured by the air injection method. The temperature is ranging from 270 Celsius degree to 295 Celsius degree and the enhanced GF – PET’s temperature can be set from 290 Celsius degree to 315 Celsius degree, etc.

Injection speed

Generally, injection speed must be fast, in order to prevent premature solidification. But if injecting too fast, the shear rate would be so high that the material would become fragile easily. The material injection is usually completed in 4 seconds.

Packing

In order to avoid wearing, the packing pressure shall be as low as possible. Generally, it’s not more than 100 bar. We usually don’t need to use it.

Detention time

It should avoid overlong detention time to prevent from the molecular weight declining. Try to avoid the temperature above 300 Celsius degree. If the machine stops less than 15 minutes, we only need to make air injection; If the machine stops more than 15 minutes, we should not start the machine again until we use viscosity PE to clean the machine and make the feed cylinder’s temperature drop to PE temperature.

Attentions

(1) Recycled material cannot be too much. Otherwise, it’s easy to form “bridging” at discharging chute which will influence the plasticizing.
(2) If we don’t control the mold temperature or the metal temperature properly, it’s easy to produce “white fog” and become opaque. When the mold temperature is low and even, the cooling speed shall be too fast with few crystallization and transparent products.

 

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Mold Trial Process

plastic mold technology

When a new injection mold manufacturing is completely finished, the next step is mold trial (testing), to trial the mold we need to check some important information to avoid any mistake, we need to check the plastic material, samples color, quantity samples that we should send to customer, any special tolerance if needs to be verified during the mold trial, etc, below is our mold trial procedures & processes,

Mold Trial Process

  1. Set barrel temperature according to recommendations from the material supplier. Middle of recommended in front and lower end of recommended in back, if don’t have date sheet, reference from mold flow report. Record actual melt temp with air shot method. If the customer is to attend the trial, the material data sheet should be printed and present at the machine.
  2. Set mould temperature to the middle of recommended temp span, if don’t have date sheet, reference from mold flow report. Also, make sure the actual mould temp is right during production.
  3. Set clamping force according to Moldflow report, or max clamp of customer specified machine.
  4. Set cooling time according to “time to reach ejection temperature” from Moldflow report.
  5. Set injection pressure to max. Make sure the mold is properly cleaned before injecting.
  6. Set injection speed to 50% of customer’s machine if have, otherwise, 50% of our machine, set holding speed to 5-10.
  7. Set holding pressure to 0 at first.
  8. Increase the shot size gradually until parts are ~90% full. Check cavity variation. If more than 7% cavity variation, write down in page and mark as the issue needs to improve
  9. Increase the shot size until parts are 100% full, parts can be sink but not short. If parts have flash, burns or air traps, write down in paper comment as the issue needs to fix
  10. Set shot size to 97% full, should be done including an estimated holding time.
  11. Set holding pressure to ½ the actual injection pressure.
  12. Start making gate freeze analysis and use holding time from where gate freezes.
  13. Adjust cooling time according to below plastics material.
  14. Record weight of full shots.
  15. Increase the holding pressure until part weight stops increasing.
  16. Adjust cycle time to customer target. Make sure that tool can run properly at this cycle time.
  17. Runoff samples and mark them trial number and date, this is very important information for us to find which samples are from the previous trial time, quantity according to customer requirements if parts are ok. 1 balance shot and 2-3 runners should always be sent together with the samples.

By above mold trial processes, the injection mold should be running very well at our customer’s mold shop.

If you have any more questions, you are welcome to contact us, if you have are interested in our service, you are welcome to send us your requirement for a quotation.

MATERIAL
Wall thickness ABS Nylon HDPE LDPE PP PS PVC
0,5 n/a n/a 1,8 n/a 1.8 1 n/a
0,76 1,8 2,5 3,0 2,3 3,0 1,8 2,1
1,0 2,9 3,8 4,5 3,5 4,5 2,9 3,3
1,3 4,1 5,3 6,2 4,9 6,2 4,1 4,6
1,5 5,7 7,0 8,0 6,6 8,0 5,7 6,3
1.8 7,4 8,9 10,0 8,4 10,0 7,4 8,1
2,0 9,3 11,2 12,5 10,6 12,5 9,3 10,1
2,3 11,5 13,4 14,7 12,8 14,7 11,5 12,3
2,5 13,7 15,9 17,5 15,2 17,5 13,7 14,7
3,2 20,5 23,4 25,5 22,5 25,5 20,5 21,7
3,8 28,5 32,0 34,5 30,9 34,5 28,5 30,0
4,4 38,5 42,0 45,0 40,8 45,0 38,0 39,8
5,1 49,0 53,9 57,5 52,4 57,5 49,0 51,1
5,7 61,0 66,8 71,0 65,0 71,0 61,0 63,5
6,3 75,0 80.8 85,0 79,0 85,0 75,0 77,5
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Mold Modification Process

mold modification

As a professional plastic mold company, during mold manufacturing, we normally have some requirement for mold modification, this is a very common issue when we manufacture molds for our customer, below is a step that how to handle this modification in our mod companymold modification

  1. When we receive a request for modification from our customer. After that, we analyze the requested modification, which must be done at least within the same day as the files have been received or latest the morning after if the files have been received in the afternoon. It is important to create a clear illustration of the modification (ppt file to list the modification items) for internal communication with our team and with customers. Note since that part drawing that is not approved for production so we cannot save to our database.
  2. We need to send this modification illustration to our mold shop manager, responsible Quotation Engineer.
  3. The mold production manager then checks out, at least within the same day, Together with the mold master to decide how long time that is required for the modification. We will specify one shortest possible lead-time and one maximum time required. Because sometimes the customer is very busy or maybe not so hurry.
  4. The Quotation Engineer then prepares an offer as soon as possible. This shall be done latest within the same day as he/she receives the working steps and lead-times from the mold manufacturing department. The offer should include the offered price and the minimum and maximum lead-time. Once ready with the offer the Quotation Engineer sends the offer to project manager, then the project manager directly sends to customers.
  5. Once the customer approves the concerned modification the Project manager will use the new valid part drawing is saved into our database and inform the mold design department to update the tool drawing immediately. Another thing that must be controlled by the Project manager is that the promised lead-time will be fulfilled. Send an email to production department or mold shop manager. That will make it easy for the mold shop manager to keep control of the lead-times.
  6. After the modification finished, new mold trial is needed, after mold trial and check the modification is done according to the new drawing, then send the new samples to customers, during the same time update the measurement report and send to customer as well.

Sincere Tech is a professional China plastic mold company, we offer one-stop service from part design, prototype, mold design, mold manufacture, injection molding parts, secondary process, and assembly, if you have a project that needs to help, you are welcome to contact us.

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PBT Injection molding

PBT injection moulding

Polybutylene terephthalate (PBT) has advantageous combination properties such as a convenient source of raw materials, and mature polymerization process has gotten easier, low cost and easily forming and processing. Nylon, polycarbonate (PC), polyoxymethylene and modified polyphenylene oxide are five major engineering plastics.

PBT Injection Molding (Moulding):

PBT is a kind of crystalline polymer with a sharp melting point (225-235 Celsius degree). Crystallinity can reach 40%. When the temperature rises above the melting point, the liquidity of melt will become obvious. However, when changing from the molten state to the gruel state, it not only has the fast rate of cooling rate but has a fast crystalline speed.

PBT injection moldingIn the state of melting for PBT, because of its low viscosity, perfect liquidity (inferior to the nylon) and better mold shrinkage, it needs to prevent the phenomena of edge flowing and flashing of products.

Influenced by factors of crystallinity, technology, mould, PBT has anisotropy to makes products warping and distorted during the molding process. Therefore, it should pay attention to proper process conditions and mold design.

PBT contains esters gene and it will hydrolyze under the high temperature with the presence of moisture. Therefore, before starting the processing, it has to conduct the drying process.

For PBTinjection molding parts, most gates are applicable to melt’s rapid mold filling, which just requests the bigger caliber to prevent the contraction of the melt to reduce the loss of pressing force.

In the actual operation, the temperature of PBT ranges from 240 to 260 Celsius degree.
Owning to PBT’s fast cooling speed, injection speed should be slightly faster in order to prevent short shot of the products, obvious welding, and poor surface fineness caused by premature condensation during the filling process. However, it needs to prevent inadequate air exhausting and the flashing of products.

The revolving speed of screw should be controlled to some extent to avoid friction heat impacting on the resin and screw speed generally doesn’t exceed 80r/min, mostly ranging from 25 to 60r/min. In order not to obstruct plasticizing of materials and make sure the air among particles of fabric materials can be discharged in time, during PBT’ shaping, the screw packing should be controlled at 10-15% of the injection pressure.PBT injection moulding

To get products with better performance and good fineness as well as the smaller deformation in the molding, PBT’s appropriate temperature is 70 -80 Celsius degree.

In view of PBT’s low viscosity, good fluidity, fast cooling and solidifying in the molding, most products don’t need a long molding cycle.

Sincere Tech offers PBT injection moulding & custom molds, if you are interested in our service, contact us to get price by sending us an email.

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