How to Make a Mold for Precision Plastic Parts

A precision plastic part begins with the precision mold. Building the tool takes time and a great deal of accuracy. It can also pay the largest investment in the manufacturing process, so getting it right is critical to the success of a project. If your goal is to manufacture parts with a high degree of precision in large volume, the tooling becomes even more complex.How to Make a Mold for Precision Plastic Parts?

When plastic meets the mold

The tool and the molding process are customized based on the type of plastic. Plastics that are amorphous are less free-flowing and tend to shrink less than crystalline or semi-crystalline plastics, which offer better flow, but higher shrinkage. For this reason, many projects call for engineering resins that offer a better melt and less shrinkage. Plastic suppliers provide information on the shrinkage rate of their resins along with temperature and melt flow rate recommendations.

Machining to exact standards

Resin shrinkage impacts the design and machining of the tool cavities. The cavities must accommodate for the amount of shrinkage that can occur. Using modern CAD software, the design engineer will create cavities that are larger than the actual finished part. The size of this allowance is based on the specific properties of the resin. Some of this shrinkage can be addressed by regulating the packing and holding rate in the mold, but all plastic shrinks as it cools, even after the part is ejected from the mold. Worse case, warpage can occur when a part has molded-in stress. This stress can be a result of issues with pressure, temperature, flow rate, gate location or venting.

A strong mold design leads to high-volume quality

Precision plastic parts can only be accomplished by meeting exacting standards not only in the cavities, but in the design of the mold components. Gates must be properly placed to allow for proper melt flow and pressure. The appearance of the final part can be improved by positioning the gates in an inconspicuous location on the part. The size of the gate is also an important consideration. The gate must be large enough to provide for proper packing of the material without extending the cycle time. If the gate is too small the packing may be insufficient to fill the cavity (also called a short shot) or the part may display other defects.

The design of the mold must also include vents. Vents allow the air that is displaced by the melted resin to escape the tool. As with gating, the size and position of the vents are key factors in producing a quality part. Vents that are too large can allow the plastic material to escape and cause flashing. Vents that are too small may not release enough of the trapped air and gas. These gas bubbles can cause an improper fill (short shot) or worse. The gas could combust and cause burn marks on the part

Proper cooling is key

An efficient and effective cooling system is the hallmark of a quality plastic injection mold. The mold needs to maintain a consistent temperature to avoid shrinkage and warping while minimizing the cycle times to maximize production output. This delicate balance is achieved with a well-designed cooling system.

Ejecting parts

Standard Caps,Plugs,Fasteners

The final step in the molding process is releasing or ejecting the parts from the mold. The part geometry, type of resin, and mold finish are all considered when designing the ejector system. The placement of the ejector pins, the type of ejection mechanism and the cycle times need to be calculated with precision to avoid any defects in the part. This is generally accomplished with a series of carefully placed ejector pins, the size and position of which are determined by the shape, size and wall thickness of the part.

Running samples improves quality

Before start up of mass production, the manufacturer would do some sample runs to test the mould performance, it was named mould trial. Avoiding any unnecessary rework. Experienced molders create a sample mold that is used to produce a test run of the part. This step is vital in determining if any adjustments to the mold, the resin selection, or molding parameters such as temperature and flow rate are needed. If there are any quality issues, the project team will work together to determine the cause and re-sample the parts until they meet the customer’s and the molder’s standards.

Jingwei industry has served the injection molding industry for over 20 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing.To know more on Build a Precision Mold for Perfect Parts,Please visit us at :jweimolding.com  or send mail to info@jweimolding.com

Plastic Injection Molding for Automotive Industry

Over the years, Jingwei industry have supplied a wide range of projects within the automotive industry, varying from components to panels.Automotive parts plastic molding need to fully consider the following factors in the design, material dry processing, glass fiber reinforced material to the new requirement of the screw, the drive form and structure, etc.

First, plastic automobile parts like bumper, instrument panel and other commonly used resin materials such as modified PP and modified ABS, modified resin, resin materials have different moisture absorption, to meet the requirements of formed when water content (generally <0.2%), plastic resin raw materials in advance into the injection molding machine screw before measurement, should be treated with hot air drying or dehumidification drying.

Second, the current domestic automotive plastic parts basically for glass fiber reinforced plastic products, and compared with chopped glass fiber reinforced resin, forming of glass fiber reinforced plastic injection molding machine used the material of the screw and the structure is quite different.Injection molding machine, when the design should pay attention to the screw cylinder of alloy materials and special heat treatment process, ensure that its corrosion resistance and strength.

Third, as a result of plastic auto molding parts is different from conventional products, it has a very complicated cavity surface, stress, stress distribution, the processing capacity needed for the key consideration in the design of it.Injection molding processing capacity in mould clamping force and injection capacity most injection volume of the two aspects.When molding products in injection molding machine, clamping force must be greater than the mould opening force produced by mold cavity pressure, or the mold parting surface will be separated from material overflow.

Fourth, based on the characteristics and complex plastic automotive spare parts for injection molding machine driving form and die structure design, domestic currently used for the hydraulic mechanical or hydraulic type hydraulic bent elbow, or the direct pressure clamping mechanism to the center of injection molding machine.

Fifth, because the cavity surface of plastic automobile molding product is very complex, injection molding machine should consider its particularity, in the design of configuration function of some special programs: such as multiple sets of core-pulling, sequential control, injection molding machine supporting device of the mould function, supporting function take manipulator device, etc.These special features has obvious advantages in the production of automotive plastic parts.

Jingwei industry has served the injection molding industry for over 20 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing.To know more on Automotive parts plastic molding. visit us at :jweimolding.com Or get a quote for your project.

The Meaning of Cavity Pressure Sensors in Custom Plastic Injection Molding

What is the meaning of pressure measurement in Custom Plastic Injection Molding?

Cavity pressure sensors are valuable tools in the plastic injection molding process to maximize productivity and minimize the number of defective parts making it through production and into the "good part" box. With accompanying integrated software, these sensors can detect abnormal conditions and, depending on the type of trouble and software settings, shut down a machine until the fault is corrected, reroute suspect parts for further inspection during the sorting process or reject parts outright.

Cavity pressure sensors are especially valuable if you are engaged in high-volume production of custom precision plastic injection molding, such as parts for body building equipment,medical devices, electronics or the automotive industry. You can employ these sensors to monitor not only cavity pressure but also internal temperature and many other factors to help you on your way to zero defects.

Cavity pressure sensors enable the skilled molder to spot Graph Showing Monitoring common faults such as shrink,short shots, flash, sinks and voids, dimensional problems, and warp. You can even detect cosmetic problems like gloss gradient. In addition to pressure and temperature, pressure sensor systems note other variations, such as in packing, cooling rate and cooling time. All of this is monitored through software output of variations in pressure during injection, packing, compression and cooling — yielding a visual, real-time cavity pressure curve on the equipment's monitor.

Why do you  put the sensor in the mold?

Typical defects in plastic injection molding production that are detected by pressure sensors include:

• Shrink.
• Short shot, the absence of plastic in a portion of the part, results when no pressure developed in the cavity's unfilled section
• Flash, essentially the opposite of a short shot, occurs when excess pressure forces a mold to spread enough to allow plastic to spill though the cavity parting line; this not only produces a defective part, it can lead to parts sticking to and damaging the mold.
• Sinks and voids, result from under packing the cavity and/or the lack of a gate seal, which would be detected as a change in cavity pressure.
• Dimensional variations, occur when a packed mold is fully compressed and cavity pressure changes at a critical dimensional point
• Warp, random distortion of a part, often results from variations in packing, cooling rate and cooling time; detected through the pressure curve.
• Gloss gradient, variations in gloss from the gate area toward the end of the cavity, may be related to the rate of packing; this would show up in the shape of the pressure curve.

For further information on the benefits of cavity pressure sensors for plastic injection molding, contact an experienced supplier of custom plastic injection molding,Jingwei industry via info@jweimolding.com.

Intro of Custom Plastic Injection Molding

Plastic Injection molding includes producing parts by injecting material and then getting into a mould. This can be performed with the use of many plastic materials like polypropylene, polyurethane and PVC etc. For this process the material is first heated, mixed properly and then cooled and moulded and configured as required as a cavity. Custom Plastic Injection Molding is basically a process of creating plastic parts by injecting the heated material into some or the other specific required molds.

Product visibility and identification is very important when it comes to conveying the brand in the market. Plastic nameplates are thus used for this purpose to convey descriptions, warnings, brand and other types of information. There comes the need of plastic injection molding. Thus, there are so many advantages of using any kind of custom plastic injection molding. All of such plastic injection moulding helps one manufacture intricate and complex shapes as per the requirement of the customer.

Advantages of Custom Plastic Injection Molding:

This process manufactures individual custom designed plastic parts
Fully automation is allowed in this machine and incredibly produces the products really fast
Injection molding is done effectively and accurately.Accuracy is the biggest advantage of injection molding
With the help of the machine and some efforts you can even get the color of the product changed
Gives a very smooth finishing at the end of the process
Most of the waste gets grinded up and re-used, so reduces waste too

Disadvantage of Custom Plastic Injection Molding:

The one and foremost drawback of this molding is that it includes high initial investment as it requires the installation of the tools and the molding machines.This process of Custom Plastic Injection Molding is mainly used only while producing high volumes of a single object.

Jingwei industry has served the injection molding industry for over 20 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing.To know more on Custom Plastic Injection Molding visit us at :jweimolding.com

13 High-Performance Plastics Used in the Auto Spare Parts Manufacturing

Jingwei industry has served the plastic injection molding industry for over 20 years and has a team dedicated to providing you with the most cost effective solutions for Auto Spare Parts design and manufacturing.

High performance plastics are playing an important role in the automotive industry these days. The light weight of plastics makes for more fuel efficient vehicles. It is estimated that every 10% reduction in vehicle weight results in a 5% to 7% reduction in fuel usage. Current economic and environmental concerns make the creation of more fuel efficient cars a top priority in the automotive industry. Some other advantages of high performance plastics used in transport vehicles include minimal corrosion, allowing for longer vehicle life substantial design freedom, allowing advanced creativity and innovation flexibility in integrating components safety, comfort and economy recyclability.
Here are the top 13 high performance plastics used in automotive hardware. While all 13 may easily be used in a single vehicle, just three types of plastic make up approximately 65% of the total high performance plastics used in a car: polypropylene (32%), polyurethane (17%) and PVC (16%).
1) Acrylonitrile styrene acrylate (ASA)
Similar to ABS, ASA has great toughness and rigidity, good chemical resistance and thermal stability, outstanding resistance to weather, aging and yellowing, and high gloss. Be careful not to burn this material. It will cause a toxic smoke.
Application: housings, profiles, interior parts and outdoor applications.
2) Acrylonitrile Butadiene Styrene(ABS)
Acrylonitrile Butadiene Styrene is a copolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The styrene gives the plastic a shiny, impervious surface. The butadiene, a rubbery substance, provides resilience even at low temperatures. A variety of modifications can be made to improve impact resistance, toughness, and heat resistance.
Application: automotive body parts, dashboards, wheel covers.
3) Poly-Vinyl-Chloride (PVC)
PVC has good flexibility, is flame retardant, and has good thermal stability, a high gloss, and low (to no) lead content. Polyvinyl chloride molding compounds can be extruded, injection molded, compression molded, calendered, and blow molded to form a huge variety of products, either rigid or flexible depending on the amount and type of plasticizers used.
Application: automobile instruments panels, sheathing of electrical cables, pipes, doors.
4) Polypropylene (PP)Polypropylene is a thermoplastic polymer used in a wide variety of applications. A saturated addition polymer made from the monomer propylene, it is rugged and unusually resistant to many chemical solvents, bases and acids.
Application: automotive bumpers, chemical tanks, cable insulation, gas cans, carpet fibers.
5)Polyurethane (PUR)Solid Polyurethane is an elastomeric material of exceptional physical properties including toughness, flexibility, and resistance to abrasion and temperature. Polyurethane has a broad hardness range, from eraser soft to bowling ball hard. Other polyurethane characteristics include extremely high flex-life, high load-bearing capacity and outstanding resistance to weather, ozone, radiation, oil, gasoline and most solvents.
Application: flexible foam seating, foam insulation panels, elastomeric wheels and tires, automotive suspension bushings, cushions, electrical potting compounds, hard plastic parts.
6) Polystyrene (PS)
Naturally clear, polystyrene exhibits excellent chemical and electrical resistance. Special high gloss and high impact grades are widely available. This easy to manufacture plastic has poor resistance to UV light.
Application: equipment housings, buttons, car fittings, display bases.
7) Polyethylene (PE)
Polyethylene has high impact resistant, low density, and exhibits good toughness. It can be used in a wide variety of thermoplastics processing methods and is particularly useful where moisture resistance and low cost are required.
Application: car bodies (glass reinforced), electrical insulation.
8) polyoxymethylene (POM)
POM has excellent stiffness, rigidity, and yield strength. These properties are stable in low temperatures. POM also is highly chemical and fuel resistant.
Application: interior and exterior trims, fuel systems, small gears.
9) Polycarbonate (PC)
high performance plasticsAmorphous polycarbonate polymer offers a unique combination of stiffness, hardness and toughness. It exhibits excellent weathering, creep, impact, optical, electrical and thermal properties. Because of its extraordinary impact strength, it is the material for car bumpers, helmets of all kinds and bullet-proof glass substitutes.
Application: bumpers, headlamp lenses.
10) Acrylic (PMMA)
A transparent thermoplastic, PMMA is often used as a lightweight or shatter-resistant alternative to glass. It’s cheaper than PC but is also more prone to scratching and shattering.
Application: windows, displays, screens.
11) Polybutylene terephthalate (PBT)
The thermoplastic PBT is used as an insulator in the electrical and electronics industries. It is highly chemical and heat resistant. Flame-retardant grades are available.
Application: door handles, bumpers, carburetor components.
12) Polyethylene Teraphthalate (PET)
PET is mostly used to create synthetic fibers and plastic bottles. You may recognize it on clothing labels under the name “polyester.”
Application: wiper arm and gear housings, headlamp retainer, engine cover, connector housings.
13) Polyamide (PA, Nylon 6/6, Nylon 6)Nylon 6/6 is a general-purpose nylon that can be both molded and extruded. Nylon 6/6 has good mechanical properties and wear resistance. It is frequently used when a low cost, high mechanical strength, rigid and stable material is required. Nylon is highly water absorbent and will swell in watery environments.
Application: gears, bushes, cams, bearings, weather proof coatings.

If you are looking for a reliable source for auto spare parts ,and need a professional custom plastic injection mould company .Contact us via info@jweimolding.com.

Why should you choose the plastic parts manufacturer in China?

In recent years, we heard more and more reports about manufacturing industry moving out from China. Compare with 2014, the total amount of Chinese export fell by 7%, however, the export of plastic part increased by 3.1%. The data shows that even though some manufacturers are leaving China, but more buyers still choose to purchase plastic parts from China. Why the plastic manufacturing in China is still attracting?

Integrated Supply Chain

Nowadays, no factory can manufacture a product without purchasing any items from other suppliers. Take us(Jingwei industry) as an example, we are able to make moulds and process of injection molding, but we have to buy raw material, some standard mould components, kinds of oil for mechanical uses, knife tools etc.. All these suppliers constitute the supply chain. After 30 years development, China has not only the strong industry foundation, but also the integrated supply china. That’s why the product made in China is high quality with competitive price.

Most Hard-working Workers

It is no doubt that Chinese is the most hard working people in the world. Most of Chinese manufacturing workers have to work 12 hours per day and 6 days per week. The workers from the so called low human labor countries don’t like to work overtime. The common situation happened in southeast countries is that the workers disappeared after receiving the payment. Chinese workers only complain the overtime hours are too few to get more reward.

Upgrading Technology and Equipment

Chinese manufacturers are upgrading their technologies and equipments. Several years ago, many factory made the mould by turning and milling machines. Now, almost every mould maker even the small factory is utilizing the CNC milling machine and EDM. Mold flow analysis is widely used now. There upgradings help the Chinese manufacturers reach the higher quality requirement like the precision and stability.

Low Wage of Engineer

The wage of engineers in China is still lower than the averaged wage in the world. Still, China has the largest number of engineers. That’s why apple inc choose the China manufacturers to fabricate its electronic products.

Above all, if you want to get a product with high quality and cheap price, Made in China is still the first choice.Contact an experienced Chinese plastic injection molding company, Jingwei industry via info@jweimolding.com

Advantages and Disadvantages of Hot Runner Mold

A hot runner system is an assembly of heated components used in plastic injection molds that inject molten plastic into the cavities of the mold. The runner is hot to maitain the plastic material molten. The molten plastic is injected into the hot runner and flow from the heated manifold into the cavity through the heated nozzles. Here we list some advantages and disadvantages of hot runner mould compare with cold runner system.

Advantages

Shorter cycle time

The plastic flows faster than the cold runner, and it has no need to wait the cooling of the runner section. The part can be ejected when solidified. The part with thin wall thickness can have the circle time less than five seconds.

Saving cost

In cold runner mould, the solidified runner section is ejected out together with the part. It wastes the raw plastic material. Hot runner system can help to save the cost of this section. If the plastic is expensive, the economic effect is not small.

Higher quality

The heat can be controlled uniformly in the runner, molten plastic flow into the cavity symmetrically. The finished part has better comestic finish, less sink marks and less warpage.

Advanced technology

Many advanced technologies are developed based on hot runner system, like the PET pre-formed precess, multi-color shot, multi-material shot and stack mould.

Other benefits of hot runners:

• hot runners available for both single cavity and multi cavity moulds
• can be used with most plastic materials and part designs
• are easy to maintain
• reduce the number of moving plates in a mold
• gives good gate vestige
• can use with close pitch mold designs

Disadvantages

Higher tooling cost

The components of hot runner are much more expensive than cold runner. It may be not economic when quantity is not large.

Difficult maching processes

Hot runner system require high accuracy of tooling components. Most of the tooling parts have to be machines precisionly.

Complicated operation and repairment

Compare with the cold runner mould, hot runner is hard to operate and repaire. It is easy for the new users to break the mould due to the incorrect operation.

Contact an experienced Chinese plastic injection molding company, Jingwei industry via info@jweimolding.com

What is parting line in mould?

Parting line is a inevitable defect for the plastic injection molded part. It happened on the surface where the moving halve and the fixed halve meets and formed an edge like circle around the surface. When the mold is closed and the molten plastic gradually fills the cavity, high pressure inside the mold will push the molten flow occupy every space in the mold core and leave the circular mark around the parting surface.A number of considerations go into the placement of the parting line, with the goal of maintaining the overall integrity of the piece. Typically, as part of the finishing process, machinery will grind and smooth the parting line so it is no longer visible, if any extra material leaked into the space when the object was cast.

The product designer should fully communicated with the mold engineer to check the location of the parting line. For the mold designers, the parting surface should not be on the cosmetic side. Also, the precessing should be properly adjusted.
Contact an experienced Chinese plastic injection molding company, Jingwei industry via info@jweimolding.com